hybridfree/eevblog-posts huggingface dataset:
nanovna F questions - Page 1
Forum section: electronics / rf-microwave

author: silly sausage
author_rank: Regular Contributor
timestamp: February 01, 2025, 05:25:26 pm
content: I have the nanovna f 4.3" hw2.3 hw3.1 firmware 1.0.2 by BH5HNU, firstly what is the max freq that they can scan too and if i set a cw frequency in the stimulus setting how acurate is the output and what level is it, also is it accurate enough frequency wise to check a thandar tf-200 counter?, the reference oscillator in the thandar has no oven , i would like a cheap way to check it reads ok and doesent lie.

author: antenna
author_rank: Frequent Contributor
timestamp: February 13, 2025, 02:15:31 am
content: I would not trust the frequency accuracy on the nanoVNA. They are close, but not perfect. The output is rich in harmonics too. I couldn't tell you the phase noise or other specs though.To check my frequency counter, this is what I do. I will tune into WWV using an HF radio, then using my signal generator with clip leads as the antenna, adjust the sig gen to zero beat with WWV in the receiver. Once I know my sig gen (or nano in your case) is actually outputting 10MHz, I use that to check/adjust the counter. Both need time to warm up though, 1 hour minimum.
BF862 replacement - Page 1
Forum section: electronics / rf-microwave

author: Quarlo Klobrigney
author_rank: Super Contributor
timestamp: April 10, 2020, 11:06:50 pm
content: So I ask now that the BF862 FET is goneand NXP says too bad so sad, does anyone know of an equivalent? This is for the PA3FWM antenna.

author: Quarlo Klobrigney
author_rank: Super Contributor
timestamp: April 11, 2020, 06:53:34 am
content: It's been discussed before here and other places that it is not a good sub. Just a few points of difference. What is the fT on the part? Can't seem to find it anywhere, then the yfs = 24 - 35 vs 35 - 45? When trying to detect fly farts at 100's of KM away it makes a difference.It's a Sanyo part rebadged by ON who are too lazy to make their own datasheet. The Japanese datasheets are notorious for being vague. Look at Sony for example, here's a chip, we make it, here are the pins.. It's Apples to Oranges.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 11, 2020, 08:36:24 am
content: https://www.onsemi.com/pub/Collateral/ENA1965-D.PDFprobably good?Tim

author: Quarlo Klobrigney
author_rank: Super Contributor
timestamp: April 11, 2020, 09:15:24 am
content: Looks like another Sanyo datasheet rebranded. I'll dig deeper in to it after breakfast.

author: Finderbinder
author_rank: Regular Contributor
timestamp: February 18, 2025, 10:10:58 pm
content: Have you found a substitute for BF862 ? I need it too.Does BF862 on AliExpress/eBay are any good?

author: Gerhard_dk4xp
author_rank: Frequent Contributor
timestamp: February 18, 2025, 10:58:32 pm
content: <https://www.digikey.de/de/products/detail/onsemi/CPH3910-TL-E/4847608>even slightly better regarding Cin vs gmGerhard

author: Quarlo Klobrigney
author_rank: Super Contributor
timestamp: February 19, 2025, 09:06:28 pm
content: Well this was a long time ago.Between then and now and my near death experience in hospitalI forgot what even the project was!So that would be a no...It was probably a preamplified shortwave antenna in a gutter mounted PVC sewer pipe that wouldn't give the neighbours any anxiety.Most have forgotten just what those SW wires did in back the day.Speaking of that, I'd forgotten a lot from back thenQuote from: Gerhard_dk4xp onYesterdayat 17:58:32https://www.digikey.de/de/products/detail/onsemi/CPH3910-TL-E/4847608>even slightly better regarding Cin vs gmGerhard
Understanding Alignment - Page 1
Forum section: electronics / rf-microwave

author: staticshock
author_rank: Contributor
timestamp: January 29, 2025, 09:34:35 pm
content: Trying to understand RF alignment.In an Insertion Loss Test, does an alignment need to be done every time when the frequency range is changed?In an Insertion Loss Test, does an alignment need to be done every time when I connect and disconnect adapters?Let's say from point A to point B I have a rf cable. I add in an attenuator to the line, but it requires an adapter between the rf cable and the attenuator. If I am introducing an adaptor(s) to the line do I need to re-align with the adaptor(s) on?

author: CaptDon
author_rank: Super Contributor
timestamp: January 30, 2025, 03:03:27 pm
content: The question as stated makes no sense. What are you aligning, an I.F. strip, a tunable filter? If you aligned an I.F. strip and then inserted or removed an attenuator from your generator it should not effect the alignment except for the absolute measured level. As far as bandpass there should be no alignment change and no realignment needed. Restate the question or give details about what you are 'aligning'.

author: stretchyman
author_rank: Regular Contributor
timestamp: February 11, 2025, 11:47:51 am
content: You 'Calibrate' to the end of the cables connected to your VNA, if that's what you're doing? No further cal needed.
SMA connectors - Page 1
Forum section: electronics / rf-microwave

author: Grandchuck
author_rank: Super Contributor
timestamp: February 08, 2025, 04:34:45 pm
content: I was wondering about SMA life expectancy and ran across this on the web:"The mating cycle of an SMA connector refers to the number of times it can be connected and disconnected without compromising performance. A typical SMA connector can withstand over 500 mating cycles. Factors like design, material quality, and manufacturing precision influence this durability."In addition, one should not allow rotation of the male pin during mating.I think this number (500) might be too high?Anyway, here is the source:https://metabeeai.com/rf-connectors/sma-connectors/what-is-an-sma-connector-everything-you-need-to-know.htmlLots of good info there!

author: jpanhalt
author_rank: Super Contributor
timestamp: February 08, 2025, 06:08:36 pm
content: That information for all connectors should be readily available. Several years ago, I was looking for small charger and programming connectors. Of course, I wanted two different styles. USB miniature and micro sizes (USB C was not so ubiquitous then) had numbers in the thousands, while pin and sockets were much lower; some assemblies were only 10 cycles. For some of those connectors, it was a hassle getting that information. I think it ought to be right up there with pin number or current capacity.

author: coppice
author_rank: Super Contributor
timestamp: February 08, 2025, 06:31:04 pm
content: SMA connectors vary enormously. With some you are lucky to successfully mate them just once. Others go on in test applications, being mated and removed, for years.

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: February 10, 2025, 07:51:48 am
content: You can use a male/female adapter to save wear and tear on the SMA socket on your instrument.Don’t forget to tighten SMA plugs with a torque spanner. The correct setting is 0.5 Nm, dedicated SMA torque spanners by Xite cost around $30. In the UK, SDR-Kits stock them.https://www.sdr-kits.net/Torque-WrenchSJ

author: radiolistener
author_rank: Super Contributor
timestamp: February 10, 2025, 08:30:05 am
content: Quote from: Solder_Junkie on February 10, 2025, 07:51:48 amBut note that adding SMA adapter add some signal loss and leads to worse SNR, so, you're adding additional element for signal path. You can see reflections on every connector and adapter with time domain reflectometer.
Quansheng UV K5 K6 SI4732 Modified Radio And Bluetooth Stereo Transmitter Modul - Page 1
Forum section: electronics / rf-microwave

author: silly sausage
author_rank: Regular Contributor
timestamp: February 08, 2025, 05:12:37 am
content: Has anyone got any info on how too fit one of these moduals ?,its the new version that has bluetooth, so its hf rx using the sis 4732 + bt, My kit included a short coax+sma fitting along with 3 small inductors, no instructions came included, has anyone tried/ fitted one of these?.https://www.aliexpress.com/item/1005008194498103.html?spm=a2g0o.order_list.order_list_main.10.65361802ajYnTU#nav-specification
MICROLOG ATR-6800 Repair Need  EPROM Files (or purchase of a complete unit) - Page 1
Forum section: electronics / rf-microwave

author: scopeman
author_rank: Frequent Contributor
timestamp: February 05, 2025, 09:44:11 pm
content: Hello,I am helping a fellow older ham fix his Microlog ATR-6800 terminal. He brought it to me to repair after an attempt to clean the PCB after the 3.6V NuCAD battery leaked.Unfortunately when he returned several chips to their sockets he didn't realize that one of the EPROM's was inserted in the socket backwards and powered the unit on and blew the fuse.Of course the EPROM was toast. The other unfortunate thing is the EPROM is the TMS2716 part which unlike modern EPROM's requires 3 power supply voltages to operate making finding an EPROM programmer difficult.I have a possible solution to the programmer issue and can obtain blank EPROM's (4 in the set IIRC) but I do not have access to a known working unit or Intel HEX or BINfiles to program new chips.I have good reason to believe that there is a really good chance that this may be the only problem as I do see video output from the device with the bad EPROM removed. The video data is scrambled but I do at least see characters.I have exhausted the internet looking for info on this system but no luck there and Microlog appears to be out of business.I do have most of the schematics I have a couple of sheets that are missing but I do have the one that has the CPU and memory.Any help to get this thing working for an old timer would be very much appreciated.Thank you and 73,SamW3OHM
Odd behavior of amplifier compression curve - Page 1
Forum section: electronics / rf-microwave

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: February 13, 2025, 07:14:00 pm
content: I was measuring an assembly with aMini-circuits ZJL-153+amplifier and a pair of filters and was trying to measure its compression characteristics at 5.6 GHz. I used a Fieldfox and a Python script to make the measurement. I estimated the small-signal gain from average of the first 5 data points and subtracted that from the measured gain to get the compression curve. I was surprised to see the gain slightly increase for input power > -10 dBm.Thinking it had something to do with the instrument, I did the following:Made the same measurement with an SMA barrel to measure cable loss and instrument characteristics. It did not show the bump in compression for input power > -10 dBmSet the Fieldfox for maximum internal attenuation (40 dB)Added an external 5 dB attenuator at the Fieldfox RF inputVerified the measurement with a different signal source and spectrum analyzerRedid the measurement with just the amp (no filters)Tested with another amp of the same type, and saw the same behaviorWhat might be the cause of this gain increase just before compression?

author: EggertEnjoyer123
author_rank: Frequent Contributor
timestamp: February 14, 2025, 02:00:36 am
content: The input/output match changes depending on the power level (see large signal S parameters)Maybe the matching is better at a higher power level.

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: February 14, 2025, 07:03:27 pm
content: That's my best guess too, since 5.6 GHz is at one edge of the supported bandwidth and the datasheet VSWR curve is not great at 5.6 GHz. To test this, I used a VNA on just the amplifier and changed the drive level from -10 dBm to 0 dBm (instrument was calibrated at -15 dBm), and did not see an appreciable change in S11 (~1 dB). The S21 did increase, by about 0.2 dB.I also checked the gain variation at a couple of spot frequencies (5.6, 10 and 15 GHz) and saw the same behavior, with gain increasing by 0.4 dB or so when going from -10 dBm drive to 0 dBm.

author: eb4fbz
author_rank: Regular Contributor
timestamp: February 14, 2025, 11:40:07 pm
content: That is gain expansion and it’s quite common, specially on Class-AB amplifiers, but even Class-A ones can show a small gain expansion near the compression point, sometimes due to bias drift.

author: radar_macgyver
author_rank: Frequent Contributor
timestamp: February 15, 2025, 01:22:21 am
content: Thank you! That was a keyword I was missing, there seems to be a fair bit written about this effect, something for me to read up on.
Crystal Filter impedance - Page 1
Forum section: electronics / rf-microwave

author: frogg
author_rank: Regular Contributor
timestamp: February 03, 2025, 04:00:56 pm
content: I'm looking to use an Anatech AM455CR181 crystal filter *https://www.anatechelectronics.com/media/pdf/AM455CR181.pdf) to replace a Collins Mechanical Filter:Anatech AM455CR181 specs:Fo: 455 KHz6dB BW: 200 Hz ±10%Ripple: 0.5 dB MaxInsertion Loss: 4.0 dB Max60 dBc BW: 800 Hz MaxImpedance: 50 OhmFor all the specs, this Crystal Filter looks like it should at least match the Collins 526-8733-010 mechanical filter I'm trying to replace, especially regarding the insertion loss:Collins 526-8733-010 mechanical filter specs:Bandwidth: 300 HzCenter Frequency: 455.0 kHzShape Factor: 2.5Typical Insertion Loss: 250 Hz: < 9 dB; 500 Hz: < 7 dB; SSB/AM: < 6 dBZin/Zout: 2000 ohms // 30 pFThe thing I need help with is the Impedance (Zin/Zout) spec on the mechanical filter.It's listed as 2000ohms // 30pF, vs. the crystal filter which is 50 ohms.Obviously the mechnical filter will have some complex impedance given its construction, but in practice, how does one usually account for this when replacing the mechanical filter with a crystal filter in an existing design?

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: February 04, 2025, 09:15:45 am
content: The way to match the filter is with an L match. 100 uH and 1nF looks about right.73 SJ

author: D2236
author_rank: Regular Contributor
timestamp: February 04, 2025, 06:02:40 pm
content: I calculated about the same values.
Ailtech 727 Spectrum Analyzer Service manual and/or clean copy (pdf) of the User - Page 1
Forum section: electronics / rf-microwave

author: Copeland
author_rank: Newbie
timestamp: February 03, 2025, 09:51:53 pm
content: I recently came in posession of an Ailtech 727 Spectrum Analyzer.I'l trying to locate the Service Manual for this beast but the only two links returned by Google are no longer functioning.Does anyaone have a pdf version of these documents?Thanks in advance!
Mounting an antenna to test with a NanoVNA? And some other calibration questions - Page 1
Forum section: electronics / rf-microwave

author: Fallon
author_rank: Newbie
timestamp: February 02, 2025, 10:03:14 pm
content: I've got a NanoVNA v2 Plus4 & a reasonable idea on how to calibrate & use it. I'm a little confused on how to properly mount a little 433mhz antenna I've built as my first antenna when I'm testing it to tune it. All the previous rubber duckie style antennas I've just been attaching directly to the VNA. I finally got a male to female adapter for a port saver & recalibrated for that.Doing some SDR stuff looking for weather stations, TPMS, & other stuff. have some decent 915mhz from Amazon or my parts box, but all of my 433mhz antennas have horrible SWR. So rather than mess with junk antennas I may as well build my own.I plan on mounting the antenna directly to the rtl-sdr or little 433mhz LoRa board in the background.Do do the calibration on the port extensions I have on the Nano VNA, then mount the antenna over the VNA with the radials sitting below & around the VNA?Do I use the 1' or so extension cable, recalibrate to the end of the cable & leave the antenna sitting on the desk?I'm getting a peak that differs by 10-15mhz depending on how I'm testing. I want to figure things out before I start cutting on the antenna to tune it.A related but less pressing question. How do I calibrate the VNA when using different connections? Say I have an antenna with an N connector on it & my VNA or calibration standards are only SMA. Do I just calibrate as close as I can get then add in some offset delay based on the length of the adapter, or some educated guessing?Do I need to calibrate the NanoVNA every time I power it up? Or is calibrating it every time I change adapters or cables acceptable?
HP Spec 853A blur text  , LED filter?  - Page 1
Forum section: electronics / rf-microwave

author: jonpaul
author_rank: Super Contributor
timestamp: February 03, 2025, 01:54:35 pm
content: Bonjour a tous, Hello all:Been comparing a few SA, TEK vs HP,My HP 1908s : 853A digital memory display, and 350 MHz/1.5 GHz plugins, 8557A/8558B.Noticed the alphanumerics text is blurred, with either plugin, regardless of intensity or focus control.original serv manual does not help...Anyone seen this? Where to start? HV, CRT and PSU seem fine....Z axis, HV/CRT, alphanumeric gen?Finally the red LED filter on the 8557A has developed a cloudy translucency.... the 8558B is fine.The filter is hard to acess, seem to need total front panel dissassembly...Are replacements avail?How to clean the filter inner surface ?MILLE MERCISHave a great day,JonPhoto 1 LED, blurred textPhoto 2 analyzerPhoto3 RF bench

author: CaptDon
author_rank: Super Contributor
timestamp: February 07, 2025, 02:01:07 pm
content: Text beam intensity can be trimmed independently. The text intensity is to high. Storage C.R.T.'s are finicky about too much beam current and will blossom like hell in the storage mode. Text intensity should only be about 50% to 60% as bright as the main trace

author: jonpaul
author_rank: Super Contributor
timestamp: February 07, 2025, 06:06:02 pm
content: Bonjour cher Capitan Don:Many thanks for the note, the text intensity seems normal but I shall try that.As the storage of 854A is digital, I dont think the CRT is storage, however, the gratucle illum is exactly like a storage CRT flood gun, entire screen has a dim raster backround that shows the internal graticule.Jon
has anyone tried one of these? - Page 1
Forum section: electronics / rf-microwave

author: silly sausage
author_rank: Regular Contributor
timestamp: January 31, 2025, 10:32:52 am
content: I an thinking of buying this to check/cal my freq counter,will it be ok?.https://www.aliexpress.com/item/1005007979567059.html?spm=a2g0o.order_list.order_list_main.5.e9ce1802aKgSaO

author: tggzzz
author_rank: Super Contributor
timestamp: January 31, 2025, 11:06:26 am
content: Quote from: silly sausage on January 31, 2025, 10:32:52 am"A good answer is more likely to come from a good question; a bad question is more likely to be ignored or to result in irrelevant answers" for reasons illustrated inhttps://entertaininghacks.wordpress.com/2024/10/30/good-questions-pique-our-interest-and-dont-waste-our-time/Hence it would be helpful if you would indicate what "this" is, preferably in the title.Will it be OK? Yes, repeat no. It depends on the purpose - and only you can define that.For <£8, just buy it and try it.

author: tatel
author_rank: Frequent Contributor
timestamp: January 31, 2025, 11:44:10 am
content: Sorry, there's some problem with the link, but you could search for "$10 OCXO board" in this very same forum sectionhttps://www.eevblog.com/forum/rf-microwave/$10-ocxo-board/msg5608727/#msg5608727

author: Gyro
author_rank: Super Contributor
timestamp: January 31, 2025, 12:18:21 pm
content: Please stop using meaningless clickbait thread titles.

author: silly sausage
author_rank: Regular Contributor
timestamp: February 01, 2025, 05:45:08 am
content: Quote from: tatel on January 31, 2025, 11:44:10 amA search brings up nothing!.

author: theHWcave
author_rank: Regular Contributor
timestamp: February 01, 2025, 09:39:50 am
content: I have one of these and initially the range of the adjustment pot was insufficient to get it to the correct frequency (verified against a GPSDO). I had to modify the circuit to extend the adjustment voltage range slightly (can't remember details, sorry). After letting it run for a couple of weeks, it had drifted somewhat and needed another adjustment but after that initial drift, it is now running for more than a year, pretty much continuously and does't drift anymore. I am planning to move it into a HP5334B that currently has only the standard oscillator on-board. One thing to be aware of is that the regulator and a polarity protection diode on the board get pretty toasty (more than 50 deg C) with just 9VDC.

author: tatel
author_rank: Frequent Contributor
timestamp: February 01, 2025, 12:16:57 pm
content: Quote from: silly sausage on February 01, 2025, 05:45:08 amYes it does. Anyway, you can just copy the link with the mouse and paste it in a new tab on your web browser...https://www.eevblog.com/forum/rf-microwave/$10-ocxo-board/msg5608727/#msg5608727

author: David Hess
author_rank: Super Contributor
timestamp: February 01, 2025, 03:49:52 pm
content: Quote from: silly sausage on January 31, 2025, 10:32:52 amNo, use a GPSDO, or even just a timing GPS if it is a universal counter.
Can I obtain S-parameters from a S11 sweep using HP 8753A - no print/plot/disc? - Page 1
Forum section: electronics / rf-microwave

author: wb0gaz
author_rank: Frequent Contributor
timestamp: January 29, 2025, 08:57:29 pm
content: Need results (as S11 S-parameter listing) of sweep of a device under test with HP 8753A + 85044A test set.Is there any practical way to extract the tabular S-parameter data without anything attached to GPIB port (=no printer, no plotter, no disc drive, no external PC)? I'm willing to transcribe and/or photograph the screen display, but don't believe I've ever seen a "list the S-parameters on the screen" menu option.Thanks!Dave

author: wb0gaz
author_rank: Frequent Contributor
timestamp: January 29, 2025, 09:31:04 pm
content: "nevermind..."After fruitlessly searching in the various display format options, the solution was where I hadn't looked:COPY (part of instrument state) > LIST VALUES (near the bottom.)The listing is R and X (ohms) which will serve the need.(so continuing to learn about this 40-year-old instrument!)

author: rfclown
author_rank: Frequent Contributor
timestamp: January 31, 2025, 10:56:43 pm
content: I strongly suggest learning to use the GPIB port. I use an NI USB-GPIB. Send the command "outpform", and it will return the s-parameters.
VNA calibraion kit for MCX/MMCX/UFL genre - Page 1
Forum section: electronics / rf-microwave

author: trp806mo
author_rank: Regular Contributor
timestamp: January 23, 2025, 07:48:09 pm
content: I need to test some s11 antennaes integration for some new 5G modem.I may change the standard SMA for some smaller type (MCX/MMCX/UFL) but as I was looking for a "real" calibration kit for the VNA I notice that the A brand don't have such kit (R&S, Keysight, ..) So do someone know how the supplier of a MCX/MMCX/UFL antenna are testing their product ? Or do i miss something ?

author: joeqsmith
author_rank: Super Contributor
timestamp: January 23, 2025, 10:57:31 pm
content: Not that I am aware of.

author: jbb
author_rank: Super Contributor
timestamp: January 24, 2025, 05:56:51 am
content: The thought occurs that these miniature connectors aren’t designed for a high cycle life. So making a proper cal kit could be a bit wasteful due to limited lifetime.

author: EggertEnjoyer123
author_rank: Frequent Contributor
timestamp: January 24, 2025, 06:17:19 am
content: You could just buy a SMA to U.FL adapter for a few bucks. The 1dB or so difference is probably nothing to worry about.

author: Miek
author_rank: Regular Contributor
timestamp: January 24, 2025, 10:35:56 am
content: I'm not aware of any cal kits for those connectors.What I do personally for U.FL is calibrate to SMA and then use a good SMA to U.FL adapter. I use the HRMJ-U.FLP(40) and HRMP-U.FLJ(40) adapters, they're designed for test use with lower retention force and a higher mating cycle rating, and they don't have any significant mismatch so you can use port extensions to de-embed them. I wouldn't recommend the cheap pigtails, they usually have some mismatch at the coax connections, so aren't easy to de-embed.

author: hendorog
author_rank: Super Contributor
timestamp: January 27, 2025, 10:28:04 pm
content: The only one I am aware of is this one:https://www.megiq.com/products/balanced-calibration-kit

author: pdenisowski
author_rank: Super Contributor
timestamp: January 28, 2025, 01:34:51 pm
content: Same as the other posters - I have not seen one

author: virtualparticles
author_rank: Regular Contributor
timestamp: January 28, 2025, 09:15:07 pm
content: There are no metrology-grade calibration kits for those connectors because the connectors themselves are not repeatable enough. Eggert's adapter suggestion is probably your best bet.

author: wb0gaz
author_rank: Frequent Contributor
timestamp: January 29, 2025, 09:03:51 pm
content: I'd suggest asking Kirkby Microwave (UK) - when I purchased one of their SMA cal kits some (3-4?) years ago, they had option (which I added to my order) for U.FL which ended up being a few adapters and a few short sections of 1.37mm coax, but by the time it got here the need at that point had passed, and I've not returned to U.FL-land so far since.I believe Kirkby Microwave have iterated on their product since then, and their broad offerings include support well beyond 6 GHz, so they'd likely have device coefficients to support the connector in the frequency range you cite.
External mixer conversion loss: Tektronix WM490 not very specific - Page 1
Forum section: electronics / rf-microwave

author: mr ed
author_rank: Regular Contributor
timestamp: January 27, 2025, 08:08:35 pm
content: I am trying to measure the rf power of a homemade 120GHz transmitter (diode tripler). I have a Tektronix 492b spectrum analyzer with diplexer. I want a ballpark rf level by working backwards from the 492 display which is -40dBm. The issue I have is documentation indicates either a conversion loss around 20 or 30dB, depending on which chapter you read! (Old doc Tek 70-03731-01) 1.7 says 30 dB up to 60GHz using 10th harmonic and page 1.20 says 30dB for 120 to 240GHz which can't be the same as page 1.7 because of a much higher 23rd harmonic is used. I would like to get to +/-3 dB accuracy.Anybody have experience with conversions at 120GHz that knows more or better.

author: mr ed
author_rank: Regular Contributor
timestamp: January 28, 2025, 04:16:43 am
content: The new series WM780 mixers which are back compatible to the older WM490 mixers have a proper table in the user manual. For 25GHz it's 30dB and ranging to 60dB at 140GHz. New mixers have individual charts good to +/- 2dB.
Suggestions on identify this THT PCB RF connector - Page 1
Forum section: electronics / rf-microwave

author: e.sotillet
author_rank: Contributor
timestamp: January 24, 2025, 10:41:02 am
content: Hi folks! I need help identify this connector used in CATV VHF outdoor devices. I need to modify a power insertor adding monitoring capability, so a new PCB has to be designed.I had contacted a couple of providers in China, all says that can provide it but in the last step it turns be out a lie. Those product are mass produced, so I think the connector must be available.The male pin has 5mm diameter and the female connector, installed in the PCB has around 5-6 metal clips that make the contact.Best regards and thanks in advance.

author: TC
author_rank: Contributor
timestamp: January 26, 2025, 12:35:35 am
content: I haven't seen those before. Have you tried searching for female socket, female receptacle, male pin, etc. rather than "connector". You might toss the pin diameter in too. Try image search? Just ideas... not sure beyond that.

author: e.sotillet
author_rank: Contributor
timestamp: January 26, 2025, 12:45:51 am
content: Hi, thanks for your messaege. Yes, I tried all that terms, including image search. Recently, I found a similar connector (https://www.molex.com/en-us/products/connectors/high-power-solutions/sentrality-pin-and-socket) used for high power pin connections but the male pin diameter options are 3.4mm, 6mm and 8mm and the male diameter of the case is 5mm.On the other hand, I evaluated to reemplace with pogo-pins but the current rating required (5-10A) is beyond their capacity.Best regards

author: TC
author_rank: Contributor
timestamp: January 26, 2025, 07:49:49 pm
content: Try Harwin and Mill-Max as vendors. They might have something similar.

author: pienari
author_rank: Regular Contributor
timestamp: January 27, 2025, 12:46:28 pm
content: I think that is a bit odd for rf connector
Bluetooth signal interference, how to investigate - Page 1
Forum section: electronics / rf-microwave

author: midnightvisions
author_rank: Contributor
timestamp: January 25, 2025, 07:38:32 am
content: Hello,In my car I listen to my music through my cellphones Bluetooth connection. In the last three months the interference and signal disruption while driving has gone from none to every couple of major intersections.The only thing I suspect is the City has installed these new led lights (the type that turn blue when they fail) as they have some kind of Wifi or Bluetooth connection in them.Is there anything on the market, a device or app that can monitor for Bluetooth collisions, or signal interference. I've tried several apps from the android store but none actually work.What I'm expecting is for the App or device to monitor the connection between my cell and the car, and to record or display the frequency band with what other signals are causing the interference.Is there anything out there that can do this, or is there another method to detect Bluetooth signal interference?Cheers.

author: rteodor
author_rank: Frequent Contributor
timestamp: January 25, 2025, 09:49:57 am
content: Quote from: midnightvisions on January 25, 2025, 07:38:32 amUnless they are very, very bad devices this situation (of interference from low traffic WiFi devices) seems unlikely. Bluetooth spreads its traffic over many channels 1MHz apart all over the 2.4GHz band while a WiFi channel has 6MHz. And WiFi only produces interference when there is lots of traffic and its interference is limited to a small portion of the band.It must be something else. Maybe try on foot hunting for the source ?Quote from: midnightvisions on January 25, 2025, 07:38:32 amYes there are spectrum analyzers that can do this. Starting from tinySA Ultra at under 200 bucks to many expensive ones (K's or even tens of K's). I assume you don't have a SA but maybe you don't need one for this. First try to determine if your devices are ok by trying other devices and/or asking some other people if they have trouble too in those areas. Then you can walk around and try to locate the source with your device.Apps are limited by the underlying hardware, they can measure signal strength and maybe noise on a per channel basis. Apps can help a bit but won't do the work for you.PS: there might be TV dongles like the ones with Realtek RTL chipset that can be attached to the phone and you have a hackish spectrum analyzer. However I do not know any of them that can receive 2.4GHz. Then there are SDR devices like HackRF or the like that would work for this purpose. Beware, this is a rabbit hole. I would encourage you again to take it on foot.
spiral antenna balun - Page 1
Forum section: electronics / rf-microwave

author: kellogs
author_rank: Regular Contributor
timestamp: February 18, 2025, 08:52:46 pm
content: Since what I need is a shrunk log spiral antenna, i.e. very low Re(Z), would it hurt anything if its feedline balun would be made out of discrete capacitors and inductors instead of the microstrip taper?[img url="https://i.sstatic.net/BHBoUenz.png"]https://i.sstatic.net/BHBoUenz.pngIf so, could I put GND on the second thin trace from the picture on the right side, the one without the SMA connector ? So that I have a GND for caps / inductors.Thanks
Yagi antenna matching - Page 1
Forum section: electronics / rf-microwave

author: W4PJB
author_rank: Regular Contributor
timestamp: January 15, 2025, 10:51:17 pm
content: I'm building a handheld 2-band satellite antenna (similar to the Arrow), and debating on which is the best way to match the impedance.Design requirements for the antenna are light weight, maximum portability, and minimum setup. That leave a Gamma match out, as I don't want to have a bulky parallel element to disassemble and pack. The beam will be non-conductive (C/F and 3D printed components), and will use a split driver on both bands. Most likely I will be using 7.2mm arrow shafts that screw into permanently mounted nuts on the beam. This means the wiring and matching circuit can stay attached to the beam, and I just need to screw on the elements when assembling. Beam will be two pieces.So for the matching, I think that just leaves a hairpin or parallel match using 75ohm coax (DK7ZB style). Pros/cons over each? Am I missing any other options?Pic attached for reference. Next step will be designing the element mounts (and matching will be part of this design). There is also a removable phone mount, so I can track satellites using Stellarium.

author: pienari
author_rank: Regular Contributor
timestamp: January 18, 2025, 07:22:54 pm
content: Well.. vhf / uhf cross yagi?What kind of dipole you have planned to use?

author: W4PJB
author_rank: Regular Contributor
timestamp: January 19, 2025, 12:31:34 am
content: Thanks for your reply. It will be a UHF/VHF cross Yagi, like the Arrow.For the dipoles, I intend to use a split dipole, rather than a solid element.

author: pienari
author_rank: Regular Contributor
timestamp: January 19, 2025, 12:28:07 pm
content: Have you antenna analyzer?.I think you chould use vhf for horizontal and connect uhf dipole elements vertical for same feed points.

author: TheSteve
author_rank: Unknown
timestamp: January 21, 2025, 09:31:01 pm
content: The hairpin worked great on some 2m tape measure yagi's I made for fox hunts.I also have an Arrow for satellite work - but the weight is a real issue. Will be watching this thread for progress updates.
New RF multi-tool: RFExplorer Pro (early tests) - Page 1
Forum section: electronics / rf-microwave

author: mehdi
author_rank: Regular Contributor
timestamp: January 18, 2025, 03:01:57 pm
content: This is the newest product from RFExplorer which is a very special and unique device in the current RF T&M market:RFExplorer Pro, a new RF multi tool (spectrum analyzer, power meter, cable tester, signal/tracking generator, and Wi-Fi analyzer) covering 15MHZ up to 7.5GHZ.It's running Windows. Display is 8 inches IPS touchscreen.Comes with a protective carrying case.It's very light at 570g (Siglent SHA852A is 3.2kg!)One thing is clear: there's no competition in this price segment: tinySA is small and with many limitations, and portable devices from established brands (Rigol, Anritsu etc) cost a few times more.Price for the base version: €1200To unlock 7.5GHZ you need to buy a license. (cable tester also needs a license to activate)I will be sharing my full review in future posts (about the design choices, build quality, accuracy, and also the software)To my knowledge there's still no review of this device, so feel free to ask questions and I will try to test the device and answer them in the upcoming days.Apart from UI/software, I'm particularly going to check the measurement accuracy, but for now I can say "DO NOT BUY IT"My initial tests show the device is very inaccurate in the "spectrum analyzer" and "power meter" modes. Signal generator works good though.I used a calibrated Anritsu MA24108A RF power meter, and a Signal Hound BB60D to compare.As the first test, I simply connected the output of a 100MHZ OCXO (which is known to produce about 7dBm)The Anritsu and BB60D read the signal very accurately (Anritsu reads 7.22dBm, BB60D reads 7.45dBm)RFExplorer Pro measures 4.75dBm in the Power Meter mode!!Also, in the Spectrum Analyzer mode, it measures the signal as -2dBm !!!The phase noise is also awful.I need to do more extensive tests in the entire frequency range, but for now and based on the initial tests I can say it's way out of spec, and I'm not sure if it will be fixed by future software updates.

author: radiolistener
author_rank: Super Contributor
timestamp: January 18, 2025, 03:18:17 pm
content: Quote from: mehdi on January 18, 2025, 03:01:57 pmYes, tinySA Ultra which works up to 4.4 GHz with their price 100 USD is definitely in different price category.tinySA Ultra Plus which works up to 7.3 GHz with their price 175 USD is also in different price category.But I'm not sure if it worth to pay 1200 EUR instead of 100 or 175 USD, just to see graphs in 3D view on large display...
400 MHz frequency RF gain block, having high input impedance - to be used as  - Page 1
Forum section: electronics / rf-microwave

author: hilper
author_rank: Contributor
timestamp: January 17, 2025, 02:03:39 pm
content: HiFor the 350 to 450 MHz frequency range, I need a RF gain block, havinghigh input impedance. The gain block is to be used as a colpitts oscillator/VCO buffer - thats why the high input impedance is needed. I'am awared of, that a transistor amplifier is normally used for that application. But due to, we more or less, need to use an existing PCB layout, a gain block is prefered.Do such a device exist ?If soo, pls provide suggestions.BR hilper

author: shabaz
author_rank: Frequent Contributor
timestamp: January 17, 2025, 03:28:11 pm
content: Maybe it's easier to just tap off with a capacitor and then transform to 50 ohm, if you wish to use a ready-made gain block. There's MiniCircuits TC8-1+, in-stock at Mouser, etc. That would have a reasonably high input impedance.EDIT: Just noticed your requirement to use an existing PCB layout. I'm not sure how that can be done without inserting components. You may need a plug/solder-on daughter board with the additions.
Help needed:  CMS1070  3.4-3.7 GHz   20W Fet amplifier  - Page 1
Forum section: electronics / rf-microwave

author: DF5VAE Charly
author_rank: Newbie
timestamp: January 15, 2025, 11:15:55 am
content: So time ago I obtained a 20W FET-Amplifier module manufactired by AR worldwide (Bothell, WA 98011, USA)Specified frequency range 3,4 to 3,7 GHz, 20W, 21dB gain, +12V DC supply via a 7W2 mixed sub-d connector.The 7W2 sub-d connector has marked +/- pins and 5 additional control pins.As I assume that more of these amplifier modules may have found their way into ham shacks I wonder if anybody is using such an amplifier modul and has information about the funtion of the control pins.I have not (yet) opened the housing....regards, DF5VAE

author: EggertEnjoyer123
author_rank: Frequent Contributor
timestamp: January 18, 2025, 02:26:54 am
content: You will most likely need to open the housing and take pictures for us to figure out what the voltages should be.The chances of causing any damage are probably zero since it probably just has a PCB inside.
aspect ratio of low frequency long ferrite antenna - Page 1
Forum section: electronics / rf-microwave

author: coppercone2
author_rank: Super Contributor
timestamp: January 10, 2025, 01:24:37 am
content: So I know some basic guidelines for smaller ferrite rod inductors to leave some of the ends unwrapped (for like 2 inch long, they seem to use maybe 50-60% of the rod)I have a real low frequency hi mu foot long rod now, and I am wondering if I should follow the same 50-60% rule or does it get different when the aspect ratio starts getting weird.It is 1 inch x 12 inches.I think it will be used somewhere about or way less then 1KHzI previously glued some crap together from junk parts but that project never went anywhereAnd I am also wondering if it should be one continuous winding, or if I should make multiple coils (like a coil gun design).This kind of gets into it, but its much larger then minehttp://www.vlf.it/romero3/ics101.htmlIs 12 inches long enough to justify winding it into sections to try to lower capacitance?

author: coppercone2
author_rank: Super Contributor
timestamp: January 11, 2025, 05:17:30 pm
content: And I even had thought about low capacitance windings, but it looks like it might be too difficult to predict what effect all these things could have.

author: coppercone2
author_rank: Super Contributor
timestamp: January 17, 2025, 09:45:07 am
content: I think it might be a good idea to do this because it has minimum difficulty but it makes it easier to modify it, because for a receiver antenna, it hardly seems to matter if you solder each of the spools together, and its easier to wind. Assembly might be a tiny bit more tricky because it involves some fine splicing.and it gives it the ability to pick the exact coil size by selecting the correct tap point.
transponder peek detector. - Page 1
Forum section: electronics / rf-microwave

author: kiwidave72
author_rank: Newbie
timestamp: January 20, 2025, 10:10:03 am
content: Hi all, anyone able to help me with a RF Peak detector with a RP2040.I have a RF transponder that sends out packets of data. for now im not worried about demodulating the data, but just having two Led's triggered based on the signal strength.when the transponder is over the loop its set an output pin (Red) Led to high, and the transponder is near it set (Orange) Led to high. and when there is no signal than all are OFF.I have a loop antenna and a impedance circuit in line than an amp to august its output gain for here i want to connect it to the RP2040.But im not sure what circuit need to have to connect the RF signal from the amp to an analog pin on a RP2040.Ive seen example that using two 10k resistors to both ground and vss of the microcontroller, but not sure if this is right.anyone here got any suggestions.ive included three pictures of the osilloscope of the signal for when the transponder off, near and over the loop.

author: jwet
author_rank: Frequent Contributor
timestamp: January 22, 2025, 04:17:16 am
content: The most expedient with no additonal components, other than 2 R's and one C would be to make a divider of say two 47k resistors to each rail into an adc input. You then take this signal through a .1 uF capacitor into the midpoint of this divider and into the same adc. What you'll get is a an average value (approximately) that have excursions of almost nothing (no signal), 170 mV (medium) and 350 mv (high). You could run the ADC in the background at 2 Khz and each 10 mS or look at the data. This would be 200 samples. These spikes come in at about 1Khz, you'd expect to get 10 samples that are offset from the mean in a 10 ms sample- they could be high or low. Your adc will be giving you 1/2 scale with no excursions with no signal, if the spikes are +-85 mV, you'd expect to see this happen almost 10 times for the mid signal and likewise for +-175 mV. I don't know what the PICO's adc resolution is but you can work out these details. You can have this little 2Khz sampler going on in an ISR and just log the number of times you're greater or less that these thresholds away from the average.
CMW500 options selection - Page 1
Forum section: electronics / rf-microwave

author: stan33
author_rank: Newbie
timestamp: January 14, 2025, 10:53:33 am
content: Hello,I am currently developing an NB-IoT device and considering purchasing a used CMW500. My primary use case for this equipment is RF pre-certification, including putting the NB-IoT module into various TX modes to measure conducted power, spurious emissions, and similar parameters.I came across a CMW500 with the following options installed:KM011, IQ VS SLOT TX MEASKM012, MULTI EVAL LIST MODEKM200, GSM RX6 TX MEASKM300,NB-IOT R13 TX MEASKM400, WCDMA R99 TX MEASKM500, LTE FDD R8 TX MEASKM550, LTE TDD R8 TX MEASKM750, TD-SCDMA TX MEASKS750, TD-SCDMA R4 SIG BASICHowever, it does not include the KS300 NB-IoT R13 Signaling option.Could anyone familiar with this equipment clarify the difference between the KM300 and KS300 options? Additionally, what limitations might I face in NB-IoT testing without the KS300 option?Many thanks for your help.
My new idea for super low bandwidth communication - Page 1
Forum section: electronics / rf-microwave

author: Circlotron
author_rank: Super Contributor
timestamp: January 11, 2025, 01:02:52 pm
content: Make this has been done before, I don’t know. How about sending to a remote station an AI model of your voice. Then, at the transmitting side, simply turn your voice into text and send the text characters. They have the words reconstructed at the far end into something that sounds the same as your voice again.

author: Kleinstein
author_rank: Super Contributor
timestamp: January 11, 2025, 01:20:55 pm
content: Ai voice is not very easy to understand it would lack the additional information in emphesis and such. It would be usually easier to directly read a text, especially if there are transmission errors.

author: jonovid
author_rank: Super Contributor
timestamp: January 11, 2025, 01:49:32 pm
content: Quote from: Kleinstein on January 11, 2025, 01:20:55 pmjust add a text to voice on the receiving end if Ai voice floats your boat.

author: mawyatt
author_rank: Super Contributor
timestamp: January 11, 2025, 03:41:25 pm
content: For the actual comm link consider BPSK, it's the most efficient modulation scheme known wrt noise immunity and why it was used with the Voyager Space Crafts.Best

author: ataradov
author_rank: Super Contributor
timestamp: January 11, 2025, 04:08:01 pm
content: If you care about voice reproduction to the extent of transmitting minor variations, then this is not going to work at all.Otherwise, the idea of using unique voice characteristics and using them for compression is not new. This is basically what Linear Predictive Coding (LPC) does on a low level. If you have a specific speaker in mind, you can create and pre-train a better predictive model. It will not be as efficient as plain text, but it will transfer actual voice.
SA6 spectrum analyzer without rf shield - Page 1
Forum section: electronics / rf-microwave

author: harrimansat
author_rank: Regular Contributor
timestamp: October 20, 2024, 06:12:34 pm
content: There is anaone with a cheap aliepress SA6 spectrum analyzer? I have just received one and is quite noise. I have taken it apart and I see that it does not have RF shield for receiver and generator. If anyone has the same unit can please make the same meassurement that I upload? There´s not signal on SMA input.Thanks

author: harrimansat
author_rank: Regular Contributor
timestamp: October 20, 2024, 08:24:16 pm
content: https://youtu.be/OXHJ6RjT8s8?si=mBr-HzrJrk_xXu83

author: Kean
author_rank: Unknown
timestamp: October 20, 2024, 08:42:36 pm
content: Without anything connected to the input you are still going to pick up ambient radio signals.Try again with a 50 ohm terminator on the input.

author: KE5FX
author_rank: Super Contributor
timestamp: October 20, 2024, 09:27:13 pm
content: What you actually wanted was a TinySA Ultra. The Zeenko store on Ali Express sells the legitimate ones, I believe.

author: harrimansat
author_rank: Regular Contributor
timestamp: October 21, 2024, 08:19:47 am
content: I have one too! and other real spectrum analyzers, Thanks!

author: harrimansat
author_rank: Regular Contributor
timestamp: October 21, 2024, 08:21:46 am
content: Thanks for your answer Kean, but this thing has low impeadance inputs. Any way you can see the same results with a 50 ohms termination.

author: electronic_guy
author_rank: Regular Contributor
timestamp: October 21, 2024, 10:53:23 am
content: Usually the input is 50 ohms. And even after connecting the 50 ohm termination, you get these spurious signals and they are considerably larger, then it’s probably originated internally and that’s not a good sign. It could be problem with the LO, mixer, power supply issue and/or many more. It’s also possible that without good shielding it couples external noise. No SA is perfect so there are known spurious signals that will appear on the spectrum, but these are usually noted on the documentations by the manufacturer. I recommend you return it and get your money back if it’s possible.

author: harrimansat
author_rank: Regular Contributor
timestamp: October 26, 2024, 11:09:33 am
content: some more photos

author: harrimansat
author_rank: Regular Contributor
timestamp: October 26, 2024, 07:45:59 pm
content: Improved floor noise with custom made shield, 27.5mm x 24mm x 3mm

author: next3tx
author_rank: Newbie
timestamp: January 26, 2025, 09:01:33 am
content: Seems I burned my SA6 with high power signal on input. Now trying to get IC for repair. Below photos of input part of SA6