hybridfree/eevblog-posts huggingface dataset:
How to take EMI measurement with MXA (N9020A) - Page 1
Forum section: electronics / rf-microwave

author: stretchyman
author_rank: Regular Contributor
timestamp: November 01, 2024, 02:08:27 pm
content: Hi there.One of the reasons a got an MXA with to conduct the measurements ness to get a product thru' CE certification.However I must admit I'm a bit stuck making a measurement using the EMI receiver.Got my LISN connected and sure I can see a spectrum in the SA view but switching to 'EMI Receiver' mode gives me a nice graticule but no data.There's a 'moan' at the base of the screen; 'Execution error; must perform scan before do search'I've read this; HP_Agilent_Keysight/N6141-90002 X-Series Signal Analyzer EMI Measurement Application Measurement Guide .pdfI'm thinking it must be me doing something obviously wrong as all seems well with the instrument.Anyone else tried this?I'm sure there are many new MXA users seeing as they're rather cheap on the SH market now.HELP!RegardsJohnB.

author: Miek
author_rank: Regular Contributor
timestamp: November 01, 2024, 03:22:20 pm
content: In section 2, "Conducted Emissions Measurement Examples" of the document you mentioned there's a whole list of steps you need to follow after switching to EMI Receiver mode. Have you done those?

author: stretchyman
author_rank: Regular Contributor
timestamp: November 01, 2024, 08:34:42 pm
content: Yes, I think so, will check tmrw.Many thanks for the reply.Regards.JohnB

author: stretchyman
author_rank: Regular Contributor
timestamp: November 05, 2024, 09:13:58 am
content: Yes indeed RTFM.I'd missed the 'sweep control start'.ALL good, Looks like I have a minor failure that I will need to rectify.Thanks again.J.
Please help me find this VCO or at least the correct name  - Page 1
Forum section: electronics / rf-microwave

author: Dario12345
author_rank: Newbie
timestamp: November 01, 2024, 10:33:44 pm
content: Plesae help me , so I can find it online

author: ftg
author_rank: Frequent Contributor
timestamp: November 04, 2024, 08:30:48 am
content: You could post more details and a larger photo about what device that VCO is in and what is it used for.The package is a bit unusual, as there seems to be seven discrete lines and not just the usual Vtune, VCC and RF out.It's Samsung branded and often the numbers on the can can point towards a frequency range, like 1885MHz in this case.Do you have an idea when the device was manufactured? That might help on tracking down the Samsung catalog that covers that era of VCO's.
OSCAR-7 ham radio satellite celebrates its 50th anniversary - Page 1
Forum section: electronics / rf-microwave

author: iMo
author_rank: Super Contributor
timestamp: November 21, 2024, 02:02:27 pm
content: Interesting insights on the technology used and how the Aliens fixed its battery design..

author: PA0PBZ
author_rank: Super Contributor
timestamp: November 21, 2024, 03:24:52 pm
content: That certainly brings back memories! I'm not sure if it was AO7 but hearing the 10M downlink for the first time certainly was one of those 'once in a lifetime' experiences that my parents and most of my friends did not understand at all...50 year anniversary:https://www.amsat.org/amsat-ao-7-a-fifty-year-anniversary/

author: iMo
author_rank: Super Contributor
timestamp: November 21, 2024, 03:28:32 pm
content: People say it still works..https://www.n2yo.com/satellite/?s=7530

author: PA0PBZ
author_rank: Super Contributor
timestamp: November 21, 2024, 03:39:09 pm
content: Quote from: iMo on November 21, 2024, 03:28:32 pmIt does, but a 'once in a lifetime experience' can only be had once, not?I've done my share of satellite communication but as with many things interest shifts and it's been years since I last used a transmitter and I don't really have the urge to go back.

author: coppercone2
author_rank: Super Contributor
timestamp: November 22, 2024, 02:10:06 am
content: does the laser cannon and compliment of class 4 nuclear weapons still work?
44MHz Modulator - Page 1
Forum section: electronics / rf-microwave

author: pinball!
author_rank: Newbie
timestamp: November 03, 2024, 07:11:18 pm
content: I have the need for a 44MHz AM modulator to do some troubleshooting on TV IF stages. It has to be capable of modulating a full NTSC 6MHz signal at 44MHz. Unfortunately 44MHz is below what normal video modulators can handle. Any ideas? Providing an external carrier frequency is not a problem. I have HP modulators that are unable to go above a few kHz.Edit: mhz to MHz

author: Bud
author_rank: Super Contributor
timestamp: November 03, 2024, 07:24:01 pm
content: mhz is milli Hertz. Maybe this is the issue?

author: pinball!
author_rank: Newbie
timestamp: November 03, 2024, 07:55:26 pm
content: It was meant as MHz. I can't say I've ever worked in the sub Hz range. Will edit for clarity

author: dobsonr741
author_rank: Frequent Contributor
timestamp: November 03, 2024, 08:18:25 pm
content: Build or get a MC1374 based modulator. The usual channel 3 and 4 are above your target, detune it, it’s spec’s down to 30MHz.http://www.bitsavers.org/components/motorola/_appNotes/AN-0829_Application_Of_The_MC1374_TV_Modulator.pdf
Where to attach antenna to one of these programmable remotes? - Page 1
Forum section: electronics / rf-microwave

author: u666sa
author_rank: Frequent Contributor
timestamp: November 01, 2024, 03:05:02 pm
content: One is on FT60E021 and the other one, the long one is on EV1527.The way I understand it, there is receiver and transmitter, both receiver and transmitter use R25 LNA, which is 2SC4226. Transmitter part for transmitting codes and receiver for programming the chip? Like that?Anyway. How to attach antenna to extend the operating range?
voltage and current transformers - Page 1
Forum section: electronics / rf-microwave

author: A.Z.
author_rank: Super Contributor
timestamp: November 04, 2024, 08:46:54 pm
content: I kept wondering why, aside losses, some people doesn't consider using both for some types of antennas; let's take a dipole or a loop (delta or quad, whatever), now imagine feeding it with a voltage transformer (galvanic) so that the radiator won't have a direct DC reference to ground: add a current transformer after it, to balance feedline currents, and we'd have a pretty good setup imVVHo, so... why not ?

author: iMo
author_rank: Super Contributor
timestamp: November 04, 2024, 09:08:30 pm
content: Because two transformers are heavy, for example..

author: Geoff-AU
author_rank: Frequent Contributor
timestamp: November 04, 2024, 10:15:46 pm
content: A fully isolated antenna builds up static electricity as the wind blows, this creates RF noise and risks damaging your radio when the charge exceeds the transformer's voltage rating and jumps across.There's really no point in a 1:1 voltage balun. Just a current balun or RF choke to make sure the feedline doesn't take on extra duties.
New 2400MHz Power Amplifier - Page 1
Forum section: electronics / rf-microwave

author: oe7dbhnew
author_rank: Contributor
timestamp: October 30, 2024, 07:06:23 am
content: HelloHere is a new power amplifier with a lot of gain for transmitters with very low output power, such as the Adalm Pluto from Analog Devices.Data:Frequency range: 2300...2450 MHzGain: over 50 dBSmall signal gain: over 53 dBOutput Power CWmode : up to 40 WattBandwidth -3dB : 300 MHz ( 2200.....2500 MHz )Signal mode: all ( with DVB reduced output power !, max. up to 8 Watt recommended )Operating voltage: 24...30V default 28 Volt ( housing is minus )Power consumption: max. 4 Amps at full powerInput-Output connector: SMA femaleRF monitor output: SMA female ( -32dB opposite output port )Input max. power: 1mW ( 100mW is damage power )Amplifier size: 15cm x 10.5cm x 2.2cmOutput protected by circulator from oversized antennas VSWRProtected against incorrect voltage reversalMore info and testreport on:https://oe7dbh.blogspot.com/2024/01/13cm-band-high-gain-power-amplifier.html

author: coppercone2
author_rank: Super Contributor
timestamp: October 30, 2024, 07:13:18 am
content: https://www.eevblog.com/forum/rf-microwave/gadget-for-high-frequency-guy/
Looking for Feedback and Suggestions to Improve RF Design Tools - Page 1
Forum section: electronics / rf-microwave

author: Hokua RF
author_rank: Newbie
timestamp: October 21, 2024, 04:37:33 am
content: Hey, I've got these new RF tools and I'd appreciate any feedback. I would like to improve the tools with your suggestions.Tools for Transceiver Design:https://hokua-rf.com/designtools/rf-systems/Converters:https://hokua-rf.com/converter-tables/Antennas:https://hokua-rf.com/designtools/antenna-design/Transmission Lines:https://hokua-rf.com/designtools/transmission-line-calculator/Thank you very much for any kind of feedback.

author: EggertEnjoyer123
author_rank: Frequent Contributor
timestamp: October 21, 2024, 06:19:24 am
content: You probably need a calculator for GCPW since that's also fairly common, especially for PCB designs.

author: radiolistener
author_rank: Super Contributor
timestamp: October 21, 2024, 03:45:01 pm
content: I don't see calculator for RF inductors/transformers which allows to select core material, core shape and size, wire material and thickness, frequency and calculate inductance, saturation amplitude, heating and max power transfer

author: jonpaul
author_rank: Super Contributor
timestamp: October 23, 2024, 05:17:44 am
content: For transformrers and inductors:MicroMetals fine calculators for powdered iron cores.https://micrometals.com/design-and-applications/design-tools/Intusoft (MicroCap) Magnetics Designerhttp://www.intusoft.com/mag.htmsee also, Class E (Nathan Sokal) RF amplifiers and power convertersJon

author: Tube
author_rank: Newbie
timestamp: October 31, 2024, 06:45:19 pm
content: The design tools look great and intuitive. Could you add a tool that calculates the total SNR of ADC and DAC depending on clock jitter, number of bits, aperture, clock frequency and analog bandwidth?

author: Hokua RF
author_rank: Newbie
timestamp: November 07, 2024, 04:54:48 am
content: Thank you very much for your valuable feedback, which we really appreciate. We are planning on extending our PCB transmission line design tools soon with CPW, GCPW, slotline, and coplanar strips, for which we have the models ready.We also like your pretty good idea regarding the total SNR of ADC and DAC. We will finish our I/Q signal category first and then we will have a look into the SNR of ADC and DAC.
DX-70 Sideband leakage - Page 1
Forum section: electronics / rf-microwave

author: ashok.das81
author_rank: Contributor
timestamp: October 24, 2024, 04:49:03 am
content: Hi all,My radio Alinco DX-70 transmits on both USB and LSB, when I set it to transmit on USB. Signal is visible in USB as well as in LSB, but signal strength is bit less in LSB. It appears that radio is transmitting as DSB. Now my question how this can happen. What could be the problem that makes a SSB radio to DSB ? One more observation is that, when I transmit on LSB, then it is fine, there is no transmission on USB at this time. I need some help as how to diagnose this problem. At least if I can understand where is the problem, then I can determine if it repairable or not.Thanks

author: iMo
author_rank: Super Contributor
timestamp: October 24, 2024, 10:02:55 am
content: First step is to get the "DX-70 Service Manual" where you may find the schematics.On the page 58 you may find the block diagram where you may see the most of the modes switching is done via diodes, so doublecheck them.

author: CaptDon
author_rank: Super Contributor
timestamp: October 24, 2024, 08:51:08 pm
content: How do you know this to be true? Looking at signal with a spectrum analyzer? Listening on another radio which may be at fault? Generally speaking they use a crystal filter and in the mixing stages shift the carrier above the upper cutoff to obtain the lower sideband, or shift the carrier below the lower cutoff to obtain the upper sideband. Could be a crystal filter problem or improper carrier offset for upper and lower sideband generation or your measuring equipment is faulty and the radio is fine.

author: geggi1
author_rank: Frequent Contributor
timestamp: October 25, 2024, 05:03:01 pm
content: If you have problem with the BFO or crystal filter you will get some of the opposite side band.If it is only on one sideband its most likely the crystal filter.
properly using HMC8193 spurios table - Page 1
Forum section: electronics / rf-microwave

author: john23
author_rank: Frequent Contributor
timestamp: October 21, 2024, 07:58:11 pm
content: Hello, given the spurios table of hmc8193, how do i know what is basic IF power shown in 100MHz?Thanks.https://www.analog.com/media/en/technical-documentation/data-sheets/hmc8193.pdf

author: Hokua RF
author_rank: Newbie
timestamp: October 21, 2024, 09:58:33 pm
content: Check Figure 60 in the datasheet. According to Figure 60 the convertion loss is approximately 8 dB typical. With RF power -10 dBm IF power is typical -2 dBm.

author: TimFox
author_rank: Super Contributor
timestamp: October 21, 2024, 10:13:12 pm
content: Quote from: Hokua RF on October 21, 2024, 09:58:33 pm-10 dBm reduced by 8 dB conversion loss is -18 dBm.

author: Hokua RF
author_rank: Newbie
timestamp: October 21, 2024, 10:32:43 pm
content: Upconverter table is used with RFpower -10dBm. Therefore IF power-2dBm.
Sony ICF-SW55 Repair Help - Page 1
Forum section: electronics / rf-microwave

author: samart94
author_rank: Newbie
timestamp: August 18, 2023, 04:54:25 pm
content: Hi everyone, Im currently repairing my sony icf-sw55, i have recapped, cleaned the board. However, i'm experiencing "cal" issues on the first start and it turns off. My quick searches revealed me to check the DC-DC section. I would like to get help from the gurus. As of the time being, im not getting 0.5V at the base of the Q46 Transistor, but im alreading getting 0.6V at the collector of the transistor. i have checked and found that R205 and R206 to be at value less than 50K Ohms, and have replaced them. Im rectiying this issue as im not getting the 16V out from the DC-DC coil (T14), but gettting fluctuating voltage of 5V and below. Im also getting 2.9V at the collector of the Q47. Any help is greatly appreciated.

author: NortliW
author_rank: Contributor
timestamp: October 20, 2024, 09:07:10 pm
content: Hi,Did you get it to work? My PLL is not running the 6.275MHz. I have replaced all the el.caps, the trimmer cap, cleaned the board, even under the PLL chip CXD1118M. No luck. When I turn the radio on the CAL function is displayed and it shuts off after 10 seconds. No oscillation on the crystal of 6.275MHz. Any ideas?Rgds,B.
Looking for any examples of applying SD2933 LDMOS FET(s) for 144MHz/2M band - Page 1
Forum section: electronics / rf-microwave

author: wb0gaz
author_rank: Frequent Contributor
timestamp: October 20, 2024, 07:10:02 pm
content: The SD2933 datasheet specifies to 150 MHz and there are numerous ham/commercial amplifier builds using the device up through 50 MHz/6M band. Although the device may not be as efficient or lack gain, I'm interested in applying it (preferably a pair in push-pull) on 144 MHz/2M band, but haven't seen or been able find any articles/discussions on that use case. Have you seen such a discussion? Tks, 73 Dave
Why do most pocket AM radio receivers have shorter (non-resonant) antennas - Page 1
Forum section: electronics / rf-microwave

author: prabhatkarpe4
author_rank: Contributor
timestamp: November 01, 2024, 09:24:35 am
content: I would like to know why most pocket radios come with a shorter whip antenna of about 20 cm, which is not a resonant one for FM or SW bands. So, how come they work like that?

author: Andy Chee
author_rank: Super Contributor
timestamp: November 01, 2024, 10:15:43 am
content: Antennas do not have to be resonant to work.Receiving antennas intercept the E-field from the transmitter, and the larger it is, the more E-field is intercepted, and the bigger the received signal.Resonance is an advantage, but not necessary.

author: Andy Chee
author_rank: Super Contributor
timestamp: November 01, 2024, 11:46:27 am
content: Also, do not start new topic. You already have threads here:https://www.eevblog.com/forum/rf-microwave/why-do-pocket-radios-have-small-antennas/https://www.eevblog.com/forum/rf-microwave/shorter-whip-antenna-of-the-pocket-radios/https://www.eevblog.com/forum/rf-microwave/why-a-longer-antenna-is-able-to-receiving-smaller-bands/
Is that a loading coil antenna - Page 1
Forum section: electronics / rf-microwave

author: prabhatkarpe4
author_rank: Contributor
timestamp: October 12, 2024, 12:36:09 pm
content: I came across one WiFi receiver of my wireless keyboard and after opening the USB receiver, I saw a strange looking printed antenna on the PCB.It's like a series of square waves printed on the PCB.Is that a loading coil antenna or something else?I have attached the snapshot of the PCB.

author: szoftveres
author_rank: Regular Contributor
timestamp: October 12, 2024, 02:31:19 pm
content: It's called "Inverted F" antenna; the zig-zagging makes them able to fit 1/4 wavelength of copper line into that small area.
Driver Software for IFR2935 GSM Head - Page 1
Forum section: electronics / rf-microwave

author: Astrodev
author_rank: Regular Contributor
timestamp: June 12, 2021, 08:05:56 pm
content: Anyone got any ideas on where either the Phonetest or Phonelib software can be found to drive the IFR2935 head from a PC.From the searching I have done so far it used to be downloadable from IFR's website, but with all the merging that has gone on the old site and the link are no longer there, so I was hoping someone may have a copy or be able to point me in the right direction to get hold of it.Alternatively if anyone has details of the communications protocol the IFR2935 understands as it seems a shame that these instruments can't be repurposed for lack of the right information.

author: DeepLink
author_rank: Regular Contributor
timestamp: June 29, 2021, 08:25:26 am
content: I also have a IFR2935, but haven't succeeded in finding any information about itI don't have any use for the software, but would like the schematic, as I would like to take it apart and perhaps reuse some parts

author: adegough
author_rank: Newbie
timestamp: October 08, 2024, 05:44:30 pm
content: I know this is an old thread. The PhoneTest softwre can be found on the wayback machine (Archive.org). look for the Aeroflex website and go to the 2005 list, then choose the full scrape from June I think. Access the IFR2935 pages from there, you will find the software in the righthand support links under software.

author: adegough
author_rank: Newbie
timestamp: October 08, 2024, 05:47:09 pm
content: I have a number of these machines (10 - 20 odd) for sale on ebay. I will include the software (untested) on CD with each machine if anyone is interested.
Anybody know what this VT input  does?  V2555 10GHz oscillator - Page 1
Forum section: electronics / rf-microwave

author: mr ed
author_rank: Regular Contributor
timestamp: October 07, 2024, 01:38:42 am
content: The F/S is freq select. What about VT on the sma?

author: mr ed
author_rank: Regular Contributor
timestamp: October 07, 2024, 01:41:24 am
content: ...more

author: uer166
author_rank: Super Contributor
timestamp: October 07, 2024, 02:04:44 am
content: Maybe trim voltage?Edit: it says tuning voltage right there

author: mr ed
author_rank: Regular Contributor
timestamp: October 07, 2024, 02:07:12 am
content: FS Changes freq. You mean small freq changes? Why a SMA?

author: Marsupilami
author_rank: Frequent Contributor
timestamp: October 07, 2024, 02:47:56 am
content: This is a VCO. VT is the tuning voltage. On the spec sheet 2.1, 2.2 tells you the valid range (depending on the F/S state), while 4.1 and 4.2 gives the sensitivity. ~18MHz/V, that is how much you can tune the nominal output frequency by changing VT by 1V.It doesn't necessarily have to be on an SMA, but if the VCO is part of a phase locked loop the tuning voltage will be a broadband signal, easily in the MHz range. The coax works better for that than the solder posts.HTH

author: mr ed
author_rank: Regular Contributor
timestamp: October 07, 2024, 02:59:29 am
content: So, there is a high and low band via f/s ttl level and fine tune via VT. Makes sense now. Thanks.
Reflective array TV antenna phasing and matching - Page 1
Forum section: electronics / rf-microwave

author: szoftveres
author_rank: Regular Contributor
timestamp: October 07, 2024, 01:58:17 am
content: I'd like to understand how this type of antenna works, wondering if someone could shed some light. The construction of this type of antenna seems so basic (basically just wires being bent and connected with each other), yet I'm having hard time making sense of it.Why are the upper and lower elements are out of phase (transmission line crossed), when the two middle elements are in phase?EDIT: I figured this one out; the wave is travelling to each element and the transmission line is forming a T-shaped distribution network; the elements can only be kept in phase when the phasing of the line is flipped 180degree along the way every 1/2 wavelength.What is the impedance of this antenna at the main feedpoint, and how can it be derived from the feedpoint impedance of the individual elements, which are close to (and presumably interacting with) each other (and of course add the effects of the in phase vs. out of phase elements and the reflector)? Does the characteristic impedance of the distribution network matter?
China vacuums capacitors  - Page 1
Forum section: electronics / rf-microwave

author: jord4231
author_rank: Regular Contributor
timestamp: October 05, 2024, 10:54:20 pm
content: Hi Just wondering if anyone has had any experience with these?https://www.aliexpress.com/item/1005005910772893.htmlCan't find anyone who's using them for radio related projects anywhereI have built a balanced L matching unit and the Jennings vac cap I have its a bit too high at minimum C for my needs.This one fits my requirements but I do wonder about it's mechanical longevity seals etc...Cheers

author: A.Z.
author_rank: Super Contributor
timestamp: October 06, 2024, 06:11:35 am
content: sorry, can't help with those, but the issue with vac caps is the sealing and "how long" they'll mantain it...as for your Jennings min capacity, did you consider adding a switchable series doorknob to them to lower it when needed ?

author: A.Z.
author_rank: Super Contributor
timestamp: October 06, 2024, 07:13:58 am
content: alternatively, you may consider something like the attached, it can be configured as either a T or an L match using S1 and S2; the C3 and C4 fixed caps will have the same value as the max value of C1 and C2 and can be inserted in both configs (L or T) if/when needed; when in T config they'll help reducing losses

author: jord4231
author_rank: Regular Contributor
timestamp: October 06, 2024, 10:02:05 am
content: Quote from: A.Z. on October 06, 2024, 07:13:58 amThanks for the reply, I've experimented with series capacitors and while it works I think it will just be easier to get something that goes to around 10p rather than 50p I have linked a video for the project so far if you are interested.https://youtu.be/PkCmKlOmHHU?si=NObs60NmXud0xFVbThanks againJordan

author: A.Z.
author_rank: Super Contributor
timestamp: October 06, 2024, 10:21:26 am
content: see herehttp://ur4ll.net/#caps3_1

author: A.Z.
author_rank: Super Contributor
timestamp: October 06, 2024, 01:18:11 pm
content: also seehttps://elektrodump.nl/en/49-variable-vacuum-capacitor
Coupled Lines Equation - Page 1
Forum section: electronics / rf-microwave

author: dmowziz
author_rank: Contributor
timestamp: October 04, 2024, 09:08:59 pm
content: Please if someone can kindly explain/ "solve" how this equation is derivedIt is from Microwave Engineering by David Pozar.The book is freely available on the webThe first equation in 8.101Zi = .... Please how is it derived?It is on page 430 in the bookTable 8.1 is on page 391Thank you very much

author: dmowziz
author_rank: Contributor
timestamp: October 05, 2024, 01:41:44 pm
content: It is just simple understanding and changing ABCD parameters to Z parametersTried to remove the topic but it is not working
Boatanchor Coupling Cap Temperature Coefficient Rating - How Critical? - Page 1
Forum section: electronics / rf-microwave

author: NY2KW
author_rank: Regular Contributor
timestamp: October 08, 2024, 03:52:38 am
content: Working on a boatanchor HF transmitter and needed to replace the old germanium diodes in the ring balanced modulator. While there I thought why not replace the old ceramic domino coupling caps (ElMenco - definitely ceramic not mica) which bring the audio signal from the Audio amp 12AT7 to the balanced modulator. As audio signal, how critical is the temperature coefficient for pair of coupling caps in the balanced modulator? Do I need NP0 /C0G or would Y5P or X5R be OK?Thanks in advance.Jerry

author: wasedadoc
author_rank: Super Contributor
timestamp: October 08, 2024, 02:42:30 pm
content: Without seeing the schematic, I expect the actual capacitance of audio coupling capacitors to be not critical.
Wiltron sweepers: Anybody know the difference between 67xxA vs B models? - Page 1
Forum section: electronics / rf-microwave

author: mr ed
author_rank: Regular Contributor
timestamp: October 11, 2024, 07:49:53 pm
content: There are at least 20 different frequency configurationsbut support files (user, maintenance, cal, fw images)seem to exist only for 'B' versions.I am assuming the B model is slightly newer or somehowbetter but close to the A versions. Correct?What are the differences?Could I use the B files on an A version? What about FW?I'm looking for a gen to at least 20GHz working or not, Wiltron seems affordable for home use.
SSB Installation and Circuit Product Detector Testing & Results National HRO-50 - Page 1
Forum section: electronics / rf-microwave

author: Peithojr
author_rank: Contributor
timestamp: September 22, 2024, 04:47:00 pm
content: I have been an avid SW listener for years , and now wanted to share my circuit for SSB detection. I put this together on my Nation HRO-50https://youtu.be/ds8Q4orb7A0

author: StuartA
author_rank: Regular Contributor
timestamp: October 01, 2024, 06:21:38 am
content: That's very interesting! I have a WWII HRO 5, which is undergoing what I like to refer to as a "mid-life update" and that is intended to include a product detector... when I get around to that bit! The audio quality you are getting is good... at least as good as SSB ever gets.
Signal improvement using a ferrite rod with a small loop antenna - Page 1
Forum section: electronics / rf-microwave

author: prabhatkarpe4
author_rank: Contributor
timestamp: September 30, 2024, 11:49:26 am
content: I have used my small loop antenna (which has a main loop and a coupling loop that can be tuned using a variable capacitor) with an AM radio receiver to receive MW broadcasts. However, the small loop antenna which was made by me was not working properly but when I connected a ferrite rod loop (which has two windings on it---one with 60 turns and the other with 30), I saw a great improvement in radio reception. I connected the 60 turns loop with the main loop of the small loop antenna and the 30 turns loop with the AM radio.The ferrite loop is not working as an antenna and when I turned it, I didn't get any difference in signal strength. However, when I turned the small loop antenna, I saw the change in signal.So, I need to know why this has happened and did the ferrite rod work like a balun?I have attached the diagram of the setup.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 30, 2024, 04:55:06 pm
content: I'm afraid, explaining why, would require RF knowledge --https://www.eevblog.com/forum/rf-microwave/number-of-turns-for-the-coupling-loop/msg5657791/#msg5657791Should I take that to understand, you are interested now in deepening your knowledge?Tim

author: radiolistener
author_rank: Super Contributor
timestamp: September 30, 2024, 04:59:52 pm
content: Quote from: prabhatkarpe4 on September 30, 2024, 11:49:26 amin your case it works like transformer with impedance transform ratio 4:1. And yes, such transformer can be used as balun.

author: prabhatkarpe4
author_rank: Contributor
timestamp: October 01, 2024, 11:54:53 am
content: But howcome that's 4:1? it's have 60/30 turns and should be 2:1.

author: ftg
author_rank: Frequent Contributor
timestamp: October 01, 2024, 11:58:43 am
content: Quote from: prabhatkarpe4 on October 01, 2024, 11:54:53 amImpedance transformation ratio is the square of the turns ratio.2^2 is 4, thus 4:1 impedance transformation ratio.

author: A.Z.
author_rank: Super Contributor
timestamp: October 02, 2024, 03:25:00 pm
content: Quote from: ftg on October 01, 2024, 11:58:43 amYep, we have 60 and 30 turns, so the turns ratio (not the number of turns) is 2:1 which means a 4:1 impedance transformation ratio, as a note it's usually a good idea to wind the lowest reasonable amount of turns (depending from core material characteristics) to reduce losses and avoid unwanted self-resonance, an example, willing to wind a 9:1 transformer using a #73 binocular core we start by obtaining the turns ratio, that is sqrt(9), which gives us 3, at that point we wind 6 turns and 2 turns which will result in our 9:1 impedance ratio corresponding to the 3:1 turns ratio we calculated
numerical electromagnetics help forum question - Page 1
Forum section: electronics / rf-microwave

author: john23
author_rank: Frequent Contributor
timestamp: September 25, 2024, 12:46:41 pm
content: Hello,Is there numerical electromagnetics forum i can consult regarding hardcore electromagnetics and numerical implementation?Thanks.

author: jonpaul
author_rank: Super Contributor
timestamp: September 28, 2024, 05:15:23 pm
content: Ansyshttps://www.ansys.com/Matlabhttps://www.mathworks.com/videos/series/finite-element-analysis-in-matlab.htmllearn to searchhttps://en.wikipedia.org/wiki/List_of_finite_element_software_packagesj
Tuned Antennas Lighting Up LEDs Video  - Page 1
Forum section: electronics / rf-microwave

author: hulk69
author_rank: Contributor
timestamp: September 26, 2024, 06:30:58 pm
content: Hey guysI came accross this video:https://www.youtube.com/shorts/aSSqrddG6B0?feature=shareWhat puzzled me is why on earth would he put a schottky diode in parrallel to make the LED light up???Would not a capacitor be a better idea?Thanks

author: Andy Chee
author_rank: Super Contributor
timestamp: September 26, 2024, 06:53:17 pm
content: The diode is to allow reverse current to flow in the opposite direction. If you remove the diode, the LED will block the reverse voltage, but will be destroyed because the reverse voltage became too high.

author: hulk69
author_rank: Contributor
timestamp: September 26, 2024, 08:29:57 pm
content: After thinking a lot about this i do not think it has anything to do with protection because of the very minimal power involved but more about the voltage/current characteristic of a fast diode.An LED would need a lot more current to get to a certain voltage.The schottky diode can start conducting @100µA -> 0.4V which would be able to drive an LED very dimlySo my theory is that the diode is there to increase the voltage at very low current

author: hulk69
author_rank: Contributor
timestamp: September 26, 2024, 08:36:55 pm
content: looking at it again makes no sense because the diodes are reversed...

author: KE5FX
author_rank: Super Contributor
timestamp: September 26, 2024, 10:18:42 pm
content: The LED has a fair bit of junction capacitance, probably 50-100 pF, and at subthreshold voltages it will appear capacitive in both directions, preventing any DC voltage from building up (unless/until you hit the diode with a lot more power than it receives here.)By shorting out the negative half-cycles (neglecting Vf), the Schottky forces the LED junction capacitance to charge only on the positive half-cycles, allowing enough voltage to build up to turn the LED on.
Baofeng UV-5RM - Page 1
Forum section: electronics / rf-microwave

author: Randy222
author_rank: Frequent Contributor
timestamp: September 24, 2024, 04:17:05 pm
content: Got a new set of low cost radios to play with. Watched many online vid reviews and their testing. Most of those vids were from early days of the 5RM release. Not sure if anything has changed but here are my test results.Test gear is tinySA Ultra v1.4-177 , and MFJ-842 power-swr needle meterUV-5RM firmware v0.14 hardware v01out-of-the-box testing, no chirp tweaksSQL 3Rx SensitivityAM 125.250MHz -116.2dbmFM 137.250MHz -121.2dbmFM 225.000MHz -123.2dbmFM 430.250MHz -126.2dbmHarmonicsVHF dirty-ugly1.25M okUHF okTx PowerLow137.250MHZ 3w (*surges to 4w when PTT releases)225.000MHz 2.5w430.250MHz 2.5wMiddle137.250MHZ 6w225.000MHz 2.5w430.250MHz 5.3wHigh137.250MHZ hi 10w225.000MHz hi 5w430.250MHz hi 11w

author: pienari
author_rank: Regular Contributor
timestamp: September 25, 2024, 05:22:23 am
content: Hi.Have tested what was the tx freq low/up limits?.

author: Randy222
author_rank: Frequent Contributor
timestamp: September 25, 2024, 03:56:40 pm
content: Quote from: pienari on September 25, 2024, 05:22:23 amOut of the box, just the lowest and highest frequency that I can key up?These are just two points, other bands have restrictions on them (out of the box)Lowest is 136.00000MHzHighest is 519.99875MHz

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: September 26, 2024, 12:00:58 am
content: I have seen a few Baofeng radios on spectrum analyzers. They all had terrible harmonics on 2 meter band. Do not recall if I have seen other bands analyzed.

author: Randy222
author_rank: Frequent Contributor
timestamp: September 26, 2024, 02:57:30 pm
content: Quote from: Wallace Gasiewicz on September 26, 2024, 12:00:58 amThere's a few vids that show 2m harmonics, but not the other bands, but they then mention "works ok on the other bands". Not sure why they just wouldn't show the other bands on the test gear.
Using earphones as a dipole antenna - Page 1
Forum section: electronics / rf-microwave

author: prabhatkarpe4
author_rank: Contributor
timestamp: September 21, 2024, 08:32:47 am
content: I would like to know how the earphones work as a dipole antenna for a smartphone to receive the FM bands?Usually, one arm of a dipole needs to be connected to the ground and the other arm needs to be connected to the receiver. But in the case of a earphone, the headphone coil would work as a resistor and there is a resistance of 32 ohms. So, how do the two arms of the dipole antenna work when there is a resistance between the two arms?

author: wasedadoc
author_rank: Super Contributor
timestamp: September 21, 2024, 08:42:03 am
content: You have started wrongly by assuming that the two wires in the headphone cable act as the two arms of a dipole. They don't. They act more like an extended telescopic whip aerial on a typical FM broadcast portable with loudspeaker.

author: radiolistener
author_rank: Super Contributor
timestamp: September 21, 2024, 01:58:02 pm
content: Quote from: prabhatkarpe4 on September 21, 2024, 08:32:47 amEarphone don't works as dipole antenna. Dipole has different geometry. Geometry for antenna is very important.It works as a random piece of a single wire.

author: I wanted a rude username
author_rank: Frequent Contributor
timestamp: September 21, 2024, 03:51:06 pm
content: Moreover it's quite likely the ground wire being used as the aerial. Some portable radios with built-in speakers came with a single wire on a non-standard short 3.5 mm plug that only made contact with ground, to serve as the aerial but not switch to headphone output. There's only one ground, and as radiolistener says it can be used as a RPOW.

author: TimFox
author_rank: Super Contributor
timestamp: September 21, 2024, 04:18:47 pm
content: In the physics of antenna radiation, one starts with an "elementary dipole", with wires much shorter than the wavelength.Integrating such elementary dipoles to longer wires gives you useful resonant structures, such as the popular "half-wavelength dipole".

author: Zero999
author_rank: Super Contributor
timestamp: September 21, 2024, 05:34:03 pm
content: My Walkman did that, but it was monopole, not dipole. I didn't take it apart, before giving it to charity, so don't know for sure how it worked, but I imagine, there was an inductor in series with the ground side, so it's low impedance to audio, yet high impedance at RF. It seemed to work well enough, but not as good as a proper portable radio.

author: prabhatkarpe4
author_rank: Contributor
timestamp: September 23, 2024, 12:24:58 pm
content: Thank you guys, I got it!
EPIG finish on 50GHz PCB - Page 1
Forum section: electronics / rf-microwave

author: rfengg
author_rank: Regular Contributor
timestamp: September 18, 2024, 06:10:22 pm
content: Hi All,Need some advice on PCB plating at 50 GHz.....our first choice was EPIG but most of the well known fabs in US do not seem to offer this option.Does anyone know fabs that offer EPIG? Any other alternatives to EPIG or any other finish that excludes the nickel barrier, so that we can minimise loss at 50 GHz?thanks

author: uer166
author_rank: Super Contributor
timestamp: September 18, 2024, 06:31:38 pm
content: Immersion Silver finish seems to be offered by a bunch of vendors. I don't know what the loss it introduces, but probably less than Ni.Edit: It's similar to OSP or bare copper.

author: rfengg
author_rank: Regular Contributor
timestamp: September 19, 2024, 01:57:02 pm
content: Thanks for your reply @uer166.The only reason we did not choose ImAg is that the surface tarnishes over time and I am not sure how detrimental this could be to loss after it tarnishes.

author: uer166
author_rank: Super Contributor
timestamp: September 19, 2024, 07:42:39 pm
content: It shouldn't affect it measurably since it's not ferromagnetic, and all current will run on the inside surface of a microstrip, so its' reduced conductivity should be a non-issue as well. The only one is dielectric loss of Silver Sulfide that I'm not sure about, and perhaps a slight reduction in impedance of trace due to that same effect.Make a test board and tarnish some traces as an experiment!
Will this Antenna Work with my Device? - Page 1
Forum section: electronics / rf-microwave

author: ZGoode
author_rank: Frequent Contributor
timestamp: September 18, 2024, 01:43:00 am
content: I recently acquired a Trak 8835-3M Rubidium GPSDO, but it did not come with an antenna. Looking at the manual I think this one I found on Digikey should be compatible, but I wanted to make sure. I was planning on using RG58 cable since most of the IP rated TNC connectors I could find were for either RG58 or RG316https://www.digikey.com/en/products/detail/amphenol-rf/031-6923-EE/16710734https://www.digikey.com/en/products/detail/amphenol-pctel/3977D-W/15998868

author: Randy222
author_rank: Frequent Contributor
timestamp: September 18, 2024, 04:03:10 pm
content: You posted looking for the user manual, did you find that yet?The gps spec sheet does say TNC, so the male TNC connector should work. TNC is like BNC, except TNC is a threaded collar and good for 11GHz.

author: ZGoode
author_rank: Frequent Contributor
timestamp: September 18, 2024, 04:15:46 pm
content: Yeah, I finally got a hold of Smithsinterconnect through their sales department. The manual is the PDF I attached to my question here.I saw in the datasheet that it listed the antenna power as 5VDC upto 50mA which seems to fit the antenna I found on Digikey from Amphenol, but since RF is not an area I am super well educated on I wanted to make sure.

author: Randy222
author_rank: Frequent Contributor
timestamp: September 18, 2024, 04:44:17 pm
content: I am not sure what the "antenna power" is. Does the trak device do power over TNC?And on page 2-7 it says "see appendix E for antenna details". There is no appendix E in the manual.The L1 antenna you listed should be good.

author: ZGoode
author_rank: Frequent Contributor
timestamp: September 18, 2024, 04:59:35 pm
content: Yes, from my understanding of the manual and datasheet the Trak device uses an active antenna which appears to receive its power from the TNC connector.I am not sure why it makes reference to an appendix E, since you are right it does not exist. Everything I have been looking at for the antenna starts on page 46 of the PDF in appendix B.
Can I source the Beken BK4819 radio IC somehow? - Page 1
Forum section: electronics / rf-microwave

author: rf-fil
author_rank: Regular Contributor
timestamp: September 15, 2024, 10:59:08 pm
content: I'd love the design a radio off of BK4819. It's the chip used in most recent cheap radios. The chip is not that bad, with some extra filtering added. However, Beken are not responding to my emails.. Excuse my naivete, but is there a way to source these, in small quantities, lets' say 1k - 10k, when outside of China?

author: Kean
author_rank: Unknown
timestamp: September 16, 2024, 02:35:12 am
content: When sourcing this kind of part, you will likely need to find a buying agent in China to handle the purchase. Ideally someone with technical knowledge.If you can find the parts on a Chinese marketplace like Taobao or Tmall then you can try using Superbuy as the buying agent. I've used it a couple of times without issue, but they won't be able to help with any technical details.Maybe there is someone on this forum who can suggest a reputable contact in China. Otherwise, look for a seller of components on AliExpress and ask them if they can help.

author: ftg
author_rank: Frequent Contributor
timestamp: September 16, 2024, 08:00:22 am
content: BK4819 is available in small quantities on Aliexpress.But some more reliable broker than random Aliexpress seller might be desirable.I have other projects that I want to get done before making my own BK4819 based modules, so I'm yet to see what I get when I order some BK4819's from ali.The QFN BK4811's I ordered seem fine.
Low amplitude from 3.6GHz DRO - potential causes? - Page 1
Forum section: electronics / rf-microwave

author: alan.bain
author_rank: Regular Contributor
timestamp: September 09, 2024, 04:40:27 pm
content: I've been looking at a DRO (in an Agilent PSA spectrum analyser) which is producing low output < -5dBm comapred to a specification of +3dBm and this is sufficiently low that the gain stage cannot compensate (the gain rolls over from 255 to 0 with amusingly non-functional effects).However the oscillator is not the one I expected to see from the service bulletinhttps://hpwiki.mcguirescientificservices.com/_media/service_notes:e4440a-20.pdfbut looks quite similar to the one written up here, but in a one port versionhttps://www.microwavejournal.com/articles/11889-high-tuning-sensitivity-dielectric-resonator-oscillator-from-optimization-of-dielectric-resonator-te-sub-01-948-sub-modeActive device may be an Avago-42086 (?) and major difference is that it is a one port design.There is a very simple microstrip BP filter after the oscillator which doesn't look corroded. But alas no easy way to inject a signal to the filter to test its response.I can try changing the active device - but does the dielectric puck in a DRO exhibit any deterioration over time that could reduce the amplitude

author: EggertEnjoyer123
author_rank: Frequent Contributor
timestamp: September 12, 2024, 08:11:38 am
content: Is the frequency at 3.6GHz? Are the voltages going in right?Try measuring the output with another spectrum analyzer. If there are oscillations coming out at the right frequency but wrong amplitude, then it's unlikely that the active device or the DRO is to blame. It might be a cracked SMD capacitor somewhere on the board.

author: alan.bain
author_rank: Regular Contributor
timestamp: September 13, 2024, 10:38:25 pm
content: Frequency is spot on once I provide a phase lock 600MHz reference and without it's pretty close. The varactor diode tune voltage doesn't seem to be bashing into the end stops either. I tried replacing the active device marked "420" with an Avagao AT-42086 and this has made a huge improvement to the output power!
What are  the key characteristics to look for in diodes for an L band Mixer? - Page 1
Forum section: electronics / rf-microwave

author: yammy_96
author_rank: Newbie
timestamp: September 11, 2024, 12:37:24 am
content: Looking for the key characteristics to look for in datasheets for diodes at L band. I want to down covert 1.42Ghz to around 20-50MHz. I plan to use a hybrid coupler for RF and LO. Then mixing through 2 diodes to produce an IF.I currently have BAT54s and BAS16s, would these work for mixer at these frequencies? What frequency could I use them for in a mixer application?I did a bit of reading and research and looked into various RF detector/Schottky diode datasheets but still cant wrap my head around what to really look for.

author: rf-fil
author_rank: Regular Contributor
timestamp: September 11, 2024, 02:08:49 am
content: Any of these:https://www.macom.com/products/rf-microwave-mmwave/diodes/schottky-diodes/schottky-mixer-and-detector-diodesshould work.But, I'd use an IC these days, to save the effort. Analog Devices has heaps that should work, athttps://www.analog.com/en/product-category/single-double-triple-balanced-mixers.html.

author: yammy_96
author_rank: Newbie
timestamp: September 11, 2024, 03:08:45 am
content: Thanks for the link! Will definitely check those out. This is more of an experiment/hobby project so I think it would be interesting to go with the 2 diode route

author: EggertEnjoyer123
author_rank: Frequent Contributor
timestamp: September 12, 2024, 07:59:52 am
content: I believe the rat race mixer would work better for your application.I've had success using these:https://www.skyworksinc.com/Products/Diodes/SMS7630-SeriesThey are annoying to solder though, especially the 0402 sized ones with pads on the bottom.Here is a picture of my design for a 2.4 GHz mixer. The RF comes from the top, and the LO and IF are the two ports on the left (the LO is on top). There is an airwire for the IF connection (basically you need to solder a jumper wire). All butterfly stubs are short at 2.4 GHz. The stub going from the RF input to the center of the board is 1/4 wavelength and is shorted, so at 2.4GHz it looks open. (This is for DC biasing). The diodes are soldered between the butterfly stubs and the coupler (make sure they are facing different directions).
Can a loading coil antenna work better for HF? - Page 1
Forum section: electronics / rf-microwave

author: prabhatkarpe4
author_rank: Contributor
timestamp: September 11, 2024, 10:12:36 am
content: Last time, I posted one topic on using loading coil antenna, but I received comments that a duplicate post was done. However, I am not able to find two posts on the same topic.So, please let me know why that post was closed if there is no duplicate post exist.https://www.eevblog.com/forum/rf-microwave/2-4ghz-antenna/?prev_next=prev#new

author: A.Z.
author_rank: Super Contributor
timestamp: September 11, 2024, 10:43:01 am
content: herehttps://www.eevblog.com/forum/rf-microwave/loading-coil-antenna-for-hf-receptionSAME questionif you want to discuss about the loading coil, carry on the discussion at the above link,DO NOT open new discussions, and NO, the fact that you connect a loading coil to a piece of wire or to a whip makes NO difference in this context.

author: Gyro
author_rank: Super Contributor
timestamp: September 11, 2024, 11:49:35 am
content: Quote from: prabhatkarpe4 on September 11, 2024, 10:12:36 amClick on your username and then click on Show posts. It's really not difficult to find with only 13 posts...https://www.eevblog.com/forum/profile/?u=1017709https://www.eevblog.com/forum/profile/?area=showposts;sa=messages;u=1017709Clicking on Posts rather than Messages makes it even easier, because it only shows threads that you have started!

author: Halcyon
author_rank: Unknown
timestamp: September 12, 2024, 03:29:13 am
content: Quote from: A.Z. on September 11, 2024, 10:43:01 amA.Z. is correct. Locking this duplicate thread.