hybridfree/eevblog-posts huggingface dataset:
Adding Amateur Digital Modes to Analog Shortwave Receivers - Page 1
Forum section: electronics / rf-microwave

author: jonovid
author_rank: Super Contributor
timestamp: January 08, 2024, 01:29:52 pm
content: today's portable shortwave receiver designs.why are some recent analog shortwave receivers designed with a digital bluetooth or USB player microchip functions.with some of the more expensive portable shortwave receivers having single sideband modes.but Non I know of has any of digital modes used by today's radio Amateurs.its about time digital modes got added to analog shortwave receiver designs that also have other digital functions.at the very least a single chip morse code translator to on screen scrolling text mode.or 1 or 2 other digital modes used by today's radio Amateurs integrated into the design of portable shortwave receivers.

author: xrunner
author_rank: Super Contributor
timestamp: January 08, 2024, 01:41:10 pm
content: Dream on ...It'll never happen because 99.237% (my estimate) of the buyers of these little portables don't know or care about the digital ham modes. Take FT8 for example. For one thing the decoding software is updated from time-to-time so how would that happen on the receiver (it's a windows app)? For another, what is there for the average person to see on FT8 besides a boring exchange of callsigns? It wouldn't hold their attention for very long.Yea there things like PSK , Hellschreiber (which is visual) and other barely used digital modes in the ham bands. CW? LOL I'm laughingnobody cares anymore. But again, average consumers wouldn't care and the hams have their own much better receivers for all of it, so again it won't happen.

author: Andy Chee
author_rank: Super Contributor
timestamp: January 08, 2024, 02:03:21 pm
content: The problem is; which digital modes should be added?You don't want another debacle like C4FM vs D-STAR happening!

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 08, 2024, 03:02:49 pm
content: Quote from: jonovid on January 08, 2024, 01:29:52 pmApart from the already mentioned reasons (they who care have much better equipment) there's also cost. Adding bluetooth and/or USB costs maybe $5, but to decode digital modes you need reasonable filters, a CPU and a screen which will make the receiver too expensive for the target customers and it's not even user friendly. I have an Icom R-9000 that has a built-in CRT and is capable of decoding FSK but I only used it once to see if it worked, today's software is much more flexible and mostly free.
Looking for Kenwood 2M model recommendation 12vdc Mobile with PL built in, - Page 1
Forum section: electronics / rf-microwave

author: CaptDon
author_rank: Super Contributor
timestamp: December 28, 2023, 11:15:06 pm
content: I am currently running a TR-7850. It works great, BUT, I have an external PL board that programs with DIP switches and isn't very user friendly when switching repeaters. My handheld is a Yeasu FT-60R which allows the PL to be programmed and stored for each repeater frequency. I am looking for the same functionality in a Kenwood brand mobile rig. 25 watts out hi with a low power setting of a few watts is desirable. Any leads that I can check out? Prefer something older, cheap and probably from Ebay. Thanks!!

author: CaptDon
author_rank: Super Contributor
timestamp: January 03, 2024, 03:05:27 pm
content: I followed the hundreds of replies and bought a Yaesu with Fusion features included. Wow, ham radio forum and Elmers abound.
Small SDR project - Page 1
Forum section: electronics / rf-microwave

author: stardropqi
author_rank: Newbie
timestamp: January 02, 2024, 01:04:03 am
content: Hi guys, I threw together this "backend" for a project I am working on, a wide-ish SDR for S band and above (Please ignore the input jack, I am not quite done with that section). However, I am not sure about the connections between the MAX2871->LTC5586, and the output of the anti alias filter to the AD9283s. Can anyone provide advice on connecting these ICs, or any other general information?
M9741G Transistor TDS - Page 1
Forum section: electronics / rf-microwave

author: metrologist
author_rank: Super Contributor
timestamp: December 29, 2023, 05:53:56 pm
content: I have a few M9741G in my parts bin but cannot find data. Anyone have an old reference?I'm looking to replace a couple 2SC2097. There are some on eBay but a bit pricey.

author: metrologist
author_rank: Super Contributor
timestamp: December 31, 2023, 12:06:50 pm
content: I think this is equivalent to the subject part:https://www.nteinc.com/specs/300to399/pdf/nte366.pdf
Looking for a 12 DPDT relay for switching different preamps at my antenna. - Page 1
Forum section: electronics / rf-microwave

author: Qmavam
author_rank: Regular Contributor
timestamp: December 19, 2023, 08:15:28 pm
content: I want to to do A/B/C testing with different amps and a transformer between my antenna and feedline. I want a long lasting relay that will hold up in my outdoor enclosure.I want a 12V DPDT relay. I'd like to keep the price under $5.I had success with an NEC RSP24H2C12H, but I don't find them available anymore.Does anyone have a favorite they recommend?Thanks, Mikek

author: A.Z.
author_rank: Super Contributor
timestamp: December 20, 2023, 07:09:51 am
content: check the Omron G5V-2-H DC12 should be ok for 30MHz and below, if instead you need to get up to VHF or above you'll need a coaxial relay and price will go up

author: geggi1
author_rank: Frequent Contributor
timestamp: December 20, 2023, 07:14:45 pm
content: You cn also look into PIN diode switching.

author: s54mtb
author_rank: Newbie
timestamp: December 30, 2023, 11:44:05 pm
content: Hope this helps:I have good experience with Fujitsu FTR-K1CK012W for HF. Here’s my project with them (intensively copied by aliexpress “producers”)…https://e.pavlin.si/2017/11/26/6x1-antenna-switch/There are measurements at the end of the page.

author: MarkF
author_rank: Super Contributor
timestamp: December 31, 2023, 02:51:56 am
content: I use these Axicom V23105 relays. But, not for RF frequencies.From their datasheet:Isolation at 100MHz/900MHz -39.0dB / -20.7dBInsertion loss at 100MHz/900MHz -0.02dB / -0.27dBVoltage standing wave ratio (VSWR) at 100MHz/900MHz 1.04 / 1.40Can that be right?
[help needed] Identify oddball coax connector - Page 1
Forum section: electronics / rf-microwave

author: nouserid
author_rank: Contributor
timestamp: December 24, 2023, 03:23:33 am
content: Hi folks,Came across this oddball coax (see attached picture) with an old Aertech/TRW tunnel (backward) diode detector from the 1970s. Structurally similar to a RP-SMA, with external thread and center pin, but not quite physically compatible. Some of its dimensions are:Thread OD: 6.2 mmPitch: about 0.8 mmDielectric ID: 3.1 mmThanks in advance.

author: MarkT
author_rank: Frequent Contributor
timestamp: December 27, 2023, 02:02:05 am
content: Sounds like 1/4" diameter with 1/32" pitch then....
SMA Attenuators (value find) - Page 1
Forum section: electronics / rf-microwave

author: Randy222
author_rank: Frequent Contributor
timestamp: December 18, 2023, 07:24:55 pm
content: I am always looking for the value items. Finally found something that is on-par with product description.Specs test out ok, seem to be really good value.https://www.aliexpress.us/item/3256805879252327.html

author: bingo600
author_rank: Super Contributor
timestamp: December 19, 2023, 02:41:34 pm
content: Is that a "Gut feeling" , or can we see the measurement data please/Bingo

author: Randy222
author_rank: Frequent Contributor
timestamp: December 19, 2023, 04:18:11 pm
content: Quote from: bingo600 on December 19, 2023, 02:41:34 pmNot gut feeling. My testing shows basically same thing as OEM. Duly noted, OEM 30db test appears to run more flat and a tick lower than on my VNA. VSWR less than 1.25 ~0-6GHz, db looks good, for $3(US), not bad.I will add pics here.

author: uer166
author_rank: Super Contributor
timestamp: December 21, 2023, 10:07:09 am
content: Just wanna say thanks, I was looking for a budget attenuation kit for ISM.

author: nctnico
author_rank: Super Contributor
timestamp: December 21, 2023, 11:36:15 am
content: But can it actually handle the rated power? A while ago there was a thread about cheap Chinese attenuators that didn't meet their power ratings.Personally I rather buy used brand attenuators from Ebay or new than taking a chance with the cheap Chinese models.

author: Randy222
author_rank: Frequent Contributor
timestamp: December 21, 2023, 02:25:30 pm
content: Quote from: nctnico on December 21, 2023, 11:36:15 amI am not sure what the actual power ability is. Ratings are typically rms, but maybe it's abs for these items. I usually like to stay below 1/2 rating, so I would expect I could use these 1w rms. Obviously some signals are not nice, square, triangle, wavvy sine.For ~$3usd you buy a few, run up some voltage on them until you get 2w, let it burn-in at 2w for 8hrs, let cool, re-measure vswr and such.For ~$3usd you buy a few, up the voltage until it frysFor ~$3usd you buy a few, cut them open and see what's inside.EEVb is home of "rip in, tear down", yes?They are however the 1st set in my china pile that actually tested to be what the seller said they are, at least in vswr & attenuation. Never did any LCR or watt testing.

author: joeqsmith
author_rank: Super Contributor
timestamp: December 21, 2023, 04:05:20 pm
content: Thanks for taking the time to post about these.I bought a similar set from China. Mine cost more (maybe $20) and are laser marked. I wasn't expecting them to be accurate at all or that the connectors would be decent enough to use them. Was I wrong. I recently used them to demonstrate a frequency extended for the LiteVNA. Timestamp showing how they compare with a few others I have at 10.16GHz. Based on my own findings, I'm not too surprised that you would find them to be fairly accurate. I am VERY much surprised that they can sell a product that works so well for so little.Power wise, I only use these for small signal applications (<20dBm) and have not had any problems with them.https://youtu.be/qxH-a0cCY3U?t=474
HP 8753C amplifier measurements - Page 1
Forum section: electronics / rf-microwave

author: rfguy2020
author_rank: Contributor
timestamp: December 08, 2023, 06:46:25 pm
content: Hello,I have HP 8753C (firmware 04.12) with 85044A test set. I have been using it mostly for antenna measurements (S11).I'm trying to use it for amplifier measurement. I'm measuring Mini-circuits ZX60-V62+ as I can see values from data sheet. I have performed one-path 2-port calibration, since my test set does not allow full 2-port calibration. I have added 20dB attenuator to B port as maximum allowed power level is +20dBm.S11 is really strange sometimes it is positive (>0dB), sometimes it is something I expected and sometimes it is between those two. S21 looks more or less expected, but it seems to go strange sometimes as well.If I don't connect my amplifier to port B and just add termination to amplifier output, then my S11 is expected. So for some reason, S11 goes wild if I connect amplifier output to port B through 20dB attenuator. I don't understand how it detects that I have connected active device to port B? Is there something broken in my VNA or do I have to change some settings?

author: rfguy2020
author_rank: Contributor
timestamp: December 09, 2023, 08:06:30 am
content: I figured out root cause by myself. I actually need to rotate the device for reverse and forward measurement as VNA instructs. For passive devices it does not make big difference if I don't follow this instruction, but amplifier or non reciprocal devices gives totally wrong results.

author: DrNefario
author_rank: Contributor
timestamp: December 21, 2023, 03:07:40 pm
content: An HP 85046A test set is the type that can automatically switch the ports around while making the measurements.
Searching for a Linear UHF RFID Antenna with 4dBi - Page 1
Forum section: electronics / rf-microwave

author: Tonsberg
author_rank: Newbie
timestamp: December 20, 2023, 01:52:53 pm
content: Hello everyone,I spent endless hours searching for an antenna that I could use on my project. I need a Linear UHF RFID with a narrow BeamWidth (less than 10 degrees) and around 4dBi gain that can fit on a device 80mm x 70mm. Do you know if it even exists this type of antenna? I'm quite new in the field so I would really appreciate it if you know someone who sells these types of antennas.Thanks in Advance.

author: RFDx
author_rank: Regular Contributor
timestamp: December 20, 2023, 03:55:51 pm
content: Unfortunately such an antenna doesn't exist.

author: geggi1
author_rank: Frequent Contributor
timestamp: December 20, 2023, 06:56:32 pm
content: Assuming the frequency used is in the 400 Mhz range and you are in ITU region 1.If you dont have the gain requirement and the beamwith you will be able to find antennas that fits on the unit.For the 400 Mhz frequencies there are plenty of redused size antennas.There are free usage frequencies still UHF in the 800 Mhz range 900 Mhz range and in the 2200-2500 Mhz range. At higher frequencies it might be possible to fulfill your requirements.

author: Tonsberg
author_rank: Newbie
timestamp: December 21, 2023, 05:26:34 am
content: Thank you guys. The frequency that I want to use is from 900mHz-980mHz. Ok I thought so that it would be difficult to find such an antenna. At least are there any linear polarised antennas with super narrow beamwidth? Beamwidth is more important than Gain.

author: RFDx
author_rank: Regular Contributor
timestamp: December 21, 2023, 02:52:27 pm
content: Quote from: Tonsberg on December 21, 2023, 05:26:34 amGain goes hand in hand with the beamwidth of the antenna.http://dg7ybn.de/1296MHz/GTV23_65w.htmNot the frequency range you need but just an example of what to expect. A long Yagi antenna that approaches the beamwidth you are looking for. The more than 60 elements used for this, leads to an antenna length (~6m) that is nowhere near the dimensions you mentioned.https://scmsinc.com/product/nicom-bkp120-stl-grid-parabolic-antenna-900-960-mhz-4ft-n-connector-100w/Grid-type parabolic antenna with a stiff price, ~1,2m diameter and beamwidth still above what you are looking for.https://www.antennaexperts.in/product-detail.asp?cat=grid-parabolic-antenna&id=10700-990MHz parabolic antennas with diameters of 2,3 or 4m that meet or exceed your demands regarding beamwidth.https://www.gsm-ant.com/sdp/2110939/4/pd-6942101/21067492-2971601/915MHZ_Parabolic_antenna.htmlChinese version of a gridtype parabolic antenna for 900MHz. To be honest the published beamwidth looks bogus for such a small antenna and only 15dBi of gain.
Multisection wideband impedance transformer design for different types of loads - Page 1
Forum section: electronics / rf-microwave

author: Vilius
author_rank: Contributor
timestamp: December 17, 2023, 04:21:31 pm
content: Hi,I am exploring and learning the properties of wideband impedance transformers. Found this wonderful book that answered a lot of my questions:http://mwl.diet.uniroma1.it/people/pisa/RFELSYS/MATERIALE%20INTEGRATIVO/BOOKS/Pozar_Microwave%20Engineering(2012).pdfChapter 5.7 describes the design of such transformer... The only thing I am not sure is are there any differences in design parameters along the load type? As I understand, all the examples around that chapter presumes purely resistive load. But I intend to design ant test this transformer for a sinuous antenna, which impedance type is yet unknown to me (The Smith chart will tell me that after tests...) So is there any difference in designing a multisection impedance transformer for resistive, capacitive or inductive impedances (or a more complex load model consisting of a little bit of every type.) The answer would be obvious for lumped element Pi or T network, but this multisection thing is more of an advanced field...

author: RoV
author_rank: Regular Contributor
timestamp: December 17, 2023, 10:24:53 pm
content: Nice book, I have the 2nd ed in paper. I'm quite surprised at finding it freely downloadable in a university site, because it's clearly a copyright violation! And there are several other books in the same folder...

author: RFDx
author_rank: Regular Contributor
timestamp: December 18, 2023, 05:24:51 pm
content: Quote from: Vilius on December 17, 2023, 04:21:31 pmSource and load needs to be resistive with this type of broadband matching networks.Quote from: Vilius on December 17, 2023, 04:21:31 pmThe simplest way to do that would be to let a RF simulation tool, that has the ability to synthesize (broadband) matching networks, do that for you. All you need is a S-, Z- or Y-parameter file of the load (e.g. your antenna).
Hallicrafters SX-25 Videos  - Page 1
Forum section: electronics / rf-microwave

author: Peithojr
author_rank: Contributor
timestamp: December 25, 2023, 05:10:01 am
content: I'm posting this in Ham Radio Section, I originally posted in the wrong section!I last week I acquired a Hallicrafters SX25 and now looking to get started, not sure why my SX25 has missing parts and the power transformer looks bigger than the one i see in the videos. Also i found the schematic online, but not detailed as i hoped for. After looking at these videos, I'm assuming i need to replace all the wax capacitors, i hope i didn't take too much on!This is not my project, but was fascinated by these videos about the Hallicrafters SX-25. I found it over the weekend, just wanted to share.Starts here and i think there are several videos.https://youtu.be/_ldhHmzeqx0https://youtu.be/1Y6z777lQcMhttps://youtu.be/SiKorZCIcDshttps://youtu.be/OFLJ6VfzFmohttps://youtu.be/JWlIdAcTbtEhttps://youtu.be/2qDs7tyUZmQhttps://youtu.be/R0vrzpXwijk
How to decrease the stray "L" in my atu - Page 1
Forum section: electronics / rf-microwave

author: p.larner
author_rank: Frequent Contributor
timestamp: December 15, 2023, 07:40:58 pm
content: my homebrew t match works fine on 80+40m but i am sure it has too much inductance,its like my roller coaster needs to unwind a few more turns but already at min inductance,the roller coaster is about 50mm dia and 35cm long,the interconnecting wires are about 30cm long so i imagine too much stray inductance?,any idea how to fix it,would using coax instaid of wire for all interconnects inside it help,or even copper tube cut into strips and use that to link the caps+ roller inductor etc,i have some porcelain pillars i can mount the strip on top off,i have 2 strips of 1mm thick+5mm wide copper strip i have made.?

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: December 15, 2023, 08:04:00 pm
content: Agree 30cm is way too long for wires in an ATU.Either build a second ATU with a much smaller inductor (and rotary switch if you can't get a roller) or modify what you've got.That could include a second smaller tapped inductor in series with the roller inductor.That second tapped inductor should be mounted on the back of a good quality rotary switch that can handle the power.You could set it up so the large roller inductor is only switched in for lower frequencies, with use made of the second tapped inductor for the higher bands.

author: vk4ffab
author_rank: Frequent Contributor
timestamp: December 15, 2023, 09:19:47 pm
content: Quote from: p.larner on December 15, 2023, 07:40:58 pmWell you have a VNA, just measure it and see what is what. Set both caps to minimum capacitance and the inductor to minimum inductance and sweep it from 1 to 30mhz. If you can take the caps out of circuit even better as you then wont have to do any math.Also dont use the tiny screen on the nanovna, download this software and put it on a PC to control the VNA with.https://nanovna.com/?page_id=90that way you can pop out images and save them for upload to the forum and the like.Here is my home brew remote tuner connected to the base of a vertical that I control over wifi, essentially with the caps and inductors off (not that you can have them off as there is a minimum always present in your design) you should not see much defection from 50 ohms resistive from 1 to 30mhz and what you do see are the strays.

author: p.larner
author_rank: Frequent Contributor
timestamp: December 15, 2023, 10:35:10 pm
content: will do it later,at the moment i am replacing the tuners internal wires with copper pipe that i have flattened and cut into strips,these are being mounted on porcalain standoffs,it looks neater and should be better in general i think?.73

author: p.larner
author_rank: Frequent Contributor
timestamp: December 15, 2023, 10:38:33 pm
content: should of mentioned the cap is a 300pf+300pf diferential cap wide spaced.
"Level shifting" a 500MHz sinus signal - Page 1
Forum section: electronics / rf-microwave

author: luky315
author_rank: Regular Contributor
timestamp: December 09, 2023, 06:42:28 pm
content: I have an AC coupled HF sinusoidal signal (0.1Vpp to 1Vpp) from a signal generator and need to level shift the signal to 0 to Vpp, idealy without manual adjustment. The problem is that I don't know for what to search - how is this sort of bipolar to unipolar signal "conversion" called?

author: Ian.M
author_rank: Super Contributor
timestamp: December 09, 2023, 07:12:14 pm
content: At 500 MHz, anything active is going to be a PITA. Feed a reversed Bias T with a DC source to offset its output. Making the DC source track the peak amplitude will be a PITA, and a PITA2if the signal is AM modulated, so if you can live with a manually set DC offset, don't try to make it tracking!

author: luky315
author_rank: Regular Contributor
timestamp: December 09, 2023, 08:48:13 pm
content: The signal ist not modulated and should be relatively stable, but I get your point.Would it be simpler to tie the 50R termination to a variable voltage?

author: Hamelec
author_rank: Regular Contributor
timestamp: December 09, 2023, 09:54:09 pm
content: more ore less a clamping (schottky) diode, but all depending of your load and your accepted DC failure..

author: tszaboo
author_rank: Super Contributor
timestamp: December 10, 2023, 12:01:48 am
content: So you could use a balun. Maybe one with a center tap, and drive that with 1/2 the peak voltage of the input?

author: Marsupilami
author_rank: Frequent Contributor
timestamp: December 12, 2023, 03:57:24 pm
content: Quote from: luky315 on December 09, 2023, 06:42:28 pmI'm a bit confused by your input/output spec. Nevertheless this sound like the typical single rail ADC drive problem.High speed opamps are your friend:https://www.analog.com/en/products/ltc6253.html#product-overviewFor a circuit you can start at:https://www.analog.com/media/en/training-seminars/design-handbooks/Data-Conversion-Handbook/Chapter6.pdfSo far this is only manual, but you can use the 2nd opamp in the package of above device to integrate either the input or the output and feed it back to create the necessary V1 voltage for an appropriate mid level shift.E.g. peak detector on the input as inhttps://sound-au.com/appnotes/an012.htmIf you need to scale the signal too automatically that's a bit more involved, but I'm sure you can solve it by throwing another opamp or two at it.HTH

author: radiolistener
author_rank: Super Contributor
timestamp: December 15, 2023, 07:51:08 am
content: Quote from: luky315 on December 09, 2023, 06:42:28 pmif you have AC coupled signal, it means that it don't have DC coupling, so you can add DC bias from some power supply in order to get DC offset. Also you can add some voltage source in series with your AC coupled signal source.
Why superheterodyne receiver or SA use mostly 3 different IF frequency(Why not2) - Page 1
Forum section: electronics / rf-microwave

author: AttacK
author_rank: Newbie
timestamp: December 12, 2023, 09:09:22 pm
content: [ Specified attachment is not available ] [ Specified attachment is not available ]Hi everyone,Firstly this is my first message in forum.I've been researching SA for a while and I've found that they mostly use 3 IF. The 1st IF is higher than the input signal, 2nd IF is a lower frequency than the input signal. 3rd IF also has the lowest frequency. After 3rd IF, demodulation is performed. The reason for turning the signal up once and down once is to get rid of the image signals, I understand why this makes a lot of sense. But why is the lowest frequency IF frequency not preferred directly, but it is lowered to the main band in 2 stages.Why we need mid-IF frequency. In this example below, why we need 322.5 MHz?Thanks in advance

author: Another Kevin
author_rank: Newbie
timestamp: December 12, 2023, 11:26:31 pm
content: Wikipedia, which knows everything, has a decent answer:https://en.wikipedia.org/wiki/Superheterodyne_receiver#Multiple_conversionEssentially, it has to do with filters. In front of each mixer, you need a filter that will reject signals that are twice the IF frequency away from the signal to be detected. If the final IF were 455 KHz (a common one for radio receivers) but the initial IF were 5 GHz, you'd need a filter that could pass a 5 GHz signal from one that's 5.000455 or 4.999555 - a tall order! When radio hams are doing receivers, it's pretty common to have a downconverter from the band of interest to 28-29.7 MHz or 144-148 MHz (so that a station receiver can be used to work with it). The station receiver is likely to have 45MHz, 9 MHz and 455 kHz IF frequencies, with progressively narrower filters in front of the mixers.Modern digital stuff means that you don't need quite as long a conversion chain, because the final filtering happens in DSP. In that case, the final IF needs to be within the bandwidth of the A/D system.

author: David Hess
author_rank: Super Contributor
timestamp: December 13, 2023, 01:46:59 am
content: A high second IF is needed to provide sufficient image rejection while a much lower third IF provides most of the selectivity.
Dickie brand 2.4 GHz walkie talkie range test - Page 1
Forum section: electronics / rf-microwave

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: December 05, 2023, 06:52:33 pm
content: At least if you're in Australia you might have seen these at Aldi and been curious as to what's inside them and their transmitting range.This video answers some of your questions. I open them up and do a range test.

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: December 10, 2023, 08:50:36 pm
content: If after seeing that you think I could have tried further, you're right.Here I go to a spot away from houses by a river to try longer distances.

author: Lambda_
author_rank: Newbie
timestamp: December 11, 2023, 12:10:34 am
content: Now add a "8 watt" Wifi PA and point it at QO100

author: LaserSteve
author_rank: Super Contributor
timestamp: December 11, 2023, 11:44:03 pm
content: What's the chipset? Inquiring minds want to know for the 2.2 to 2.4 Ghz ham band. With suitable improments, mmic amps and filtering for harmonics added of course.Steve
Experiments with an SAA1057 Synth PCB from a Revox B261 Tuner - Page 1
Forum section: electronics / rf-microwave

author: djsb
author_rank: Super Contributor
timestamp: December 16, 2023, 09:16:07 am
content: I have finally found some BASIC code for a PIC16F628A MCU that I can use to control a spare SAA1057 based synthesizer PCB that is used in a Revox B261 FM tuner. I have attached the schematic of this synthesizer below. Here is more information about the digital control system of this tunerhttps://www.eevblog.com/forum/microcontrollers/old-cbus-serial-protocol-specification-any-info-out-here/msg4348648/#msg4348648I am just wondering if it is as simple as just applying the required supply voltage to this synth PCB, or do I have to create something for the tuning voltage to control. The local oscillator is already on the PCB and its output is supplied to the balanced mixer through a buffer transformer.I just want to control the SAA1057 using the PIC16F628A and see what happens. Would this work?PS, I intend to translate the BASIC code to C and move it to a more recent PIC (maybe a PIC18F16Q41) later on.

author: CJay
author_rank: Super Contributor
timestamp: December 16, 2023, 11:47:42 am
content: Well, you're going to need +15, -15 and +33V but outside of that, yeah, it really should be as "simple" as hooking up a CPU and have it set up the dividers, counters etc. in the chip, it looks like everything else is already there.
3d print emi honeycomb? - Page 1
Forum section: electronics / rf-microwave

author: coppercone2
author_rank: Super Contributor
timestamp: December 09, 2023, 03:20:59 am
content: had a interesting idea, to make those honeycomb EMI filter vent panels by 3d printing and paint dipping the parts. I found thishttps://www.printables.com/model/163200-openscad-parameterized-honeycomb-storage-wallI have a chassis I will be working on that can be used for tests before its filled (it has connectors and plenty of vent holes)thought someone might find the idea useful
Wideband RF power amplifier - Page 1
Forum section: electronics / rf-microwave

author: stenborg
author_rank: Newbie
timestamp: December 07, 2023, 05:39:08 pm
content: I have bought an amplifier on an auction that I need some help with. It is built by RF power labs, a company that doesn't exist anymore. And Google doesn't say much either.My tests so far concludes that it at least works and gives output. Someone said I could expect 5-10W output power. My intention is to use it for immunity testing in a TEM cell.I've attaches some photos.Questions:1. Have anyone seen this before? And if so have any documentation.2. I have swept it from 1-500MHz with a -10dBm signal (0dBm seemed to overdrive it). The output is very nonlinear with peek power around 65MHz. Is this expected?3. A sticker says 0.5-1000MHz What could be the expected band width with this construction?4. Any further information that could be helpful.ThanksPer-Ola

author: pienari
author_rank: Regular Contributor
timestamp: December 07, 2023, 05:58:30 pm
content: I can not see what fets is in the board?.

author: stenborg
author_rank: Newbie
timestamp: December 07, 2023, 08:28:54 pm
content: All are POLYFETs. The FET in the final stage is a F2012 and in the 2nd stage it is aF2001. 1st stage is hard to read but begins with F200.

author: jonpaul
author_rank: Super Contributor
timestamp: December 07, 2023, 09:05:30 pm
content: like many CATV line amps. Millions were made.Most like a 72 or 75 Ohm Zo.Jon

author: tszaboo
author_rank: Super Contributor
timestamp: December 07, 2023, 09:07:51 pm
content: Quote from: jonpaul on December 07, 2023, 09:05:30 pmThose are clearly 50 Ohm BNC connectors.

author: jonpaul
author_rank: Super Contributor
timestamp: December 08, 2023, 12:01:26 pm
content: BNC type connectors exist in BOTH 50 and 75 Ohm versions.Broadcast equipment has many 75 Ohm BNC, with slightly different inner conductor dim.Eg used for Composite FM FMCX digital audio or AES2id.What is measured Zo 50 or 75 Ohm?Jon

author: tszaboo
author_rank: Super Contributor
timestamp: December 08, 2023, 12:12:36 pm
content: The isolation is also different for 50 and 75 ohm. This looks like 50 ohm( middle row)

author: stenborg
author_rank: Newbie
timestamp: December 08, 2023, 03:03:41 pm
content: Hi,thanks for helping me understand this amplifier. Regarding the impedance. What speaks for 50ohm is the company that used it before, I can hardly think why the could have the use for a 75ohm amp. But connecting its input to my VNA isn't conclusive, see attachment. It's all over the place, but at least centered around 50ohms. Maybe a 6dB attenuator on the input would be wise.But at least the datasheet for the F2012 confirms the 5-10W expected power.Keep up the good work!/Per-Ola
looking for a book - Page 1
Forum section: electronics / rf-microwave

author: p.larner
author_rank: Frequent Contributor
timestamp: December 06, 2023, 02:06:07 am
content: looked for Transmission Line Transformer Handbook.by Jerry Sevick,it was on the amidon site but has since gone,has anyone the pdf copy they can post or send me via email?,cheers+73.

author: Andy Chee
author_rank: Super Contributor
timestamp: December 06, 2023, 06:22:40 am
content: Here you go:https://letmegooglethat.com/?q=transmission+line+transformer+sevick+amidon

author: Smokey
author_rank: Super Contributor
timestamp: December 06, 2023, 09:41:40 am
content: https://ia601609.us.archive.org/17/items/fe_Ham_Radio_Transmission_Line_Transformers_Handbook/Ham_Radio_Transmission_Line_Transformers_Handbook.pdf

author: p.larner
author_rank: Frequent Contributor
timestamp: December 06, 2023, 02:27:16 pm
content: thanks,the link in the post before the last one was spam.

author: A.Z.
author_rank: Super Contributor
timestamp: December 06, 2023, 06:12:21 pm
content: Quote from: p.larner on December 06, 2023, 02:27:16 pmno, no spam, it was a suggestion

author: tggzzz
author_rank: Super Contributor
timestamp: December 06, 2023, 08:22:46 pm
content: Quote from: p.larner on December 06, 2023, 02:27:16 pmNo, it isn't spam, by any definition.It is something that, when you master the techniques to the same extent that everybody else on this forum has, will change your life for the better. And ours.

author: armandine2
author_rank: Frequent Contributor
timestamp: December 08, 2023, 07:48:51 am
content: Quote from: tggzzz on December 06, 2023, 08:22:46 pmit linked me to Ebay ?

author: tggzzz
author_rank: Super Contributor
timestamp: December 08, 2023, 11:14:19 am
content: Quote from: armandine2 on December 08, 2023, 07:48:51 amCurious. This is where I "ended up". I wonder why the difference?

author: jonpaul
author_rank: Super Contributor
timestamp: December 08, 2023, 12:07:42 pm
content: Google is just ads and a sales market now.Use a decent SE like DuckDuckgo,https://ia801503.us.archive.org/17/items/Ham_Radio_Transmission_Line_Transformers_Handbook/Ham_Radio_Transmission_Line_Transformers_Handbook_text.pdfj

author: tggzzz
author_rank: Super Contributor
timestamp: December 08, 2023, 01:16:07 pm
content: Quote from: jonpaul on December 08, 2023, 12:07:42 pmI'm not convinced that duckduckgo always "passes on" things like quotes and minus symbols in search queries.SometimesI get more useful results by entering the same search terms directly into gurgleOf course that could also be gurgle being "awkward".

author: jonpaul
author_rank: Super Contributor
timestamp: December 08, 2023, 02:11:56 pm
content: Anyway the book is a great find for fans of baluns!Jon
Rigol MSO5000 - % modulation measurement? - Page 1
Forum section: electronics / rf-microwave

author: 6SN7WGTB
author_rank: Regular Contributor
timestamp: December 02, 2023, 12:13:42 pm
content: I know how to measure % modulation easily enough using AY BY cursors on a 'scope.But am I missing the obvious on my MSO5000 - is there actually a 'Measure' or 'Math' setting that does this for me?

author: BRZ.tech
author_rank: Regular Contributor
timestamp: December 07, 2023, 10:49:40 pm
content: Hi6SN7WGTBYou can measure the Modulation Index, Modulated Amplitude, and See the Carrier and LSB and USB lanes, through the FFT.However, the measurements of the FFT lines are generally in dBV, but knowing the measurement in dBV, you can convert it to Vrms.In theory, the Amplitude of the LSB and USB FFT lines should be exactly the same, but they are not always the same, for several reasons.Knowing the Amplitude of the FFT range of the Carrier, and of the LSB or USB, you can divide it into Vrms of the LSB/Carrier, or USB/Carrier, and multiply by 100%. Then you will have the measurement in % of the Modulation Index.I suggest that you initially use the SG1 or SG2 of the MSO5000 to learn, and produce a 1MHz Sine Signal, with 1Vpp, with AM Modulation of a modulator signal of f = 10KHz, and Modulation Index at 80%.As we are talking about RF and Amateur Radio, you can select the SG1 output to 50 Ohm, and use an RG58 or RG316 coaxial cable, with 2 BNC connectors. and at the CH-1 input, use a “T-BNC” and a 50 Ohm terminating load.In FFT, the main tip is to use the “Span-Center” mode and place the center at 1MHz and Span at 50KHz.If you injected 80% Modulation Index, you should measure approximately 80%.For myself to learn, as I have some difficulties using DSO/MSO, I made some videos for beginners on the MSO5000, and a quick use manual.There are many commands, and you can save the program in STORAGE, and use it whenever you want.You can download the quick use manual and watch the videos on my YOUTUBE channel.The video to configure the FFT for measuring AM signals is #17.Here the channel and instructions for downloading the quick use manual are indicated in the description: RIGOL MSO5000 QUICK SETTINGS.The text is in English, and the speech is in my country's language Portuguese, but you can use the YouTube translator.Good luck. 73.
9:1 transmission line transformers (TLT) BalBal Balun Ruthroff - Page 1
Forum section: electronics / rf-microwave

author: Lambda_
author_rank: Newbie
timestamp: December 07, 2023, 07:03:36 pm
content: This Excellent LDMOS build sparked my interest in this kind of Impedance matching transformer.https://qrpblog.com/2019/10/a-600w-broadband-hf-amplifier-using-affordable-ldmos-devices/https://qrpblog.com/wp-content/uploads/2019/10/circuit-schematic.pngI head to think about this for a while to understand how the output impedance matching transformer works.And im still not fully convinced i get it right so let me explain.The Transformer is in the build is just keeping the Transmission line short and ignores the added delay.(right?)it works like a "Ruthrof autotransformer"simplified and rearranged it looks like this:"As this is a 1:9 transformer and the output has to be 50ohm, the input impedance works out as 50/9 = 5.56ohm and the coax characteristic impedance is sqrt(50*5.56) = 16.67ohm."For some TLT this is somewhat intuitive since the transmission lines outputs are in parallel and the outputs are in series or vice versa.for example 50Ohm to 12,5OhmHere the 2 25Ohm Transmission lines are in series at the input to form a 50Ohm input and in parallel to form a 12,5Ohm output.Can i Analyze this by looking into the Transformer replace the Transmission line ends with resistors of the characteristic impedance?this seams to work for the 4:1 version but not the 9:1 version?But the 9:1 Version only uses 2 transmission line with a 1/3 of the impedance of 16.667OhmAlso if i would want to add the Delay line to correct the phases shift (like in the linked video) what would be the Ideal impedance for the Delay line?If i draw it like this it starts to makes sens... (?)For the version with the third delay line it would add up to 50Ohm on the output if all 3 lines have 16.66Ohm and to 5.56ohm on the input.For the Balanced version with 4 lines the delay lines would need to have 16.66/2 Ohm?List of resources about this topic:https://www.mikrocontroller.net/attachment/217383/Trask_TLT_Tutorial.pdfhttp://k5tra.net/TechFiles/Transformers.pdfhttps://www.jstage.jst.go.jp/article/elex/7/8/7_8_534/_pdfhttps://www.highfrequencyelectronics.com/Feb04/HFE0204_Sevick.pdf
heath robbinson panadaptor idea - Page 1
Forum section: electronics / rf-microwave

author: p.larner
author_rank: Frequent Contributor
timestamp: December 06, 2023, 03:41:13 pm
content: I have a cheap chineese sdr reciever like this onehttps://www.aliexpress.com/item/1005003954483936.html?spm=a2g0o.productlist.main.1.25b2290aNK2I7n&algo_pvid=160734b4-a329-47e2-9279-f9e7246bfcf0&algo_exp_id=160734b4-a329-47e2-9279-f9e7246bfcf0-0&pdp_npi=4%40dis%21GBP%2114.66%2114.66%21%21%2117.94%21%21%402103890917018769376058822e5da7%2112000034890967339%21sea%21UK%212308464272%21&curPageLogUid=ZLK588cpURc8i also have an old yaesu ft 707 txcr,can i tap the if and feed it into the sdr antenna and use it with sdruno as a bandscope/panadaptor?the sdr is a RSP1 Msi2500 Msi001 SDR Reciver 10kHz-1GHz /10kHz-2GHz

author: Andy Chee
author_rank: Super Contributor
timestamp: December 06, 2023, 04:27:51 pm
content: Yes, it is possible to tap the IF and feed it into your SDR.For example:https://swling.com/blog/2015/12/how-to-use-the-sdrplay-rsp-as-a-panadapter/

author: p.larner
author_rank: Frequent Contributor
timestamp: December 07, 2023, 05:25:19 am
content: it says this in the service manual: The RF signal is fed to the Schottky barrier diodering module, Q1008 (ND487C2-3 R), where the RFsignal is mixed with a local signal delivered from- -- --·------ --- -·-91012 ( 2SC2407 ) ,_resulting in a first IF of 8.9 875MHz. The input and output of the diode ring areprotected by 50 ohm attenuators, which stabilizethe input and output terminations for optimumintercept characteristics. The IF signal is thenamplified by mixer post-amp Q1009 ( 2SC2407) andfed to pin 5 of J 1 0'01 for delivery to the IF Unit.so do i pick off the if sig from pin 5 of j1001 then?

author: Andy Chee
author_rank: Super Contributor
timestamp: December 07, 2023, 06:14:59 am
content: Remember to use a high impedance buffer on your IF tap.For example:https://hamwaves.com/sdr/doc/z10000b-u.v1r02.manual.pdf

author: Hamelec
author_rank: Regular Contributor
timestamp: December 07, 2023, 10:40:16 am
content: ..or a resistive power splitter.
Morgan Systems M-302 VHF/UHF Serge Arrestor on the VNA - Page 1
Forum section: electronics / rf-microwave

author: kj7e
author_rank: Frequent Contributor
timestamp: December 05, 2023, 01:19:58 pm
content: I have a UHF repeater at work I am going to refurbish, new Commander Technologies 1151 antenna (replacing an old DB636-C), new RCA RDR9000 repeater (replacing 25 year old Motorola MTR2000) and a few other improvements. No one ever installed a surge arrestor on this system, so picked up a Morgan Systems M-302 VHF/UHF Surge Arrestor and decided to put it on the VNA for fun. I prefer the Morgan Serge Arrestors over the PolyPhaser up through 500MHz as the Morgan is a gas discharge with DC ground on the antenna side with a DC blocking cap to the radio side with a static bleeder, not just a gas discharge like the PolyPhaser.Also picked up one of the NMOSPL-4 calibration OSL's fromhttps://rftestparts.com/, very impressed with the build quality. Of course, I have no way to verify the validity of the load test data, but have no reason to doubt it either. Used this as the reference calibration between the RG142 jumpers.
diy atu case options - Page 1
Forum section: electronics / rf-microwave

author: p.larner
author_rank: Frequent Contributor
timestamp: December 05, 2023, 09:22:38 am
content: i have a homebrew atu i has an aluminium open frame with a steel painted front and sheet steel bottom,can i use metal sheet for the top and sides or is plywood better,thinking of circulating rf currents using metal.whats best?.

author: vk3yedotcom
author_rank: Frequent Contributor
timestamp: December 05, 2023, 10:25:16 am
content: Aluminium is OK provided your coils are not too close to the case.
3 to 1 low level VHF RF switch - Page 1
Forum section: electronics / rf-microwave

author: kj7e
author_rank: Frequent Contributor
timestamp: December 03, 2023, 03:43:30 pm
content: Needed a 3 input 1 output low level RF switch for 100 MHz for a work project. Not wanting to pay $500-800 for some commercially available switches, I built this one for about $50. Used some Panasonic HD video relays, needed to be 24v and these fit the bill. Tested, <0.1dB insertion loss, <1.15:1 VSWR, >65dB port to port isolation. May also just be an excuse to play with the VNA upgrade on the Siglent Spectrum Analyzer.

author: joeqsmith
author_rank: Super Contributor
timestamp: December 03, 2023, 04:24:42 pm
content: I have an old HP 59307A which has 2 X 4:1 relays. BNC connectors. It uses GPIB to control it. These show up on eBay from time to time. Here is one for $50 with shipping.https://www.ebay.com/itm/235324953012

author: kj7e
author_rank: Frequent Contributor
timestamp: December 03, 2023, 04:43:37 pm
content: Joe, those are nice, not seen those before. For this project the switch needs to fit inside another box we build. PLC based transmitter and audio switchers we deploy at our TX sites. The 3 -> 1 relay I built is to switch and select which transmitter RF sample to feed a modulation monitor.This one will be for our KRTH site on Mt Wilson (completed front panel photo attached). Attached are some photos of a previous unit we built for KNX AM.
RFID with non-ideal antenna - Page 1
Forum section: electronics / rf-microwave

author: charliehorse55
author_rank: Contributor
timestamp: December 17, 2023, 09:10:25 am
content: I'm working on a project that uses motor coils embedded in the PCB. There are multiple, separate, moving parts. In order to identify them, it would be great to be able to put an RFID chip in the base. The PCB is already nearly full, so it'd be nice to re-purpose the existing motor coils as antennae. The problem is, their natural resonant frequency is ~1.45 MHz. After careful measurement, I've come up with these numbers:2.52uH, 4.78nF, 1.00 ohmsI'm not sure what the minimum Q required for 125 kHz RFID is, but for any reasonable Q a large value/low resistance inductor is required. I haven't done any RF stuff before, so not sure if this is a viable solution, A quick glance at parts on mouser wasn't too promising, hard to find >20uH and <0.5 ohms while keeping the size reasonable so it fits on the board.The one thing I have helping the situation is that the only time I need to read the RFIDs is when they are directly above a coil, perfectly aligned. So, effectively you end up with two identical geometry ~50mm antennae, spaced ~2mm apart. Hopefully that's enough to compensate for a much lower Q.Any tips would be appreciated. Worst case, if I have to abandon RFID entirely, there may be a simpler solution that differentiate between 20-50 objects, while operating over a frequency band compatible with the coils on the board.
High Speed Voltage to Current Converter - Page 1
Forum section: electronics / rf-microwave

author: luky315
author_rank: Regular Contributor
timestamp: December 03, 2023, 09:33:28 am
content: I want to measure the frequency response of a high speed transimpedance amplifier (2GHz) Signal chain including filter and post gain stage with an NWA. So I have to convert the stimulus signal (-40 to -10dBm) to a current. The lowest relevant Input ist arround 1-2uA so for a -40dBm Signal a 1-2k resistor ist needed. The question ist, if a few simple passive resistors (I found 250R with a reasonable flat impedance up to 3 GHz) would be OK or if a high speed Opamp based solution would perform better? Has anyone experiences with this sort of signals?
AC coupling capacitor 200MHz to 2 GHz - Page 1
Forum section: electronics / rf-microwave

author: luky315
author_rank: Regular Contributor
timestamp: December 02, 2023, 11:27:39 am
content: I am looking for an AC coupling capacitor (0603, if possible) with the lowest possible loss (we have a very weak signal) in the frequency band from ca. 200Mhz to over 2 GHz. I have a few unlabeled 10nF Caps in my drawer which perform significantly better than all others caps I have laying arround and I found out that a nickel plating can lead to higher losses. So which component should I try to get the lowest losses?

author: Odysseus
author_rank: Regular Contributor
timestamp: December 03, 2023, 02:55:15 am
content: There's the530Land520L0402 caps from ATC.You can also dig throughMurata's SimSurfingtool, which has insertion loss data on most of their caps.

author: luky315
author_rank: Regular Contributor
timestamp: December 03, 2023, 09:09:31 am
content: The ATC caps are looking good, thanks. I was looking in the wrong category (RF caps) but "Broadband" seems to be the correct category