hybridfree/eevblog-posts huggingface dataset:
Mystery Anritsu microwave relay - Page 1
Forum section: electronics / rf-microwave

author: ChristofferB
author_rank: Frequent Contributor
timestamp: June 05, 2025, 11:10:59 am
content: Hi all!Picked up a strange coax relay last week (thought it was an active mixer or something similar). I'm trying to wrap my head around it. See attached pictures.Anritsu MM700022A-two solenoids can connect either side port to the center port. Or both. They're momentary and switches fine at 9V (33mA)-when not switched to the center port, the side ports are shorted to groundThe contacts are gold plated leaf springs being pushed up to contact the center port.There is a secondary set of contacts parallel to the first, seemingly not connected to anything. Is there RF magic in that, or is it just to act as a spring with the same force as the contacts?My main question is: is there a common application for a coax relay that grounds the non-selected input? Is there any case where you would want to connect all three ports?Clearly you'd have to be careful using this as a two-in-one-out switch, if there is any kind of power behind the inputs! Maybe it would be OK for receiving antennas, but I guess this is meant as a one-in two out switch.

author: Bud
author_rank: Super Contributor
timestamp: June 17, 2025, 05:18:31 am
content: There are absorbtive (50 Ohm) and reflective RF switches, like this one, which short the ports to ground. In high dynamic range applications you want maximum isolation between input sources. In my experience reflective switches provide better isolation, though i worked with solid state switches.

author: ChristofferB
author_rank: Frequent Contributor
timestamp: June 24, 2025, 10:06:29 pm
content: Thank you for your reply, that makes sense. Would this be the kind of thing used as VNA transfer switches?

author: Bud
author_rank: Super Contributor
timestamp: June 24, 2025, 11:28:43 pm
content: Yes.
CTK file make it readable - Page 1
Forum section: electronics / rf-microwave

author: Starpoint
author_rank: Newbie
timestamp: June 05, 2025, 03:58:09 pm
content: Bought a new Siglent SNA5000A network analyzer but need to make one CTK file readable.I have an extensive N calkit from Ceyear up to 9 GHz but without this file it is of no use.Have already tried online conversions but nothing.Who can help me?

author: Halcyon
author_rank: Unknown
timestamp: June 15, 2025, 02:50:38 am
content: What's a CTK file other than being VMware related?

author: hugen
author_rank: Newbie
timestamp: June 16, 2025, 02:39:53 am
content: Do you need the CKT file for AV20201? The attachment contains a CKT file and a CKX file for the AV20201 which should be able to be imported into your VNA.I also recommend libreCAL, which has now added a Siglent VNA compatible mode that makes it easy to automate the calibration process.

author: Starpoint
author_rank: Newbie
timestamp: June 19, 2025, 04:18:42 pm
content: Sorry Hugen there is a CKT file with the call kit but it should have an XKT file.Only an XKT file is readable by a Siglent SNA5000A VNA.The Ceyear N call kit type 20201 up to 9 GHz is fantastic especially for that price (about 800 euro).This 9-way N call kit is also supplied by other brands, but they are more expensive, while they are exactly the same kits.I also looked at a LibreCal but didn't find it exciting.
New antenna for my FPV goggle fatshark HDO - Page 1
Forum section: electronics / rf-microwave

author: XxMandragoraxX
author_rank: Contributor
timestamp: June 17, 2025, 06:49:26 am
content: Hi guys, Im new in analog FPV and im so confused with the all types of antenna exist, What type of antenna I have to buy for fly freestyle, now im flying with 2 foxeer lillipop 3, but I feel like I need more penetration, so I was thinking that get the VAS Crosshair XTREME 5.8G its a good idea in combination with omnidireccional antenna but I dont know if its correct or not
Shielding Measurement Cables Against EM Radiation Emitted by Marx Generator - Page 1
Forum section: electronics / rf-microwave

author: DoveSocket
author_rank: Newbie
timestamp: June 17, 2025, 11:13:20 am
content: Hello dear forum members,I am trying to measure the current produced by partial discharges (PD) under switching impulse voltages using an HFCT in the ground path. The voltages induced by the PDs are on the order of 10 or 100 mV but the noise produced by just the trigger of the Marx generator, which is a spark gap, already has a higher voltage ampltiude than the signal I want to measure. I can’t imagine how bad the interference of the 640 kV switching impulse would be.These are the countermeasures I came up with:- Clamping ferrite cores around the coaxial measurement cable. The amplitude of the noise voltage puls wasn’t even reduced by 50 %.- Using a shielded twisted pair cable instead of a coaxial one, which was just an ethernet cable with two BNC connectors soldered to both ends. This turned out worse than my initial setup with just one coaxial cable.- Pseudo differential signaling with two coaxial cables: The signals/channels were subtracted using my oscilloscope’s SUB function but the two noise waveforms were completely different. No noticeable improvements.To be fair, the last two ideas are a little exotic.Any help is appreciated, though.Thanks!

author: David Hess
author_rank: Super Contributor
timestamp: June 17, 2025, 12:05:28 pm
content: Double shielded coaxial cables might help, but common mode noise is likely overwhelming everything. I would try double shielded coaxial cables with ferrite cores wrapped at the oscilloscope end.This might be a good place for an oscilloscope with isolated inputs.

author: mtwieg
author_rank: Frequent Contributor
timestamp: June 17, 2025, 07:26:55 pm
content: You need a good model of how the interference is coupling to your measurement setup. Randomly adding shields/ferrites might improve things, but it sounds like luck probably won't be enough for you.What makes you think the cable itself is the issue? Does the current transformer itself have shielding against electric fields?Best practice is to make a diagram showing the major components of the system and how they're connected (including any connections they have to earth).

author: gnif
author_rank: Unknown
timestamp: June 18, 2025, 05:35:59 am
content: @DoveSocketis an alt of@servoGuyand as such has been banned.
FSK preamble detection, polling issue - Page 1
Forum section: electronics / rf-microwave

author: kellogs
author_rank: Regular Contributor
timestamp: June 03, 2025, 08:28:11 am
content: The datasheetsays on page 17 on the first line:QuoteWhat I have done was to program detection window of 0.48ms, then sleeping for the same 0.48ms, with one bit (two symbols) to detect for an expected symbol rate between 12 and 20 kbaud.Firstly the detection works instantly for white noise. It works either instantly or within 15 seconds when my transmitter is putting out `0101...` non stop. How come ?Secondly, detection for two or more bits just does not happen, on neither noise nor the transmitted continuous `01` sequence (@ 19.2 kbaud). For the transmitted signal I would have thought 4-bit detection should be possible as 4 * 2 * ~52us (symbol interval) = 416us which is lower than the 480us detection window. I must be missing something basic here, any clues ?THanks
Matching network question - Page 1
Forum section: electronics / rf-microwave

author: siyar
author_rank: Contributor
timestamp: June 20, 2025, 07:39:54 pm
content: HiIm a bit new and have som RF related question.I am doing a heart monitoring project where i want to measure ECG signals, put it through my AFE (analog frontend), then into the ADC inside the MCU and then output the data through BLE into a phone.I am using STM32WB55CEU6. My question is: Is it very important to get the two matching networks correct (one for the RF pin on the MCU and one for the antenna)?Can i just copy the matching networks from the reference example in the application notes of the MCU and the antenna even though im using different PCB-stackups then the examples on the application notes?I don't know enough about RF to design my own matching network. Keep in mind i just want to make the BLE work, im not trying to have optimal performance.Thanks in advance

author: RoGeorge
author_rank: Super Contributor
timestamp: June 20, 2025, 07:53:11 pm
content: If the receiver is close enough, it will probably work anyway, by simply copying the values from the AN example, without properly matching the antenna with the help of a VNA. If the range is not enough, eventually you can use a higher transmitting power, if the chip allows that (I'm not familiar with STM32WB55CEU6).If possible, I would use the same PCB layout, the same PCB material, the same part numbers for the matching network components, and the same antenna as they used in their example, but this is only if you need the maximum range cover.

author: rf-fil
author_rank: Regular Contributor
timestamp: June 23, 2025, 12:43:35 am
content: You'll be OK if you just copy the RF circuit layout from the reference design. You may lose a few dB, but that's still OK for normal BLE experimentation.
what is this weird magnetotracker antenna? - Page 1
Forum section: electronics / rf-microwave

author: coppercone2
author_rank: Super Contributor
timestamp: May 30, 2025, 06:08:44 am
content: https://aaroniausa.com/product/antennas/magnetic-field-antennas/magnotracker-elf-1hz-9khz/https://aaroniausa.com/product/antennas/magnetic-field-antennas/magnotracker-lf-6/there is a pdf catalog on LF6Is it two cores, or a figure 8 wound core? I wound a small figure 8 "pick up head" for some sort of EM probe meant to work in the 100MHz range, but it was air core. The author called it a pick up coil. It kind of had that shape.https://www.edn.com/06-04-98-sniffer-probe-locates-sources-of-em/Is that what that is? Also it looks like it took the style of the new system shock remake game for the outer texture (and their preamp looks like a foot pedal for a welding machine)https://rpgamer.com/wp-content/uploads/2024/05/systemshockscreen2.pngOr could it be two independent coils that are doing something with phase?It's really uncanny for system shockhttps://platform.theverge.com/wp-content/uploads/sites/2/chorus/uploads/chorus_asset/file/24688115/20230527221003_1.jpg?quality=90&strip=all&crop=21.875,0,56.25,100https://cdn.cdkeys.com/700x700/media/catalog/product/s/y/system_shock__enhanced_edition_pc_img_5.jpg
Using SDR as wideband scanner - Page 1
Forum section: electronics / rf-microwave

author: SarSar100
author_rank: Newbie
timestamp: June 24, 2025, 06:31:42 am
content: Hi everyone.Recently I wrote a soft that allows me to use the USRP SDR as a wideband spectrum analyzer 70-6000 MHz with automatic frequency switching. I tested it on my b205mini, but I think it will also work for the b200mini and maybe some other models. If someone has the opportunity to test this, I will appreciate this.Also, if someone wants to help with the program, for example, making exe or AppImage from source (for some reason its very hard to wrap all Uhd dll to the exe) - I will be grateful.Link to repositorium -https://github.com/MVG1016/USRP_wideband_spectrum_analyzer_and_signal_generator
Wireless outlet interference (solved) - Page 1
Forum section: electronics / rf-microwave

author: antenna
author_rank: Frequent Contributor
timestamp: May 27, 2025, 12:36:58 pm
content: I have a remote controlled outlet from Home Depot. I do know the remote uses OOK data at 433MHz. I cannot remember the exact number of bits or the rate, but it was probably 24-32 bits, something like that. We use that 15A outlet to control a high current contactor for a 3HP water tank pump. Whenever I leave home, I unplug it out of fear that a stray signal will turn it on and the pump will run dry for 3 days.I always thought it was possible, but I knew the odds were very slim given I live in northern MN with mostly forests around me. Last week it happened, pump turned on all by itself.What do I blame this on? Faulty receiver? Solar flare bit flipping? Someone with a drone and a flipper zero being a shithead at 1k feet from town? It hasn't happened again. Not sure if I should keep using it or abandon it and come up with something more coded. Has this ever been an issue for anyone else?edit: Transmitter had a bad switch. Not the unlikely interference I thought it was.

author: CaptDon
author_rank: Super Contributor
timestamp: May 28, 2025, 12:48:34 pm
content: As a safety measure could you also install some sort of 'time out' timer to shut down the contactor after some time limit? Those off-the-shelf time out timers will reset when you drop the power and then perform a sensible time out function again when power comes on again. We used a lot of those 8pin and 11pin socketed timers with the adjustable knob in industry. They aren't cheap but can be found on Ebay and the surplus market at a reasonable price.
Icom 7300 power switch - Page 1
Forum section: electronics / rf-microwave

author: Gargoyle
author_rank: Newbie
timestamp: June 21, 2024, 03:49:46 am
content: Hello. My 7300 had a hard time turning on this morning and would not turn off. Has anyone replaced there switch? Easy, difficult?

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: June 21, 2024, 07:07:02 am
content: You can leave the 7300 turned on and switch off the power supply without a problem. That is how Icom radios with an Ethernet connection (9700, 7610, etc) are turned on/off when used remotely. Crude but effective.SJ

author: Teledog
author_rank: Regular Contributor
timestamp: June 25, 2024, 04:07:59 am
content: Email Icom.Used to work for them, ..they may be nice & send you a replacement switch (I would)Service manual is online:http://logqslbyc.com/qsl/icom/IC-7300_Servicio.pdfG'Luck!

author: Halcyon
author_rank: Unknown
timestamp: October 16, 2024, 08:38:13 am
content: Another fake account banned.

author: Teledog
author_rank: Regular Contributor
timestamp: May 28, 2025, 03:10:41 am
content: Here today, gone tomorrow.. welcome to the innerweb!This weeks link anyway;https://www.f1nqp.fr/fichier/IC-7300/IC-7300_Service_Manual.pdf
Agilent/HP/Keysight AWG CAL 33250A/33220A - Page 1
Forum section: electronics / rf-microwave

author: jonpaul
author_rank: Super Contributor
timestamp: May 26, 2025, 07:01:44 am
content: hello everyone Bonjour a tous...This fine 80 MhZ AWG (circa 2016) needs a full calibrationsimilar to the 33220A 20 MhZ.Do either of these generators, use a back up battery or NV ram that can lose the calibration Constants over the years?Can calibrate in a few hours?Any tips or experience (on either part number) is appreciated.Bon Soireejon
Data Sheet Hunt: MCL25 - Page 1
Forum section: electronics / rf-microwave

author: dobsonr741
author_rank: Frequent Contributor
timestamp: May 24, 2025, 09:36:55 pm
content: I’m looking to find the data sheet of MCL 25 marked SO-8 RF amp, found in a Herley-CTI PLL. Would you please let me know if you have details on this part? Pin1 is Vcc, 2 is NC, 3 is input, 6 is output, all else to GND. Frequency is ~1GHz. Manufacturing year is about 2000, give or take 3.

author: Kean
author_rank: Unknown
timestamp: May 24, 2025, 11:26:44 pm
content: Minicircuits MCL-25 - no datasheet easily found, but the parts are still available as NOShttps://www.rfparts.com/review/product/list/id/8677/category/434/A new Minicircuits VNA-25+ will possibly work as a replacement, same pinout.https://www.minicircuits.com/pdfs/VNA-25+.pdf

author: dobsonr741
author_rank: Frequent Contributor
timestamp: May 25, 2025, 12:27:50 am
content: Awesome, thanks!

author: DaJMasta
author_rank: Super Contributor
timestamp: May 25, 2025, 07:24:24 am
content: It's worth mentioning that the package marking example for the VNA-25+ is just "MCL 25", so it's highly likely it's just the same thing.
Importing Schottky diode model into Ansys Nexxim for RF rectifier HB analysis - Page 1
Forum section: electronics / rf-microwave

author: Ciji
author_rank: Newbie
timestamp: May 22, 2025, 06:10:45 pm
content: I'm using Ansys Circuit Simulator (Nexxim) to perform Harmonic Balance (HB) simulations for RF energy harvesting, specifically to evaluate RF-to-DC conversion efficiency using a Schottky-based rectifier circuit.The diode I'm working with is the HSMS-282E (Avago), and I have the SPICE parameters provided in the datasheet.Questions:Is it possible to directly define a nonlinear diode model in Nexxim using these SPICE parameters (e.g., Rs, Is, Cjo, n, etc.)?Alternatively, can I create and validate the model in LTspice or MPLAB Mindi, then export it for use in Nexxim HB simulations?I'm particularly interested in ensuring the diode behavior is accurately captured in harmonic simulations, not just DC/transient. Any guidance or example flow would be appreciated.
Coaxial Dynamics 82136 element in a 7/8" line section aka Bird wattmeter problem - Page 1
Forum section: electronics / rf-microwave

author: komradebob
author_rank: Contributor
timestamp: April 27, 2025, 06:34:38 am
content: So somewhere in the past, not understanding there was a difference between the CDI 1 5/8" line section elements and the 7/8" line section elements, I bought a CDI 82136 1000W 400-1000MHz element to use in my Bird 43.However, it reads quite high. How high? Dunno, I don't have a Bird 1KW element to compare it to. However, I'm betting it's about 2x based on what I should be seeing.Has anyone else ever run across this? Know what the conversion rate should be? Is it in the range of 'can adjust with the cal pot'?Thanks!Bob

author: CaptDon
author_rank: Super Contributor
timestamp: May 10, 2025, 02:24:07 pm
content: Suggesting a phone call directly to Coaxial Dynamics in Cleveland. They should be able to help. I don't think changing the calibration pot is the correct answer. The detector is non-linear and the meter scale is non-linear, therefore I am guessing a slug being used in a mis-matched application could possibly be correct near one end of the scale but not at the opposite end? Perhaps C.D. would offer a trade-in allowance? Let me know! Sadly the most often desired ham radio slug (2-30MHz 1000 watt) costs more than a complete excellent quality ham radio style VSWR meter that has either two meters or the often preferred 'crossed needle' style meters. I was lucky with my 43. It was a dumpster dive. The company owned two and some 5S / Six Sigma Dumbfuk said the second one was wasting 'valuable space' and put it in the dumpster complete with slugs!! Many years back during the 'real days' of engineers wanting to promote the craft and act as mentors we had 'Free stuff on the avenue' days. All surplus unwanted gear was set out on tables for the employees to grab and take home. Ham radio guys like me and electronic hobbyists went nuts over the gear. Often there were computers (minus the hard drives of course, that was a rule) printers, external drives/cases, monitors and many items of interest on the tables. I almost scored the Red Led digital version of a Simpson 260 complete with charger and carry case. There were also a bunch of the Sorenson 1 / 2 / 3 kilowatt rack mount power supplies!!

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: May 19, 2025, 10:47:03 am
content: The correct Coaxial Dynamics element for the Bird 43 is the 82052. The pickup loop size/spacing will be wrong if you use the 82136, hence the wrong power reading.This chart shows the elements:https://www.rfparts.com/wattmeters-vswr/bird-coaxial-elements.html?cat=492SJ
Looking for Info: SAF45.5MA20G - Page 1
Forum section: electronics / rf-microwave

author: kleiner Rainer
author_rank: Regular Contributor
timestamp: May 25, 2025, 11:29:30 am
content: The subject says it all: I am looking for a datasheet for the Murata SAW filter SAF45.5MA20G, or at least the pinout and input/output impedances. It comes in the classical crystal oscillator metal package, but with 6 pins (two of them grounded to the package).I suspect it was used in TV IF applications, so even a schematic excerpt of such an application would help.Greetings,Rainer DG1SMD
What is the correct phase shift here? - Page 1
Forum section: electronics / rf-microwave

author: kellogs
author_rank: Regular Contributor
timestamp: April 07, 2025, 10:23:33 pm
content: Theory predicts 180 degrees over a wide band for this balun simulated in QucsstudioSince I need the parasitic P2 and P3 there in order to compute the phase shift, I thought making their Z very big as not to affect the overall circuit; this way S[1,1] remains unchanged, but the phase shift looks really bad:Making P2 / P3 's Z very small gives an expected phase shift but then S[1,1] is no longer correct.Is any of the two analyses to be trusted ? Please disregard the microstrip lines, they barely move the needle.

author: jwet
author_rank: Frequent Contributor
timestamp: May 16, 2025, 01:19:33 pm
content: Can you remove the antennas and make P2 and P3 just regular NA ports with 50 ohms. This decouples the network from the antenna.

author: kellogs
author_rank: Regular Contributor
timestamp: May 16, 2025, 07:17:29 pm
content: Regular NA ports ? How do i do that ?

author: jwet
author_rank: Frequent Contributor
timestamp: May 16, 2025, 09:08:26 pm
content: Just remove the antenna's and replace them with a 50 ohm R.

author: kellogs
author_rank: Regular Contributor
timestamp: May 17, 2025, 11:26:59 am
content: Like so ?

author: jwet
author_rank: Frequent Contributor
timestamp: May 18, 2025, 04:57:34 pm
content: You might use two 50 ohm R's each going to ground- is 50 ohm the nominal impedance that you're expecting from the antenna.

author: kellogs
author_rank: Regular Contributor
timestamp: May 18, 2025, 09:47:52 pm
content: I have done that in the past, not sure what there is to see about it. Anyway, it is 3.92 ohm and I have also zeroed L14 and L15 which were there to cancel out the reactance of antenna. Here it is:
Help identifying signal - Page 1
Forum section: electronics / rf-microwave

author: hberg
author_rank: Newbie
timestamp: May 05, 2025, 11:25:37 am
content: Hi,i've found these signals around 7.8 GHz which are quite strong (see attachment).Anybody an idea what this could be? I'm based in germany.Thanks

author: Lord of nothing
author_rank: Super Contributor
timestamp: May 14, 2025, 10:28:31 pm
content: (sry for speaking german)Schaue ob du etwas vergleichbares für DE findest:https://www.ris.bka.gv.at/Dokumente/Bundesnormen/NOR40251378/II_61_2023_Anlage_2.pdfzb:Blockzuteilungen für Rundfunkzuspielung möglich: 7905,0 MHz - 8073,0 MHz

author: hberg
author_rank: Newbie
timestamp: May 15, 2025, 05:29:43 am
content: I've found something for germany:https://funknetzplanung.com/frequencytable.phpBut the frequencies are overlapping, so i'm not sure. Actually, it might be that these are spurious signals from the tinySA and might be not really there.If i enable the spur removal, it is greatly attenuated (but only attenuated, not removed completly). Very odd!
Reverse protection for PA - Page 1
Forum section: electronics / rf-microwave

author: enemra
author_rank: Contributor
timestamp: May 03, 2025, 07:21:03 am
content: I am designing an RF transceiver for TX RX at 435MHz. I have the module working fine without any issues with PA TX at 2W.The only issue is the reverse power from the antenna if both units are placed next to each other and transmit simultaneously. The reflected power damages the PA. While a circulator is an option to terminate the reflected power, it is not a solution as they are huge (around 2.5cm dia and 10mm in height) for me to be mounted on the PCB.Friends, any suggestions or feasible solutions for my problem?

author: mtwieg
author_rank: Frequent Contributor
timestamp: May 03, 2025, 11:57:11 am
content: To clarify, these two transmitters are on completely different PCBAs?If so, I don't think there's many options besides the obvious:1. Add isolators/circulators2. Choose different antennas which couple to each other less3. Redesign the PA to be more tolerant of VSWR4. Don't let the transceivers get that close to each otherHave you measured the S21 between the antennas in the configuration which damages the PA? I'm guessing it's something enormous like -3dB. At that point the performance of the transceiver is likely impacted, so even if the PA survived you would still have a design problem.

author: enemra
author_rank: Contributor
timestamp: May 04, 2025, 07:01:30 pm
content: S21 is perfect. Each transceivers works perfectly and delivers the required power output without any issues when they are placed away. However, when they are kept nearby, the PA gets damaged sometimes

author: mtwieg
author_rank: Frequent Contributor
timestamp: May 05, 2025, 11:41:05 am
content: Quote from: enemra on May 04, 2025, 07:01:30 pmIf S21 is "perfect" (meaning near zero), then how do you suppose the transceivers are interacting?It's also possible that the antennas coupling to each other affects their S11 significantly. This might actually be a bigger issue than S21 increasing.edit: I'm referring to the S parameters of the two antennas, not the PA.

author: enemra
author_rank: Contributor
timestamp: May 08, 2025, 06:41:24 am
content: Well, I was referring to the S parameter of PA.However, I am using passive antenna. Hence, S12 is ideally equal to S21.

author: mtwieg
author_rank: Frequent Contributor
timestamp: May 08, 2025, 11:27:38 am
content: Quote from: enemra on May 08, 2025, 06:41:24 amRight, have you measured the S parameters of the coupled antennas?If not, why do you think reflected power is your problem?Does your PA have any specs on maximum VSWR?
ICOM FL-80 filter impedance - Page 1
Forum section: electronics / rf-microwave

author: Dobby
author_rank: Newbie
timestamp: May 01, 2025, 06:30:17 pm
content: I have an ICOM FL-80 crystal filter. Does anyone know the input impedance ?Thanks in advanceKind regards

author: Co6aka
author_rank: Unknown
timestamp: May 08, 2025, 06:49:19 am
content: It's been 25 years since I fiddled with this series of filters in the R71 receiver ... which means I've aged 25 years and no merember much of anything except for how fast I could copy Morse as a young'n. Therewasa spec for them, but one thing I do recall is that specs != actual, so I derived impedances. RF-gen, 2-channel scope, and two tiny ceramic 1k pots are all you need. Derive the output impedance first, terminate the output, then derive the input impedance. Repeat the process a couple of times. For any not familiar with the process, you're creating a voltage divider with the pot and filter. If you then use a spectrum analyzer you can tweak the terminations to tweak the filter's response, to flatten it out.I built test jigs with a JFET source follower buffer as a termination; one small pot as the filter termination, and the other pot in series with the filter input. Fixed resistor from the filter output to the JFET gate for isolation; maybe it was 1k, wasn't critical. Capacitance of the radio circuitry is usually more than that of the JFET gate.Also you can fiddle with trimcaps across the filter ports, but that mostly helps the crude 3-pin ceramic filters. For FM BCB, use a VNA and aim for balanced phase delay instead of amplitude flatness. Technique is useful for taming series-connected filters. Hmm, maybe I remember more than I don't merember. Anyway, perhaps my nostalgic rambling will help someone sometime.
SmartPhones as LoRa gateway nodes - Page 1
Forum section: electronics / rf-microwave

author: A.Z.
author_rank: Super Contributor
timestamp: May 05, 2025, 09:17:51 am
content: let me start from the beginning; I was looking at this projecthttps://kv4p.com/which allows to turn a smartphone into a ham transceiver; interesting maybe, but it can be improved.Imagine designing the RTX board to work at LoRa frequencies and adding an android app allowing to use the hardware (smartphone + trx board) as a LoRa node; since the smartphone will already have a network stack and internet access, it won't be difficult to use it as a WAN gateway/repeater for LoRa trafficmore infos herehttps://github.com/VanceVagell/kv4p-htthoughts ?

author: RoGeorge
author_rank: Super Contributor
timestamp: May 05, 2025, 09:58:58 am
content: Looks like the dog in the video would like to add some comments about that transceiver add-on.Yes sounds like a practical idea. A phone should be able to control a LoRa radio module, too, just as in that video, where the phone controls an external radio transceiver.

author: ftg
author_rank: Frequent Contributor
timestamp: May 05, 2025, 12:10:42 pm
content: Isn't that kainda what the Meshtastic boards do?They connect via Bluetooth, Wifi or serial to the host with the user interface and manage the Sub-1GHz LoRa radio.

author: A.Z.
author_rank: Super Contributor
timestamp: May 05, 2025, 04:42:54 pm
content: Quote from: ftg on May 05, 2025, 12:10:42 pmnot exactly, those board have a "cpu"; so we are using TWO CPUs one on the board and anoylther one in the phone, a wastesee it now ?

author: ftg
author_rank: Frequent Contributor
timestamp: May 07, 2025, 12:11:24 pm
content: That will be very hard to do with most normal phones, as SPI is usually not exposed.The easiest and cheapest method to connect that SPI to the phone is via some microcontroller acting as a bridge.Some newer Sub-1GHz chipsets have some internal Cortex-M0+ MCU core to handle the protocol stack and manage the radio. But even those often don't include even a UART, let alone USB.Annoyingly phones have terrible general purpose interfaces, so the most cross platform interface is something like Bluetooth Low Energy (BLE).And now you are running a full BLE stack on the accessory anyway.

author: A.Z.
author_rank: Super Contributor
timestamp: May 07, 2025, 12:14:48 pm
content: Quote from: ftg on May 07, 2025, 12:11:24 pmI see, ok; bad idea, discarded.

author: dzwer
author_rank: Contributor
timestamp: May 07, 2025, 12:37:24 pm
content: For one channel only it will be not difficult to be made, like in this project:https://www.hackster.io/pulsartronic/lorawan-gateway-esp8266-rfm95-arduino-4914a8If you want full LoRa Gateway - then you have to use a concetrator board like in this project:https://www.thethingsnetwork.org/forum/t/build-a-lowcost-usb-gateway/62155In all cases to receive LoRa Modulation signals you need a LoRa radio receiver!It is very specific modulation.
2200m rf amp Mosfet Question - Page 1
Forum section: electronics / rf-microwave

author: whees
author_rank: Newbie
timestamp: May 03, 2025, 10:49:55 pm
content: I'm looking at this amplifier for the 2200m and 630m bands. There are not a lot of commercially available amplifiers that go down to 100 KHz. Since this is a MOSFET-driven amplifier, I'm wondering if with a little bit of modification to the input Filtering, this would work. The data sheet says it will go down to 1.8 MHz. I don't see a reason why these wouldn't work, even down to DC.It is a beast of an amp 600 watts of power for 2200 meter would overcome a short antenna. My plan for it is to make a wire loop antenna in the attic. I think I can get about 7 feet in diameter. I'll get 2 500-foot spools of 18 awg stranded and make a Dipole Antenna. ill have to use a Balun. I can't find one for the frequency and power, but it should not be too hard to makeHF600W 1.8-30MHz 5W Power Amplifier Board Short Wave Power Amplifier Single Sideband SSB Amplifier Radio Station DIYpower TransistorsMRF300ANMRF300BN

author: mtwieg
author_rank: Frequent Contributor
timestamp: May 05, 2025, 03:15:02 pm
content: Did you mean to attach or link something? Maybe this?https://www.ebay.com/itm/363833498142For such a low frequency you really don't need LDMOS FETs. Can make use of more generic power MOSFETs. Just need to make sure their SOA is rated properly for operation in saturation. The old HEXFET devices work pretty well for this.If you wanted to modify that PA to work at 100kHz you would likely need to change all the passive components on the input and output. The output chokes and balun would especially need to be bigger.
stabilock si4015 - Page 1
Forum section: electronics / rf-microwave

author: ME
author_rank: Frequent Contributor
timestamp: May 02, 2025, 10:16:40 pm
content: can a stabilock si 4015 be used to align an ssb transceiver or only am+fm?.

author: Lord of nothing
author_rank: Super Contributor
timestamp: May 02, 2025, 11:27:17 pm
content: Hi the former Silicone what ever chips are support officially only AM, FM but there are some hacks.I toughy about use them as cheap SDR Style to Monitor some Short Wave Frequency 24/7.

author: ocelot
author_rank: Contributor
timestamp: May 04, 2025, 05:08:02 pm
content: If you mean the RF test set, you can use CW signals from the generator for RX testing. And AM is just two SSB signals and a carrier.And if you modulate the TX with an audio tone, the TX can be measured.
can a CMT2220LS chip used for receiving a 477MHz CB frequency? - Page 1
Forum section: electronics / rf-microwave

author: jonovid
author_rank: Super Contributor
timestamp: April 28, 2025, 06:44:42 am
content: can a CMT2220LS chip used for receiving a 477MHz CB frequency?-whytriggering an external circuit with a 477MHz signals on an Australian CB frequency? between 476.4250 to 477.4125 MHzsay use UHF low power handheld CB radio to unlock a door . or trigger a light.see CMT2220LS data sheetwith the right crystal. can get up to 480MHzwhat is the output type? CW on off on modulationwhat is the interconnected circuits inside the chip?radio frequency detector circuit used inside the chip.will circuit bending the CMT2220LS work.https://www.hoperf.com/uploads/CMT2220LSDatasheet-EN-V1.0-20210917_1695350128.pdf

author: loulou31
author_rank: Contributor
timestamp: April 28, 2025, 08:19:48 pm
content: Hi,This circuit is design to demodulate a signal,it cannot operate with CW on / off carrier. The circuit implement a CAG circuit that requires a modulated carrier to opererate, and to detect "0" and ,"1".For my opinion for a reliable activation, ou have to send / decode specific binary sequence to activate / disable your device.Jean-Louis

author: jonovid
author_rank: Super Contributor
timestamp: April 29, 2025, 01:23:24 am
content: as thw chips are cheap I will experiment on some when I have them as to the type & mode of modulation that can be detected at its output pin.the transmitter chips may hold the key as to if this receiver can detect the presence of 70 cm 440MHz or 477MHz CB narrow band FM signals activitythis AN100 IC may be the companion transmitter chip for the CMT2220LShttps://hoperf.com/uploads/AN100_CMT211x5x8x_Transmitter_Chip_Schematic_and_PCB_Layout_Design_Guide-EN-V0_81-150916_1702430504.pdfby posting here- I was hoping that someone else had experimented with the same CMT2220LS receiver on 70 cm 440MHz or 477MHz signals. to see what worked?with different types of modulation. for example touch-tone phone codes or DTMF audio over narrow band FMmy research on OOK pulse modulation-On-Off Key OOK transmitting a signal in the form of pulses. OOK modulation is high-speed Continuous Wave modulation CW -am I right?the receiver may detect the start & end of keying of a carrier signal?
Help with HFSS 3D component - Page 1
Forum section: electronics / rf-microwave

author: chipsosaurus
author_rank: Newbie
timestamp: April 24, 2025, 07:31:40 am
content: Hi,I have a HFSS 3D component model of coaxial connector available and need it in .step, would somebody here help and do the export? I would be immensely grateful!Thanks.

author: Sun_
author_rank: Newbie
timestamp: April 27, 2025, 06:22:07 am
content: Hello,If you import the 3D component and then go to Modeler > Export, is it working ?You have to check if it is encrypted also
I start with IEEE 802.11ah! - Page 1
Forum section: electronics / rf-microwave

author: Lord of nothing
author_rank: Super Contributor
timestamp: May 29, 2025, 07:45:29 pm
content: Hi everyone!I bought from an "well known Company" an Kit for IEEE 802.11ah who here work on the 868 Band.I will test during the Summer what the max. range is in real life.If someone have question pls ask me. I dont know how long the shipping take.

author: Lord of nothing
author_rank: Super Contributor
timestamp: June 16, 2025, 11:46:27 am
content: Hey today I have received the Equipment.Here how it look like with en SDR.
SE2576L: why there are two RF out pins? - Page 1
Forum section: electronics / rf-microwave

author: zulunation
author_rank: Contributor
timestamp: April 24, 2025, 01:47:06 pm
content: HI allI want to use SE2576L amplifier but it has two RF outputs.And there is no description in datasheet.How they should connected and why are they not connected inside the chip?I found similar amplifier SKY65006-348LF-348LF.It has also two output's but they are used also for powering secondamplifier stage.But my amplifier has separate pin for powering second stage.Why two RF out pins?Thanks,

author: szoftveres
author_rank: Regular Contributor
timestamp: April 24, 2025, 02:55:48 pm
content: I'm guessing that you need to use both RFout pins in parallel, to provide a good 50ohm transition to the PCB trace to the antenna, and the self-inductance of the single input RFin pin (bondwire) is part of the input match network that makes S11 acceptable.
Antenna feed question - Page 1
Forum section: electronics / rf-microwave

author: OrionResident
author_rank: Newbie
timestamp: April 17, 2025, 04:38:43 pm
content: Hello all. Hope all is well! First post here.I have a quick ques/ clarification about an antenna layout. Below, in the black and white pic, you can see the pads of the antenna on the left and right part of the bottom of the antenna . The leftmost pad is the WiFi/DSRC feed and the rightmost pad is the GPS/GLONASS feed.The green colored pic shows the recommended PCB layout. So far so good.Here is the question.If we were to solder this antenna onto that PCB with that recommended PCB layout, it seems highly likely that the GPS/GLONASS pad of the antenna will contact both the pads labeled 1 and 3 ( shown in the pcb picture inside yellow boxes ) simultaneously.This would be bad, I think because Pad 3 is labeled as ground and it definitely seems to be connected to the larger ground plane.The GPS/GLONASS pad of the antenna will be soldered to both the Feed GPS ( Pad 1 ) and GROUND ( Pad 3 ) !!Is the datasheet incorrect or is there more to this assembly?https://www.digikey.lv/htmldatasheets/production/3646046/0/0/1/w3095.pdf

author: antenna
author_rank: Frequent Contributor
timestamp: April 24, 2025, 08:07:54 am
content: I won't be much help because I too am very confused by that. It says 1.6GHz, so I don't think they are taking advantage of trace shunt inductance as part of the matching, too short IMO. There is a "For more information" contact on the datasheet, I would write them and ask. If they don't answer you, you can always cut the foil and float #3 and see if the GPS works.
Any info on Logimetrics RF Generator? - Page 1
Forum section: electronics / rf-microwave

author: watchmaker
author_rank: Unknown
timestamp: September 28, 2024, 11:58:31 am
content: Running with scissors.Does anyone have information on the Logimetric 750 RF generator?I finished my Elenco AM/FM kit and learned a lot (some of it not intended by Elenco). The issue is this kit has been in production for over 30 years and thee are parts changes that are not documented. In particular, there are no hints for how to modify the IF bandwidth when it is well below specs. But I researched and learned and was successful.My Sig 1064 does not hit the high end of the FM. Being somewhat OCD I looked at RF gens that were intuitve and a Freq Deviation display so that I could do the final adjustments on the Elenco (which really is not worth it as a radio, but in for a penny, in for a pound.)Looked at the stuff on Ali and such and was not comfortable.I was offered this Logimetric 750 at a "what the Hell price" AND returns.https://www.ebay.com/itm/266951477367I researched Logimetric, and it seems those few who have one like it. Internally it looks well laid and solid. The unit I have coming looks pretty clean.Thanks.

author: watchmaker
author_rank: Unknown
timestamp: October 04, 2024, 02:49:02 pm
content: Just to finalize.The Logimetrics was very clean inside and out and looks like a serious piece of kit. But no output. Checked on repair and it was around $600. So back it went; because it was defective, ebay provided free shipping.After a couple hours of research, I realized the Tiny SA Ultra has a decent sig gen and a very small footprint and price. On its way!Never found schematics or manual.

author: WRXcrusher
author_rank: Newbie
timestamp: April 23, 2025, 07:33:59 pm
content: Hi watchmaker - I won a bid on a 750 and am awaiting arrival, then I found your question here. How much you want to bet I just bought your returned unit?! Anyway I found a manual for it so if this indeed has no output I'll take a stab at a repair.

author: EggertEnjoyer123
author_rank: Frequent Contributor
timestamp: April 24, 2025, 02:42:00 am
content: The HP 8640B is the gold standard for these types of RF signal generators (at least not phased locked ones).You can generally get them for 300 bucks, or cheaper at the ham swap meets. One of my friends got a working military version for 30 dollars.
Reverse-engineering III-V HEMT MMICs - Page 1
Forum section: electronics / rf-microwave

author: D Straney
author_rank: Frequent Contributor
timestamp: April 26, 2025, 04:29:48 pm
content: Curious if someone who's an expert in non-silicon IC processes can help me out:I've been lucky to have access to a good microscope, and have been getting shots of a bunch of MMIC dies. I'm now trying to trace the circuitry on some of them, but have run into some two-terminal structures I don't understand.These 3-terminal structures are clear to me: they look like (wide) lateral FETs, with a source and drain terminal on either side, and a gate terminal running down the middle.These 2-terminal structures, I'm not sure about though:I've seen a mixer with similar-looking structures, so they could be diodes - but the mystery structures above have their contacts on the same layer, while the (Schottky?) diodes here look like one terminal comes in on the metal layer, and the other exits on a doped well (as, y'know, you'd expect from a Schottky diode):I've also seen some amplifiers with similar-looking structures, but these seem to be arranged vertically, with the substrate as the source connection.In the circuits I've traced out so far, though, the 2-terminal structures appear where a FET with a grounded source or drain doesn't really make sense. They do appear where a cascode would make a lot of sense: but this would mean the two terminals (accessible from the metal layer) are the source and drain, and the gate is effectively connected to the substrate. Is this possible? I can't really picture what the cross-section would look like.

author: D Straney
author_rank: Frequent Contributor
timestamp: April 26, 2025, 04:35:13 pm
content: (Ignore that last image, I'd missed the thin gate connections in those interdigitated FETs. Here's a better example of a 2-terminal FET with source tied to substrate, although that substrate connection appears to be happening through some big-ass metal squares?)
Load Pull simulations - Page 1
Forum section: electronics / rf-microwave

author: tancheehao
author_rank: Contributor
timestamp: April 22, 2025, 06:35:18 am
content: How to find the load pull simulations at the Drain of an amplifier? Is the load pull guaranteed Maximum power transfer, maximum gain and maximum power added efficiency?

author: stretchyman
author_rank: Regular Contributor
timestamp: April 22, 2025, 07:41:22 am
content: Most (?) RF transistors should have this information available direct from the manufacturer as either they or a 3rd party will carry out the required tests.Load pull is a rather complex and expensive procedure requiring a 4 port VNA.The information will yield the information you require and show at what impedances these occur.

author: tancheehao
author_rank: Contributor
timestamp: April 22, 2025, 07:52:46 am
content: I am running simulations on figuring out the right optimal impedance at the load side before 50 ohm. I want to design an impedance matching network for it.

author: stretchyman
author_rank: Regular Contributor
timestamp: April 22, 2025, 07:57:17 am
content: Thats the simple bit.Conjugate matching.Done!

author: tancheehao
author_rank: Contributor
timestamp: April 22, 2025, 08:57:36 am
content: Should I cater for the Power Added Efficiency or output power at the 50 ohm? Like a balance point between them.I noticed that output power have different optimal load impedance than max power added efficiency.

author: mtwieg
author_rank: Frequent Contributor
timestamp: April 22, 2025, 12:23:13 pm
content: Quote from: tancheehao on April 22, 2025, 08:57:36 amThis is entirely your decision. You decide what parameters are most important for your application, and choose the bias and matching conditions to optimize those.For example if this is a radio transmitter for a battery powered device, then PAE is certainly important. If you're transmitting only FM, then linearity is unimportant and you could just focus on PAE. But if it's AM you may need to balance that with linearity, etc.

author: tancheehao
author_rank: Contributor
timestamp: April 22, 2025, 03:39:37 pm
content: Got it. The load pulling got so many points to choose from. Could try to balance the output power as well as PAE.
IC-905  Icom expensive VHF UHF SHF Multimode transceiver - Page 1
Forum section: electronics / rf-microwave

author: oe7dbhnew
author_rank: Contributor
timestamp: April 22, 2025, 02:27:29 pm
content: I finally got an IC-905 to do a comparison test with my IC-905.Since I'm primarily interested in FMTV mode, I only tested that mode.The entire review has many pictures, and to avoid uploading everything here, please use the following link...https://forum.batc.org.uk/viewtopic.php?f=2&t=8337&p=37441#p37438The errors I noticed in the review shouldn't occur with such an expensive device:1.Frequency response in the 2 MHz to 5 MHz range could be linearly boosted from 0 to 1 dB.2.Audio carrier level is 6 dB too low and should be boosted.3.ICOM designers chose a poor component for the connectors ( audio-video input and audio-video output ).The 4-pin 3.5 mm ( 1/8 inch ) jack (of which only 3 are actually used) doesn't always make proper contact. Once again, they skimped on connector quality for such a cheap €4,000 device.This defect was noticed in both devices and both jacks !! - They could have used something different, with more safety, right ?How does this defect affect operation ? - See here in a short 19-second video...4.The scope of delivery is missing an original ICOM AV cable with the correct 600 ohm and 75 ohm impedance for the output and input jacks, respectively; then perhaps there would have been less of a problem with the contact.Do you also have an IC-905 ? .....Have you noticed this error ?
IC-705 STM32L051 Dump - Page 1
Forum section: electronics / rf-microwave

author: Abdul00
author_rank: Newbie
timestamp: April 20, 2025, 08:58:02 am
content: Hi Group,Has anyone got an IC-705 on the bench and can check whether the STM32L051 (IC901) is read-protected? If not, would it be possible to get a firmware dump from that chip? I have a damaged main board and the SUB-CPU is faulty. I’ve replaced the processor, but I’m missing the flash content. If someone is currently repairing this radio, I would really appreciate the help.73'sSP7VMX
RF Diplexers - Page 1
Forum section: electronics / rf-microwave

author: bootloader9800
author_rank: Contributor
timestamp: April 09, 2025, 08:39:27 pm
content: Hi everyone,Quick question—do RF diplexers work both ways? I know they can be used to split one signal into two different frequency bands, or combine two signals into one. But if we feed two signals into the low and high ports, can we just assume they'll combine properly and come out the common port without any issues?I ask this because diplexers are passive, reciprocal devices, and they should ( it seems to me ) work bidirectionally.Thanks in advance!

author: RFDx
author_rank: Regular Contributor
timestamp: April 10, 2025, 03:14:06 am
content: Quote from: bootloader9800 on April 09, 2025, 08:39:27 pmYes.

author: fourfathom
author_rank: Super Contributor
timestamp: April 10, 2025, 04:57:04 am
content: Definitely yes -- bidirectional. Many diplexers are VHF cavity resonator types, but I make one for nine ham radio bands in the 3.5 - 28 MHz range using discrete components (this is for <10W power levels). So I guess it's a Nonaplexer (9-plexer).