EEVblog #1256 - Most Gorgeous Test Gear Teardown Ever! - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: October 23, 2019, 12:11:04 am
content: Probably the most gorgeous test gear teardown yet!A master class in modular product design and design for servicing, a mystery retro bit of test gear from the bunker that was found in a dumpster.

author: Deodand2014
author_rank: Regular Contributor
timestamp: October 23, 2019, 12:23:27 am
content: Most impressive. I hope you can find the full manual, sorting out the problem that resulted in it winding up in a dumpster may prove to be as interesting as the teardown.

author: N2IXK
author_rank: Frequent Contributor
timestamp: October 23, 2019, 12:23:50 am
content: That thing isn't simply an AC millivoltmeter. It is a selective level meter, also called a frequency selective voltmeter. It is essentially a laboratory-grade radio receiver with a huge input level range (microvolts to volts without overloading), and a hyper-accurately calibrated "S-meter". If you hook the input to a longwire antenna, you can use the speaker to listen to frequencies from VLF up through HF. The major use of these was in telco central offices and the like, for checking various channels of carrier (FDM) systems. You can enter a specific frequency of interest, and measure the signal level at that specific frequency, while tuning out unwanted ones. A very specialized bit of gear, but lots of fun to play around with. I have an HP 3586C, which is similar in vintage, build quality, and functionality.This thing is a DEFINITE candidate for a repair and play around video series. Almost certainly a linear PSU for low noise, so repairs should be simple.Manuals available free onlinehttp://ftb.ko4bb.com/getsimple/index.php?id=manuals&dir=06_Misc_Test_Equipment/Wandel_and_Goltermann

author: wn1fju
author_rank: Frequent Contributor
timestamp: October 23, 2019, 02:29:25 am
content: I have the W&G SPM-19 Selective Level Meter and it really has no equal. I find it to handle the AGC better and overall to be more accurate than myHP 3586B unit.When I received mine, the power supply was blown up. And I mean literally blown up - the big can electrolytics had spewed their oily insides all overeverything. The stuff must have been caustic since it dissolved a lot of the wire insulation in the power supply. I managed to fix it, but the fix didn'tlast too long and I ultimately took the whole supply out and replaced it with a 120 watt Meanwell switching power supply.It's fun to hook the thing up to my outside (ham) antenna and listen to broadcast AM at night. Readable stations virtually every 10 kHz throughout theentire band. That's because the SPM-19 receive sensitivity is maintained across all frequencies, unlike my ham transceiver that has much poorer sensitivity inthe AM band than in HF.

author: johnlsenchak
author_rank: Frequent Contributor
timestamp: October 23, 2019, 02:51:34 am
content: I bet Shahriar Shahramian over at "The Signal Path" would go totally nuts if he got his hands on something like thatYou should do a video on those isolating penetrator's , that's something that I never knew existed inside electronic equipment .

author: vk6zgo
author_rank: Super Contributor
timestamp: October 23, 2019, 03:05:38 am
content: Telecom Australia was a good customer for Wandell & Goltermann.They used selective voltmeters to look at multiple channel landline carrier systems, as well as similar signals on microwave systems.They also used similar units from Rohde & Schwarz, & some other companies, notably Siemens, with their "Pegelsender" & "Pegelmesser" test setup.Interestingly, W&G & R&S, although competitors, entered into an agreement that guaranteed their equipment was compatible between the two companies, so special interfaces worked between both brands.By the way, Dave, "Verstarker" (literally "strong maker") means "amplifier".

author: Bud
author_rank: Super Contributor
timestamp: October 23, 2019, 04:13:30 am
content: Just speechless...

author: szymon019
author_rank: Contributor
timestamp: October 23, 2019, 06:59:53 am
content: Hi Colleagues,Nice to see this topic. In the same time I decided to clean out dust and check electrolythic capacitors in my low frequency Vector Network Analysator SNA-2 (chaper equivalent to Bode 100 + Spectrum Analysator for DCDC converters, conducted emission etc.). It consist of two units analog section and upper controlling digital section. This construction is also pretty nice. I am going to make some photos and maybe copy EPROMs because they are getting the end of lifetime. This instrument can measre in range of 100Hz up to 180MHz and plotting Bode, Nyquist, Smith plots. It have GPIB interface and can controll HPGL plotter. It can still be usefull for analog circuit stability optimisation with external coupling transformer + HiZ fet probe. My unit is equipped with 50Ohm input / output.I have idea to attach some modern MCU + SD card to store GPIB HPGL prints for exchange with standard PC.Since I am going to check electrolythic capacitors condition old ROE and Siemens datasheets are welcome, also if somebody have SNA-2 documentation and could share with me would be nice.

author: SparkyFX
author_rank: Frequent Contributor
timestamp: October 23, 2019, 07:11:09 am
content: Very entertaining, but still informative

author: daqq
author_rank: Super Contributor
timestamp: October 23, 2019, 07:58:51 am
content: Beautiful build quality... the amount of engineering must have been amazing.Using today's state of the art tech, would it be possible to make such a device, only weighing far less, with much less shielding? Or is there simply no other way around noise at such low levels than to use a ton of shielding?

author: BrianHG
author_rank: Super Contributor
timestamp: October 23, 2019, 08:17:54 am
content: Quote from: daqq on October 23, 2019, 07:58:51 amExcept for pre-stage amplifiers and a low pass filter, today for 20hz to 25Mhz range, we would just use a 16-20 bit 100Mhz-200Mhz ADC, then everything else would be 100% software.

author: EEVblog
author_rank: Unknown
timestamp: October 23, 2019, 08:25:12 am
content: FYI, someone on youtube comments said it was released in 1980 and cost US$45k in today's dollars

author: thinkfat
author_rank: Unknown
timestamp: October 23, 2019, 12:01:13 pm
content: Some translations, Dave did a good job already with these, but maybe I can fill in some blanks.Ordered by assembly group number (which is not unique for some reason).1, 6V Gleichrichter -> "6V rectifier"2, Eingang 75 Ohm -> "Input 75 Ohms"3, Vorteiler -> "pre divider"4, Nachteiler -> "post divider"4, Vorverstärker -> "preamplifier"5, 25MHz Tiefpass Entzerrer -> "25MHz low-pass equalizer"6, Umsetzer HF/40MHz -> "converter/mixer HF/40MHz"7, 40MHz Quarzbandpass -> "40 MHz crystal band pass filter"8, Umsetzer 40MHz/10kHz -> "converter/mixer 40MHz/10kHz"10, Eichmischer -> "calibration mixer"11, Trennstufe" -> "isolation amplifier"12, 10Mhz Übertrager -> "10 MHz coupler"12, 40,01MHz VCO -> "40.01 MHz VCO"12, 40,01MHz PLL -> "40.01 MHz PLL"12, Vervielfacher -> "Multiplier"13, Breitbanddetektor -> "wideband detector"15, ZF-Verstärker -> "IF Amplifier"16, Gleichrichter -> "Rectifier" or "Detector"17, Demodulator -> "Demodulator"26, 10 MHz Eing. u. Mitlaufs. -> "10 MHz input and tracking transmitter"25, 10kHz Bandpass/25Hz -> "10kHz band pass / 25Hz bandwidth"27, Phasenjitterschaltung -> "phase jitter circuit"51, Rastphasenmesser -> "locking phase discriminator"52, Rastoszillator -> "locking oscillator"55, TTL-Stufe -> "TTL stage", "TTL converter"56, Trägerphasenmesser -> "carrier phase discriminator"57, Trägeroszillator -> "carrier oscillator"60, Interpol. Phasem -> "interpolation phase discriminator"63, Normalfrequenzteiler -> "reference frequency divider"63, 10 MHz Trennstufe -> "10 MHz isolation amplifier"64, 10 MHz-Oszillator -> "10 MHz oscillator"65, Normalfrequenzoszillator -> "reference frequency oscillator"

author: schmitt trigger
author_rank: Super Contributor
timestamp: October 23, 2019, 01:32:50 pm
content: Impressive beyond belief!Having being personally involved in electronics assembly for most of my professional life I was wondering:How did they build this thing?What did the test and alignment procedure looked like?How many details would have to be included in dozens of assembly drawings?The bill of materials?And I concluded something:This must have been assembled by nude blonde virgins, working in secluded cottages deep in the woods of the Schwarzwald, assisted by elves while singing Gregorian chants.Or something similar.

author: WattSekunde
author_rank: Regular Contributor
timestamp: October 23, 2019, 02:11:46 pm
content: Nice product overview from 1947-1998 about the test and measurement equipment "elektronische Messgeräte" from Wandel & Goltermann. The text is only in german but the pictures...https://www.wg-foundation.de/fileadmin/templates/pdf/Fert_Prog.pdfPSM-19 is on page 11. The price tag on page 4 says: 34.650 DM. I would agree around 45k$ today.Source:https://www.wg-foundation.de/index.php?id=1

author: SilverSolder
author_rank: Super Contributor
timestamp: October 23, 2019, 04:08:41 pm
content: Would a lot of this fine instrument have been laid out by hand, back in the day?In any case, an impressive expression of the science and art of electronics!

author: German_EE
author_rank: Super Contributor
timestamp: October 23, 2019, 06:13:33 pm
content: Looking for those high resolution teardown photographs, anybody know the link?

author: tszaboo
author_rank: Super Contributor
timestamp: October 23, 2019, 06:48:44 pm
content: Very impressive, lot of engineering.Imagine the teamwork in this modular design. Maybe a dozen EE was involved in designing and laying out each board. Every board with clear specification and requirements. Every board individually had their performance benchmarked, characterized and documented. Imagine you have to go back and make your board just a little bit better, an extra 2dB noise floor. Tens of thousands Deutsche Mark worth of testing equipment lying in the lab.1600 Employees in 1998.Now I want to go here and see this:https://www.wg-museum.de/das-museum/

author: PA0PBZ
author_rank: Super Contributor
timestamp: October 23, 2019, 07:27:42 pm
content: I got one in working condition! Very nice to receive VLF communication. Also, I wonder why the manual in the drawer says SPM-16?

author: SparkyFX
author_rank: Frequent Contributor
timestamp: October 23, 2019, 08:06:11 pm
content: Quote from: German_EE on October 23, 2019, 06:13:33 pmDaves flickr account

author: chronos42
author_rank: Regular Contributor
timestamp: October 23, 2019, 08:26:55 pm
content: Several years ago, I have made a repair report about a W&G NFA-1 audio analyzer for Ralf Ohmbergers Website amplifier.cd.(https://www.amplifier.cd/Test_Equipment/other/NFA-1/Teil1/NFA-1_Teil1.html) Only in German language, I also did not open the cans to take photos, but you can recognize the typical W&G design. Same sort of construction like all W&G instruments from the 80th and early 90th. I got it defective from eBay for 300 Euro. At this time, I did not know much about Wandel & Golterman. It blowed my mind when I saw the unit from inside the first time. I have never seen something like this before. I have repaired this wonderful piece of measurement gear and I am still using it when doing some audio stuff.Althought the NFA-1 is a very complex design the repair was not too hard because of the modular design, the very good documentation and the firmware with lots of internal selftest functions.The NFA-1 uses 4 processor boards with Intel 8085 and 8086 CPUs, two of them are also fitted with an AMD 9511 math coprocessor. There was a defective 74HC27 at one of the processor boards. After replacing this chip the NFA-1 came back to life. I also had to do some re-capping in the power supply and had to replace the old and leaking Ni-cd backup-accus, that was all. The unit is still working 10 years after repair without any problems.

author: Fungus
author_rank: Super Contributor
timestamp: October 23, 2019, 11:36:57 pm
content: C'mon Dave, we gotta see inside that power supply!I can't believe it'sthatdifficult to access in a design like that.

author: schmitt trigger
author_rank: Super Contributor
timestamp: October 24, 2019, 02:52:37 am
content: I second your motion!We need a part 2 for this product’s video.Your insightful comments on the individual components would also be interesting.

author: Dundarave
author_rank: Regular Contributor
timestamp: October 24, 2019, 03:38:21 am
content: I noticed what appeared to be something that looks like a bodge in this otherwise flawlessly built instrument... Any ideas what these "flying leads" might be doing? Their orientation looks a bit "undisciplined" and possibly in danger of shorting out some other parts, but it might be just the depth of field playing tricks... I thought it most unusual considering the care and attention given to the design and build.

author: BrianHG
author_rank: Super Contributor
timestamp: October 24, 2019, 03:53:15 am
content: Quote from: Dundarave on October 24, 2019, 03:38:21 amAdjustable sub-picofarad and inductive filter for the 2 germanium mixing diodes tied to the adjacent balun transformers.You adjust them by bending them closer and further apart. I've also seen this trick in old FM radio tuners where 2 shielded wire, around the type of network cable, are twisted together, but, the top is cut with no connection anywhere. The filter/mixer is tuned by the number of twists (around 2-4 twists, sometimes 2 or 3 wires together depending on design). In the case of this unit, it is tuned to an unbelievable super sharp edge as the 2 wires are just spaced apart floating in mid air. Altering the bend of those 2 wires would alter the characteristics of that transformer-diode mixing/detector filter.

author: Bud
author_rank: Super Contributor
timestamp: October 24, 2019, 04:01:41 am
content: It is called "gimmick capacitor"https://en.m.wikipedia.org/wiki/Gimmick_capacitor

author: rf-messkopf
author_rank: Regular Contributor
timestamp: October 24, 2019, 08:10:42 pm
content: Quote from: WattSekunde on October 23, 2019, 02:11:46 pmThe PSM-19 was actually intended to be part of a combo of three instruments. The other two were the PS-19 "Pegelsender" (level transmitter) and the SG-4 "Sichtgerät" (display unit). Together these three instruments make up a very nice and high dynamic range low frequency scalar network analyzer that can even measure frequency converting DUTs.But even alone the PSM-19 is still a very useful and capable instrument today, and is definitely worth fixing. It also makes good VLF, LF and short wave receiver, and could be used as a measuring receiver.The coaxial connectors on these units are Wandel & Goltermann Versacon convertible connectors. The outer part of them can be detached and changed to another connector standard. There is a special wrench for them with a stud that fits in the holes in the connector body. A very nice system that unfortunately is extinct today (no idea if the W&G successor companies still make them).By the way: There is a small Wandel & Goltermann museum near Reutlingen, where the company was headquartered. No idea if it's worthwhile, I haven't gotten round to visit it. Anybody been there? Link (German only):https://www.wg-museum.de/W&G also manufactured emergency vehicle lighting, sirens, and destination displays for trains, hence the police car in there.

author: schmitt trigger
author_rank: Super Contributor
timestamp: October 24, 2019, 08:46:37 pm
content: Unfortunately the museum, based on my scant German language abililities, it is only open to the public for a few hours every two months or so.

author: szymon019
author_rank: Contributor
timestamp: October 24, 2019, 09:26:02 pm
content: Thank you: rf-messkopf about mentioning story about their Versacon connectors. I though to replace front connectors on my W&G SNA-2 (VNA) to something standard but since I saw how it is made I decided don't to touch this.Maybe someone have 2pcs of 50Ohm BNC Wandel Goltermann Connectors and would like to share/ sell them in some normal price to Poland?Kindly RegardsSimon

author: rf-messkopf
author_rank: Regular Contributor
timestamp: October 24, 2019, 10:00:15 pm
content: Quote from: szymon019 on October 24, 2019, 09:26:02 pmSometimes they pop up on ebay, for example auction 223660316714 for a lot of five (I'm not affiliated with that auction):https://www.ebay.com/itm/Wandel-Goltermann-Versacon-Einsatz-BNC-5Stk/223660316714?hash=item341331982a:g:nckAAOSws0JaYguJNo idea if they are 50 Ohms and will fit on the SNA-2. Another idea might be to ask some German used equipment dealers.Quote from: schmitt trigger on October 24, 2019, 08:46:37 pmTrue. And you have to register in advance. But according to the website it's free, includes a guided tour and a talk, and a light meal will be served.Plus Reutlingen has a beautiful historical center and is located in a very pleasant area.

author: BrianHG
author_rank: Super Contributor
timestamp: October 25, 2019, 03:11:02 am
content: Is it just me, or, does it appear that they deliberately scratched off the part numbers on these 3 transistors I circled in red?2 of them appear to have 3 pins while the third is a four pin transistor/fet. Must be some kind of secret sauce...

author: langwadt
author_rank: Super Contributor
timestamp: October 25, 2019, 03:14:48 am
content: Quote from: BrianHG on October 25, 2019, 03:11:02 ammight have the print on the side instead of the top

author: langwadt
author_rank: Super Contributor
timestamp: October 25, 2019, 03:16:13 am
content: I wonder what such a thing might have cost when it was new

author: BrianHG
author_rank: Super Contributor
timestamp: October 25, 2019, 03:31:15 am
content: Quote from: langwadt on October 25, 2019, 03:14:48 amA closeup of the top-right transistor looks like it still shows a little of the part-number ink at the edge of the scratch/sanding marks.The other 2 also have a rough scratched appearance on top of them.Without better photographs or side view, we cant be sure.

author: mengfei
author_rank: Regular Contributor
timestamp: October 25, 2019, 04:05:29 am
content: Quote from: langwadt on October 25, 2019, 03:16:13 amI wonder why parts are soldered on the copper/ trace side, more prone to shorts

author: Kleinstein
author_rank: Super Contributor
timestamp: October 25, 2019, 08:23:24 am
content: Quote from: BrianHG on October 25, 2019, 03:31:15 amSome of the To18 case transistors have there marking on the side. There are some RF transistors with an extra 4 th pin for the case.There are even service manuals available - so not much secrecy.It is a complicated, high end instrument, but still the parts on itself don't really need very special performance. It is more about really keeping things isolated - thus the large number of separate shielded boxes. Though the input signal is only up to 25 MHz, there seem to be an internal 40 MHz IF. The main concept is likely more like a low frequency spectrum analyzer in the old way - so the similarity to an SA in not such a surprise. It is low frequency, but high accuracy.

author: EEVblog
author_rank: Unknown
timestamp: October 25, 2019, 09:10:52 am
content: Quote from: langwadt on October 25, 2019, 03:16:13 amSomeone said US$45k in todays dollars

author: EEVblog
author_rank: Unknown
timestamp: October 25, 2019, 09:14:16 am
content: Quote from: Fungus on October 23, 2019, 11:36:57 pmMaybe not, but I knew the video was already way too long.I have to do a part two because apparently I missed an entire side of cans!I might clear some bench space to set it up for a semi-permanent repair series.

author: langwadt
author_rank: Super Contributor
timestamp: October 25, 2019, 11:07:23 am
content: Quote from: mengfei on October 25, 2019, 04:05:29 amseveral components go to single pads so it must be a dual sided pcb

author: JeanF
author_rank: Regular Contributor
timestamp: October 25, 2019, 11:27:14 am
content: back in 2016 when I was collecting stuff for a GPSDO (in the end this project never started, but I'm still thinking about it from time to time) I bought the oscillator that can be seen at the 20 minute mark on ebay for cheap.Do some of you have documentation about this oscillator ? I wasn't able to find any datasheet, I think I managed to find Vcc and GND and the output pin, but I didn't find what the 4th pin is. It seems to be not connected to anything but I can't be sure and I don't want to open the can. I thought it could be VCO control pin but I wasn't sure about how to check that without risking damaging anything. And there is a screw for adjustment showing through a hole in the can, is it possible to have at the same time a mechanical adjust screw AND a VCO control pin?Unfortunately I don't have the PCB anymore, only the blurry picture (not mine, from ebay listing) attached.The fact that I don't have the datasheet nor the full pinout is a serious limitation to using it for anything too serious, but what do you think I could still use this XO for ?

author: rf-messkopf
author_rank: Regular Contributor
timestamp: October 25, 2019, 11:35:37 am
content: Quote from: JeanF on October 25, 2019, 11:27:14 amSorry, I don't have a datasheet. But the manufacturer is Quarzkeramik GmbH. They were bought by Kristallverarbeitung Neckarbischofsheim in 1997. You can try to ask there, but I wouldn't have too much hope. Link to their homepage:https://www.kvg-gmbh.de/.

author: Fungus
author_rank: Super Contributor
timestamp: October 25, 2019, 12:17:20 pm
content: Quote from: BrianHG on October 25, 2019, 03:11:02 amIt's just you.Think: Those things come with full schematics...

author: wn1fju
author_rank: Frequent Contributor
timestamp: October 25, 2019, 08:17:10 pm
content: As rf-messkopf alluded to in the earlier post, one can make a very nice scalar network analyzer with the PS-19 generator, SPM-19 receiver and SG-4 display unit. Here's a picture of my setup measuring the frequency response of a 7.15 MHz center frequency bandpass filter (not shown). Enjoy!(and it took a while to make up all the cables one needs to get these three things to play nice)

author: xi00
author_rank: Newbie
timestamp: October 27, 2019, 06:44:23 pm
content: Quote from: wn1fju on October 25, 2019, 08:17:10 pmHi. Does anyone know if it is possible to use the SG-4 display unit without the SPM-16/19, ie providing the x and y deflection voltages on the 14pos connector(i think using cable K145) manually and not interfacing with the IEEE-488 bus at all? I am asking because i couldn't get my hands on a manual for the SG-4, but according to the SPM-16/19 manuals it is possible, at least for the SG-2/3, and i only have the SG-4 and none of the other instruments.Thank you in advance

author: wn1fju
author_rank: Frequent Contributor
timestamp: October 27, 2019, 08:20:34 pm
content: There might be a work-around if only we had the manual. I never found one, although I haven't searched again in quite a while.On my SG-4, if I power it up without hooking it up to the other equipment, all I get is the message "SPM ?" on the screen and the unit is otherwisetotally unresponsive to the front panel.If I recall (it has been a few years since I had everything running), it wants to see both the 14-pin analog and the 24-pin GPIB cables hooked up.And if the GPIB settings aren't right on the SPM-19, it will pass by the "SPM ?" message and the screen will say "GP-IB?".Not that it can't theoretically be done, but it looks as though W&G really intended the SG-4 to work only with the SPM-16/19 receivers.

author: rf-messkopf
author_rank: Regular Contributor
timestamp: October 27, 2019, 11:09:14 pm
content: Quote from: wn1fju on October 27, 2019, 08:20:34 pmYou can order photocopies of the SG-4 manuals from Rainer Förtig in Germany. See his price list athttp://rainer-foertig.de/unterlagen/WG-9_2009.htm.Translation:"Service-Unterlage ohne Schaltbilder" = service manual without schematics"Beschreibung + Bedienung" = operations manual"Schaltbilder" = schematicsThe manuals I got from Rainer Förtig in the past were all of excellent quality.Edit: I forgot to mention that the manuals might be in German. You should ask before ordering.Edit 2: The price list actually says that they are in German.

author: xi00
author_rank: Newbie
timestamp: October 28, 2019, 10:44:17 am
content: The language shouldn't be a problem as I'm from Austria, and thanks a lot so far.Maybe it is possible to "hardcode" some required GPIB init messages and then it works without more GPIB, i will see what can be achieved with the manuals...

author: Syntax Error
author_rank: Frequent Contributor
timestamp: October 29, 2019, 09:51:47 pm
content: Dave, indeed a master class in construction.How many drawings do you think it took to make this? I suspect the designer's other jobs were in avionics and space systems, as there's very little waste of anything. Hardware like this kept a lot of skilled people in work. And if you find any youngsters complaining that FPGAs are "a bit difficult", show them how it was done... analogue style.

author: thinkfat
author_rank: Unknown
timestamp: November 02, 2019, 09:41:53 pm
content: Look what I found in an old EEVblog video:https://youtu.be/3yTL06ZU5SU?t=249Hint: Top shelf on the left side.

author: German_EE
author_rank: Super Contributor
timestamp: November 03, 2019, 08:43:46 am
content: Good spot!

author: bsdphk
author_rank: Regular Contributor
timestamp: November 03, 2019, 11:31:18 am
content: I gather from the debate that nobody here truly appreciate how much of an engineering marvel "carrier-frequency telephony" was back in analog days.Here are some info to try to put it in proper perspective:The "L5" system, which for all practical purposes was the final and ultimate in carrier-frequency transmission before everything went digital, modulated 10,800 telephone channels, each 4kHz wide, onto a single coax-cable, and transmited the signal in "toll grade" quality, which includes 44dB S/N ratio, from one side of USA to the other, or rather: up to 4000 US miles.This required a repeater every single mile, literally 4000 repeaters one after the other, each amplifying the signal 25dB to compensate the loss of one mile of telco-grade coax. Well, "approx 25dB" because the attenuation depends on the temperature...And yes, that means the total amplification from coast to coast was 100,000 (a hundred thousand) dB at the top frequency near 60 MHz.Now, imagine if those 4000 amplifiers due to some accident of design or manufacturing all had 0.01dB dip or bulge at the same frequency ?Or imagine if the coax had a little nick every N meters, due to a piece of debris on a pulley wheel in the factory ?Ohh, and since the total frequency range is 1.5 to 60 MHz, better watch those I2 and I3 distortion products.And did I mention that the repeaters live in a damp hole in the ground or boltet to the top of a tall wooden pole, out in the middle of nowhere ?*Now* you can start to appreciate why HP, W&G and others built instrumentation to those insane specs, in particular with the ability to measure dB to part of thousands.The HP3336 and HP3586 for example were built as a matched pair, directly focused on the L4 Carrier systems "only" 3600 telephone channels. They were some of the first microcontroller controlled instruments ever, which made it possible to measure all 3600 channels in a matter of minutes.For more information on L5 see:https://archive.org/details/bstj53-10-1901(And the entire rest of the BSTJ december 1974 issue on archive.org)

author: vk6zgo
author_rank: Super Contributor
timestamp: November 03, 2019, 03:33:12 pm
content: Quote from: bsdphk on November 03, 2019, 11:31:18 amThe difficulties involved are why PMG/ Telecom Australia shifted largely to terrestrial microwave systems.Those were the days, though---when the "coax" from Perth to Geraldton was laid, they used Cat D9 dozers with a ripper on the back, with the cable direct laid in the trench formed.All went well with the sandy coastal soil & sandstone, but everything slowed to a crawl when they hit some really hard rock which seemed to go on forever.The wear of the ripper blades was horrific, too, so much so, that Cat sent an Engineer over from the USA , with the instruction " Don't come back till you find out how to fix it!"He dutifully studied the problem, sent all the data back to his home base, who came up with special ripper blades which did the job!I bet you wouldn't see that sort of response these days!

author: bsdphk
author_rank: Regular Contributor
timestamp: November 03, 2019, 05:25:08 pm
content: Well, it's not like microwave didnt come with its own baggage...For that you want to read about the TD3 system in the September 1968 issue of BSTJ :-)Link to intro article:https://archive.org/stream/bstj47-7-1143The technical stuff is all the rest of that issue.But if you want to read about the *truly* crazy project, read about the WT4 system in the December 1977 issue: A 60mm waveguide all the way across USA.Again: Link to intro:https://archive.org/details/bstj56-10-1829Read full issue for the gory details, especially the article about the 20 millisecond waveguide shunting machine...

author: szymon019
author_rank: Contributor
timestamp: November 03, 2019, 06:36:58 pm
content: Some other photos of internal parts of SNA-2 (Spectrum Vector Network Analysator -2). Attenuators section on glass.

author: vk6zgo
author_rank: Super Contributor
timestamp: November 04, 2019, 01:57:29 am
content: Quote from: bsdphk on November 03, 2019, 05:25:08 pmThe East-West microwave system in Oz suffered from the problem of tube technology, but still did a very good job.The ongoing fantasy among EEs of turning Techs into "module jockeys" also raised its head.Unfortunately, not everything could be swapped back through the "Central Maintenance Depots", so a fair amount of "on site" repair was still needed.Another problem was tropospheric ducting.Re-use of frequencies was restricted to several "hops" ( you may use the same frequencies every two or three hops).Unfortunately, "ducting" sometimes caused interference between the local "direct" signal from the desired site & the ducted signal from several (or more) previous sites.This was minimised by changing the direction of transmission between each site & the previous ones, as much as practicable.Even so, there were still minor problems from time to time during the Summer.Australia lent itself well to the extensive use of microwave systems, with much of the country fairly flat, & large population centres being quite far apart.

author: Ray Gianelli
author_rank: Contributor
timestamp: November 06, 2019, 06:13:05 pm
content: I've seen several of these laying in corners in various central office's I've been in.

author: schmitt trigger
author_rank: Super Contributor
timestamp: November 07, 2019, 04:27:13 pm
content: The calibration stickers show that the last due date calibration was July 17, 2002.So it has been a while since they were last used.

author: johnh
author_rank: Regular Contributor
timestamp: November 08, 2019, 06:18:08 am
content: I wouldn't' say that.Where I work we often use some equipment that hasn't being calibrated for a long.

author: exor
author_rank: Regular Contributor
timestamp: December 01, 2019, 01:03:59 pm
content: I have SPM-19 and also NFA-1. They have been resting long time waiting for my new lab bench to get ready.SPM seems to be fine but it looks that the rest hasn’t done any good for the NFA-1. No picture, just small dot on upper left corner. Maybe (hopefully) it is some power supply issue.. Fortunately I have manual and circuit diagrams for it.Last week I found SG-4 from eBay (PL) for the SPM, should arrive next Tuesday (there is still one available if someone is interested). I hope that beginning of next year I’m able to fix the NFA and pile them all on my new bench

author: jt
author_rank: Regular Contributor
timestamp: February 24, 2020, 05:04:59 am
content: I watched this when I was a bit tipsy... and I ordered one from ebay... No regrets

author: Pixelvore
author_rank: Newbie
timestamp: January 06, 2021, 11:47:41 pm
content: Quote from: xi00 on October 27, 2019, 06:44:23 pmHi could you please tell me if the cables attached on SG4 are pin to pin on the spm-19? Do you have a pin out table? Thanks i just bought them but there were no cables included. Please help