hybridfree/eevblog-posts huggingface dataset:
unable to simulate oscillator's open loop gain & phase with OscTest probe - Page 1
Forum section: electronics / rf-microwave

author: biastee
author_rank: Regular Contributor
timestamp: June 05, 2019, 06:00:19 am
content: I am trying to simulate the 2 MHz crystal oscillator from the Gonzalez text, "Foundations of oscillator circuit design", pg 213, fig. 4.19..Specifically, I want to evaluate the open-loop gain and phase using the OSCTEST probe (http://edadocs.software.keysight.com/pages/viewpage.action?pageId=5919109orhttps://awrcorp.com/download/faq/english/docs/Elements/OSCTEST.htm), but has been unsuccessful; i.e. the Nyquist pole / zero plot just showed a dot at 1-j0.Aside from simulating with the OscTest probe in the position shown in the Gonzalez text, I have also tried relocating it to the alternate position between amplifier output and network (see image below), but, again, it failed to work.Strangely, when I replaced OSCTEST with OSCPROBE (harmonic balance probe), the simulation can converge and produce the output spectrum & waveform.Please help. TIA.
FST3253 for 500MHz Tayloe Detector? - Page 1
Forum section: electronics / rf-microwave

author: frogg
author_rank: Regular Contributor
timestamp: June 03, 2019, 04:14:40 pm
content: Does anyone know if the FST3253 can be switched at a frequency high enough to implement a Tayloe Detector for 500MHz signals? (let's say for an IF of 1MHz or less)Is there a better part for that application?Or is it more typical to design a double downconversion so the Tayloe Detector would be clocked at a more "reasonable" frequency?

author: ogden
author_rank: Super Contributor
timestamp: June 03, 2019, 04:40:27 pm
content: Quote from: frogg on June 03, 2019, 04:14:40 pmYes. Exactly. I am not aware of mux that can operate at 2GHz switching frequency. Downconvert 500MHz into 10.7 MHz IF - to use widely available filters, run Tayloe detector at 4*10.7MHz. Sounds like a plan

author: frogg
author_rank: Regular Contributor
timestamp: June 03, 2019, 04:59:12 pm
content: you rock, ogden, thanks!
Derivation for ABCD matrix of backward-wave directional couplers - Page 1
Forum section: electronics / rf-microwave

author: promach
author_rank: Frequent Contributor
timestamp: June 02, 2019, 10:35:58 am
content: How to derive theABCD matrixfor the followingbackward-wave directional couplers?Note: I could not locate Table 2.2 in the book
[SOLVED] Using HP 5086-7151, 2-18GH YIG multiplier - Page 1
Forum section: electronics / rf-microwave

author: widlokm
author_rank: Contributor
timestamp: April 27, 2019, 02:52:34 pm
content: Hello,I am working on a project (for fun and learning) that need an RF generator with about 4-18GHz range. I would like to use HP YIG multiplier like that, that accepts 2-6GHz source and produce 2-18GHz output (more then needed).Do You know some details about this HP module?Do You know a HP device that this module was used in, that has schematics available?I already know something, that module was used in HP8672A generator and some info can be gathered from a service manual. Unfortunately the manual does not have a schematic or control voltage details.While I think that I can find most of the things by trial, an info would be a great help.Thanks in advance,Michael Widlok

author: widlokm
author_rank: Contributor
timestamp: April 28, 2019, 12:03:59 pm
content: After some searching I found ~600 page HP8672 manual with full schematics. I can also confirm that all data for the HP5086-7151 YTM and HP5086-6151 board is there.Manual can be downloaded from:https://elektrotanya.com/hp_8672a.pdf/download.html#dl

author: cx1cnc
author_rank: Newbie
timestamp: June 01, 2019, 09:11:45 pm
content: Hi Michael,I am curious to know if you put your YIG multiplier to work.I got a 5082-6272 YTM from eBay several months ago and now I've got it performing acceptably (for my standards at least), but it does show a rather jumpy passband and higher than expected multiplication loss.So I was wondering if your unit shows this kind of response or it is "tidier" because I am considering getting another unit if there are chances of improvement.I am suspicious of this particular unit because it received at least one smash that broke the heater-control opamp ceramic 8-DIP (I replaced with a plastic OP07) and the YIG sphere (there is only one) might have been displaced by that event.I am attaching a hand-sketch of the response of my unit at 18GHz multiplying x3 a +20dBm input signal of 6GHz. I got an output peak power near +5dBm in this particular test, so 0dB loss in the graph is relative to this output level.Regards,Fernando
Do I need DC blocking caps with the HMC1118 RF switch? - Page 1
Forum section: electronics / rf-microwave

author: pratiken
author_rank: Contributor
timestamp: June 12, 2019, 06:47:42 am
content: HiI'm using HMC1118s in a design and I'm wondering if I need DC blocking caps or not.In the datasheet (attached) it states " A dc blocking capacitor is required if the RFline potential is not equal to 0 V dc. " What would cause the RF line potential to not equal 0V?Would it hurt anything negatively if I added some 90pF caps either way?I'm testing WiFi 2.4 and 5Ghz bands with power no more than 27dBm.Thanks!

author: rfengg
author_rank: Regular Contributor
timestamp: June 12, 2019, 08:00:30 am
content: It is very common to "multiplex" dc voltages with RF lines (think of how the booster on the top of your TV mast is powered with a single coax?) which causes dc to appear on the RF lines.It seems obvious that the RF ports of the switch are dc coupled , so if you had DC voltage on the RF lines they would dissipate power in the internal 50 ohm when the switch is terminated internally. If the voltage is high enough, it could the damage the internal 50 ohm termination as well. Remember that this is a non-reflective switch which means that when the switch is not routed to the RF port, it is internally terminated.If you are absolutely sure that there is no dc voltage on the RF lines , no need for any caps at all.If there is dc voltage, consider the ESR and voltage rating of the cap depending on the dc bias on the RF line as well as choose a cap which is a TRUE bypass for the frequency of use.In other words, the cap you use should be of low reactance (>5ohms) at your frequency of use.90pF at 2.4GHz is less than 1ohm but the internal and external lead inductance could be significant, so avoid long leads and parasitic inductance.90pF is a standard value? Could you post the data sheet of the capacitor that you plan to use?

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: June 12, 2019, 08:42:21 am
content: Also consider the fact that you don't only need to protect your switch from other devices putting DC on the transmission line, but your switch (or amplifier or whatever) could be injecting DC voltages itself, so you might need to protect other circuits from the switch.I used to have a set of standard DC block capacitors. You can have two causes of loss here: First, the mismatch that your capacitor introduces, but also the loss due to the dielectric loss within the capacitor. So if you want really high performance, consider using a good capacitor (good dielectric). Also realize that you don't care that much about just how much capacitance you have - so long that it is big enough to be close enough to an RF short you are fine.
Propagation delay through coaxial cable? - Page 1
Forum section: electronics / rf-microwave

author: rfengg
author_rank: Regular Contributor
timestamp: May 30, 2019, 03:25:27 am
content: If I assume that the dielectric constant of the coaxial cable that I use is constant with respect to frequency, then, is the propagation delay through the cable constant with respect to frequency?In order words, if at one time, I send a sine wave of 1Mhz down the line and in another case send 100Mhz down the line, will the propagation delay of these two frequencies through the cable be the same?

author: RoGeorge
author_rank: Super Contributor
timestamp: May 30, 2019, 03:41:30 am
content: No. The speed of light isv = 1 / sqrt(epsilon * miu), so the dielectric property being constant will not be enough if the magnetic permeability varies with the frequency.See page 3 for the speed of light formulahttps://topex.ucsd.edu/rs/em_summary.pdf

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 30, 2019, 05:55:34 am
content: Which, since coax isn't magnetic, that's fine.More subtle things apply though. At low frequencies, the magnetic field penetrates deeper into the conductors (skin effect), thus the impedance is slightly higher, and the velocity slightly....lower? I forget.In general, dispersion is a thing, it happens. If you need low dispersion line, either find some that's better than usual, or compensate it with filters (and amps as needed).Tim

author: radiolistener
author_rank: Super Contributor
timestamp: May 30, 2019, 11:53:31 am
content: no, it depends on the frequency. For example:Also, coax cable on low frequencies has too high impedance error.
Power off Pre-Amp during Tx - Page 1
Forum section: electronics / rf-microwave

author: RobBarter
author_rank: Regular Contributor
timestamp: May 28, 2019, 09:15:32 pm
content: I have a preamp mounted at the mast alongside a 300W 1.2GHz amp. The input and output to the preamp is protected by RF relays (approx 80dB isolation).Anybody also turn the power off to the preamp during transmit as an added protection?

author: rfengg
author_rank: Regular Contributor
timestamp: May 29, 2019, 08:09:01 am
content: 300W is approx +55dBm, so with 80dB isolation , you have -25dBm into your preamp; most preamps should survive this sort of power.Cant see how switching the preamp how will protect the preamp better?Its the voltage swing across the typical LNA pHEMT's (or ather active devices) gate that cause a breakdown across the thin gate region.If you switch off the preamp , you need also to be concerned and account for the recovery time of the preamp from its OFF to ON time to which it stabilizes.If you are overly concerned, a low capacitance anti-parallel fast schottky diode will ease your mind.......or you can actively clamp the input of the preamp with a PIN diode.Things to be concerned about with this implementation : Some preamps do not like a short across its inputs and could oscillate.PIN diode capacitance and recovery time will degrade your preamp slightly.

author: cgroen
author_rank: Unknown
timestamp: May 29, 2019, 08:32:39 am
content: In my "moonbounce" days, I was always told that it was much safer to let the preamps be powered up also during TX (I got a long explanation that I no longer remember). This was both on 144 MHz with killowats of power as well on 1.2GHz with 200W (and a 8m dish)

author: RobBarter
author_rank: Regular Contributor
timestamp: May 29, 2019, 08:53:29 am
content: Thanks for the replies. Saved me a re-spin of my masthead controller pcb. I had circuitry that turned off the preamp during Tx but my latest pcb had a few "enhancements", one that didn't work. I can easily fix it to not turn off during Tx, without a new pcb, but still be able to turn off from down below (good for checking if the preamp and aerial are still ok).The fault was caused by me labeling an input incorrectly which resulted in the design of the switching circuit being the wrong way round (switching on when pulled to ground when it should have been switch off when grounded. Took about 0.75 seconds to realise when I looked at the schematic after the leds didn't act as expected.
Unitary property of scattering matrix - Page 1
Forum section: electronics / rf-microwave

author: promach
author_rank: Frequent Contributor
timestamp: May 20, 2019, 09:56:45 am
content: Froms-parameter lossless network definition, The sum of the incident powers at all ports is equal to the sum of the reflected powers at all ports.But how do we derive the above unitary property expression involving S22 and S21 ?

author: in3otd
author_rank: Contributor
timestamp: May 22, 2019, 07:35:48 am
content: That same Wikipedia pages says that a lossless network has an unitary S-parameters matrix, that is \$\mathbf{S}^{H}\mathbf{S}=\mathbf{I}\$. If you do the matrix multiplication, you'll obtain three independent equations, one of which it the one you posted.

author: promach
author_rank: Frequent Contributor
timestamp: May 26, 2019, 03:42:23 pm
content: WhySHS=I?

author: ejeffrey
author_rank: Super Contributor
timestamp: May 28, 2019, 03:46:01 am
content: Its just from the conservation law. Conservation of energy states: \$\vec{a}^\dagger\cdot \vec{a} = \vec{b}^\dagger\cdot\vec{b}\$ (power in = power out). But \$\vec{b} = \mathbf{S} \vec{a}\$. That leaves you with \$\vec{a}^\dagger \mathbf{S}^\dagger \mathbf{S} \vec{a} = \vec{a}^\dagger\vec{a}\$. That implies \$\mathbf{S}^\dagger\mathbf{S} = \mathbf{I}\$ which is the definition of unitary.
Watertide LNA? - Page 1
Forum section: electronics / rf-microwave

author: Lord of nothing
author_rank: Super Contributor
timestamp: May 28, 2019, 06:41:12 am
content: HiI looking for an Watertide LNA. I got a long time ago a Discone Antenna who I mounted on a Pole next to the House. Now I will buy a cheap Antenna Cable and since the Discone have no Gain I would need a LNA to receive anything.Maybe with an Bias-T to.Thanks
Dry erase Smith chart? - Page 1
Forum section: electronics / rf-microwave

author: 0culus
author_rank: Super Contributor
timestamp: May 27, 2019, 03:10:32 pm
content: Does there exist anything like this? I've used web apps and there's also plenty of engineering notebooks out there with Smith chart paper, but I'd like something I can hold, that is also easily erasable.Or something similar to the jig the stereotypical 1960s engineer is holding in thisHP app note, page 3.

author: mzzj
author_rank: Super Contributor
timestamp: May 27, 2019, 04:01:51 pm
content: Smith chart printed to overhead projector sheets, draw your scribbles with non-permanent OHP pen or whiteboard pen.If you print in mirror image and draw to opposite side the print is going to last forever

author: DaJMasta
author_rank: Super Contributor
timestamp: May 27, 2019, 04:24:27 pm
content: As a similar sort of workaround, you could have one printed on in whatever size format you wanted and then laminate it.

author: 2N3055
author_rank: Super Contributor
timestamp: May 27, 2019, 04:51:42 pm
content: Google "smith chart slide rule"

author: 0culus
author_rank: Super Contributor
timestamp: May 27, 2019, 05:00:45 pm
content: Thanks for the suggestions everyone. I guess now the problem is to find a lamination machine...or a print shop willing to make overhead projector sheets. I'll look at slide rules too.

author: ogden
author_rank: Super Contributor
timestamp: May 27, 2019, 05:12:27 pm
content: Quote from: 0culus on May 27, 2019, 05:00:45 pmPreprinted paper put into translucent document sleeve will work a treat. Also you need "dry wipe" whiteboard markers.

author: 2N3055
author_rank: Super Contributor
timestamp: May 27, 2019, 05:14:39 pm
content: there is self adhesive transparent film for inkjet printers..

author: David Hess
author_rank: Super Contributor
timestamp: May 27, 2019, 06:52:16 pm
content: Quote from: mzzj on May 27, 2019, 04:01:51 pmYep, that is exactly what I was going to suggest. Printable overhead projection sheets for laser or inkjet printers are still available. They are made of Mylar (polyester) which is incredibly tough. Print a reversed Smith chart and then write on the smooth (non-printable) side.This also works well for quick and dirty front panel overlays and punch out diagrams.
B4063 RF Filter - Page 1
Forum section: electronics / rf-microwave

author: mpradio
author_rank: Newbie
timestamp: May 23, 2019, 03:58:57 pm
content: Hi, I would need to find the data sheet for component B4063, apparently it's an RF filter manufactured by Pulse Electronics. It is not on the website of the manufacturer may not be sold more, and they does not answer the email I sent them.thank you.

author: nabnab
author_rank: Newbie
timestamp: May 25, 2019, 11:26:23 pm
content: Hi,Please you find it here:https://pdf1.alldatasheet.com/datasheet-pdf/view/189268/EPCOS/B4063.html

author: mpradio
author_rank: Newbie
timestamp: May 26, 2019, 10:14:05 pm
content: thank you nabnab!, but that is not the same component.
PCB Coil calculator  - Page 1
Forum section: electronics / rf-microwave

author: DimitriP
author_rank: Super Contributor
timestamp: May 26, 2019, 12:19:22 am
content: A coil exists and I've been trying to calculate its inductance. That was yesterday.The closest usable calculator I've stumbled on is this one:https://www.allaboutcircuits.com/textbook/reference/chpt-1/inductor-sizing-equation/It has two formulas, one for the trace width equal to the trace spacing and one "not".Other than there seems to be an error in the formula for the "unequal width vs spacing" formula where the number of turns is conveniently ignored, I can't really use the formula on the left sinceA) the trace width is different from the spacing,B) the coil for which I''m trying to calculate its inductance is not "square".Pictures worth a thousand words etc... I've included a pictureThe trace forming the coil is 1.3 mm, and the spacing 0.8 mmMaybe someone knows of a better formula or calculator "out there" ?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 26, 2019, 01:04:34 am
content: Not aware of any that are particularly accurate. The old Wheeler formula is a pretty common sight.Use the square formula, dimensioned for equal area (i.e., width = sqrt(height*length)).You probably aren't going to get much closer without a numerical simulation or actual build, anyway. Plan for a wide tuning range (multiple taps, adjusting tuning/matching capacitors before design release) or a few rounds of prototypes.Note that the solid copper around the outside acts to short out the external field, giving much lower inductance than a free spiral will. I would guess this about halves the inductance of the shape shown.Note that the few turns in the middle, contribute very little inductance, meanwhile they contribute not just series resistance, but parallel (eddy current) resistance as well. It is more inductance than without, but it is much lower Q. If a higher Q is desirable, consider a ring with OD = 2*ID or thereabouts.If a still higher Q is desirable, consider using both layers (if possible) and clamping two ferrite plates on either side. This can give mu_eff ~ 10, and significantly reduces the external field.Higher still, consider a gapped planar core and multilayer board.Or if this is an antenna, and you need the external field, a bigger loop is always better. Maybe you don't need too much after all (e.g., NFC), or want it fairly localized, in which case an intermediate design will have the best compromise between power consumption and range.Tim
North Hills Signal Processing app notes? - Page 1
Forum section: electronics / rf-microwave

author: mark03
author_rank: Frequent Contributor
timestamp: May 23, 2019, 06:25:40 pm
content: Wondering if anyone here has an archive of these? I am looking for #160, "Measurements of two-port balanced networks." It is still in google at the old URL (http://www.nhsignal.com/pdf/appnote-wb-160.pdf/), now defunct. It redirects to ddc-web.com which has a fairly horrible interface, but struggling with their "file library" I am 99% confident the NH app notes did not survive the transition. The Internet Archive has some, but not all (and not #160).

author: in3otd
author_rank: Contributor
timestamp: May 24, 2019, 01:23:31 pm
content: is it this one? :https://www.datasheetarchive.com/whats_new/2d8c4234f436be5ad6137622b07b45e1.html

author: mark03
author_rank: Frequent Contributor
timestamp: May 24, 2019, 04:17:44 pm
content: Thanks Claudio! My google-fu is apparently weaker than yours; I tried everything and still couldn't find it. Although, now that I see it, it's a rather superficial treatment which doesn't tell me anything new. I was just looking for practical advice on how to best perform antenna and matching network measurements at HF, because I am planning to use ladder line rather than coax. I found an HP app note somewhere else which has better detail.I wonder if there is anything special inside the North Hills' baluns that couldn't be achieved just as easily by hand with a binocular core and some small wire...
matching network - Page 1
Forum section: electronics / rf-microwave

author: khiworld
author_rank: Newbie
timestamp: May 24, 2019, 10:01:25 am
content: I just finished the PCB antenna design and then I will measure the S11 and VSWR from VNA. Before the measurement, I would like to make sure if my understanding about matching network is right or not.The first step is to measure the s11( input impedance) of antenna itself.The second step is to match it to be 50 ohm. I could add the matching network before the antenna to set to 50 ohm or I could cut the copper tape on antenna to set to 50 ohm. I guess the later is better.It will be matched z1* to 50 ohm.The next step is measure the output impedance(or s parameter) of RF chip. We want it to be 50 ohm. But, I won’t be…So, I will add another matching network to match z3* to z2*( 50 ohm)U.FL( red square in the attached file) will be placed to measure the s11 value. Smith chart will be used for matching too.Please correct me if I am wrong.Thanks.

author: radiolistener
author_rank: Super Contributor
timestamp: May 24, 2019, 10:39:32 am
content: First you're needs to measure output impedance. And then you're needs to match antenna to output impedance.If you're don't use long 50 Ohm feed line and antenna is connected directly to transmitter, there is no need to match both to 50 Ohm.Also note, that coax pigtail will affect your measurement
Information about Schlumberger Antenna Switch - Page 1
Forum section: electronics / rf-microwave

author: Radiosonde
author_rank: Contributor
timestamp: May 21, 2019, 07:06:24 pm
content: HelloI was able to get this nice and well build antenna switch from the german company Schlumberger.I didnt knew that they produced antenna accesoires, I just know the service monitors.Sadly there is no information about this device available.Inside is a Narda SEM163 switch up to 18 Ghz (!) and some logic, also an Eprom and a HD6402.According to the parts inside there must be more then the simple method of just giving voltage on a certain in to switch between antennas.It would be sad if I had to scrap the electronics to insert my own.Some information would be useful.Regards

author: Radiosonde
author_rank: Contributor
timestamp: May 21, 2019, 07:09:12 pm
content: Pictures...Gesendet von meinem SM-J730F mit Tapatalk
Use this damn cheap 75Ohm Antenna? - Page 1
Forum section: electronics / rf-microwave

author: Lord of nothing
author_rank: Super Contributor
timestamp: May 19, 2019, 08:34:13 pm
content: HiI was searching for some different at my IT Distributor Online Shop and Found a damn cheap Antenna. One of them 20€ and the other 30€.Both are 75Ohm.Both cover47 - 230 MHz/ 470 - 790 MHz. Its cool the cover the lower VHF freq and DAB+ where I haven't any Atenna yet for.https://www.raidsonic.de/products/accessories/antennen/index_de.php?we_objectID=5560#propertieshttps://www.raidsonic.de/products/accessories/antennen/index_de.php?we_objectID=4434#propertiesSo can I use them even when the are 75Ohm for SDR Stuff ?!

author: ogden
author_rank: Super Contributor
timestamp: May 19, 2019, 08:51:34 pm
content: Indeed you can use those for SDR. 50/75 Ohm impedance mismatch signal loss for active receive antenna is insignificant (< 1dB or so). Further reading:https://www.eevblog.com/forum/beginners/how-bad-is-a-5075-ohm-impermanence-mismatch/

author: radiolistener
author_rank: Super Contributor
timestamp: May 21, 2019, 10:03:53 am
content: you can use it, 50 to 75 Ohm mismatch leads to VSWR = 1.5 (Г = 0.2).It means that if antenna produce 10 Volt signal, your 50 Ohm receiver will get just 8 Volt and 2 Volts will be reflected back to the antenna.But this antenna has too wide bandwidth, it means that it's efficiency is very low.So, it will works much worse, than half wavelength dipole.

author: Lord of nothing
author_rank: Super Contributor
timestamp: May 21, 2019, 03:25:55 pm
content: THX i dont need to use it. Good I was looking for that thinks befor I bought it.
CAD Tools for modelling LF 125 kHz antenna fields inside a vehicle - Page 1
Forum section: electronics / rf-microwave

author: karthiks
author_rank: Newbie
timestamp: May 21, 2019, 02:56:58 pm
content: Hi all,I am working on designing a comprehensive TPMS/PEPS system.And right now in the process of analysing the LF antenna field patterns that operate on 125kHz and their coverage.What CAD tool is the best for modelling such low frequencies (125kHz) since its a magnetoquasistatic field?I am currently investigating FEKO and its pros and cons. I will update my findings here.Thanks in advance-Karthik
IF Amplifier Differential Output Impedance - Page 1
Forum section: electronics / rf-microwave

author: ignilux
author_rank: Unknown
timestamp: May 21, 2019, 02:39:56 pm
content: All-I'm in the process of designing the IF stage of a receiver that I started a few months ago. The signal is a frequency modulated 10.7 MHz IF, and I'm feeding it through anAD8309log limiter amplifier in order to A) square-up the signal for demodulation with a PLL, and B) provide a RSSI output for an S meter, etc. Anyway, the AD8309 readily lists the input impedance seen by the signal, and I have no problem using a Smith chart to match that to the IF filter.Where I'm stuck, though, is the output impedance. The '8309 uses an internal reference to create a bias current through an external resistor. The differential open collector outputs of the limiter have their emitters fed in to the current drain setup by the external resistor, thus the current into the differential outputs is proportional to the bias current through the resistor. External load resistors connected to the differential output set the output voltage at each output. See page 17 in the datasheet (linked above) if I butchered that description. My current line of thinking is that I can simply divide the output voltage by the output bias current to find the output impedance, but I'm assuming that will only address the real component of the impedance. How can I properly calculate-- or evenestimatethe output impedance?The output will be at 10.7 MHz, and I realize that transmission line effects will be minimal here. Nonetheless, I need to transform the differential output to single-ended for the next stage anyway, so I might as well transform/match impedance there, too. For whatever reason I get really turned around anytime I have to deal with differential I/O. I know that it's relatively simple, and potentially much better for noise and signal integrity, but it always gets me.Thanks in advance for any and all input.
Glowlink Model 1000 - anyone ever touched one of these? - Page 1
Forum section: electronics / rf-microwave

author: David Chamberlain
author_rank: Frequent Contributor
timestamp: May 21, 2019, 06:15:40 am
content: I have picked up this Glowlink Model 1000 as part of a satellite downlink station teardown and was hoping to make use of it. It's a rackmount PC (pentium) running Windows XP, and has a PCI card for the RF front end that I've not yet pulled out to see what it is.http://www.glowlink.com/products/spectrum-monitoring/standard-dsp-spectrum-monitoring/model-1000What's interesting about it the front end ADC is 950-2150MHz with a 36MHz bandwidth and 115dB dynamic range, and the software that would be running on it. That frequency range is exactly what I need for another project, that's if I can re-purpose the whole machine or perhaps just the card out of the box.Only problem is that the OS has an admin password that I can not get past. If any one knows a good default password to try please let me know. p.s. it's not 'satellite', 'password', or 'glowlink'.I also have an LC100, same problem no administrator password, this time it's Windows NT.http://www.glowlink.com/products/earth-stations-mc-systems/lc1000This one has a bunch of GPIB ports on the back of and ethernet, that's about it.ThanksDave

author: David Chamberlain
author_rank: Frequent Contributor
timestamp: May 21, 2019, 06:43:08 am
content: I don't exactly believe the price of these things but there it is. That's the card from the Model 1000.http://www.ni.com/en-nz/shop/select/oscilloscope-device?modelId=122520

author: LapTop006
author_rank: Unknown
timestamp: May 21, 2019, 02:29:48 pm
content: Try this:http://pogostick.net/~pnh/ntpasswd/Or there's still tools that will take the user databases and crack the password fairly quickly if you have a grunty PC to hand.I'd make drive images before doing this, just in case.
#206 Yaesu FT 101 Series - Distorted Receive - Page 1
Forum section: electronics / rf-microwave

author: Radio Tech
author_rank: Frequent Contributor
timestamp: April 15, 2019, 12:07:24 am
content: Back after a long season I have brought the 101 series back.In this video I take a look at a rig with distorted receive and a flaky VFO.

author: German_EE
author_rank: Super Contributor
timestamp: April 15, 2019, 07:38:45 pm
content: More FT101 goodnessKeep 'em coming Buddy.

author: Radio Tech
author_rank: Frequent Contributor
timestamp: April 16, 2019, 01:51:11 am
content: Quote from: German_EE on April 15, 2019, 07:38:45 pmThanks my friend. This is one of my favorite radios to operate and work on. All the 101's and 520's from this era are great old classic rigs. At the moment I have 7 FT-101's in the shop. Six of them are mine so many more videos to come.

author: xrunner
author_rank: Super Contributor
timestamp: April 16, 2019, 02:05:00 am
content: Good to see you back - will view video shortly.

author: German_EE
author_rank: Super Contributor
timestamp: April 16, 2019, 04:30:40 pm
content: A related question. The tubes in the FT101 series are getting difficult to find, or at least good ones. Some time ago I was approached by an FT101 owner who wanted me to strip out the PA stage and the driver and install a solid-state PA. I said no, but I know that he went to someone else and got the work done.Comments anyone?

author: Radio Tech
author_rank: Frequent Contributor
timestamp: April 16, 2019, 10:24:35 pm
content: Quote from: German_EE on April 16, 2019, 04:30:40 pmI remember an article in QST May of 1999 called "A new life for your FT-101". It was a conversion to 6146 tubes. The mod came from an amateur radio group from Africa. I never liked the idea of that conversion then. Fast forward a few years I had a couple of tech friends that did the modification and it never worked as published. There was flaky tuning on the 10 meter band. That is when I said to them "why not solid state the thing". We worked on the circuit for a while and my friend past away. Never got completed.I think the idea is noble. If I had the time I would do it.

author: tkamiya
author_rank: Super Contributor
timestamp: May 26, 2019, 02:29:30 am
content: I think the problem will be the power supply. Solid state amp of this size will take 12V 20A or so. Of course, tube rig has 800V ish output for final. It will also require banks of low pass filters and associated switching circuit. It's probably better off just getting all transistor rig.I always liked keeping radios as original as I could. I have several FR101 and FL101. It may not be cheap but tubes are still available. I really hate to modernize what is now considered an antique from good old days.
GHz Pipe cap filters and similar - Page 1
Forum section: electronics / rf-microwave

author: CJay
author_rank: Super Contributor
timestamp: May 17, 2019, 08:37:53 am
content: I'm homebrewing gear for QO-100 and need a 2.4GHz filter, I've seen the really simple to build pipe cap filters at W1GHZ but the price of the pipe caps alone is double the price of a ready made WiFi filter that will handle the power I need.I am however very curious about the pipe cap filters, I think I'm right to assume that I could make these from almost any metal, sheet, tube or even mill them out of a solid block (I think it might be advantageous to silver plate them)?If that's the case, how do I go about calculating the sizes?Is there a decent simulator or calculator out there to use?

author: Lord of nothing
author_rank: Super Contributor
timestamp: May 19, 2019, 08:35:41 pm
content: There are a lot avaiable on ebay.

author: CJay
author_rank: Super Contributor
timestamp: May 20, 2019, 08:39:41 am
content: There are, plenty of WiFi filters on eBay that'll handle a couple of watts and do what I need so I've ordered one but I'm thinking ahead for when I need something different and/or more power, plus I figure the knowledge would be useful too.
LTE Cat M1 Femtocell - Page 1
Forum section: electronics / rf-microwave

author: tszaboo
author_rank: Super Contributor
timestamp: May 28, 2019, 04:17:25 am
content: Hi. Did anyone see already a solution, which is in the title? Does it exist? I read a bunch of articles, that they are adding technologies in 3GPP release 14, but so far I haven't seen anyone offering a hardware which supports it.

author: Lord of nothing
author_rank: Super Contributor
timestamp: May 28, 2019, 06:52:51 am
content: The problem is still you would need an (Cell) Server Infrastructural behind.So what did you want to do with?

author: tszaboo
author_rank: Super Contributor
timestamp: May 28, 2019, 05:16:04 pm
content: Sell it to customers with bad or no coverage. Well not me, I just want to investigate if it is possible, before making very important design decisions.I've asked this from several telecommunications company on business meetings, and they had no idea what I'm talking about.Yes, and I'm aware that this is also question of IT infrastructure, business model, RF regulations and so on.

author: Lord of nothing
author_rank: Super Contributor
timestamp: May 28, 2019, 07:07:48 pm
content: I gues you cant do it yourself.
6GHz balun - Page 1
Forum section: electronics / rf-microwave

author: OwO
author_rank: Super Contributor
timestamp: May 19, 2019, 08:30:11 am
content: I'm looking for a surface mount balun (common mode choke/transformer) that goes from VHF to 6GHz. The application is detecting a differential mode signal (not necessarily balanced) while rejecting the common mode signal, in other words I need to build a wideband difference amplifier up to 6GHz, but with lax requirements on gain accuracy and flatness as long as the common mode rejection ratio is reasonable (10dB or so).For up to 2.7GHz there are cheap ones from TOKO, these sell for about $0.5 from the usual sources. However if I want to go any higher, there seems to be no options other than mini-circuits and MACOM, and the cheapest I can find is TCM1-63AX which sells for no less than $6 everywhere including taobao. The TCM1-63AX also did not perform in this application when I tested it because it has a third winding that enforces a 180 degree phase relationship on the "balanced" side, which is fine for the usual balun application but inappropriate in this case.Does anyone know of a balun like the TOKO 617DB-1023=P3 but can work up to 6GHz, and costs no more than $3?

author: yl3akb
author_rank: Regular Contributor
timestamp: May 19, 2019, 07:11:17 pm
content: Look at 937-MABA-011082:https://eu.mouser.com/ProductDetail/937-MABA-011082
Including test ports in a receiver circuit. - Page 1
Forum section: electronics / rf-microwave

author: djsb
author_rank: Super Contributor
timestamp: May 18, 2019, 06:38:21 pm
content: What is the least intrusive way of including a test port (for measuring frequency, amplitude etc with an oscilloscope) in an FM receiver circuit? I want to be able tap into the IF amplifier and local oscillator circuits etc with the minimum of loading. I am thinking the best way is to build in a properly buffered test port. Does anyone have any simple circuits (op amp or discrete) or methods that I could use? I'd like to use a 50 Ohm SMA connector to connect the scope. Any tips? Thanks.

author: bob91343
author_rank: Super Contributor
timestamp: May 18, 2019, 07:31:33 pm
content: Unless the amplitude is important, just put a resistor in seires. Don't try to make a serious buffer circuit. You can use a capacitor as well to avoid hum pickup.If you want to measure the frequency at a considerable distance, say more than a foot or so, then maybe you ought to think about an interface.One thing that can work is to use an emitter follower to drive a Schmitt trigger circuit that operates at TTL level or something. You will need fast components but they exist.

author: radiolistener
author_rank: Super Contributor
timestamp: May 18, 2019, 11:14:07 pm
content: Use U.FL SMD RF connectors, it is small and don't needs a lot of space.https://www.aliexpress.com/item/10PCS-IPX-U-FL-RF-Coaxial-Connector-SMD-SMT-Solder-PCB-Mount-Socket-Jack-Female/32857074315.htmlYou can also buy U.FL to SMA cables for test equipment connection:https://www.aliexpress.com/item/Mini-PCI-U-FL-to-SMA-Female-Connector-Antenna-WiFi-1-13-Pigtail-Cable-IPX-to/32807394006.html

author: tkamiya
author_rank: Super Contributor
timestamp: May 19, 2019, 12:37:02 am
content: It all depends on what the test point is for, and what you would be measuring.Any buffer circuit or active/passive component will have some impact in your reading. You'd also have to wonder, if the reading is actually same in the circuit as well as the test point. I'd tend to just make a "raw" test point on circuit (pad or very short lead) and take care of the rest on probe side.
Ground plane at Reception path only - Page 1
Forum section: electronics / rf-microwave

author: nabnab
author_rank: Newbie
timestamp: May 22, 2019, 09:32:42 am
content: Hi,I'm designing a RF path operating at 868MHz. So I have added a ground plane at reception side and only at one side of transmission path.It's a problem to do not extend the ground plane at the other Tx path?.Please see attached the image.Thanks
president jackson alignment issue- PB042AE - Page 1
Forum section: electronics / rf-microwave

author: tozitom
author_rank: Contributor
timestamp: May 14, 2019, 03:15:47 pm
content: Hi techs!I'm slowly comming back to my old passion, electronics repair! and few days ago I received this jackson CB Radio on my bench from a friend, to give a full restoration, also it was out of frequ as he said. After inspection/measurments it's really out of frequ so I've started a full alignment as per the manual; I've donne so far the carrier and receive parts, but I've a doubt on 1º step for "CARRIER OSCILLATOR PORTION". The manual states:- CH: 40, Band: E, Mode: RX AM, Clarifier: Center- DC Voltmeter to TP2- Adjust L12 for 6 V +/- 0.1 V + Confirm 2 V on CH 1 Band AThe thing is if I ajust 6v on TP2 (Band E + Ch 40) I get 2,8V on CH 1 Band AIf ajusting 2V on TP2 (CH 1 Band A) I only get 4,87V on CH 40, Band Ethat seems not to be critical as I can get the correct frequencies on all bands... but would like to know your opinion.Thanks to all.

author: CJay
author_rank: Super Contributor
timestamp: May 14, 2019, 05:27:10 pm
content: Which manual are you using and does it match the board you have?Some of the manuals (notably the CB City ones) are terribly vague and sometimes completely wrong but then so are the original manuals so it's often a case of wokring out what you should actually be doing instead of what the manual says you should do.Plus, lots of these radios have been modified to within an inch of their lives so you'll often need to work out what the radio is doing compared to what the manual thinks it should be doing.Things to check, compare the PLL N-Codes the manual says you should have to the ones the PLL is 'seeing', check the band crystal is what you expect it to be as well, both of those will have an effect on the VCO control voltages

author: tozitom
author_rank: Contributor
timestamp: May 14, 2019, 06:03:50 pm
content: thanks for reply.I've been following those 2:http://www.radiomods.co.nz/alignments/presidentjacksonalign.htmlhttp://www.cbradio.nl/president/Service_Manual_President_Jackson_226ch_Old_Silver_version_Homer_ENG.pdf

author: CJay
author_rank: Super Contributor
timestamp: May 14, 2019, 08:42:13 pm
content: OK, they're pretty much the same, grab a copy of the Export manual but first, check this sheet outhttp://www.zen96216.zen.co.uk/cb/uniden-esm-06.htmYour downmix input frequency is the N-Code, so Ch1 Band E should have an N-Code of 262 on the P0-P whatever pins of the MC145106, if it's not then the radio is modded.Verify the Loop crystal fitted is the correct one too.
USA : FCC  47  - 15.247  900MHz  Compliance Experience - Page 1
Forum section: electronics / rf-microwave

author: JoeyG
author_rank: Regular Contributor
timestamp: May 14, 2019, 02:56:20 pm
content: I is there a better forum than this one for my question.I am looking to put my product through FCC testing , do I have to lock down the product so the skilled operator can't go outside the 902 - 928MHz band.The product will be a multi country product mostly with a subset of frequencies to 902 - 928MHz, but if want to also operate the product in Europe it operates on 868MHz.Can I make a single product that can be FCC and European approved, where the operator has the choice of mode setting for either country?How can a penta-band (5 band) Mobile phone achieve global compliance, but other products must have locked down frequencies and channels for specific countries?
Microwave dielectric materials - Page 1
Forum section: electronics / rf-microwave

author: Earendil
author_rank: Regular Contributor
timestamp: May 12, 2019, 05:58:56 pm
content: I found some interesting material in a 18 GHz coupler. It looks a bit like teflon but I'm not sure. Does anyone recognize it?Also I'm wondering what kind materials are used in microwave passives generally. What about HDPE for example?

author: rfeecs
author_rank: Frequent Contributor
timestamp: May 12, 2019, 07:05:54 pm
content: Probably a woven glass teflon material:https://www.4taconic.com/page/woven-glass-reinforced-ptfe-laminates-136.htmlOne of the most popular materials:http://www.rogerscorp.com/acs/products/55/RO4350B-Laminates.aspx
Help direct wiring 5.8 GHz video transmitter module?.?.?  - Page 1
Forum section: electronics / rf-microwave

author: bigjoncoop
author_rank: Regular Contributor
timestamp: May 20, 2019, 03:57:47 am
content: I recently posted a thread asking how to repair or which component may have failed while putting 12 volts into a 5-volt out pad on a video transmitter for RC quadcopters. I had no luck narrowing down the problem so I'm thinking of just directly wiring the transmitter module on the PCB. I'm assuming that the rest of the PCB is just voltage regulation, and a switch and LED readout to show Power output Channel and frequency. Since we use a protocol called smart audio I can control all three of those from my transmitter.I have four of these exact video transmitters one of them was used so I sacrificed it and used a hot air station to remove the transmitter module from the PCB to get a model number or a pinout from the back of it. I "successfully" removed it and to my surprise there was a complete pinout on the back. I tried to research the model number and get no helpful information.There are nine pads. Ground, + 5 volts, FWR, PD, CS 0, CS 1, CS 2, video, and I believe another ground.Normally we attached the wire for smart audio control to a pad called audio or smart audio or A6.5 Does anyone have any idea which one of these pads I should connect it to? I tried to continuity check on all four of the video transmitters between the pad labeled smart audio to each of the nine pins on the transmitter module with no luck.Also should I be able to directly input that smart audio signal into the transmitter module itself or does the PCB has some sort of filtering or processing of the signal before it goes into the module? I've looked everywhere online for some type of information on this and haven't come across what I'm looking for. I have researched the main chip inside the module I got the schematic for it but it is a little too technical for me understand. Because I was thinking maybe if I can't get smart audio to work I could at least wire up a button in order to change channels power and whatnot.Information I do know:AKK FX2 - 5.8Ghz 40CH 25mw/200mw/500mw/800mwActual Transmitter module - 1312TX-v1.0Main IC - RTC6705 / A749 / 175259Smart Audio signal comes from a Uart TX padSmart audio input on some transmitters is also labeled A6.5( which on the schematic for the rtc6705 shows a pin labeled A6.5)ThanksI have attached some photos. ( the picture of the actual transmitter module with the shielding removed burned up in missing components for me removing it from the PCB)

author: CJay
author_rank: Super Contributor
timestamp: May 20, 2019, 09:03:01 am
content: I think you might need to do a little research into the other chips on the carrier board.Can you see any markings on them?

author: Omicron
author_rank: Regular Contributor
timestamp: May 20, 2019, 03:59:39 pm
content: Your plan won't work. There is a micro controller on the PCB that implements smart audio. The module contains just the RF hardware.
Balun design analysis - Page 1
Forum section: electronics / rf-microwave

author: promach
author_rank: Frequent Contributor
timestamp: May 05, 2019, 04:02:21 am
content: ForAnalysis and Design of Miniaturized Lumped-Distributed Impedance-Transforming Baluns,1) Why use admittance Y (or 1/Z) instead of impedance Z ?2) What is Teven?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: May 05, 2019, 05:50:17 am
content: 1. No idea. Do they make use of it in the equations? Y is easier to build parallel circuits with, while Z is easier series. The Y and Z matrices are equivalent of course and there is a simple conversion between them.2. Transmission.Tim

author: promach
author_rank: Frequent Contributor
timestamp: May 05, 2019, 08:54:27 am
content: QuoteYes, they do. Could the pdf link be accessed without any problem ?I am sending an email to ask the author on how to derive expressions (2a) and (2b) in the paper

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: May 07, 2019, 09:00:48 am
content: Quote from: promach on May 05, 2019, 08:54:27 amI wish you the best of luck with that, but chances are that person forgot about the paper in the first place (it is more than 15 years old, after all).They just use Y-param because it is easier for the math in this case, I think. No more to it. There are basic transformations between Y, Z, ABCD, S and T parameters (I think those are the main ones in RF design?) for all these things. You just pick whatever you are used to (and sometimes, it can be usefull to look at one vs the other because you can 'relate' what you see better to what is going on).Teven is the transmittance for even-mode. Transmittance is kinda like S21, but normalized. I dn't remember the details. I'll look them up later, I have it written down somewhere. Keysight has a appnote about de-embedding which also contains a primer on T-parameters, could be worth checking that.

author: promach
author_rank: Frequent Contributor
timestamp: May 07, 2019, 12:58:47 pm
content: I am reading another paper by the same author :Analysis and Design of Impedance-Transforming Planar Marchand BalunsWhat does it mean by "coupling factor, C" in equation (1) ?And how to derive equation (2) which is basically the S-parameters matrix of the Marchand balun by using Figure 1 as suggested by author ?

author: MarkF
author_rank: Super Contributor
timestamp: May 07, 2019, 05:33:03 pm
content: I can't answer your questions. But, I think you will find this series of videos interesting.
Is there an all in one package that allows you to detect adsb on the SDR for win - Page 1
Forum section: electronics / rf-microwave

author: Beamin
author_rank: Super Contributor
timestamp: May 08, 2019, 01:05:45 am
content: I used to have this program on my computer but can't find where I first downloaded it. it was an adsb software for your sdr where it contained a file with the .dll and all the setup stuff; just open an .exe and it did the rest with a program called dump1090 or 1090dump but that was just part of it.. An old site I used to use doesn't work anymore and I'm getting frustrated trying to find this with my limited eye sight. ARGGGH!!!1 Seems like the only software I can find needs a dedicated or special sdr. I have the sdr play.I just want to see the planes fly around!!!