hybridfree/eevblog-posts huggingface dataset:
Yaesu FT-902DE ALC/outputpower problem - Page 1
Forum section: electronics / rf-microwave

author: PA3BBV
author_rank: Contributor
timestamp: March 08, 2022, 11:52:45 pm
content: Hi guys, I'm new to the forum here, thanks for letting me in. I am trying to repair a classic tranceiver type Yaesu FT-902DE and I would like some advice...The radio does not give full power. maximum approx. 60 watts on all bands. The strange thing is that I can get full power in ssb if I switch the s-meter to the ALC position. The ALC meter always is full scale when transmitting. I'm afraid there's something wrong with the ALC. However, I can't figure it out, because the overview diagram is printed on A4 copies, it is very difficult to follow the wiring. Could somebod explain how te ALC works? Anyone has a suggestion? Thank you all ver much.73es Leo

author: m3vuv
author_rank: Super Contributor
timestamp: March 14, 2022, 08:08:30 am
content: heres a quote from the fox tango site,dont know if it helps?:The meter problem nagged me: The meter works fine inreceive mode, but in transmit I get no deflection in eitherthe IC, ALC or PO position.After studying the (rather small copy) schematic, I sawthat the meter is switched via relay RL1, and, because Ihad read that the relays could be a problem, I cleaned thecontacts, and measured the contact resistance.They were all good, but the problem remained. So it had tobe the rocker switch on the front who switches the meterto the IC, Power output and the ALC.Strange, because all other switches are working normally.Well, it was disassembling time again. After taking outsome modules, the counter, VFO and the frontplate, I cantake the switchboard out.Fortunately I have the Service Manual, with the foil patternand a detailed schematic of the board, and after somesearching I find a connection point (15) that is not attachedto anything, but should connect to the relay. After pryingthe cable harnass apart, I find the loose wire. It is so short,that it must have been broken off, the first time this switchboard was worked on.There were signs that the switchboard was taken off earlier, by one of the previous owners, maybe to try to cleanthe switch contacts, because some of the small screws ofthe switches are missing.I think they have been looking for the same fault.I made the connection with a short piece of wire and someshrinking tube, to get more stretch in the wire, to preventfuture problems.While I was at it I sprayed the contacts of the switcheswith tuner spray, it can be applied via the upper mountingscrew holes. I was able to test this by disassembling asimilar switch, that was in my junkbox. The switches havesliding silverplated contacts, and should normally cleanthemselves.The switches are ALPS, and are also used in some audioequipment of the time.After re-assembling, the meter works fine, and I am ableto measure the IC current, ALC and the output power.link:http://foxtango.org/FT901/FT-901-902%20Web%20Page.htm

author: m3vuv
author_rank: Super Contributor
timestamp: March 14, 2022, 08:12:28 am
content: this maybe better :http://foxtango.org/Files/FT901-902%20SG5.pdf
Assigning waveport error in my design - Page 1
Forum section: electronics / rf-microwave

author: lottarn418
author_rank: Newbie
timestamp: March 02, 2022, 12:54:00 pm
content: Hi guys!As you can see in the attached picture, I have two waveports and these are the red and green one. The red one is fine but when I try to assign waveport to my WR I get the following error:Port refinement, process hf3d error: Port 2 does not have a solved inside material on either side.. Please contact Ansys techincal support.How can I fix this?Basically I'm going to design a CPW-to-WR transition where I am going to measure my return loss by simulating my S parameters.Regards

author: fourierpwn
author_rank: Regular Contributor
timestamp: March 02, 2022, 02:44:51 pm
content: One of two potential problems.Ensure that Port 2 is making contact with the selected face and confirm that the size of the rectangle you assign an excitation to is sufficient for making contact with the selected face.If this is all fine then go through your objects one by one and check their properties. There should be a tick box 'Solve Inside', which obviously, needs to be ticked in the regions where you want to solve inside. This is off by default for materials other than PEC/high conductivity materials.

author: Bud
author_rank: Super Contributor
timestamp: March 06, 2022, 03:46:52 am
content: Try creating another box with dimensions equal to inner dimensions of the waveguide and assign Air material to it with Solve Inside box ticked.
Which Radio Support IP, Data Transmission between? - Page 1
Forum section: electronics / rf-microwave

author: Lord of nothing
author_rank: Super Contributor
timestamp: March 03, 2022, 12:02:36 am
content: HiI saw some Video who a Guy use 2 Motorola Radio to transfer Data between them. I guess it was an DMR and not a Tetra one. Well I am a Hytera "Fanboy" and what the claim there Car Radio is there first who support IP Data Transfer:https://hytera-europe.com/products/hm785Well.. Its big, chunky and ... not for Handheld use.Are there other Company who have an Radio with Data Transfer from Radio to Radio now?Thanks
Pulsed Power Amplifier Characterization - PAE - Page 1
Forum section: electronics / rf-microwave

author: fourierpwn
author_rank: Regular Contributor
timestamp: March 01, 2022, 01:23:47 pm
content: Commercial pulsed characterization solutions appear to be mainly targeted for devices, with the likes of Auriga, AMCAD, Keysight, Keithley, ... pulsed IV systems.Curious to know if people in the MMIC business also apply such systems for characterizing PAs, under pulsed bias (drain) conditions? Or perhaps more custom solutions are being implemented, i.e., gate driver with a switch FET to supply pulse bias (or something else to generate pulses with enough power handling for high PAs?), then measure the pulsed PAE with some current sense circuit, scope, ADC? (Proprietary?) . How would these handle the influence of the RF (presuming it is also pulsed) as it turns on within the drain pulse? For example, the RF may want to "pull" the drain voltage down, and "push" the drain current up, or vice versa, when the PA is being driven into compression. How would one deal with this for accurate PAE measurements? Does it matter if the pulsed Pdc is being sampled within the "push-pull" window?Keysight have an app note from a few years back about doing CW PAE measurements on a PNA-X. Does this approach also work for pulsed PAs, with pulse widths of 10-100us? (Looking at you Dr. Joel). What do the typical setups look like?
Microstrip-To-Waveguide transition - Page 1
Forum section: electronics / rf-microwave

author: lottarn418
author_rank: Newbie
timestamp: March 01, 2022, 10:37:30 am
content: Hello everyone!I'm currently working on a bachelor thesis, where I am going to design Microstrip-To-Waveguide transition. Right now I'm working with a rectangular waveguide - WR12. However, as seen in the pictures that I've posted, the microstrip consists of 2 WR, one on the upper side and downside. My question is that in order to backshort my WR on the upperside, should I assign a perfect E boundary?Also, in order to connect these to WR, I have to implement via holes, but this will for sure increase my simulation time, is there another easy way to connect these to WR?Thanks in advance!
Assigning waveport error in a HFSS design - Page 1
Forum section: electronics / rf-microwave

author: microwaveking
author_rank: Newbie
timestamp: March 09, 2022, 03:24:23 pm
content: Hi guys!As you can see in the attached picture, I have two waveports and these are the red and blue one. The red one is fine but when I try to assign waveport to my circular waveguide I get the following error:Port refinement, process hf3d error: Port 2 does not have a solved inside material on either side.. Please contact Ansys techincal support.How can I fix this?Basically I'm going to design a CPW-to-circular waveguide transition where I am going to measure my return loss by simulating my S parameters.Regards

author: Bud
author_rank: Super Contributor
timestamp: March 09, 2022, 05:03:46 pm
content: Did you post same question under a different user account there?https://www.eevblog.com/forum/rf-microwave/assigning-waveport-error-in-my-design/

author: microwaveking
author_rank: Newbie
timestamp: March 09, 2022, 05:46:55 pm
content: No,but its the same project we working om me and my classmateI working with a circular waveguide and he working with rectangular.

author: Bud
author_rank: Super Contributor
timestamp: March 09, 2022, 06:13:50 pm
content: And you two write practically exact same posts?See my answer there if you can use it.
VNA Active Device Characterization Essentials Webinar - Page 1
Forum section: electronics / rf-microwave

author: xmo
author_rank: Regular Contributor
timestamp: February 26, 2022, 06:56:28 am
content: Yours Dr. Joel?

author: Joel_Dunsmore
author_rank: Regular Contributor
timestamp: February 26, 2022, 05:47:17 pm
content: My colleague, Nizar, a Canadian guy (but don't hold that against him). He's been working on EVM measurements w.r.t. load on the device (EVM load pull)
Unwanted Noise - Page 1
Forum section: electronics / rf-microwave

author: imk
author_rank: Regular Contributor
timestamp: February 23, 2022, 11:06:17 pm
content: Hello,I am trying to debug a STM32 micro controller robot project and keep find this noise.So i have switched off most stuff, and with a few inches of wire as an aerial in the scope input I get this noise.I have tried it on two scopes and old Tektronix and a new hantek and can see the same signal on both of them.it is about 806 khz Any ideas please?I live in UK North West about 53n 2wMany thanks in advance imk

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 24, 2022, 12:08:00 am
content: Oh hey, the tone bursts are opposite directions, it's actually 403kHz (well, a hair lower, 390kHz maybe?). But yeah, same idea, you'll likely get all the harmonics/sidebands (i.e. spikes every 390kHz or so, clustered around the, 10MHz or so tone burst?) so it's not much of a distinction.Jesus, it's actually a whole volt? From a "few inches" of wire? Even if there's something nasty plugged in elsewhere (reaching the scope by mains conduction), it'd be hard pressed to be that nasty I think. Gotta be the scope itself?Seems like it comes from a symmetrical square wave, and it's fairly fast suggesting a resonant power supply or something like that; maybe CCFL lights (which wouldn't be the scope, that'd use LED backlights right?),possiblya PoL (point of load DC-DC) converter but it would have to be something very luckily near 50%, like a 5 to 2.5V buck converter or something; even then, the rising and falling edges are rarely so symmetrical.Tim

author: imk
author_rank: Regular Contributor
timestamp: February 24, 2022, 03:22:23 pm
content: Much searching:Turning off mains socket circuits with built in usb chargers.Turned of all switch mode PC's monitor, PC's, router, multi drop wireless phone, mobile phone, ethernet over over mains, cooker, microwave, mains clocks, power circuit to workshop etc etc.And it was the Class D amplifier i use for my PC sound, think speakers are massive aerial for the 800kHz switch :-(Going back to class AB :-)

author: ConKbot
author_rank: Super Contributor
timestamp: February 24, 2022, 08:04:16 pm
content: That much from speakers? Did they 'optimize' the output filter out of the BOM for that amp? Jeeze.

author: imk
author_rank: Regular Contributor
timestamp: February 24, 2022, 08:07:01 pm
content: lack of "output filter" on amp is problem.I have put one of those little Yamaha's in it's place temporally and can now look for the real noise problem i have in this project.imk
RF Radiation Safety training (Australia) - Page 1
Forum section: electronics / rf-microwave

author: SmallCog
author_rank: Frequent Contributor
timestamp: February 18, 2022, 10:46:03 am
content: I work in a bit of a mixed bag sort of workplace, electronics, PLC’s, RF, Cellular, instrumentation, geophysicsSo my workplace wants me to be a radiation safety officer. I’ve been working with radiation for years, I’m comfortable with Gamma and Neutron. No big deal just another thing to keep me at my desk instead of my bench.The RF side of things is something I have less experience with. I’m a proficient tech I know how to set up/fix RF gear. Doing up the safety paperwork for a new install isn’t something I’ve had anything to do with.The existing guy came from a role specialising in RF safety in another organisation. All of his training was internal from that organisation and while my employer recognises his training it’s not available for me to go and do. He’s happy to teach me everything he knows but my employer wants me to have a piece of paper as well, something formal.Only course we’ve found so far is this one, anybody aware of any others?https://www.unsw.adfa.edu.au/professional-education-courses/radio-frequency-radiation-safety] https://www.unsw.adfa.edu.au/professional-education-courses/radio-frequency-radiation-safetyHardware wise it’s UHF data under 20W, satellite IP links, and cellular modems, nothing fancier than a yagi or bgan. It’s ok if the training covers other stuff but I don’t want to sit through a course on only microwave links or carrier cellular gear.

author: El Rubio
author_rank: Regular Contributor
timestamp: February 22, 2022, 06:41:48 pm
content: I am probably in the situation like your co-worker. I have had extensive employer provided training on RF safety. Some courses are instructor led and others self guided online. I would reach out to the manufacturer of your RF safety equipment. Here ( in the USA), our company gets safety monitors from NARDA. They offer various types of training including in-person. I'm sure someone down there is doing it and the manufacturers should know who.I work in wireless ( cellular) communications and our RF safety training has always been about RF safety in general and not specific to our bands. The most common dangerous exposure-wise is FM broadcast on a rooftop.

author: SmallCog
author_rank: Frequent Contributor
timestamp: February 22, 2022, 09:34:03 pm
content: Thanks,I've also reached out (unofficially) to some other large users of RF equipment who do similar work to usSo far the replies have been "we use a consultant" or "we have guys who brought the experience with them"The only exception seems to be the military who use the course I linked above, it's run by the University of New South Wales on behalf of the Australian Defense Force Academy but is available to other parties occasionally
HC-12 Module antenna termination - Page 1
Forum section: electronics / rf-microwave

author: Jester
author_rank: Frequent Contributor
timestamp: February 26, 2022, 11:21:54 pm
content: I might be overthinking this, I guess that's what you do when you don't know what you don't know in the RF world.I proto-boarded a couple of these HC-12 modules and then tested with good success using an external antenna connected via the IPEX connector shown. Typically people use the supplied spiral antenna instead of the external anttena via the IPEX connector as these seem to work fine for short distances.I'm now doing a proper layout for the uC etc that will interface to this module. As can be seen the HC-12 module can be mounted either with a 100mil spaced sip header or directly to the board using the castellated terminals, I'm planning on soldering directly to the board I'm doing now so pads to match the castellated terminals.I'm assuming that the transmit amplifier connects to both the IPEX connector as well as the pad for the spiral antenna option (they are about 3mm from each other and the resistance between these to points is close to zero ohms. To me it seems less than ideal in that there will always be a short unused stub (either the IPEX connector if you use the spiral or the pad for the spiral antenna if you use the IPEX connector. Perhaps it is not that important because the used path is properly terminated?Finally the questions.1) Should I pour ground plane under this module on my board or leave it as just bare board?2) I'm thinking of not including the pad that would solder to the castellated pad for the spiral antenna, as this seems like it would just make that unused stub that much longer, does this make sense?3) The two castellated pads on either side of the antenna connection appear to be ground and I'm planning on grounding these two pins, this will be in addition to the main ground pin on the other end of the board. Does that make sense?Thanks in advance.
(S) STABILOCK 4022 user manual - Page 1
Forum section: electronics / rf-microwave

author: m.p.h
author_rank: Newbie
timestamp: February 24, 2021, 08:45:55 pm
content: Hi guys,I'm (desperately) searching for a owner/user manual for my new old SCHLUMBERGER STABILOCK 4022 radio communication test set.Thanks for reading!Kind regards,Michael

author: Lars71dk
author_rank: Newbie
timestamp: February 21, 2022, 11:18:57 am
content: Hello,Did you find the manual? I am looking for it as well!Thanks, br Lars

author: El Rubio
author_rank: Regular Contributor
timestamp: February 22, 2022, 02:39:35 pm
content: Back in the mid 90's, I used a Schlumberger Stabilock 4031. Sent it in for an update and was it returned with a Wavetek badge on it. Search for Wavetek 4022 and you may find something. I found this:https://mods.dk/manual.php?brand=wavetekThe 4022 is listed. I have downloaded amateur radio manuals over the years from that site without any issues, although not in the past 5 years or so. You do have to sign up, but it is free. Good luck.
Place to get odd ends of various coaxes, cheap? - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: February 25, 2022, 03:27:44 am
content: I am looking for deals on shorter pieces of coax for use in in antennas, stubs, etc. And other rf-useful junk..Cheap Noncommercial.Thanks

author: bob91343
author_rank: Super Contributor
timestamp: February 25, 2022, 05:59:19 am
content: Go to a swap meet.

author: El Rubio
author_rank: Regular Contributor
timestamp: February 25, 2022, 01:16:34 pm
content: Amateur radio hamfest. Contact a local ham radio club and ask about upcoming hamfests, and ask the club members themselves. You can also get some knowledgable antenna guys in the mix. You can also search for hamfests at ARRL.org

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: February 25, 2022, 09:36:22 pm
content: If you can stand 75 ohm coax, ask the cable guys for scrap. 75 Ohm is good for supplying some antennasI think a lot of ham bands the dipole is about 73 ohms.You might want a balun , which is easy to make.

author: cdev
author_rank: Super Contributor
timestamp: February 25, 2022, 11:39:04 pm
content: I agree. For a single frequency balun, or 90 degree phase shift that definitely is the way to go.I also save 93 ohm coax (which used to be used for networking) for those phase shift transitions/baluns. I have some 93 ohm coax that Ive been using for a long time. Works great for making 90 degree phase transitions for use making circular polarization antennas. (like a turnstile antenna) A turnstile antenna is very simple to make but works quite well for 137 MHz APT. (satellite weather radio reception).Yes, when I see the cable guys I always ask them if they have cable scraps.. They always do and often they will install F connectors on it for me.. Thanks!
Erie Pennsylvania ham busted big time, - Page 1
Forum section: electronics / rf-microwave

author: CaptDon
author_rank: Super Contributor
timestamp: February 19, 2022, 03:53:45 pm
content: Google up Erie Pa man arrested for bomb threats. He has been a royal pain the ass to all local hams for several years. Numerous letters and audio submissions to the F.C.C. brought absolutely NO action. Multiple calls and letters to the A.R.R.L. brought NO action. Recordings of his threats to persons and objects that were submitted to local police investigators brought a hell's fury of swift response!! Confiscating this guy's equipment was long overdue and now that very equipment is part of a police investigation. He did a lot of 'text to synthesized voice' communication. Why do people think they can be 'on-air-asswipes' for months or in this case years and not come to a bad end?? Well Richard, it's time to "Say goodnight Dick".

author: bob91343
author_rank: Super Contributor
timestamp: February 19, 2022, 08:16:22 pm
content: Jerks like this are begging to be punished. When no action is taken, they escalate so as to see how far they can go before their death wish is brought down upon them.
Agilent E4432B vs E4432BU 3 GHz ESG-D Series Signal Generator - Page 1
Forum section: electronics / rf-microwave

author: StevePollitt
author_rank: Newbie
timestamp: February 17, 2022, 09:06:26 pm
content: Anybody know what the difference between the Agilent E4432B and E4432BU is? I know that the attenuator in the BU model is rated for 4 GHz while the one in the B model is 6 GHz but the B model is only rated to 3 GHz anyway.

author: MarkL
author_rank: Unknown
timestamp: February 17, 2022, 10:51:24 pm
content: According to this doc, the "BU" version is an upgraded "A" version:https://docplayer.net/123796176-Agilent-g-support-release-information-rev-10-20-00.htmlThe relevant passage:QuoteE4432BU also seems to be the order code to get it done:QuoteThe implication of these statements is that the "BU" is the same as the "B", just tagged that is was once an "A".

author: StevePollitt
author_rank: Newbie
timestamp: February 18, 2022, 04:28:10 am
content: Thanks MarkL. The reason I was curious about this is that the attenuators are different. The E4432BU is listed under the 4 GHz 33322-60014 attenuator and the E4432B is listed to have the 8 GHz 33322-60020 attenuator. Not clear it really makes a difference since the E4432B is only a 3 GHz generator but just wondering fi replacement with the older 4 GHz attenuator maintains specs. - Steve

author: MarkL
author_rank: Unknown
timestamp: February 18, 2022, 02:38:04 pm
content: According to Keysight's Find-A-Part page, the 33322-60014 was obsoleted and replaced by the 33322-60020.I think it's safe to assume that going back to the 33322-60014 is ok from a compatibility perspective. However, if you replace the attenuator, the Service Guide specifies that the following adjustments should be re-done:Gain AdjustALC AdjustmentsPower Level AccuracyDetails of the procedures are in the Calibration Guide. Some of the procedures involve a lot of extra equipment. I wouldn't mess with it unless it was really necessary (like your attenuator was dead).
signal generator  - Page 1
Forum section: electronics / rf-microwave

author: otpisani
author_rank: Newbie
timestamp: February 06, 2022, 10:53:52 pm
content: I want to made signal generator with whom I can play with RTL-SDR cards, testing digital modulation,. I have couple of questions regarding that I'm not skilled with soldering, but know basic of programming with GNU radio or arduino. What would be easisest but also efficient approach to manage that task, build something based on signal generator, connected and controlled over arduino, or with rtl-sdr cards like hackrf, hermes, pluto, lime.1. Approach I don't know much about clock generators like Si5351a or AD9959, which is better, maybe something else that I connect to arduino, please something with already build libraries on github, etc.2. Second approach, I have hackrf, but think that tx specs are pretty pure, not sure to invest in external tx amplifier or to buy better rtl-sdr card, speciffically for HF band, like Hermes lite plus, but again I don't even know if it's compatible with GNU radio, can't find block module on GNU radio, although on hermes site specs, they claim that it's full compatible with GNU radio.Main goal is to made device for generating signals like FSK, PSK, but also that I play with replay attacks, just for testing purpose.

author: LM21
author_rank: Regular Contributor
timestamp: February 21, 2022, 08:46:05 pm
content: Ebay has some MAX2870 signal generator boards. They have no modulation but cost is low, like under 100£$€
Open lines in de-embedding - Page 1
Forum section: electronics / rf-microwave

author: ffrank
author_rank: Newbie
timestamp: February 13, 2022, 10:50:51 pm
content: Hi, I want to de-embbed the fixture using open lines with different electrical lenghts.Could you help me with this?

author: Joel_Dunsmore
author_rank: Regular Contributor
timestamp: February 14, 2022, 07:44:55 am
content: I'm not quite following your question, does Sxykrepresent the lines, or the thing you are trying to measure? Is S11 the impedance you want to see? and is it you want to see the effects of the lines on S11 (that is, emulate lines in AWR to see how S11 rotates and presents a different S11m?), or you want to see S11 after de-embedding the lines (which are represented by Sxykwhere k is indexing different lines?) ? A better problem statement would be needed to give a better answer.

author: Marsupilami
author_rank: Frequent Contributor
timestamp: February 16, 2022, 04:54:54 pm
content: ffrank, is this a practical problem or school homework?We might have different suggestions depending.Regarding your last comment, you can absolutely use the 3 term vna error model and solve as you'd with SOL. (How good it will be is another question.) Your 3 standards will be an open (on the end of your fixture) and two offset opens (offset = length - fixture length). You have a linear system of 3 equations but it's unclear what are your unknowns. The short is going to be one, unless you're assuming it's ideal. If not then you can pick 2 for your line which means you have to have some knowledge about them.(also Dr. Dunsmore might know better, in which case listen to him not to the random dude on the internet.)
Need help identifying a RF component  - Page 1
Forum section: electronics / rf-microwave

author: vamax
author_rank: Newbie
timestamp: February 08, 2022, 08:59:42 pm
content: Dear community,I need help identifying a RF component in the attachment! I need to find out what exact type it is.It is a probably a RF filter or mixer.Silver plated coaxial cable, with two solid wires inside - red and yellow-orange.It is a 2,4Ghz RF device!Thanks in advance!

author: bob91343
author_rank: Super Contributor
timestamp: February 08, 2022, 11:30:27 pm
content: A directional coupler perhaps.

author: vamax
author_rank: Newbie
timestamp: February 09, 2022, 07:10:08 am
content: Thanks for your reply!Have you seen something like this on the market, or you think it is a custom made product!? To me it looks like peace of semi-ridged RG405 whit the two wires installed in place of the central wire.

author: geggi1
author_rank: Frequent Contributor
timestamp: February 09, 2022, 07:41:45 am
content: I have seen this i the ARRL handbook from about year 2000.I think it was used in a combiner between two rf pa blocks.Its called something like like a sarge line or something.

author: mikepi
author_rank: Newbie
timestamp: February 09, 2022, 09:00:49 pm
content: Google "sage wireline" for all you need to know about this coupler. It's used in a lot of microwave amps.Mike w7ghz

author: vamax
author_rank: Newbie
timestamp: February 10, 2022, 05:29:37 am
content: Thanks to all for the information!Cheers!

author: Paul B
author_rank: Contributor
timestamp: February 12, 2022, 12:39:27 am
content: hi is it a watkines divider / combiner
antenna mesh reflector - Page 1
Forum section: electronics / rf-microwave

author: Jack_Scott
author_rank: Newbie
timestamp: February 14, 2022, 04:20:13 pm
content: How would one go about determining a suitable mesh size for a parabolic reflector. I'm assuming it is a function of wavelength.

author: 9aplus
author_rank: Regular Contributor
timestamp: February 14, 2022, 05:29:27 pm
content: Less than 1/3 of wave works....

author: max-bit
author_rank: Frequent Contributor
timestamp: February 15, 2022, 12:11:16 pm
content: Largest mesh size <1/4 wavelength
ICOM IC-471a Ram file - Page 1
Forum section: electronics / rf-microwave

author: aa6dq
author_rank: Newbie
timestamp: February 11, 2022, 03:26:54 am
content: I am looking for an image file for the ram in the IC-471A. I need to reprogram the ram after replacing a dead battery. Does anyone have one they can send me? Any format is fine.
Low bands (160m-80M short range hilly terrain experiences?) - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: February 18, 2022, 01:36:20 am
content: Is it reasonable to expect to be able to use these lower bands for short range, reliable communications?Maybe with a magnetic loop as a compact antenna, and QRP? I live in a hilly area so lots of nearby towns - which might be close, are over hills making line of sight communications impractical. Can low frequencies utilize NVIS or similar to speak, reliably?
Low size VHF duplexer - Page 1
Forum section: electronics / rf-microwave

author: e.sotillet
author_rank: Contributor
timestamp: January 31, 2022, 12:19:45 pm
content: Hi FolksI need a low size, low power duplexer for VHF. The two center frequencies are separated by 10MHz, I had two SAW filter for those frequencies but I want to avoid the additional loss (-3dB) of the splitter.So, it is feasable to add a order 7 or 8 diplerxer before the SAW filters or sounds like a bad idea?Best regards!!

author: TheSteve
author_rank: Unknown
timestamp: January 31, 2022, 07:30:37 pm
content: What frequency exactly and what isolation are you looking for, and just how small?

author: fourfathom
author_rank: Super Contributor
timestamp: January 31, 2022, 08:09:47 pm
content: And what power level?

author: geggi1
author_rank: Frequent Contributor
timestamp: February 01, 2022, 06:40:44 am
content: Have a look on Ebay.There are some supplyers in china that sells duplexers 25w with a split of 8-10Mhz pretty cheep.You should check a bit on the reviews because I assume variating quality.

author: e.sotillet
author_rank: Contributor
timestamp: February 01, 2022, 02:00:13 pm
content: Hi, I proceed to answer the questions:1.- Frequency and isolation: I was wrong in this point, the two center frequencies are separed by 20MHz. One is 140MHz (8MHz BW) and 160MHz (10MHz BW). Isolation higher than 45 dB (The actual SAW filters achieve this).2.- Power level: 0dBm3.- Size: As small as possible. A comercial helicoidal duplexer is to heavy and large to add in the system.Best regards

author: e.sotillet
author_rank: Contributor
timestamp: February 15, 2022, 05:56:21 pm
content: Hi Folks,I builded the duplexer using the commented block diagram. It work fine, the only detail is the high part of the low band (lower center frequency filter) been attenuated by the low pass filter of the diplexer.I designed the later using the DiplexerDesing software by Tonne Software. Is any way to transform this diplexer topology to elliptip? Im concerned only about the transitions, the rest job is done by the SAW bandpass filtersBest regards and thanks for the time!!
RF Australia  - Page 1
Forum section: electronics / rf-microwave

author: Cujo
author_rank: Regular Contributor
timestamp: February 11, 2022, 03:49:22 am
content: I'm a third year EE that is going into RF in Australia. Would there be any need/benefits to get a white card?https://en.wikipedia.org/wiki/White_Card

author: bob91343
author_rank: Super Contributor
timestamp: February 11, 2022, 05:12:09 pm
content: I don't have an authoritative answer, but my educated guess is that the White Card, if needed, can be obtained at the time. It is tantamount to having an FCC Radiotelephone license here in the States; any engineer can get one when it's required.
solar flares - Page 1
Forum section: electronics / rf-microwave

author: m3vuv
author_rank: Super Contributor
timestamp: February 09, 2022, 11:46:22 pm
content: Hi all,has there been any solar flares this week,as hf seems bead on the low bands here ?

author: bob91343
author_rank: Super Contributor
timestamp: February 10, 2022, 04:32:54 am
content: HF has been dead, for the most part, for several years.Google solar flares if you want more info.

author: ahbushnell
author_rank: Frequent Contributor
timestamp: February 10, 2022, 04:11:35 pm
content: Quote from: bob91343 on February 10, 2022, 04:32:54 amI have been working FT8 on HF and from California I have contacted New Zealand, Falkland Islands and many other places. 40m to 10 m. HF is back.

author: bob91343
author_rank: Super Contributor
timestamp: February 10, 2022, 11:47:16 pm
content: No. FT8 contacts don't count. For HF propagation to return, we need voice and CW with signals of S9 and more.

author: ahbushnell
author_rank: Frequent Contributor
timestamp: February 11, 2022, 04:17:01 am
content: Quote from: bob91343 on February 10, 2022, 11:47:16 pmThey don't count. Is there a law?

author: bob91343
author_rank: Super Contributor
timestamp: February 11, 2022, 05:02:52 pm
content: I am not referring to legal issues. Technically, the signal is buried in the noise and specialized techniques are required to extract and identify. What is referred to here is the familiar presence of hundreds of loud signals, signifying lively ionosphere propagation.

author: ahbushnell
author_rank: Frequent Contributor
timestamp: February 12, 2022, 02:30:17 am
content: In the past year the FT8 signals have improved on HF. They are moving up into the 10m world.Plus yesterday I modified my antenna to work on 10 and 20 m (it was only 20 m before) and wow there is a bunch of signals on FT8. including NZ, Australia (from Southern CA).Here is some good information from the ARRL.http://www.arrl.org/here-comes-the-sun
(Crimean) SDR enthusiast arrested by Russian FSB for collecting ADSB data - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: February 07, 2022, 07:43:46 pm
content: (Crimean) Ukrainian SDR enthusiast arrested by Russian FSB for collecting ADSB data!?This is an automated Google translation by way of the RTL-SDR blog web siteWTF? Why don't they ask some Russian SDR fans. He did not commit any crime, as their own aircraft broadcast ADSB data. And its public information."Today it was reported about the arrest of a Crimean resident, either intending to transfer, or transferring military data abroad."The FSB has published footage of the arrest. The time on the laptop caught on the video during the search of housing 07:40 date 06/22/21. The laptop is turned on, the AIRSPY radio frequency scanning program is running, the laptop is in the dust - only traces of pressing some keys are visible, and the touchpad was not used. There are many icons in the room, books on radio engineering, a Ukrainian flag, aircraft models, several pennants "Tavria 1958", an ICOM IC-R6 radio, maps."Looks like he's a geek, like zillions of Russians are too. Not a spy. I feel bad for him and his girlfriend or wife."The detainee transferred the information received to Ukraine on one basis, collected it on the other and intended to transfer it.The court sent the man to the pre-trial detention center for 2 months. If his guilt is proven, then high treason "shines" and does not shine to see the will for 25 years.According to an article on RadioFreeEurope, the man was detained as he was "collecting data on the flights of Russian military planes for Ukrainian intelligence".I bet the data was going to an ADSB site like Flight Aware.com, or some similar service that lets people visualize it. Tens of thousands of people around the world do that. The Russians are just showing their cluelessness . They are not fooling anybody."It is unclear if the man was knowingly providing intelligence services, or is simply an aviation hobbyist caught up in politics. If anyone has more information about his story, please let us know in the comments".UPDATE 29 June 2021: More information on the story at [url https://grani-ru-org.appspot.com/Politics/World/Europe/Ukraine/m.282043.html]this link.
3d fractal antenna (discone) - Page 1
Forum section: electronics / rf-microwave

author: coppercone2
author_rank: Super Contributor
timestamp: February 04, 2022, 07:22:52 pm
content: https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=8012467Has anyone looked at fractal 3d antennas before? I guess planar fractal antennas are not as interesting as this.It seems that that antenna reminds me of a fractal discone. I am thinking a fractal biconical antenna would do something as well. This would be a fascinating use of 3d printing and metal casting IMO.It does look difficult to cast however, the metal used would need to have a very high flow and it would need to be die cast (hard) or maybe vacuum poured.But I don't think there is anything preventing anyone from cutting a whole bunch of pyramids out by hand and soldering/brazing them together in a fixture.. it would just require the use of heat sink putty to prevent the previous bonds from desoldering themselves. Might get quite tricky to solder that by hand.

author: richnormand
author_rank: Unknown
timestamp: February 08, 2022, 12:27:00 am
content: Looked at fractal antennas about 10 years ago. Although they looked intriguing and nice in many cases, we went with the concept of metamaterials.The metamaterial approach allows you to better control the apparent dielectric constant of the support material, yields a very compact geometry andpolarisation and permittivity matching.Several modems and cell phones integrated that technology and there was interest from several antenna manufacturers.I don't really know what is the state-of-the-art at this time.This might give you a start should you be interested:https://en.wikipedia.org/wiki/Metamaterial_antenna#:~:text=Metamaterial%20antennas%20are%20a%20class,(electrically%20small)%20antenna%20systems.&text=Some%20applications%20for%20metamaterial%20antennas,space%20vehicle%20navigation%20and%20airplanes.Also there was lots of metamaterial interest in microwave and optics for cloaking applications at the time.
Making a cable assembly, N-Type on RG402 - Page 1
Forum section: electronics / rf-microwave

author: pratiken
author_rank: Contributor
timestamp: February 08, 2022, 03:34:14 am
content: Hi!I want to take some RG402 (0.141"OD) cables I have with SMA male connectors, cut them, and put N-Type bulkheads on them.I've never made RF cable assemblies myself before. Can I use these N-type connectors on RG402?https://www.digikey.com/en/products/detail/rf-industries/RFN-1021-5/13159131and just use any of the N-type connector video guides on Youtube?Thank you!!

author: El Rubio
author_rank: Regular Contributor
timestamp: February 20, 2022, 08:19:58 pm
content: well, it depends. I want to suggest terminating with another SMA or N-type and getting a bulkhead adapter with N female on one end and SMA female ( or N female) on the other end. The problem is connectors for RG402 are expensive. If you require high frequency ( above 500MHz) operation, then the solder connector you linked to will not do so well since it will require the cable shielding to be unravelled and then attached to the body of the bulkhead connector. A significant portion of the center conductor will be exposed and not shielded. This will cause a larger 'bump' in return loss at the connector and could be a source for signal egress. Can you afford to not cut your pieces and just use the longer pieces with already made-up connectors? Depending on what the purpose is, you could just use a different type cable altogether. A complete cable made from something like LMR240 or 195 would cost less than just a connector for RG402. You can get bulkhead adapters made for RG402, but they're also around $30-50.
Declassified footage on UAP's anybody know of any SIGINT from UAPS? - Page 1
Forum section: electronics / rf-microwave

author: cdev
author_rank: Super Contributor
timestamp: January 30, 2022, 12:24:34 am
content: As everybody knows last year the US armed forced declassified video foorage of several unidentified airborne phenomena. To my knowledge these releases did not include any signals intelligence on these objects which defied the laws of physics however, at least the physics we know.I am a US citizen and want to know more. There is now a global community of people who - if any recordings of signals emanated from these "spaceships" would love to attempt to analyze them. If you had the opportunity, wouldn't you want to attempt to figure out what they contained? They should crowd source whatever data exists.https://www.youtube.com/embed/6rWOtrke0HY

author: Kees Hofwegen
author_rank: Newbie
timestamp: February 03, 2022, 08:10:27 pm
content: Hi,Check thunderf00t on YT. He did a debunk of this.Greez Kees
Why does the circuit composed of AD834 measure different power values, please he - Page 1
Forum section: electronics / rf-microwave

author: daisizhou
author_rank: Super Contributor
timestamp: February 02, 2022, 01:36:55 pm
content: The schematic diagram of the circuit is shown in the figure below. AD834 and AD711 form a square circuit。Of course, there is a filter circuit in front of。Two groups of AD820 form a ten-fold amplification and a hundred-fold amplification circuit。TP4\TP5\TP6 are respectively connected to the analog switch and finally connected to the AD converter。The AD converter is then sent to the microcontroller for processing and calculation。---------------------------------------------------------------------------------------------------------------------------------------------------------------I use the signal generator as the signal source, set the 500K sinusoidal waveform signal 224mVrms voltage value input, and input it at the RF IN port2 identical A and B boards, why do I get 2 different sets of test data, I don't know why, if you know please tell me the reasonThank you for your help
Simple chopper MOSFET mixer - Page 1
Forum section: electronics / rf-microwave

author: profdc9
author_rank: Frequent Contributor
timestamp: February 01, 2022, 11:23:39 pm
content: I was wondering if it would be possible to come up with a simple discrete alternative to the analog switches such as FST3253 used in commutating/switching mixers. The analog switches are a back-to-back P-channel and N-channel MOSFET. However, if the switch is biased in one direction, only one of the MOSFETs is used, for example the n-channel MOSFET. So I thought I would simulate a common-base amplifier which acts like a switch when the RF input is fed into the source and the MOSFET is switched using a digital LO. Because of the bias, there is strong feed through of the LO, however, if the IF is much lower in frequency (kHz) it is easily filtered.I think the advantages of a scheme like this might be that it should have fairly high IP3 because it is simply a switch conducting the RF input and there is strong drive to the MOSFET gate. It would be fairly immune to AM noise because of the switching nature of the mixer does not depend much on signal amplitude, but if there was a variation in duty cycle or a lot of phase noise, that would be present at the output.Is there some reason why this would be a bad idea? Is one of the problems I identified too severe to be practically solvable, or is there some other problem I may be missing?
ICOM IC-R70 RAM board problem - Page 1
Forum section: electronics / rf-microwave

author: pe1juz
author_rank: Newbie
timestamp: January 30, 2022, 06:39:13 pm
content: The RAM board from my Icom R-70 doesn't work anymore since I removed the battery. I tried an Italian replica, but every 10kc (10 kHz) I can hear a 'tic'. Not good, even annoying.Does somebody know how to solve this problem or where to get a decent working RAM board?PSI'm not a programmer and do not know anybody to programm, so that's not a solution I guess.Alexander

author: geggi1
author_rank: Frequent Contributor
timestamp: February 01, 2022, 06:31:01 am
content: Check your settings if you got a marker function on the reciever.This can give a tic on every 10khz or in other intervals dependant how it is set up.
My Microwave Lab is Taking Shape! - Page 1
Forum section: electronics / rf-microwave

author: 0culus
author_rank: Super Contributor
timestamp: December 26, 2021, 03:20:49 pm
content: I picked up my new baby just before Christmas! Can’t wait to get this home to the lab. I was able to set it up temporarily while I’m out of town though.Not shown: 8515A test set and 8340B synthesized sweeper.

author: xmo
author_rank: Regular Contributor
timestamp: December 26, 2021, 04:58:00 pm
content: Looks like Santa was good to you.

author: 0culus
author_rank: Super Contributor
timestamp: December 26, 2021, 08:42:33 pm
content: Quote from: xmo on December 26, 2021, 04:58:00 pmIndeed, even if Santa in this case was me and my own wallet!

author: antenna
author_rank: Frequent Contributor
timestamp: January 03, 2022, 03:19:08 am
content: OK, time to turn in that 90 day TEA chip..... Start over

author: TheSteve
author_rank: Unknown
timestamp: January 03, 2022, 05:54:31 am
content: Such a nice toy.Now on to cables, connectors, adapters, torque wrenches, calibration kits, frequency doublers, DC blocks, attenuators and more!

author: 0culus
author_rank: Super Contributor
timestamp: January 06, 2022, 02:39:06 am
content: Quote from: TheSteve on January 03, 2022, 05:54:31 amMicrowave is very much a pay to play game.

author: jjoonathan
author_rank: Frequent Contributor
timestamp: January 06, 2022, 10:27:33 pm
content: Suhner clicky wrench! Pavlovian condition yourself to torque everything correctly

author: 0culus
author_rank: Super Contributor
timestamp: January 07, 2022, 12:41:55 am
content: Quote from: jjoonathan on January 06, 2022, 10:27:33 pmAh man, I want one of those but the prices are steep.

author: jjoonathan
author_rank: Frequent Contributor
timestamp: January 07, 2022, 04:03:33 am
content: Yeah. Sometimes they drop in batches on ebay. It's definitely worth setting an alert, but they'll never be cheap.Actually, come to think of it, it looks like the N size Suhner wrenches are not too bad. I bet an enterprising individual could make an adapter. Material strength is the big problem with resin printing wrenches, but if it's hugged by N size jaws on all sides I bet that problem goes away. Hmm.

author: 0culus
author_rank: Super Contributor
timestamp: January 07, 2022, 04:37:30 am
content: Quote from: jjoonathan on January 07, 2022, 04:03:33 amI need to get better test port cables before I upgrade torque wrenches though. My Maury Microwave 5/16" wrench is good enough for right now.

author: jjoonathan
author_rank: Frequent Contributor
timestamp: January 07, 2022, 05:04:08 am
content: Yep, a tool in hand is worth two in the bush.

author: Paul B
author_rank: Contributor
timestamp: January 26, 2022, 12:45:45 am
content: now is the time to go through your connectors and trash the ones that are not good qualitythese are normally highly chromed or gold chrome instead of gold platedalso be weary of cheap connectors as the pin can be offset or even covered with insulationthese will destroy your connectors on the front of the HP test equipment and these are not cheap to replacePaul