E4407B Tracking Generator Repair - Page 1
Forum section: electronics / repair

author: smgvbest
author_rank: Unknown
timestamp: September 24, 2020, 12:56:44 am
content: I installed a tracking generator I got off ebay into my repaired E4407B and after making the LO and 600Mhz Reference Cables fire it up and found it does have an issue.When it fire up and enabled the TG I received a Source TG Unlevel, i double checked my cabled and snugged up the LO cable at the LOIS side and the Source TG Unlevel went away and was replaced with a Source Unlevel. Doing some checking at 0.5DdB intervals I checked from 4dB to -66dB and got the table below.Interesting that at a fairly regular interval it goes from Source Unlevel to No Error (Pass in the table)Code:StartEndRangeStatus3.0-6.5-9.5Source Unlevel-7.0-9.5-2.5Pass-10.0-14.5-4.5Source Unlevel-15.0-17.5-2.5Pass-18.0-22.0-4.0Source Unlevel-22.5-25.5-3.0Pass-26.0-29.5-3.5Source Unlevel-30.0-33.5-3.5Pass-34.0-37.5-3.5Source Unlevel-38.0-41.5-3.5Pass-42.0-45.5-3.5Source Unlevel-46.0-49.5-3.5Pass-50.0-53.5-3.5Source Unlevel-54.0-57.5-3.5Pass-58.0-61.0-3.0Source Unlevel-61.5-66.0-4.5PassAt the suggestion of Jürgen over on the HP-Agilent-Keysight group.io group I disconnected the RF out to the attenuator and ran same test. I got same resultthe idea being is the issue with the LO on the control board or in the BITG which is not documented.So I'm going to basics and starting with a visual inspection then checking the LO Path on the control board.So what follows is a boat load of images of the control board. after those images I will continue posting on testing

author: smgvbest
author_rank: Unknown
timestamp: September 24, 2020, 01:01:02 am
content: This is the top side of the control board E4403-60004

author: smgvbest
author_rank: Unknown
timestamp: September 24, 2020, 01:03:02 am
content: rest of top board

author: smgvbest
author_rank: Unknown
timestamp: September 24, 2020, 01:04:34 am
content: Board side of Control Board

author: smgvbest
author_rank: Unknown
timestamp: September 24, 2020, 01:06:30 am
content: Close up of the LO Amps and Pin Modulator sections

author: smgvbest
author_rank: Unknown
timestamp: September 24, 2020, 01:09:05 am
content: here's the Attenuator/cables and exterior of the BITG

author: smgvbest
author_rank: Unknown
timestamp: September 24, 2020, 01:13:26 am
content: so after getting all those images (yes from the phone not a real camera)I checked all the FETS and PIN Diodes using the diode test feature of the DMMattached at the relavant reading on the schematic sheetsAll the FETS should be a ATF-13484, the marking though are a mix of F25 and 101 on themit looks like Q12, Q13,Q11,Q10 and Q9 may have been replaced which are all labled F25.the one that stood out to me is Q15 though.the other ones marked 101 has reading of 0.465/1.329vdc where as Q15 read .549/2.497vdc. the question is, is Q15 the odd ball or is it Q14/Q16That's where I am at this pointAny one with suggestions or feedback I welcome the input

author: smgvbest
author_rank: Unknown
timestamp: September 24, 2020, 02:03:25 pm
content: Continuing the teardown aspect of the Tracking Generator, next is the A2A2 BITG module. This is the black box. it's not documented in the CLIP

author: smgvbest
author_rank: Unknown
timestamp: September 24, 2020, 03:12:10 pm
content: These pics are more for inspection of certain points on same board

author: analogRF
author_rank: Super Contributor
timestamp: September 24, 2020, 03:23:06 pm
content: maybe I missed something but why dont you just simply start by checking the levels at the major LO connections? I mean the LO in/out levels at the control board and the LO in at the TG module (which is the same as LO out from control board)? just vary the center frequency at zero spanand vary the TG amplitude and monitor the LO levels at these 2 points (one at a time) it should be fairly easy to rule out one of the modulessince the error occurs at some intervals , it seems to me the problem could be eitheran electronic attenuator somewhereORan electronic RF switch which changes the signal path depending on the level requested(more likely in my opinion). I think I saw a couple of them in one of the pictures. I need to look again. But the circuits are very simple and easy to diagnose. there is no need for schematics

author: smgvbest
author_rank: Unknown
timestamp: September 24, 2020, 03:32:58 pm
content: Here's the PICs of control board for the BITG

author: smgvbest
author_rank: Unknown
timestamp: September 24, 2020, 03:36:28 pm
content: and last two

author: analogRF
author_rank: Super Contributor
timestamp: September 24, 2020, 03:38:01 pm
content: there doesn't seem to be any RF switches or electronic attenuators at first glance. I may have missed something though...but clearly you have several Minicircuits MCL29 gain blocks and HMC311 Hittite/analog device/ gain blocks and I would suspect them. You can start by checking their supply voltages based on their datasheets. if you can make an extension ribbon cable and bring the board out then it would be fairly easy to probe even with a home made 500Ohm RF probe and a spectrum analyzer or power meter at least.

author: smgvbest
author_rank: Unknown
timestamp: September 24, 2020, 03:46:17 pm
content: Quote from: analogRF on September 24, 2020, 03:23:06 pmHi,So a few thing on that. the only SA I have that can look at the LO is the E4407B. when you enable the TG it turns on the LO to the TG and your range is reduced to 0-3Ghz. if you go outside the 3Ghz range which you need to for the LO (starts around 3.9 Ghz if I recall) the TG LO is turned out so you can't view it on the SA itself.Second item is there are 2 errors associated with the TGSource LO Unlevel (whcih I am not getting) and points to the LO being a problem on the Control Board.Source Unlevel (which I am getting) points to a problem on the A2A2 (BITG) board.I've disconnected and terminate the LO coming from the control board and still get same errors.The only reason to check those FETS and PIN diodes was because at least a few of the FETS had been replaced and that's me doing my due diligence it looking at themthe good thing with the BITG is it sits high enough that if I leave the shield off I can likely probe the board.I've spent most my time right now documenting these board as there's nothing out there on the TG.Now that I have its time for troubleshooting.I welcome any advice I can get here. RF is not my specialty by any means. I think I see the signalpath (not trying to steal their name or anything) so there's not many places I can see it could go bad on the BITG

author: analogRF
author_rank: Super Contributor
timestamp: September 24, 2020, 04:38:41 pm
content: some thoughts...

author: analogRF
author_rank: Super Contributor
timestamp: September 24, 2020, 06:01:27 pm
content: Quote from: smgvbest on September 24, 2020, 03:46:17 pmso clearly the problem is only inside the A2A2 and in that module the entire section behind the RF output (marked by yellow color below) is 0-3GHz and you should be able to probe it. The level problem is more than likely happening in this section and not in other sections (there are scenarios that it can be traced to other sections but the most likely cause of unlevel issue must be the section I have highlighted with yellow color here)there are only two RF gain blocks (check their supply first) and if they are ok the only problem is the IGG hybrid which does the level detectionand RPPif someone applied RF power or DC to the tracking gen, the IGG5 is gonejust to make sure, you can also check the AD620 opamp that is most likely connected to the IGG5 and completes the level detection and probably generates the error signal based on some reference value.

author: suj
author_rank: Regular Contributor
timestamp: September 24, 2020, 06:13:24 pm
content: Maybe try to set the TG frequency quite low and try to check the level with an oscilloscope? In this case, I prefer the 3 GHz HP 85024A probe, but I have other SA's at my disposal. Maybe diode detector with additional resistor at the input??

author: smgvbest
author_rank: Unknown
timestamp: September 24, 2020, 08:27:35 pm
content: Quote from: analogRF on September 24, 2020, 06:01:27 pmThank you for the analysis. that's very helpfull.I've been collecting datasheets so here they are for referencemy thought was with HMC346, the variable attenuator.The area you mention is much easier to probe though. my other sa's go to 1.5Ghz (Rigol) and 2.7 Ghz(Agilent Base Station)

author: analogRF
author_rank: Super Contributor
timestamp: September 24, 2020, 08:36:29 pm
content: I would start by checking the output section. any unlevel issue most likely happens in there (+ probably the opamp on the upper right of the IGG5)if that section is fine, then we can think of other scenarios.1.5GHz SA is fine. I believe your unlevel errors happen at any frequency, right? or do they happen at certain frequencies?!if they happen at certain frequency ranges, then perhaps that HMC346 is a better place to start. But I thought your errors were happening at all frequencies

author: analogRF
author_rank: Super Contributor
timestamp: September 24, 2020, 09:08:41 pm
content: not sure if the golden mixer is HMC129. The packaging does not match. still it could be an old version of hmc129 with different specs...another peculiarity here is that MNA6 (bottom right) is specified as 0.5-2.5GHz amplifier. So the signal in that path cannot be 3.92GHz as we expect.I am thinking maybe that path is 1.96GHz and the golden mixer H129, actually does a harmonic mixing (mixing with the second harmonic of 1.96) ?I wish you could do some tests and verify what frequency is there..

author: analogRF
author_rank: Super Contributor
timestamp: September 24, 2020, 09:36:00 pm
content: Quote from: analogRF on September 24, 2020, 09:08:41 pmor maybe the signal is 1.96GHz at the MNA6 amplifier but then they multiply it by 2 using something similar to a diode at the bottom edge of the PCB right before the bandpass filter. So after that the BPF, filters in the 3.92GHz. This looks more plausible....that BPF must be very sharp with such widely spaced resonators.

author: smgvbest
author_rank: Unknown
timestamp: September 25, 2020, 02:15:36 am
content: Quote from: analogRF on September 24, 2020, 09:08:41 pmWhat specifically would help the most to test? I will work on doing that.It is a 600Mhz in to this unit in the upper right.the section you mark oscill? freq? there are 3 pins this coming from the other side of the board as seen in the attached imagethe other image is of the signals on the 10pin header input coming from the control board. ALC_MON goes back to a OPAMP on the control boardALC_EXT is suppose to be on same page but I cant' locate it.

author: analogRF
author_rank: Super Contributor
timestamp: September 25, 2020, 03:05:40 am
content: Quote from: smgvbest on September 25, 2020, 02:15:36 amwhat pins are coming out of that area? can you mark them? do they connect to the other board?w.r.t. tests, as I mentioned, i would start by just looking at the yellow marked area with an RF probe (even a home made 450ohm series resistor with RG316 cable. you can use two back to back female sma-to-board connectors and solder the SMD resistor between the center pins of the two and solder the surrounding pins together to make a cage around the resistor and then insert a pin inside the center and solder a solid wire to the body as ground pin. The other side is connected to your measuring device with standard RG316 SMA cable. I'll post a picture of mine tomorrow. It has worked for me flawlessly up to 7GHz before)or if you can even check at low frequencies by an oscilloscope. Check to see if you have a good signal at the input to the IGG5 hybrid or not when the error occurs. and if not, work your way back to the two amplifiers. Check their supply voltage (seems to me it should be 12V by the value of series resistor they used for biasing)one thing that is important is to see if your unlevel errors happen at all frequencies or only at certain ranges. because that makes a big difference in strategy

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: September 25, 2020, 03:57:16 am
content: Hi,I don't know what documents you have. I found this one:https://www.testworld.com/wp-content/uploads/service-guide-agilent-e4402b-e4404b-e4405b-e4407b-e4411b-e4403b-e4408b.pdfIn this document there is this block diagram for the tracking generator:This is very useful. It shows that the course steps 8 dB steps are set by A2A3.The LO oscillator is levelled by the A2A1 to +16dBThe fine control of the TG output level comes from modulating the level of the 600MHz A2A2J5 -11.5dBm to -4dBmI don't know what instruments you have to confirm the signal levels.But I suggest setting the SA to a low frequency say 10MHz and zero span. This will cause the TG output frequency to be fixed and easy to measure with a scope. Terminate in 50.You could measure the output at A2A2J2. As you change the TG output level the signal should change in amplitude by 8dB (2.5x) and then go back to times 1.Once you have measured the output of A2A2J2 you can reconnect the A2A3 attenuator and measure the output again. This will confirm the attenuator is working. It seems be doing the 8dB steps, but it may have a high insertion loss.After this it is measuring the A2A1J1 which is the LO drive at 3.9 to 6.9 GHz and 16dBm. This is going to be hard without another SA or a power meter.You should also measure the signal level on the 600 MHz signal at A2A2J5.If you don't have a suitable instrument, consider a power detector demo board.Regards,Jay_Diddy_B

author: smgvbest
author_rank: Unknown
timestamp: September 25, 2020, 10:49:03 am
content: Probably I should say I have the following equipment (test probes are where I am short) and limitationsMy lab is not accessible at the moment so I'm not near the equipment, I am pulling things out as I need them*Oscilloscope Rigol 100MhzSA *Rigol 815TG ((1.5 and most accessible) and Agilent E7495A (2.7Ghz)*Tekbox Probes (near/far field)2.5 Ghz Active Probe (untested, got off ebay)*U2001H (USB 6GHZ)HP E4418B w/ E4412*Nano VNAThose I starred are easy to access and move to the E4407/TG for testingNote: I did Terminate A2A2J2 with 50ohm and checked attenuator settings and had same "Source Unlevel" message, if it helps but seeing as it's measured before the A2A3 that may be expected?it sounds like plan is1. I need to re-assemble the TG and verify if "Source Unlevel" is at all frequency's (initial test was at 3Mhz-3Ghz) or some as well as the attenuator values2. check 600Mhz in to TG at A2A2J5 (note SMB not SMA)3. Check RF out at A2A1J1 (zero span and set based on finding in #1)4. Make @analogRF RF Probe.5. figure out how to measure Yellow section, will likely have to make or find some extender cables to be able to access the board without the shielding on. shouldnt' be hard. just need to do itthere's more I'm sure but a start@analogRFA2A1P1 to A2A2J1 Cable sends back ALC_MON to the A2A1 Driver boardI have both the service guide and CLIP but CLIP only shows the A2A1 board,Attached is where I mention the ALC_MON from the A2A2 board is feed back to the A2A1 board and into OP AMP to create the Unlevel Signal

author: smgvbest
author_rank: Unknown
timestamp: September 25, 2020, 01:56:14 pm
content: I put the TG back together and hooked it back up. Setup for zero span starting at 10Mhz @ -10dB, enable the TG and all was good. went up to about 1.5Ghz in 100Mhz steps and at 1.5Ghz it went unlevel.I attached the U2000H to it and the actual reading at close, not perfect but close. the U2000H is way over due for a CAL. (see attached images)so yes, TG goes unlevel initially only above 1.5Ghz but longer it is on the frequency keeps getting lower. it's now unlevel at 1.29Ghz.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: September 25, 2020, 02:13:36 pm
content: Hi,The U2000H Power meter will be very useful when tracking this problem down.The output amplitude of the TG is proportional to the product of the signal levels at A and B.The signal level at A should be fixed at +16dBm.The signal level at B should vary depending on the setting of the TG output level. It is the 'fine' control. The coarse steps come from the step attenuator.Can you use the U2000H and measure the signal levels at A and B?Jay_Diddy_B

author: analogRF
author_rank: Super Contributor
timestamp: September 25, 2020, 02:41:55 pm
content: Quote from: Jay_Diddy_B on September 25, 2020, 02:13:36 pmlooking at the circuit, I don't think the final amplitude is controlled by the amplitude of 600MHz. Rather I think it is controlled by the Hittite variable attenuator just before the main mixer. The 600MHz goes to a mixer directly and then through quite a bit of processing including what I think is a frequency doubler and then reaches the variable attenuator just before the mixer. Maybe -4.5 to -11dBm only indicates the acceptable range for 600MHz? or could it be that both the 600MHz amplitude and the Hittite chip together control the RF amplitude?What I still dont quite get is that what they are mixing with the 600MHz? It looks like a free running oscillator!? with no locking?!They need to create a 3.92GHz out of the 600MHz but it should be a very stable and locked signal...i cannot see how it is....

author: analogRF
author_rank: Super Contributor
timestamp: September 25, 2020, 03:15:21 pm
content: I just traced back the 600MHz from A8A1A1 and as I expected there is no amplitude control/variability on this signal. -4 to -11dBm probably shows the acceptable range. Actually on the schematic where the 600MHz to BITG is generated only says -7dBmThe fine tune is done by the Hittite variable attenuator as explained before.still I dont know what kind of signal they are mixing with the 600MHz and if it is not a locked signal then it makes little sense... so I may be still missing something in that regard

author: analogRF
author_rank: Super Contributor
timestamp: September 25, 2020, 03:29:09 pm
content: Quote from: smgvbest on September 25, 2020, 01:56:14 pmmmm...so the unlevel is frequency dependent AND perhaps temperature dependent??since it looks like having to do with temperature as well, see if you can locate any overheated component on the BITG boardand also check the supply voltages on that board maybe...still my main suspicion is the output section of BITG including and specially that IGG5 hybrid. However, it would be helpful if youcould check the LO input and 600MHz input to the BITG at a frequency that level fails (zero span) just to make sure those inputs are ok although most probably they are. power meter should be enough to do this.

author: smgvbest
author_rank: Unknown
timestamp: September 25, 2020, 04:05:26 pm
content: Quote from: analogRF on September 25, 2020, 02:41:55 pmOn the other side of the A2A2 board is a component marked 40 / 0410-2110 / 9251 is 0410-2110 a freq range?see picswould the 600Mhz mix with that, then later mix with the LOThere is a TUNE signal coming in on J1 from the control board

author: suj
author_rank: Regular Contributor
timestamp: September 25, 2020, 10:08:24 pm
content: Quote from: smgvbest on September 25, 2020, 04:05:26 pmMaybe it's a heated quartz resonator? Or another type of oscillator. Maybe the mixer mixes the 6th harmonic of the 600 MHz signal with the signal of this oscillator? Then strong filtering. In my opinion this part of the system must provide a signal with a constant frequency of approximately 3.92 GHz. The 6th harmonic of 600 MHz is 3.6 GHz. 320 MHz is missing to 3.92 GHz. A lot for a quartz resonator ...See the service manual for the 1.5 GHz tracking generator block diagram. Some 800 MHz oscillator is used there. Maybe it's something similar?EDIT.It's a bit of a mystery to me. The mixer is up to 1 GHz. I can't see the PLL closing anywhere. The 600 MHz signal is synthesized, but for this oscillator (if it's an oscillator) I don't see dividers or phase detector.

author: smgvbest
author_rank: Unknown
timestamp: September 25, 2020, 10:26:33 pm
content: Something though is getting a tuning signal from the A2A1 board as well as osc-pwr. So there is a oscillator there somewhere and it gets tunedI’m going to have to get a SMB connector as well as 10 pin extension cables made up before I can do some measurements. The boards fir the A2A2 are stacked tightly. I do have one of the thermo cams for my iPhone but need to see the components.

author: KE5FX
author_rank: Super Contributor
timestamp: September 25, 2020, 11:26:48 pm
content: That looks like a big inductor, usually something you'd see in an HP switching supply. 0410-2110 is the HP part #. Odd that it has polarity markings, though.

author: smgvbest
author_rank: Unknown
timestamp: September 25, 2020, 11:35:31 pm
content: And it’s got 3 terminals

author: analogRF
author_rank: Super Contributor
timestamp: September 26, 2020, 12:47:36 am
content: Quote from: KE5FX on September 25, 2020, 11:26:48 pmthat's why it is not an inductor. and it has 4 terminals by the way not three, two of them go to ground.it should be easy to trace the pins and see where they are connected to and where the supply lines are

author: smgvbest
author_rank: Unknown
timestamp: September 26, 2020, 12:56:06 am
content: Oh. I missed that center one. Thanks for pointing that out

author: suj
author_rank: Regular Contributor
timestamp: September 26, 2020, 01:05:25 am
content: The element marked LF3 is probably 850 MHz LPF from Mini-Circuits (LFTC-850). One of the possibilities is then to multiplicate x6 frequency behind the LPF (maybe x2 + x3 - is the black element in front of the interdigital filter a diode?). If we assume that the MC ADE-2ASK mixer has a maximum frequency 1 GHz, the BPF should be 653.56 MHz (if the multiplication is x6). Then this signal would be created by mixing 600 MHz and a free-running (!!!) 53.56 MHz oscillator. If the multiplication behind LF3 is x7 (rather cumbersome), the BPF is 560.2 MHz and the oscillator is 39.8 MHz. Strange...

author: analogRF
author_rank: Super Contributor
timestamp: September 26, 2020, 02:17:35 am
content: Sandra, can you post close up pictures of the designated components in this photo? their markings are not readable

author: analogRF
author_rank: Super Contributor
timestamp: September 26, 2020, 02:27:43 am
content: the RLC Elec. filterP/N 9135-0389 is a 783MHz bandpass filter. 784 x 5=3.92GHzso there must be a multiplication by 5 (picking up 5th harmonic) before reaching the main golden mixerhowever, the mystery remains how this frequency is locked if at all. In all low frequency TGs that I have repaired before (HP and Anritsu and Advantest) there is always a VCO generating a fixed frequency which is the start frequency of LO and it is always locked to a stable reference.i was thinking that maybe they used that ADE-2 mixer as a phase detector (hard driving of RF and LO ports) but with above information, it is not possible....

author: analogRF
author_rank: Super Contributor
timestamp: September 26, 2020, 02:45:45 am
content: I think I was wrong about that black mystery component at the back of pcb. Ithas in fact 6 pins(see the pic)still no idea what that is but the +/- pins are Vcc and GND. But now it is beginning to look like a VCO. I think the control voltage is probably thesingle pin on the top that connects to the big through hole resistorSandra, can you post a close up photo of the rectangular area that I designated on the picture

author: smgvbest
author_rank: Unknown
timestamp: September 26, 2020, 03:45:51 am
content: Quote from: analogRF on September 26, 2020, 02:45:45 amI'm posting all the close-ups I did but those 2 components I think will need better photo's than thesei think the close-up of those 6 pins may be good if not let me know and tomorrow (its bed time) i'll open the BITG back up and get better photos

author: smgvbest
author_rank: Unknown
timestamp: September 26, 2020, 03:48:31 am
content: More

author: analogRF
author_rank: Super Contributor
timestamp: September 26, 2020, 11:20:05 am
content: the markings on those components are not visible

author: smgvbest
author_rank: Unknown
timestamp: September 26, 2020, 02:20:31 pm
content: Quote from: analogRF on September 26, 2020, 11:20:05 amDidnt think they where. i'll work on getting the BITG torn down again for pics and post soon as possible

author: analogRF
author_rank: Super Contributor
timestamp: September 26, 2020, 06:59:36 pm
content: Quote from: smgvbest on September 25, 2020, 10:26:33 pmosc_pwr just turns the TG on/offthe TUNE voltage (pin 5) comes from a SPI DAC on A2A1 and is 0 to 12V. It must be for tuning a VCO on BITG so I think that dark cylinder is indeed a VCO creating 1384MHz and it is fine tuned by this TUNE signal perhaps during the calibration process for TG.Is there a frequency calibration process for TG in this instrument?It does seem there is no phase/freq lock mechanism on this TG board and it is just tuned by A2A1 and then it is let go. That VCO is probably very stable... there is no feedback from the BITG to A2A1 board to give information about frequency accuracy, so that TUNE voltage is set just once during some calibration routine i guess ... It seems the 600MHz is there just to make up the math 1.384-0.600=3.92/5why didnt they make that VCO just to be 784MHz then?there is also a PWR_LVL (pin 8 ) coming from another SPI DAC on A2A1 (0 to -11V) and I think that signal controls the HMC346 variable attenuatorcan you trace that TUNE signal from the connector to a pin on the BITG RF board?

author: smgvbest
author_rank: Unknown
timestamp: September 26, 2020, 08:08:54 pm
content: Got it apart and took some picsHope they help

author: smgvbest
author_rank: Unknown
timestamp: September 26, 2020, 08:11:42 pm
content: Jury Rigged back together got a FLIR pic as best I could in unlevel state

author: smgvbest
author_rank: Unknown
timestamp: September 26, 2020, 08:14:56 pm
content: There is an align TG in the SYSTEM/ALIGNMENTS/ALIGN NOW menuYes I can trace the TUNE signal. BRB

author: smgvbest
author_rank: Unknown
timestamp: September 26, 2020, 10:07:14 pm
content: Tracing it so far. It does not go directly to the RF side of the A2A2 boardGoes thru a analog switch which switches between a fet op amp and J3 which is not connected, then to Q1 which I haven’t been able to find yet. It’s a 6 pin can. See Attached

author: smgvbest
author_rank: Unknown
timestamp: September 27, 2020, 03:06:42 pm
content: Quote from: smgvbest on September 26, 2020, 10:07:14 pmOye, I just did a SUT, I was not tracing TUNE on Pin5 I was tracing ALC_EXT on Pin10. I don't' know where I got Pin10 from but pretty much ignore my previous post. I'll go retrace Pin5 for Tune and see where it goes.

author: analogRF
author_rank: Super Contributor
timestamp: September 27, 2020, 04:07:37 pm
content: Quote from: smgvbest on September 27, 2020, 03:06:42 pmI kinda knew because from the pictures I had already seen pin 5 (I had mentioned it is pin 5 it in my post) goes directly under that connector...

author: smgvbest
author_rank: Unknown
timestamp: September 27, 2020, 06:37:45 pm
content: So when you trace the correct PIN its pretty easy to find.See attached

author: seronday
author_rank: Regular Contributor
timestamp: September 27, 2020, 11:44:38 pm
content: Sandra,I have just started reading this topic.Correct me if I have misunderstood one of your earlier posts, but I understand that you have the schematic drawings for the 3Ghz A2A1 Driver board but not for the 3Ghz A2A2 RF board.I have a printed copy of the drawings for the 1.5Ghz version of the tracking generator A2A2 RF board which I may be able to try to have scanned if this will be of any use to you. (There are 13, A3 size sheets).Regards.

author: smgvbest
author_rank: Unknown
timestamp: September 28, 2020, 12:10:20 am
content: @serondayThanks for the offer.It definitely could help if your able to get those scannedSandra

author: analogRF
author_rank: Super Contributor
timestamp: September 28, 2020, 01:21:13 am
content: Quote from: smgvbest on September 27, 2020, 06:37:45 pmStill I cannot find what that sot-23 package MC-0 is but it appears to be (probably) a two diode package and since pins 1&2 are connectedit is a back-to-back connected diode which connects the TUNE voltage (0 to 12V) to that VCOit all makes sense I believe...the schematic of this thing is pretty much all clear now. you need a probing strategy to check various pointsduring fail conditions. But it is pretty clear now what you should expect at different pointsI see most people who have had TG issues in these ESA series it usually has been the IGG5 hybrid ....

author: smgvbest
author_rank: Unknown
timestamp: September 28, 2020, 03:13:02 am
content: So not a exact replacement if this is what wrong. I found this the attached.The pinout is very close, mainly NC pins on the side that do not appear on the device in the unit.I will pull out the Rigol tomorrow and probe before and after that component with the TG set to zero span and 50Mhz. at -9dB i do not get the Source Unlevel, at -10dB I do. so the output will be well withing the range of the Rigol SA, I can also probe the 600Mhz in and the VCO. I will get that done soon with a poor mans rf probe.Also found this on Keysights sitehttps://www.keysight.com/en/pc-1748995/millimeter-wave-and-microwave-gaas-limiters?nid=-33897.0&cc=US&lc=eng@analogRFyou mentioned you where going to post a pic of your RF probe, where you able to find the pic?

author: analogRF
author_rank: Super Contributor
timestamp: September 28, 2020, 03:21:21 am
content: Quote from: smgvbest on September 28, 2020, 03:13:02 amthis chip does not have any peak detector output for level control loop. the one in your TG does RPP and has level detector.it's good strategy to probe before and after that IGG5 when the error appears and when it doesn'talso at that point I suggest checking the control voltage that goes to the HMC346 variable attenuator and see if it is changing or notand also check the the PWR_LVL signal that comes from A2A1 to the connector pin 8 and also the ALC_MON at pin 6.these are all DC so easy to probe and document what you see

author: smgvbest
author_rank: Unknown
timestamp: September 28, 2020, 09:08:57 pm
content: Quote from: analogRF on September 28, 2020, 03:21:21 amSet for 50Mhz Zero Span, -10dB was Level, 3dB was unlevel.reading at Top for Level, bottom was unlevelsee photoAlsoVCO? 782.5Mhzsee photo

author: analogRF
author_rank: Super Contributor
timestamp: September 28, 2020, 09:52:59 pm
content: 1-what are these numbers? what does -57 mean?2-what did you measure them with? I mean was it scope or a spectrum analyzer?3-the most important thing is what probe did you use?4-for VCO this is very strange! but we dont know what that pin is so please measure the VCOat the RF input to the mixer (pin 3) and also more importantly measure the IF outputyou can measure at pin 2 of mixer but better is to measure at the output of the big filter which is the input pin of the blue "LF3" filter

author: smgvbest
author_rank: Unknown
timestamp: September 28, 2020, 10:25:32 pm
content: Everything is in dB on first photoMeasured with Rigol 1.5 ghz SAscope probe. Still waiting on sma to make that diy probe you mentionedInterested in relative values in this case. Should show if amps workingAnd IGG5 has same in/outFor VCO I measured with just a 50 ohm lead first. Then probe. Got same value except probe was lower dBI’ll check areas you mention.

author: smgvbest
author_rank: Unknown
timestamp: September 28, 2020, 10:50:48 pm
content: Quote from: analogRF on September 28, 2020, 09:52:59 pm#4, Pin3 is 182.5Mhz, 600Mhz Pin4 782.5Mhz at input/output of LF3

author: smgvbest
author_rank: Unknown
timestamp: September 28, 2020, 11:12:04 pm
content: HMC3463dB unlevel, then -10dB reading levelall vDCCode:V1 = 0.181/-1.7v2 = -4.191/-2.48I = -0.585/-5.85

author: analogRF
author_rank: Super Contributor
timestamp: September 28, 2020, 11:29:58 pm
content: Quote from: smgvbest on September 28, 2020, 10:25:32 pmyou mean regular scope probe with SA?? that will kill all the signal and significantly disturb the signal path whenever you touch itno need for sma connector, just solder a 450 or 470 ohm resistor to the center of a piece of coax like rg316 (or a rigid coax and then solder the rigid coax to a longer regular coax like rg316 in order to have a solid probe head) and then solder a piece of short wire to the shield of the coax (at the tip where you had the 450 ohm) to use it as your ground lead and your are good to go with 500ohm impedance you are gooduse 20dB level offset on your SA in order to read the amplitudes correctlysomething that is a bit strange is that between -10dB and +3dB setting the values dont change much. This could be due to attenuator section beingswitched in/out so the levels at the TG out change little or it could be symptom of your underlying problem. based on the attenuator that you have at the output and also the range of TG level settings, you should be able to figure out what level at the output of TG must exist to have XdBmat the front panel connector. Normally (not necessarily) for anything above 0dBm there should be no attenuator switched in but for -10dBm there is perhaps a section switched in like 8dB for example then your BITG must produce -2dBm at output.anyways, if the closeness of the two measrements are symptom of underlying problem, then since the ALC loop is closed on the A2A1 board (the PWR LVL DAC) then i suggest check the control voltage the comes to the HMC346C8 chip. see the datasheet, there is an opamp on the other BITG board related to this chip. and also the voltage coming from PWR_LVL is 0 to -11V according to A2A1 schematic so it must be transformed into 0 to -2.5V for HMC346 and that is done in the other BITG board.so you need to do some DC measurements. maybe there is bad opamp on that board!also see if the PWR_LVL oltage coming from A2A1 is ok (for example it is not stuck at a value)

author: smgvbest
author_rank: Unknown
timestamp: September 28, 2020, 11:34:45 pm
content: I did check the Bias on the MCL29 which read 3.57vDC and the MCL59 which was 4.7vDCat the front panel connector. Normally (not necessarily) for anything above 0dBm there should be no attenuator switched in but for -10dBm there is perhaps a section switched in like 8dB for example then your BITG must produce -2dBm at output.at the -10db it says the 8db attenuator is active.I will have to trace the board to find the op amp the pwr_lvl goes to.

author: analogRF
author_rank: Super Contributor
timestamp: September 29, 2020, 12:23:27 am
content: Quote from: smgvbest on September 28, 2020, 11:34:45 pmgood, so we know that at +3dBm the TG must output 3dBm (no attenuation after that) and at -10dBm the TG should output -2dBm (only 5dB jump)your numbers did jump but not by 5dB between the two cases.The control voltage for HMC346 clearly show the controller has gone into saturation in order to minimize the attenuation to retain the 3dBm output but has failed. HMC346 control voltages must always remain between 0 and -2.5V and the maximum tolerable range (before killing the chip) is +1V to -5V. So for +3dBthe controller is driving the HMC346 very hard to lower its attenuation.In my opinion this is probably just a symptom and may not be the actual cause of the unlevel issue. For example, still IGG5 may wrongly report a low level and therefore the controller loop will drive the HMC346 into saturation because of that. But it also could be the source of problem, I mean maybe the DAC on A2A1 is giving out wrong voltage or the opamp circuits driving V1,V2 on HMC346 have problem.it would be useful to check the ALC monitoring signal that goes out from TG to A2A1 board in the two cases and some levels in between to see how it changes

author: seronday
author_rank: Regular Contributor
timestamp: September 29, 2020, 03:42:26 am
content: Quote from: seronday on September 27, 2020, 11:44:38 pmI have managed to scan these drawings. Some of the scans may not be very good as the printed copies are very feint.There is a total of around 8Mb so I will split the files across a couple of posts.Also included is a scan of the 1.5Ghz A2A1 Interconnect drawing for reference.Hopefully they will be of some use.Regards.First lot of files.

author: seronday
author_rank: Regular Contributor
timestamp: September 29, 2020, 03:44:45 am
content: Second lot of files.

author: analogRF
author_rank: Super Contributor
timestamp: September 29, 2020, 10:28:34 am
content: Quote from: seronday on September 29, 2020, 03:42:26 amThis one is a completely different beast. Has no resemblance to the 3GHz version.

author: analogRF
author_rank: Super Contributor
timestamp: September 29, 2020, 10:39:02 am
content: Quote from: smgvbest on September 28, 2020, 11:12:04 pmchange the level setting from -10dBm to 3dBm, 1dBm at a time and at each step monitor these signals (all DC) : the ALC monitor that goes from TG to A2A1. The PWR LVL that comes from A2A1. and V1,V2 on HMC346

author: smgvbest
author_rank: Unknown
timestamp: September 30, 2020, 01:44:34 am
content: Quote from: analogRF on September 29, 2020, 10:39:02 amI'm at a conference so been a little slow getting things right now, will get them soon as possibleOk, got them (see attachment)Notes: all reading done at 50Mhz, Zero Span. Did one column at a time thru -10 to 3dBmAlso read the P15BITG, N15BITG and P5BITG, the supply railsRED Cells is when it went UNLEVEL, but by time i got to ALC_MON/PWR_LVL the UNLEVEL state moved down to -1dBBLUE Cells have variability to them, not a fixed value

author: analogRF
author_rank: Super Contributor
timestamp: October 01, 2020, 02:22:25 am
content: these numbers look pretty consistent with each other (except one thing that I will mention below) and i cannot see which part might be the main culprit. which part is failing that causes the ALC loop go into saturation. maybe someone else can draw a better conclusionhowever here is my take and my recommendation1-the PW_LVL signal coming from a DAC on A2A1 was supposed to be between 0 and -11V (says on the schematic) here it does not go below -9.7it does not necessarily mean anything and it could have been designed that way because for example V1 should not go too much positive but stillit's worth to check if that circuit (PWR_LVL) is ok both on A2A1 and also on the TG board because that signal eventually generates V1 (so what is between V1 and PWR_LVL)2-The only inconsistency that I see in your measurements and that may be the path to the root cause is that all numbers are and must be similar (very close) for -2dBm and -10dBm settings. Because the TG has to generate -2dBm for both cases. However there is ONE voltage which is very different between the two cases and that is the ALC_MON. In fact between -3dBm and -2dBm it suddenly jumps -1V which never occurs anywhere else. At -10dBm where TG must be generating -2dBm the ALC_MON correctly stands at about -0.17.What happens to ALC_MON at -2dBm and above looks like the TG OFF state. Since I believe the ALC_MON is coming directly from the IGG5 hybrid (please confirm whether this is right or not) the issue may be the IGG5. Or maybe a supply voltage to IGG5 if it has one?3-Your 5V rails looks a bit low. Is it clean? did you check it when the failure occurred?4-since the failure moves to lower amplitude as time passes, it is probably affected by heat. Why dont you spray some freeze spray (aim very locally) at different components and see if the error goes away. starting with that IGG5!

author: smgvbest
author_rank: Unknown
timestamp: October 01, 2020, 03:13:43 am
content: Quote from: analogRF on October 01, 2020, 02:22:25 amI will check these item outon the IGG5, I did check and I see no bias/dc at it's input so if it's providing the level information I'm not seeing it.I do have freeze spray and will target different IC's starting with the IGG5.I'll also check the P15/N15/P5 without the TG attached so see if it's still being pulled down.

author: analogRF
author_rank: Super Contributor
timestamp: October 01, 2020, 03:26:15 am
content: basically IGG5 should not need any DC bias, it has a peak detector and should generate a DC proportional to the power leveland that voltage after some amplification and conditioning by opamps or transistors will become ALC_MONw.r.t. supplies, I think only the 5V rail seems a little low. check for any ripple/noise specially when the error happens and also for current draw.

author: smgvbest
author_rank: Unknown
timestamp: October 01, 2020, 03:29:11 am
content: Quote from: analogRF on October 01, 2020, 03:26:15 amwhen I say no DC/BIAS I mean there is no DC of any kind at the input to IGG5.

author: analogRF
author_rank: Super Contributor
timestamp: October 01, 2020, 03:31:54 am
content: Quote from: smgvbest on October 01, 2020, 03:29:11 amat its RF input you mean?how many pins does it have? cannot be just an input and output!

author: smgvbest
author_rank: Unknown
timestamp: October 01, 2020, 03:47:30 am
content: Quote from: analogRF on October 01, 2020, 03:31:54 amyes at RF in12 pins total. 3 on each side. RFin, RFout, all others go to ground.Could the part the arrow points to be the detector?

author: suj
author_rank: Regular Contributor
timestamp: October 01, 2020, 08:17:17 am
content: Quote from: smgvbest on October 01, 2020, 03:47:30 amYou may be right. Input resistive divider, filter capacitors and signal to AD620. On the second input of AD620, setpoint . The error signal at the AD620 output (in the sense of the difference between the actual value and the setpoint) being the ALC signal. You need to check the DC levels at the AD620 inputs and output at different RF signal levels.

author: analogRF
author_rank: Super Contributor
timestamp: October 01, 2020, 10:45:14 am
content: Quote from: smgvbest on October 01, 2020, 03:47:30 amobviously there is no DC anywhere in the RF path. there shouldn't be.yes, it is. If IGG5 has no other pin than the RFin/RFout and GND then it is only functioning as RPP.And by the looks of it, that circuit you pointed is indeed the peak detector (that must be a schottky diode)this makes it easier to probe in and also to repair if the problem is in this part.you need to find out why at -10dBm setting and -2dBm setting the ALC_MON signal is so differentbecause the TG must have the same -2dBm output amplitude in both cases.

author: smgvbest
author_rank: Unknown
timestamp: October 01, 2020, 05:58:49 pm
content: Quote from: analogRF on October 01, 2020, 02:22:25 amDid this. the only component that had effect using cold spray was the HMC346 it only shifted it down (lower db reading) but unlevel condition continuedtried the other board on the TG (one with OPAMPS and Analog Switch) , no effect there either

author: analogRF
author_rank: Super Contributor
timestamp: October 02, 2020, 04:17:27 pm
content: Quote from: smgvbest on October 01, 2020, 05:58:49 pmdid you also try freezing the the capacitor and the schottky diode of the peak detector circuit?based on the table you provided before, you should have got unlevel error even at -2dBm because the ALC_MON drops below -1Vand according to the schematics of A2A1 this will set the unlevel error. it is puzzling that you didn't get that.something is happening between -3dBm and -2dBm. Can you try to measure the RF amplitude at these twi levels and see if theRF actually drops? because the ALC_MON is reporting that it drops quite a bit instead of increasing by 1dB. So check the actual RF amplitude(assuming IGG5 is ok, you can do it at the SMA port) if the actual RF amplitude does not drop then the problem is in the ALC_MON reportingand the circuit between the schottky peak detector (and its ceramic cap) and the ALC_MON pin must be checked (most probably the opamp on the top right)but if the amplitude does indeed drop, then I think the HMC346 is the main suspect.by the way, is the frequency spot on?

author: smgvbest
author_rank: Unknown
timestamp: October 03, 2020, 03:36:26 pm
content: Quote from: analogRF on October 02, 2020, 04:17:27 pmYes, no effect noticed.Quote from: analogRF on October 02, 2020, 04:17:27 pmWill do this.I did trace and verify that indeed the via pointed in the peak detector circuit does go to the input of the AD620 as indicated.I also did more tracing of the RF board and its 2 10 pin connectors. i've got most pins traced out. will post image with labels shortly for referenceQuote from: analogRF on October 02, 2020, 04:17:27 pmyes it is

author: analogRF
author_rank: Super Contributor
timestamp: October 03, 2020, 03:52:34 pm
content: one other thing you can test, if you set the TG ALC to External and dont apply any DC to the Ext ALCthe output should stay fixed at around 0-1dBm I think. At least this is how it worked in 8590 series I rememberI dont know what DC levels can be applied to the EXT ALC to control the TG output level. Maybe it's somewhere in the manual....

author: smgvbest
author_rank: Unknown
timestamp: October 05, 2020, 08:21:54 pm
content: I've been trying to figure out what's happening at the AD620.but overall its looking like the Reference voltage is fluctuating and the output of the detector is stable at about .0446vDC. so the output of the AD620 is also fluctuating.also the output is not very stable as read at same time as the input to the AD620. which kind of aligns with the output of the AD620.So is the AD620 causing the Reference to fluctuate or is the Reference to the AD620 the problemI need to record the rest of the reading for my table here. hopefully latter I can do thisalso as the unit warms up it more seems to change behavior. the notable items is the output from the detector seems stable. so this to me so far is pointing to the AD620 or Reference to the AD620more info to comeCode:AttenuationdBm MindBm MaxdBm AVG(A)in3dB-3.0201.200-0.9100.04472dB-1.7201.220-0.2500.04461dB-0.9401.2200.1400.04470dB-2.8400.620-1.1100.0446-1dB-0.910-0.390-0.6500.0447-2dB-1.990-1.370-1.6800.0446-3dB-3.420-2.490-2.9550.0447-4dB-4.370-3.560-3.9650.0446-5dB-5.110-4.540-4.8250.0447-6dB-6.140-5.560-5.8500.0446-7dB-6.670-6.680-6.6750.0447-8dB-7.780-7.750-7.7650.0446-9dB-9.660-8.750-9.2050.0447-10dB-10.110-9.470-9.7900.0446

author: analogRF
author_rank: Super Contributor
timestamp: October 06, 2020, 12:15:03 am
content: what are these numbers?

author: smgvbest
author_rank: Unknown
timestamp: October 06, 2020, 12:29:44 am
content: Quote from: analogRF on October 06, 2020, 12:15:03 amWhat I have so farThe Attenuation is the 1st column, next is the dB min/max values (ie it was not fixed it varied) as measured with the power meter, the next is the average dB and last is the Peak Detector Input to the AD620i need to complete this by getting the reference into the AD620 and the output of the AD620, just sharing the values so far.

author: analogRF
author_rank: Super Contributor
timestamp: October 06, 2020, 01:49:11 pm
content: Quote from: smgvbest on October 06, 2020, 12:29:44 amyou mean the amplitude actually fluctuates when sitting there? How? keeps oscillating up and down? That clearly means the ALC loop is not working. It is like having no closed "loop" control of the amplitude which is possible but unlikely from a high quality tracking generator. If there is indeed a control loop and the amplitude just plays around like that, then the loop is not working (not closed)It actually starts very early on even at -5dBm or -6dBm.From the schematics I know that the Unlevel error only happens when ALC_MON goes out side the +/-1V window. So the loop control (if exists) must be closed somewhere on the BITG circuit. Perhaps somewhere on the RF signal path they sample the amplitude and compare with a reference and then control the V1 to HMC346 to keep the amplitude steady. If this loop is broken then the behavior you see is explained.It is important to figure out the circuit behind generating V1. I think it originates from the PWR_LVL from DAC on A2A1 but that voltage could be just providing the reference value for the control loop.But another (unlikely) option could be that there is no control loop and they just set the V1 based on some previously calibrated values and let it go and then only check whether ALC MON is within range or not. again we need to know how V1 is produceda little bit of reverse engineering is needed I think

author: smgvbest
author_rank: Unknown
timestamp: October 06, 2020, 10:11:11 pm
content: Quote from: analogRF on October 06, 2020, 01:49:11 pmSo yes, reading from the power meter (U2000H) i see the levels jumping around and the numbers I show are the Min/Max for each Attenuation level.Quote from: analogRF on October 06, 2020, 01:49:11 pmI was planning on having to look at both the V1 which feeds to the HMC346 from the interface board on the TG so may have additional circuitry there and the how the peak detector circuits are fullly implemented to see if there is more on the interface board. PWR_LVL appears to go direct to the RF board with no circuit on the interface board.Quote from: analogRF on October 06, 2020, 01:49:11 pmBeen figuring this was comingLots of probing ahead I see.

author: analogRF
author_rank: Super Contributor
timestamp: October 07, 2020, 11:07:18 am
content: Quote from: smgvbest on October 06, 2020, 10:11:11 pmFirst thing I would check is the control voltage PWR_LVL coming from A2A1 to see if it has any instability/fluctuation in it. Also that 5V rail which was a bit low and must be checked for noise/ripple too.If those are good, then there is a ALC loop on BITG which is open thus the amplitude fluctuates. there should be a feedback mechanism from peak detector circuit to generating V1. I think that circuit is on the other TG board. At this point I think lots of things are pointing to that other board. The problem is more likely in there I think. The only components on the RF board that might be of concern now are the HMC346 itself which "most probably" is ok and the peak detector diode and cap which you can easily check. if those check out, I think something is happening on the other board

author: smgvbest
author_rank: Unknown
timestamp: October 08, 2020, 11:47:03 pm
content: @analogRFI'm working to trace the circuit out for the PWR_LVL and ALC_MON and othersin the mean time I fired up benchview and took a look at the TG Output at a few levels, I added a strip chart which lets you see whats going on better than just looking at the MIN/MAX valuesI'm posting the -10dBm and 3dBm screen capsWhat's interesting to me is the dips in the chart are very regular.

author: analogRF
author_rank: Super Contributor
timestamp: October 08, 2020, 11:59:13 pm
content: Quote from: smgvbest on October 08, 2020, 11:47:03 pmyeah, these are very interesting and weird. the dips occur almost a little more than 3sec apart regularly but some are very prominent and someare very tiny which makes it more puzzling.-10dBm is the same as -2dBm. you should check something like -5dBm or -6dBm and see how flat it turns out.it would be useful and illuminating if we could have a recording of PWR_LVL, ALC_MON and V1 time correlated with these power graphs.is it possible that the unit tries to do self alignment of TG every 3 seconds? 3 seconds is normally a lot longer than a normal sweep time of spectrum analyzer when you are using the TG to measure a filter for example, so maybe in an actual measurement these dips occur every let's say 100 sweeps in the dead time at the end of the sweep and if you actually use the TG for measurement you wont see them?! In other words your TG is finejust a thought..

author: smgvbest
author_rank: Unknown
timestamp: October 09, 2020, 12:12:06 am
content: Quote from: analogRF on October 08, 2020, 11:59:13 pmI had trouble with Benchview crashing on me when saving the screen caps but here's -8dBm, -7dBm and -6dBm capsAutoalign is on by default for SA, I will try turning it off and do these again tomorrow and see if it is related.far as trying to time correlate them. would doing that with a oscilloscope work? I have the Rigol MSO1024 4 channel? but not sure how I would sync them with the power meter in Benchview

author: analogRF
author_rank: Super Contributor
timestamp: October 09, 2020, 12:32:26 am
content: Quote from: smgvbest on October 09, 2020, 12:12:06 amoh, so they do exist at all levels and always at regular intervalsNow I am beginning to think that your TG might be ok afterall.... why dont you try to do a practical measurement/sweep with it? like a filter or an amplifier or even a piece of coax cable. let's say in a 3GHs span or whatever else...still having time correlated measurements of those 4-5 signals will give a better insight. but I admit it's a bit of a challenge to implement thatat the very least you can record those PWR_LVL, ALC_MON, V1 and I'd also add TUNE with your 4 ch scope in roll modeand when we put them next to these power graphs, if there is any anomaly happening at 3 sec intervals we know they are correlated with powerdips

author: analogRF
author_rank: Super Contributor
timestamp: October 09, 2020, 12:40:22 am
content: just out of curiosity, i cannot find Rigol MSO1024 datasheet anywhere...

author: smgvbest
author_rank: Unknown
timestamp: October 09, 2020, 12:55:26 am
content: Quote from: analogRF on October 09, 2020, 12:40:22 amprobably because it doesn't exist, what happens when users take their sleeping meds and try to typeTry MSO1104ZShttps://www.tequipment.net/Rigol/MSO1104Z/Mixed-Signal-Oscilloscopes/

author: smgvbest
author_rank: Unknown
timestamp: October 15, 2020, 10:36:55 pm
content: Just an update, have had some things come up in personal life so had to step away from this for a bit. will be back with soon I hope

author: smgvbest
author_rank: Unknown
timestamp: October 16, 2020, 11:29:44 pm
content: Looking for help in identifying some componentsin PICT0007.jpg looking to identify all marked ones. the one I put a D on, the D is the only marking on the component. I think this is a dual diode package for the peak detector.I loose allot of power at the point of this component. like -25dB. this is suppling the 786.5hz RF to the Mixer (5x that but I can't measure on my 1.5Ghz SA)in IMG_2867-1.jpg

author: smgvbest
author_rank: Unknown
timestamp: October 16, 2020, 11:37:11 pm
content: these 2 Sot-23's marked 8F I think are 5.1v zeners but 8F can be a NPN transistor as wellboth read strange but reading is in-circuit. one reads 24.7K forward and reverse and other is like 30meg forward and reverse. I'll get them out of circuit to test but they are connected to V1/V2

author: smgvbest
author_rank: Unknown
timestamp: October 17, 2020, 06:43:46 am
content: Here's another area. all but the one with a ? is identified but I marked one component that looks damaged? any thoughts on that?

author: analogRF
author_rank: Super Contributor
timestamp: October 17, 2020, 12:28:35 pm
content: Quote from: smgvbest on October 16, 2020, 11:29:44 pmthe white elements are most likely resistors. you can check with multimeterthe "D" element is most likely HMPP-3890 single schottky diode by Agilent/Avago but are you 100% sure about the marking? sometimes it is tricky to read the labelsseems that all 4 pins of it have been usedalso for a good temperature compensated peak detector it makes sense to have two diodes in one package but if the marking is only a "D" then I couldn't find anything other than HMPP-3890 which is still applicable...the element with red dot is what is used to generate 5th harmonic if i remember correctly from previous discussions, so it is probably a diode of some kind.

author: analogRF
author_rank: Super Contributor
timestamp: October 17, 2020, 12:32:46 pm
content: Quote from: smgvbest on October 16, 2020, 11:37:11 pmclearly they are not transistors (they are marked by CRxx) and they are definitely diodes. seems to be used for clipping/clamping a signal or a dc voltage (from top and bottom)use diode test mode not resistance mode in your multimeter

author: analogRF
author_rank: Super Contributor
timestamp: October 17, 2020, 12:49:18 pm
content: Quote from: smgvbest on October 17, 2020, 06:43:46 amthe ? element looks like RF amp but it has an extra supply pin (other than the usual one that is connected through a ferrite bead) that is a bit puzzlingmaybe it has a on/off switch in it too? there must be a marking on that package. what is the marking??the discolored element does look like damaged but at that point i dont think there is anything stressful to elements, maybe it can be cleaned? can you try to clean it? looks like a capacitor of course but it could be a resistor so check with multimeterafter those you have a bandpass filter at 784MHz I think..

author: smgvbest
author_rank: Unknown
timestamp: October 17, 2020, 11:16:33 pm
content: Quote from: analogRF on October 17, 2020, 12:28:35 pmThe White elements do read as resistors of 50 and 125 ohmfor the part with the D marking. see image for best I could getUsing the Diode test here are reading for all 4 pins (see image for pin numbering used) all reading Vdc1-2 1.3908v/1.447v3-4 1.6304v/0.1447v1-3 0.0691c/0.0691v2-4 1.4398v/1.3723vfor the damaged elementDid multiple checksResistance OpenCapacitance 0Diode opensee image for better view

author: smgvbest
author_rank: Unknown
timestamp: October 17, 2020, 11:23:10 pm
content: heres image of damaged part

author: smgvbest
author_rank: Unknown
timestamp: October 17, 2020, 11:25:19 pm
content: Quote from: analogRF on October 17, 2020, 12:32:46 pmHere are reading for CR1/CR2 Forward and reverse voltages meter set for 15V testCR1 0.789v/2.773vCR2 0.789v/2.763v

author: analogRF
author_rank: Super Contributor
timestamp: October 18, 2020, 12:26:48 am
content: Quote from: smgvbest on October 17, 2020, 11:16:33 pmsee the picture for my comments.are you sure about the diode test voltages? you have a 1.447 and a 0.1447? which one is correct?what was the test current of your multimeter diode test? 1mA as usual? in that case you are reading 69 ohm between 1 and 3 but I think that's because of the outside resistors forming a loop. I think 1 and 3 are in fact not connected in the devicew.r.t. the discolored component it is definitely a capacitor and it cannot be zero of course. if you want, you need to measure it with a LCR meterwith at least 10KHz or above because it is definitely just a few pF or maybe several 10s of pFI dont think it is damaged otherwise your TG wouldn't work at all.

author: analogRF
author_rank: Super Contributor
timestamp: October 18, 2020, 12:28:00 am
content: Quote from: smgvbest on October 17, 2020, 11:25:19 pmso they are 2.7V zener diodes.what is your multimeter by the way?

author: smgvbest
author_rank: Unknown
timestamp: October 18, 2020, 01:34:46 am
content: Quote from: analogRF on October 18, 2020, 12:28:00 amin this case I'm using the eevblog 121GWon the 2.7 zener though. isn't a 8F a 5.1V zener?

author: smgvbest
author_rank: Unknown
timestamp: October 18, 2020, 03:41:24 am
content: at peak detector I did have a typothis is the correct value1-2 1.3908v/0.1447vin PICT0042-1.jpgthe Cap did clean up as seen and the LCR at 10Khz says 9.65pF

author: smgvbest
author_rank: Unknown
timestamp: October 18, 2020, 03:50:31 am
content: Would this be of any value in doing.my Rigol 815 only goes to 1.5Ghz.I need to look at signals up to 6hgz (LO)I go have a Divide by 4 that's good up 8Ghzwhat if I ran my probe into the /4 then into the SA. adjust reference to give good readingsThe 3.92Ghz would come out at 981.875Mhz if present.I would also be able to see the LO sweepingI know its not ideal but working with what I have would that be useful to do?

author: smgvbest
author_rank: Unknown
timestamp: October 18, 2020, 04:08:58 am
content: here's an update RF board where signals gonote the labels PD+/PD- in the peak detector that go to the AD620.

author: analogRF
author_rank: Super Contributor
timestamp: October 18, 2020, 10:24:56 am
content: Quote from: smgvbest on October 18, 2020, 03:50:31 amwhy do you need to do this? I think we concluded long ago that LO was present and workingin fact your TG is working normally most of the time except some short dips in amplitudewhich you must find out their correlation with other signals to see what is causing themother than that between those blips, the TG is working normally. Obviously if you didnt have LO coming inthis would not have worked at allSo i dont see the point of this test. Besides, if anything, you would need to know the precise amplitude of coming LOwhich this test will not tell you but you measured that with power meter and it was alright.

author: analogRF
author_rank: Super Contributor
timestamp: October 18, 2020, 10:59:39 am
content: Quote from: smgvbest on October 18, 2020, 03:41:24 amso there are two separate schottky diodes in one package, one for peak detection and one for the temp and V_fwd compensation. It's a classic RF peak detector circuit. But the part number I could find for "D" was a single diode which makes no sense so it must be a different part...

author: analogRF
author_rank: Super Contributor
timestamp: October 18, 2020, 11:05:55 am
content: Quote from: smgvbest on October 18, 2020, 04:08:58 amB1 and B2 are power supplies for the RF ampliiers.C8 is the output of peak detector and must eventually become ALC_MON after further processing on the other boardyou need to find out the relationship between V1/V2 and PWR_LVL signal coming from A2A1is there any jump/dip in OSC_PWR consistent with the dips in the TG output power?

author: analogRF
author_rank: Super Contributor
timestamp: October 18, 2020, 01:58:19 pm
content: Quote from: smgvbest on October 17, 2020, 11:16:33 pmI dont think the marking on the dual diode package is "D". It must be 2 letters and "D" seems to be the second letter which is a date codethere is a very faint letter before "D" it's either "B" or "C" i thinkyou need to look carefully at proper angle

author: smgvbest
author_rank: Unknown
timestamp: October 18, 2020, 03:30:16 pm
content: Quote from: analogRF on October 18, 2020, 01:58:19 pmI have twisted and contorted in every possible way so see and what I posted is the best I can getQuote from: analogRF on October 18, 2020, 01:58:19 pmThis was to look at the 768.5Mhz getting multiplied by 5x and where it happened is all.If I didn't already say so I'm also documenting as much as possible about the BITG for others in the future. (you can still get the BITG from Keysight for a mere $4500This is why the boat load of pics and sometimes extraneous informationQuote from: analogRF on October 18, 2020, 01:58:19 pmworking on the other board to trace the signals aroundi did not note any DIPs in OSC_PWR. it is very stable.unrelated, now is the only time I regret having done lasic eye surgery. my near vision it shot and everything I do is under a microscope.wouldn't change having done it but this does get frustrating at times

author: smgvbest
author_rank: Unknown
timestamp: October 20, 2020, 12:27:37 pm
content: Here's another part I'm having trouble findingMarking is a Linear Technologies 531 (LT531) but I can find no such beast.Anyone recognize this 8 pin guy?

author: analogRF
author_rank: Super Contributor
timestamp: October 20, 2020, 12:30:15 pm
content: Quote from: smgvbest on October 20, 2020, 12:27:37 pm531 is the date code (2005/ week 31)This is LT1021 precision reference 10.000V

author: smgvbest
author_rank: Unknown
timestamp: October 20, 2020, 01:25:49 pm
content: Quote from: analogRF on October 20, 2020, 12:30:15 pmThank you very much.That would make sense where it is in the circuit.i don't see how how to get from the marking 2110 i guess to a LT1021, is this some vodoo magic or am I (very likely) missing something simple)?

author: analogRF
author_rank: Super Contributor
timestamp: October 20, 2020, 01:36:04 pm
content: Quote from: smgvbest on October 20, 2020, 01:25:49 pmI already knew that part because I had seen and used it before myself but if you search for Linear Technology 2110 SOICyou'll find it after a little while

author: smgvbest
author_rank: Unknown
timestamp: October 21, 2020, 12:02:12 am
content: Quote from: analogRF on October 20, 2020, 01:36:04 pmYeh, like the first result returned. oyeThanks againstill working on reversing the control board (A2A2-BITG)Making progress slowly.Don't know how many layers this board is but its' more than 2

author: smgvbest
author_rank: Unknown
timestamp: October 25, 2020, 03:40:01 am
content: Just a quick update.while reversing the board. I decided to go ahead and replace the H346 on the RF board. while this did not fix the issue it did have an impact on the outputthe dB steps are now much more visiable and it much more consistent. for every 6db (1-6) on the H346 its unlevel then for 2db (7-8) it's level. this is now consistent all the way down to -66db (limit of the TG).I also pulled the 2 zenners to check out of circuit. they are 5v zeners and working okI also pulle Q1 an tested it out of circuit. this is a LS312 Dual NPN transistor. one Transistor has a hfe of 285 the other of 108. I had ordered 2 LS312s just in case and the new ones are hfe of 276 and 277so I'm going to replace Q1.Next. I pulled all 5 trimming pots and inspected themR2/R3 have been messed withPWR_LVL goes into R3 before going to U7 TL074 and the other input of this opamp (+12,-13 and out14) is the output of the peak detector.this then goes to ALC_MON and thru R4 to U5 which controls V2. R5 looks to set the reference for one opamp on U5. U5 other opamp handles V1 which uses R1 and R2.just for reference I'm attaching a image of the board with the trimmers and Q1 removed.I also did record the settings for each Pot (R1-R5) just in caseNOTE: replacing Q1 had no noticeable effect

author: analogRF
author_rank: Super Contributor
timestamp: October 27, 2020, 12:35:36 pm
content: Quote from: smgvbest on October 25, 2020, 03:40:01 amI would never start replacing components at random for no reason unless there is evidence it is not working. Not only this will not achieve anything and waste a lot of time you end up tampering with the calibration of instrument. Q1 was already tested fine, so no surprise there.and why did you take out all the potentiometers?if you are sure R2/R3 have been messed with and PWR_LVL and peak detector are related to them, that's your clue!that could very well be the cause of your problem because so far there does not seem to be any defective component anywhere.i would like to see a schematic of that board (not the RF section which is quite clear already)

author: smgvbest
author_rank: Unknown
timestamp: October 27, 2020, 03:59:53 pm
content: I did not replace randomly anythingH346 when looking at it the RF IN was at -60db after the filter and into the H346. without the H346 it was at about -10db. I replaced it because it appeared to be pulling down the RFinQ1 is a matched pair of NPN transistors HFE's that different are not matched. which is why I pull it and replaced it.the Pots where pulled to inspect out of circuit due to tampering. They did not remove the silistic on the adjustment screw and where visibly damaged. I wanted to be sure they were ok and while out I got a good read on how they where set. as well as a pic of the board.I've hand drawn it in various parts. I'm now putting it all together and will verify it against the board then plan to post when it's done

author: analogRF
author_rank: Super Contributor
timestamp: October 27, 2020, 04:11:59 pm
content: Quote from: smgvbest on October 27, 2020, 03:59:53 pmhow did you measure the 3.92GHz signal at the RF pin of HMC346? how much was the output amplitude?it is critical how you measure it and besides when you leave that open circuit(by removing the chip) that changes the whole dynamics...it will be a totally different reading of course....

author: smgvbest
author_rank: Unknown
timestamp: October 27, 2020, 08:20:13 pm
content: I used a near Field probe, calibrated the output thru a div/4 into my 1.5Ghz SA. the reading was accurate to about +-1dB.

author: zmetzing
author_rank: Contributor
timestamp: February 03, 2021, 07:36:31 pm
content: Could I ask what you searched for on eBay to locate one of these TG assemblies? I've got a E4402B arriving soon, and I'd like to add this option. I bought it due to the DSP/Comms hardware boards, which are tough to find. I'm still looking for a broken E4407B at a good price.

author: analogRF
author_rank: Super Contributor
timestamp: February 03, 2021, 10:26:49 pm
content: Quote from: zmetzing on February 03, 2021, 07:36:31 pmjust look for the TG part number as per service manual (look for replacement parts tables)but it is very very rare and hard to find.In my case for my E4407 I found a defective E4402 with TG on it and I convinced the seller to sell it for $400then I kept the TG which was working and repaired the SA which had unlock LO and also bad attenuator (both simple repairs)and then sold the SA. Interestingly the TG was retrofitted on that SA so the sticker in the back did not have it listed

author: dj9ss
author_rank: Newbie
timestamp: September 13, 2023, 01:05:18 pm
content: Alas, some weeks ago my E4407 TG has developed the same symptoms: "Output Unlevel" at >2GHz at levels above -3dBm.I already did extensive investigations and replaced all parts which were easy to source, even playing with the various attenuators to see whether there is any effect, but to no avail.The only parts left are the mixer and the mystery 1BR MMIC which I couldn't identify.However, I doubt the issue is in the 768MHz path since neither replacing MGA-6 with MGA-6A (more gain) nor changing the 5dB attenuator did change the symptoms.I'd also rule out the LO amplifier with the two HMC311 - reducing the 10dB attenuation didn't show any effect.Accordingly, my current conclusion is that it's probably the HMC129G8 mixer.Unfortunately this part is obsolete and not easily available anywhere, so I'm planning to replace it with HMC129ALC4 and an adapter PCB.During my work, I compiled a set of schematics in Kicad. There are surely still a few errors, especially in the control board, but I'll attach the current version anyway.Additionally, I accidentially popped the cover off the mysterious black cylinder labelled 0410-2110 and take a picture. I bet that's a crystal oven.Cheers, Jürgen

author: dj9ss
author_rank: Newbie
timestamp: October 02, 2023, 12:17:27 pm
content: I finally succeeded replacing the HMC129G8 mixer with HMC129ALC4 using a self-designed adapter PCB - see attached picture.Alas, it works exactly alike the original HMC129G8, i.e. the "Output unlevel" message at >2.5GHz and more than roughly -3dBm hasn't changed.I could improve situation by replacing LEE-29 in the output amploifier by LEE-39 which has a few dB more gain.Now I'm only getting the "output unlevel" only with >0dBm.Otherwise, I'm frankly out of ideas what could possibly be wrong.There might be an issue with the unknown 1BR amplifiers or even with the 1GG5-4202 output limiter.The limiter is available at some places for horrendous amounts of money (several hundred $$), so I'm very reluctant to consider replacement.Some update about the 0410-2110 crystal oven:the oven part can be simply pulled off, it's just plugged onto the board. Inside there's a 92,140MHz crystal, see attached pictures.

author: m2012
author_rank: Newbie
timestamp: January 14, 2025, 01:55:47 am
content: Hello,the unknown component 1BR is an amplifier from Agilent. MGA-565P8