hybridfree/eevblog-posts huggingface dataset:
IQ FM Demodulator to Analog Audio - Page 1
Forum section: electronics / rf-microwave

author: FredWDaniel
author_rank: Newbie
timestamp: February 05, 2024, 11:36:16 pm
content: I am trying to piece together a simple programmable 30 MHz to 1300 MHz single-channel narrow-band FM receiver design using a ADL5387 and ADF4350 synthesizer. I presume a zero-IF or near zero-IF design would be the best choice. I have looked at the simple IQ analog demodulators used in the uSDX Transceiver and the SuperH receiver, but neither seems a perfect fit for a stand alone receiver. Each receiver would be programmed for a specific frequency and would use a custom made pre-selector front-end. The output would typically be flat analog audio at 600 ohm line level of 0 dBm, but a option for de-emphasis would be nice. The stand-alone receiver would be an open source hardware and software project. I have looked at other designs using a high-performance stereo DACs like the MAX9860 and a STM32 processor, but cannot locate the necessary software to bring it all together. Any thoughts?

author: David Hess
author_rank: Super Contributor
timestamp: February 06, 2024, 01:19:05 am
content: Quote from: FredWDaniel on February 05, 2024, 11:36:16 pmWhat kind of demodulator do they use?The first thing which occurs to me is to use a Costas Loop for demodulation which provides FM and synchronous AM demodulation.

author: radiolistener
author_rank: Super Contributor
timestamp: February 06, 2024, 01:33:02 am
content: I think the most flexible way is to use some high speed STM32 MCU with DSP features.For example there is cheap Chinese module with STM32G431CBU6:https://www.aliexpress.com/item/1005005303669884.htmlIt has onchip ADC and DAC, they are 12-bit, but you can use it to implement test code and then add external audio codec for audio output with 24 or 32 bit dynamic range and (in case of needs) external 16 or 24 bit ADC to digitize IF.I know that this MCU is able to do AM and SSB demodulation in realtime, but didn't tried FM.Needs to check if it can calculate atan2 for 200 kHz IQ stream in realtime.

author: glenenglish
author_rank: Frequent Contributor
timestamp: February 08, 2024, 03:20:42 am
content: just use an arctan approximation. there are lots of possibilities there. you might need to figure out what quadrant you are in.
coupler type id - Page 1
Forum section: electronics / rf-microwave

author: p.larner
author_rank: Frequent Contributor
timestamp: February 07, 2024, 08:21:03 pm
content: this is a pic of the coupler in my swr meter,unlike all ive seen with 2 coils,this has 4,what type is it called,ie tandem match etc,thanks.
VIAs or unfilled holes for grounding top and bottom layers  of PCB together? - Page 1
Forum section: electronics / rf-microwave

author: LM21
author_rank: Regular Contributor
timestamp: February 07, 2024, 05:05:45 pm
content: I was looking at some EMC pdf and it looks that RF current needs an unfilled hole to run from layer to layer. That is because RF current does not run through copper due the skin effect, it runs on the surface. Is there really a difference, what about at GHz frequencies.

author: yl3akb
author_rank: Regular Contributor
timestamp: February 07, 2024, 05:35:44 pm
content: Doesnt matter. The current flows on inside surfaces, in other words on surfaces touching the dielectric.

author: radiolistener
author_rank: Super Contributor
timestamp: February 07, 2024, 06:21:27 pm
content: vias always worse than normal transmission line wire, it has some inductance which leads to reflection and radiation loss. So if you you can make transmission line without vias it will be better.
A good low cost 20-40dB attenuator for 20-50W - Page 1
Forum section: electronics / rf-microwave

author: LM21
author_rank: Regular Contributor
timestamp: January 31, 2024, 09:07:09 pm
content: I noticed that attenuation and impedance of my old Bird 20W 20dB attenuator have changed. I may have overloaded it. Ebay has some with reasonable cost. Has anyone experience about any of them or any other attenuator with reasonable price. Note the price, I rather buy a new car than spend the money for a down payment of fine attenuator.I think it is reasonable to expect at least 3GHz of maximum frequency

author: fourfathom
author_rank: Super Contributor
timestamp: January 31, 2024, 09:23:25 pm
content: Quote from: LM21 on January 31, 2024, 09:07:09 pmHere's a recent topic that discusses some of this:https://www.eevblog.com/forum/testgear/amazon-attenuators-any-good/And an older one:https://www.eevblog.com/forum/rf-microwave/cb-and-ham-radio-techs-love-their-bird-wattmeters/msg4463101/#msg4463101

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: February 04, 2024, 01:04:28 pm
content: M0MAT_radio (Matt Jeffery from Bristol) on eBay is a good supplier and he has 40 dB, 50 Watt, attenuators. See eBay item 153471693209 or his shop at:https://www.ebay.co.uk/str/m0mat/He will ship using Deutsche Post for international postage.SJ

author: radiolistener
author_rank: Super Contributor
timestamp: February 04, 2024, 01:52:12 pm
content: I'm not sure about frequencies above 1 GHz, but if you're planning to use it for HF and VHF, up to 500 MHz, and there is no expectation of high precision, you can use Chinese attenuators, they works. 100 W Chinese attenuator will be enough for low power (< 50 W) amateur testing. Don't expect ideal parameters, but it works...But be careful they are not bidirectional, they can get high power only on input connector, if you apply high power on the output it will be burned out...

author: LM21
author_rank: Regular Contributor
timestamp: February 05, 2024, 09:56:47 pm
content: Mini-circuits is a good manufacturer, and I trust their specs, but they have also higher price than some Ebay sellers. I wish I could find something usable at lower cost. I will look at your recommendations. Also thank you for the links to previous discussion.By the way postal charges from USA to Finland are ridiculous.Edit: Post and handling from UK is not free either, those matter, too.
IEEE Video -- The Origins of Silicon Valley: Roots in Ham Radio - Page 1
Forum section: electronics / rf-microwave

author: fourfathom
author_rank: Super Contributor
timestamp: February 04, 2024, 05:49:30 am
content: Here's an interesting video of a presentation by Paul Wesling / KM6LH, at The West Valley Amateur Radio Association, with commentary by guest Steve Wozniac.https://ieeetv.ieee.org/video/origins-of-silicon-valley-roots-in-ham-radio
Quartz Filter for FM slope detection  - Page 1
Forum section: electronics / rf-microwave

author: met12
author_rank: Newbie
timestamp: February 02, 2024, 04:17:37 pm
content: Hi, as I am trying to demodulate a narrowband FM signal. The signal needs to demodulate a 10kHz baseband signal with maximum 5kHz deviation. The IF I use doesn't matter, and I will use whatever works best. I have tried with a transformer based slope detector, tuned to 200kHz IF. However, this only worked when the FM signal had 50kHz or more deviation. I have also tried lowing the IF to about 100kHz, and it is not much better, needing 30kHz deviation, and it can only support up to 1kHz baseband.I have seen quartz filters, and was wondering if I could use this instead of an LC resonator in my circuit?https://www.mouser.co.uk/datasheet/2/122/mono_crystal_filters-1916784.pdfWould this work to demodulate FM waves if I add an envelope detector to it? I have never used quartz crystals in circuits before, and wanted to check if there's anything extra I need to add, or if anyone has done something similar before.frequency-modulation-fm-slope-detector-operation-01 (1).png(8.99 kB - downloaded 45 times.)

author: mawyatt
author_rank: Super Contributor
timestamp: February 02, 2024, 04:40:48 pm
content: Is this linear FM or FSK? What's the RF input frequency?Best,

author: wasedadoc
author_rank: Super Contributor
timestamp: February 02, 2024, 04:55:06 pm
content: Quote from: met12 on February 02, 2024, 04:17:37 pmIs this the same as the other topic you started?https://www.eevblog.com/forum/rf-microwave/making-a-narrowband-fm-disciminator/msg5306893/#msg5306893

author: met12
author_rank: Newbie
timestamp: February 02, 2024, 09:10:25 pm
content: Quote from: mawyatt on February 02, 2024, 04:40:48 pmIt will be linear FM and 1GHz RF signal, which I will convert down to an IF which works with the demodulation circuit.
Resonating Antenna is 10cm less than calculated !! - Page 1
Forum section: electronics / rf-microwave

author: AtoMick-u235
author_rank: Newbie
timestamp: February 01, 2024, 09:17:20 pm
content: I have made a 4 watt 108mhz transmitter, and setting up a duel band antenna. With my calculation of 27mhz 1\4 wave = 300 / 27 = 11.111 / 4 = 2.777mtr and fullwave 108mhz = 300 / 108 = 2.777mtr, , i am using an end fed mono-poleWhen setting up for both bands, i find the fullwave 108mhz antenna setup resonates at 2.677 or less, a full 10cm less than calculated, , i have noticed this in a dipole design, is there a reason for this, , i have no problem with impeadence, and get better than a 1.5:1 SWRHas anyone got any idea's !!PS :- this is what appears to be happening, , i will confirm it next week with a new antenna !!

author: vk4ffab
author_rank: Frequent Contributor
timestamp: February 02, 2024, 01:52:18 am
content: Quote from: AtoMick-u235 on February 01, 2024, 09:17:20 pmAll antenna are shorter than theoretical because of the velocity factor of the material used and the diameter to length radio of the elements. A vertical monopole made with a 22Awg wire might be half a meter longer than the same vertical monopole made with a 1m diameter tube as an extreme case example. Then there are shape and design factors, near by obstructions etc, a dipole for X Mhz should have a feed impedance of say 72 ohms when flat top, make it a V shape and that changes, move the feedpoint 2cm to the left it changes again. There are a multitude of reasons why things end up shorter than expected.

author: p.larner
author_rank: Frequent Contributor
timestamp: February 02, 2024, 12:19:42 pm
content: as the radiating element covered in pvc for example,using insulated (pvc) covered wire for a dipole at hf will electricaly make the legs electricaly about 6% longer if i remember,so in the real world the elements need to be shorter than the calcs predict.

author: A.Z.
author_rank: Super Contributor
timestamp: February 02, 2024, 08:46:38 pm
content: @vk4ffab... and due to the "end effect", and in case we use insulated wire, due to the insulator, and then...When it comes to simulation, the accuracy of the model counts, if the idea is obtaining something which may reflect the real antenna
Eagle Brand RF Bridge with N Female Removal Center Pin - Page 1
Forum section: electronics / rf-microwave

author: NY2KW
author_rank: Regular Contributor
timestamp: February 02, 2024, 04:39:26 am
content: A now defunct company, Eagle (Sedona AZ, USA) made great return loss bridges with female N connectors and these had replaceable female center pins using a simple pin vise.Has anyone seen replacement pins for female N connectors?Jerry NY2KW
Request for recommendations - Vector Signal Generator - Page 1
Forum section: electronics / rf-microwave

author: QuasiCoherent
author_rank: Newbie
timestamp: February 01, 2024, 09:33:37 am
content: I have a new project in sensing and interferometry that i am trying to bring up... for this, I will need a vector signal generator (as a reference point to test against) that can operate into X-band. My target frequency is 10Ghz, and I am looking primarily to phase-modulate the waveform. I am wondering what units (if any) are known to be budget-friendly (<5K USD), particularly those that might have known hackable upgrade paths to enable internal ARB features. I am expecting most any of these units will also have atleast some IQ inputs externally, but an internal ARB would be nice (if I have no luck, I will buy one of my trusted Siglent IQ ARBs and use that...)I know 10 Ghz is a lot to ask for, just wondering if anyone had some tips.
Current FM/FSK modulator / demodulator chips - Page 1
Forum section: electronics / rf-microwave

author: philpem
author_rank: Frequent Contributor
timestamp: January 25, 2024, 03:08:56 pm
content: Question in short: what are the current "preferred chips" for superhet FM/FSK demodulators and FM/FSK modulators?I've a need for an FM (more accurately FSK) modulator and demodulator with the following specs:Demodulator - frequency 6MHz to about 12MHz in 100kHz steps.Modulator - frequency 80MHz to 125MHz in 100kHz steps.Signal spec - 15kbps data rate, Manchester biphase coding, +/- 75kHz FM deviation, roughly +/-200kHz bandwidth. (same on both the uplink and downlink)RF interface - 75 ohm impedance, F-type connectorRX performance doesn't need to be magnificent, the 'transmitter' will be on the other end of a piece of co-ax. it just needs to not get swamped by CATV-level (5 to 15 dBmV, or about -40 to -30dBm) VHF and UHF signals - and I think a good front-end filter will do most of that.Back in the day I'd have probably built a PLL-synthesized exciter out of a VCO and one of the Philips TV-tuner-style chips (TSA5511 probably). Set up the PLL loop to be far slower than the data rate (1/4th of it at the fastest), and use an opamp to sum the TX Data with the PLL before feeding it into the VCO's VIn.For the receive side I'd have probably used an SA636 or SA615 with a similar PLL VCO arrangement for the LO, but without the TX-In. Probably order the IF filters and quad coil from Cirkit or rob them from a junked FM radio.Problem is all these chips are obsolete, and quad coils are pretty hard to find too. Are there any modern alternatives - or more modern ways to build an RX/TX?I'd considered using one of the lower-end Analog Devices DDS chips followed by some filtering and an upconverter (diode ring mixer?). I'd probably generate the LO with something like an Si5351... but the whole setup seems like overkill for generating FM, and very high component count.For RX it seems like SDR is the way things are going, but that also feels like absolute overkill. The second-best option I came up with was a 74HC9046 PLL, but I'd still need a limiting amplifier.Hams and RF gurus, what do you suggest?

author: jut
author_rank: Newbie
timestamp: January 31, 2024, 02:12:02 pm
content: it looks like your far more experienced than i,but you might find the QRP labs QDX FSK transmitter interesting since the design is reasonably well published as DIY kit.its not FM, or VHF even. i got one and its designed for HF FSK. But you might find it an interesting study.looks like it uses a Si5351A/B/C "ANY-FREQUENCY CMOS CLOCK" (8 kHz to 160 MHz) chip for signal generation.https://qrp-labs.com/qdx.html
crystal or  feeder inductor, who is the culprit ? - Page 1
Forum section: electronics / rf-microwave

author: kellogs
author_rank: Regular Contributor
timestamp: February 11, 2024, 02:28:36 pm
content: i have an ISM band transmitter device based on theMAX41460chip. It expects a 16Mhz, 12 pF crystal. Has been working fine for years. Until recently when I haveSwitched from set A of parts:- crystal:ManufacturerYICType of resonatorquartzFrequency16MHzResonator tolerance±10ppmCapacitance12pFMountingSMDFrequency stability±10ppmOperating temperature-10...70°CBody dimensions2.6x2.1x0.65mm- PCB antenna feed inductor:SRF = 1050 MHz DCR = 0.15 ohm Q = 15To set B of parts:- crystal:Frequency: 16 MHzLoad Capacitance: 12 pFTolerance: 25 PPMFrequency Stability: 30 PPMPackage/Case: 3.2 mm x 2.5 mmMinimum Operating Temperature: - 40 CMaximum Operating Temperature: + 85 CTermination Style: SMD/SMTESR: 80 Ohms- PCB antenna feed inductor:SRF = 1400 MHz DCR = 1.5 ohm Q = 32With same everything else, i am seeing a frequency difference of about 6 kHz at 433.92 MHz, OOK, room temperature. Oddly, this is enough to cause trouble with black box receivers. Or perhaps there is some other thing causing the issues. Line code is Manchester so desynchronization should not be part of it. Difference seen via SDR.What is the likely cause for the issue, frequency shift, power too low, something else ?Thank you

author: RoGeorge
author_rank: Super Contributor
timestamp: February 11, 2024, 02:55:11 pm
content: Don't know about the coil, but the quartz replacement is 3 times worst regarding the max possible deviation.433MHz*(25+30)ppm = 23.8kHz433MHz*(10+10)ppm = 8.6kHzThen, the receiver has its own max deviation. In the worst case scenario, the 2 max deviations from Rx and Tx will add up.

author: kellogs
author_rank: Regular Contributor
timestamp: February 12, 2024, 12:56:16 am
content: I suppose it would. To... maybe 40 kHz? Would that be enough to throw off a 19.2 kbaud transmission ? Receivers are built generally within the last 15 years. I have read somewhere that the 433.92 band is 1.8 MHz. I don't suppose a receiver would be listening over all of that, but still. Hmm...

author: MarkT
author_rank: Frequent Contributor
timestamp: February 15, 2024, 09:27:47 pm
content: Crudely put those 30ppm crystals are best for digital logic or lower RF frequencies, not narrowband UHF transmitters. A good TCXO is what you should ideally use for stable transmission frequency. 2.5ppm is readily available for instance, but I think the MAX41460 can't take an external oscillator so you can't have temperature compensation.Failing that a 10ppm xtal is definitely a much better choice than 30ppm. And you have to check its correctly loaded too (another advantage to the TCXO approach is that loading doesn't matter).In clock terms 30ppm is 15 minutes error per year, 10ppm is 5 minutes/year. A 25kHz channel spacing at 432MHz is like 30 minutes/year - its easy to see that the extra accuracy makes a difference.
Zero IF demodulator DC offset compensation circuit - Page 1
Forum section: electronics / rf-microwave

author: rfguy2020
author_rank: Contributor
timestamp: January 30, 2024, 12:40:23 pm
content: Hello,I'm designing Zero IF demodulator circuit. Output of my IQ demodulator has signal, which as significant DC offset. My received signal has AM modulation.My challenge is that my signal has first strong AM modulation (leakage from transmitter) followed by weak AM modulated signal, which is my desired signal, with DC offset caused by transmitter. DC offset can vary, but it has level of ~1V. My desired signal has amplitude around 1mV. I would like to have voltage gain around 1000-10000 for my ADC.I have tried AD8338 with AC coupling. The problem with AC coupling is that my desired signal (square wave) has distortion due to high pass filter. I could live with that but bigger problem is the transition from transmit phase to receive phase. AD8338 is in saturation during transmit phase (modulation is on/off signal ~0V/~1V). If I'm using gain of 1000, it takes too much time to recover back to 0V output.Ideally, I would like to compensate DC offset, so I would not have distortion in my wanted signal. I have evaluated servo loop circuits (opamp integrator in amplifier output and integrator output summed to amplifier input). I have an analog switch, which is turned on, when I need to compensate dc offset. It looks promising in LTspice, but it looks a bit complicated.Do you have recommendations for good differential DC offset compensation circuits?

author: mtwieg
author_rank: Frequent Contributor
timestamp: January 30, 2024, 02:20:53 pm
content: Quote from: rfguy2020 on January 30, 2024, 12:40:23 pmSounds like your problem isn't DC offset from the demodulator itself, but rather RF power leaking from the transmitter. I don't know what your modulation scheme is, but it's unlikely that the receiver side can correct for this unless the unwanted leakage and desired signal can be modulated differently from each other.

author: rfguy2020
author_rank: Contributor
timestamp: January 30, 2024, 05:02:29 pm
content: Quote from: mtwieg on January 30, 2024, 02:20:53 pmCarrier leakage cancellation circuit is another option, but it is going to be more complex (expensive) than removing dc from baseband signal.
RF/LF SA Mixer - Page 1
Forum section: electronics / rf-microwave

author: Homeoffice
author_rank: Newbie
timestamp: January 29, 2024, 06:20:23 pm
content: Hello everyone,i hope I can find some help here on this forum.I'm looking to expand the frequency range of my TinySa,I've seen some Video on Youtube by (IMSAI Guy) who expand his TinySa with an external Mixer (Frequency increase).His connection looks like this:RF (signal to be messured)- RF INLO - LO INIF - TinySaNow I want to messure signals below the TinySA specification of 100Khz-350Mhz, preferably a few hz.I've looked at some mixers online like the ZAD-8+ by minicircuits, but IDK if its the right one for my needs.Hopfuly somebody can help me finding one with correct specification.

author: erikka
author_rank: Regular Contributor
timestamp: January 30, 2024, 06:31:54 am
content: First try to understand what you are doing.You wil convert a certain frequency range to a higher frequency.Suppose you take 1 Hz to 1 kHz and simply upconvert with 10MHz you get from the mixer 10MHz +/- (1 to 1000) HzWith the minimum RBW of 3kHz the tinySA won't be able to show any detail.What frequency range are you interested in?
(Solved) Need service manual / schematics for Motorola R-1010A signal generator - Page 1
Forum section: electronics / rf-microwave

author: CaptDon
author_rank: Super Contributor
timestamp: January 17, 2024, 03:08:50 pm
content: Would any of you radio service shop guys have a manual for the Motorola R-1010A 1MHz to 520MHz signal generator? I bought it from Ebay, the power supply board needed repair. Currently 2 of the 4 P.L.L.'s are unlocked. I need a service manual showing how to align the unit. Any help greatly welcomed! I couldn't find anything useful online. Thanks!!

author: RFDx
author_rank: Regular Contributor
timestamp: January 17, 2024, 08:25:16 pm
content: Take a look at the SM for the Wavetek 3000 signal generator.http://ftb.ko4bb.com/getsimple/index.php?id=download&file=Wavetek/Wavetek_3000_Signal_Generator_1_-_520_MHz_Service_Manual-Wavetek_3000_Manual_complete.pdf

author: CaptDon
author_rank: Super Contributor
timestamp: January 17, 2024, 11:08:13 pm
content: RFDx, you are a God send!!!! Thank you very much indeed!!! That is identical to my unit. I am servicing module by module. The PLL #1 was going in and out of lock. It had a bad 4558 / 1458 dual opamp messing up the loop control voltage. It is fixed and working well. I also replaced the filter caps for the 5vdc regulator in the PLL #1 module. It never had any bulk capacitor on the 5 volt side of the 7805. Also, the PLL #1 ONLY gets power ground through the mounting screw!!!! Wow, bad design!! I am so anxious to get this thing running. It does have R.F. output but very erratic due to two of the PLL's still being unlocked. Thanks again!! I'll report the progress.

author: CaptDon
author_rank: Super Contributor
timestamp: January 28, 2024, 03:19:57 am
content: RFDx, Thanking you again!!! I got the unit fixed and it would have been impossible without your help. Almost every MC4558 in the whole unit was wiped out along with several 20vdc capacitors which run at 18VDC. I think the power supply must have went nuts and went into some form of overvoltage. It looks like someone turned every adjustment in the unit trying to make it work again. It was a royal P.I.T.A. to get everything back into alignment.
Quansheng UV-K5  AM/FM/DTMF 2 way radio modifications  - Page 1
Forum section: electronics / rf-microwave

author: Ebel0410
author_rank: Contributor
timestamp: January 27, 2024, 08:42:32 pm
content: Hi,I recently discovered the Chinese VHF-UHF RX/TX Quansheng UV-K5(radio and decided to buy one for less than 20 euros!!It is indeed a fantastic piece of hardware for this price.However I found the sound too high and I decided to make a first modification.We can already find examples of modifications on the web, however they are not really documented with measurements taken before and after the modification.Inserting a 330pF cap between pins 4 & 5 on the audio ic LN4898 allows an attenuation of -3 dB at 2200Hz and up to -10dB at 10kHz.This cheap chinese jewel sounds really better now !I invite you to discover the modification and the measures that I carried out, your comments will be welcome.RegardsEric
RESOLVED : Owon XSA810-TG randomly freezes on TG - Page 1
Forum section: electronics / rf-microwave

author: Microbit
author_rank: Newbie
timestamp: October 12, 2023, 09:45:22 pm
content: Resolved.Found that setting stop frequency < 1 GHz eg 900 MHz stops freezing behaviour.

author: minsik
author_rank: Contributor
timestamp: January 25, 2024, 11:14:52 am
content: Useful info thanks. Did you contact Owon for any FW update? Might be worth it.They mighty actually fix something that should not be happening..Considering purchase one for myself.Minsik
Why are sleeved-balum WiFi antennas more expensive than PCB trace (on Digikey)? - Page 1
Forum section: electronics / rf-microwave

author: ghawkins
author_rank: Newbie
timestamp: January 21, 2024, 11:29:59 am
content: I wanted to say "waymore expensive" in the subject line but there's a limit on subject-line length.I was looking, on Digikey, for a basic sleeved-balun style antenna with a U.FL connector, like this:However, I was surprised to find that while I can find patch and PCB trace antennas for almost nothing, sleeved-balun style antennas start at around $10.A length of wire with a short copper tube over part of it seems equivalently complex to a piece of wire soldered to a patch. Yet one seems to cost at least three times more than the other.Is there an obvious reason for this?I'm just looking at active normally stocking products on Digikey (i.e. avoiding last-time-buy end-of-life products).PCB trace antennas start at around US$1.20, e.g. thisMAF94264from Laird.Molex have something similar - product number2069940100- for US$2.10.The cheapest whip-style, I could find, was theW1049B030from Pulse at US$3.20 (and I don't even want a plastic cover for my antenna).And the cheapest sleeved-balun style antenna was three times more expensive than that - the TaoglasCBD01.07.0100Cat US$11.80.Why are these sleeved-balun style antennas so much more expensive?I know it's stupid to compare prices with Chinese products but FrSKY (not an anonymous no-brand Chinese company) sell sleeved-balun style replacement antennas for their 2.4GHz radios for less than US$2 (e.g.here).Sorry if this is just a case of "it's a mystery of modern manufacturing" or "PCB trace antennas are more popular and there's more competition in that space".

author: A.Z.
author_rank: Super Contributor
timestamp: January 21, 2024, 01:22:30 pm
content: well, you may build one yourself, just start herehttps://nomonsuhendar.blogspot.com/2020/12/flower-pot-antenna-calculator.htmland replace the coiled coax choke with a W2DU choke/balun, not so difficult

author: ghawkins
author_rank: Newbie
timestamp: January 21, 2024, 02:12:47 pm
content: Thanks for the reply A.Z. I could make one myself or buy them super cheap on AliExpress.But I was looking on Digikey as I was interested in doing a small production run and wanted a standard product that's readily available (and will probably continue to be available should I want to repeat the run in the future).Sorry for not explaining why I was looking at Digikey. I'm genuinely kind of interested in what kind of factors might make sleeved-balun antennas more expensive than PCB trace ones as this seems surprising to me.As Digikey have zillions of any given product type, I tend to view the minimum price I see there as indicative of things in general.

author: MarkT
author_rank: Frequent Contributor
timestamp: January 24, 2024, 01:17:56 pm
content: Manufacturing cost is usually dominated by the amount of steps involving a human. PCB manufacture is fully automated, whereas I suspect the coliinear is assembled by hand as well as using more material and requiring better packaging to avoid damage?
MLA-30 Shortwave Loop Antenna  - Page 1
Forum section: electronics / rf-microwave

author: CC58
author_rank: Newbie
timestamp: January 24, 2024, 02:10:35 am
content: I was looking to get an active shortwave loop antenna for my shortwave radio and found the MLA-30+ antenna is popular. Discovered it is based on the Philips NE592N14 IC and a seller on ebay has this on a board for $9. Looking at the IC specs it looks like it will work down to 3V supply limiting it to 60mhz which is fine for shortwave. I should be able to power it with SDRplay T-Bias at 4.5vdc?Am I missing something here? Anyone see a problem with this?Ebay has many sellers for this $9 board, but the board has no name. One seller names it "HA SDR Short Medium Wave Radio Adjustable Gain Loop Antenna 100kHz-30MHz".Here is spec for Philips NE592N14:https://html.alldatasheet.com/html-pdf/17989/PHILIPS/NE592N14/1507/6/NE592N14.html

author: A.Z.
author_rank: Super Contributor
timestamp: January 24, 2024, 06:51:02 am
content: check this active loop schematichttp://techlib.com/electronics/antennas.htmlit works much better than the MLA-30, not only the latter has several design flaws, but being wideband is easily overloaded by strong signalsnote: if you prefer a wideband antenna, check the figure 8 at the above link
Difference between the HP83620A and the HP83620B - Page 1
Forum section: electronics / rf-microwave

author: pe2ben
author_rank: Contributor
timestamp: February 05, 2024, 07:22:54 am
content: Hello,Does someone know the difference between the HP83620A and the HP83620B?In the specs i can't find that except small differences in spectral purity where the HP83620A even looks better that the HP8620B but maybe i am wrong and i could misinterpreted this.I also can't find any operational differences.Thanks Ben
Low frequency downconverter - Page 1
Forum section: electronics / rf-microwave

author: DannyCoates
author_rank: Newbie
timestamp: January 11, 2024, 03:41:11 pm
content: Hello, I'm trying to create a simple downconverter for a relatively low carrier frequency of 10MHz and IF of about 500kHz. Aiming for minimal number of parts and maximum integration. Trying to avoid designing a discrete mixer because it will inevitably take up more board space. Also trying to avoid an IC so general-purpose that it ends up taking more space than a discrete mixer.Looking at modern mixer IC's most of them have aminimumfrequency. Please can anyone tell me why there's a lower limit and if they would work with lower frequencies regardless? I don't think it's because they have internal tuning because most of them require an external matching network.

author: PA0PBZ
author_rank: Super Contributor
timestamp: January 11, 2024, 03:48:53 pm
content: Did you think about something like an SBL-1? RF and LO starts at 1MHz, IF from zero. You just need a bit more LO juice to make it go.

author: geggi1
author_rank: Frequent Contributor
timestamp: January 11, 2024, 09:25:36 pm
content: You can use one of these circuits.https://www.qsl.net/n9zia/vlf/index.htmlhttps://www.giangrandi.org/electronics/lwupconv/lwupconv.shtmlI have seen variations of vlf converters where the If port is used for the low frequency.You might see some loss in port isolation and require som extra filtering.

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: January 21, 2024, 09:55:51 am
content: Use a low noise crystal oscillator, such as the ones used in this BFO circuit, amplify the oscillator level to +10 dBm and use a 3 dB attenuator to feed it into a level 7 diode ring mixer. The oscillator circuit is based on one suggested by Dr Ulrich Rohde (of Rohde and Schwarz).https://www.qsl.net/g4aon/pdfs/BFO%20v2_3.pdfDiode ring mixers need to be terminated in 50 Ohms on all ports, otherwise the isolation degrades.A 50 Ohm input low pass filter can be designed using the free program "Elsie"http://tonnesoftware.com/elsie.htmluse sensible values for the Q of the inductors and capacitors, try 200 to 500.SJ
Variable power outputs in splitter - Page 1
Forum section: electronics / rf-microwave

author: caillou
author_rank: Newbie
timestamp: January 19, 2024, 03:17:15 am
content: Hi all,I was wondering if there were RF splitters out there that didn't just passively split by powers of two, but rather tunable ratios? For example 100 W -> 30 W/70 W in one tuning, 40 W/60 W in another tuning, with theoretically 0 degree phase difference. Little loss would be a plus.

author: EggertEnjoyer123
author_rank: Frequent Contributor
timestamp: January 19, 2024, 09:54:05 am
content: You can look at the unequal Wilkinson splitter (and it's lumped element equivalent)https://www.microwaves101.com/encyclopedias/unequal-split-wilkinson-power-divider-simplified

author: caillou
author_rank: Newbie
timestamp: January 19, 2024, 06:51:39 pm
content: Thanks! If we want it to be electrically tunable, say in the lumped elements model, we could use variable capacitors (perhaps in the form of biasing varactors)? Is it fair to say that by tuning the ratio, the phase between the outputs would most likely change as well? What sort of compensation would I need to keep the phase difference close to 0?

author: EggertEnjoyer123
author_rank: Frequent Contributor
timestamp: January 20, 2024, 09:52:49 am
content: The math for turning the transmission lines into lumped elements can be found here:https://baltic-lab.com/2014/09/lumped-element-wilkinson-splitter-combiner-design/You can see that making it adjustable will not be easy since there's at least 5 components that need to be tuned. Can I ask what you're using it for?

author: caillou
author_rank: Newbie
timestamp: January 21, 2024, 06:27:15 am
content: Trying to inductively heat multiple coils with one power amplifier and vary the power delivered to each load using a single RF splitter. Would be nice if the outputs can maintain the same phase too
White source noise (ENR device) attempt  - Page 1
Forum section: electronics / rf-microwave

author: Sariel
author_rank: Regular Contributor
timestamp: January 20, 2024, 10:57:43 am
content: Hello,I've attempted to construct an ENR device (up to 1GHz) for measuring the Noise Figure (NF) of various Low Noise Amplifier (LNA) devices.The circuit I designed is illustrated in the attached figure.I've successfully built a PCB and assembled all the components.However, I'm facing an issue where I don't observe any increase in noise when connected to the Spectrum Analyzer (SA), even with the SA preamp activated.Initially, the C15 (capacitors between amplifiers) was absent, so I cut the trace and added it.The Zener diode is operating at approximately 4.3mA.Strangely, there's no noticeable increase in noise attributed to the amplifiers themselves [amplifers NF+GAIN].I'm reaching out for some brainstorming to identify the malfunction.It's worth noting that all LDO voltages are correct, and the amplifiers receive their 5V with the current consumption falling within the nominal range for the amplifiers.Any insights or suggestions would be greatly appreciated.Thank you.

author: Andy Watson
author_rank: Super Contributor
timestamp: January 20, 2024, 11:45:56 am
content: Have you checked the footprint of the MAX2650 - the pins are numbered differently to what I would expect for any package!

author: Sariel
author_rank: Regular Contributor
timestamp: January 20, 2024, 06:12:44 pm
content: Quote from: Andy Watson on January 20, 2024, 11:45:56 amThanks. Good advice.This was exactly the problem.
1/8th wave GNSS monopole antenna  - Page 1
Forum section: electronics / rf-microwave

author: uer166
author_rank: Super Contributor
timestamp: January 19, 2024, 07:36:21 pm
content: I'm looking for a compact antenna for 1575MHz, and stumbled upon this little antenna that looked like a half-wave monopole:https://www.digikey.com/en/products/detail/taoglas-limited/TS.07.0113/5120278Upon taking it apart, 80% of the height is just the orange plastic with no metal. This is quite dumb for my handheld application where I want to minimize size. Can y'all confirm this is a 1/8th monopole based on measurements? The element is approximately 25mm long.What is the compromise with such an antenna? And finally if someone knows of another part that's similar but without the extra plastic that would be ideal.
How used the TinySA ULTRA  spectrum analyzer ? - Page 1
Forum section: electronics / rf-microwave

author: 1enry1
author_rank: Contributor
timestamp: February 04, 2024, 08:58:06 pm
content: How used theTinySA ULTRAspectrum analyzer .... for many infos about the use ?tnx 73

author: kripton2035
author_rank: Super Contributor
timestamp: February 04, 2024, 10:06:41 pm
content: just check youtube there are a lot of review videos

author: Solder_Junkie
author_rank: Frequent Contributor
timestamp: February 05, 2024, 10:49:33 am
content: Join in with the discussion on the support group at:https://groups.io/g/tinysaSJ
coils function - Page 1
Forum section: electronics / rf-microwave

author: p.larner
author_rank: Frequent Contributor
timestamp: January 17, 2024, 06:32:27 pm
content: can anyone explaine the role of L4 in this atu schematic?.

author: fourfathom
author_rank: Super Contributor
timestamp: January 17, 2024, 06:44:01 pm
content: To provide a minimum series inductance when all sections of L3 are shorted out by the switch.

author: Andy Chee
author_rank: Super Contributor
timestamp: January 17, 2024, 06:48:02 pm
content: A designer can omit L4, and combine it into the winding construction of L3 with appropriate inductance. However, sometimes the physical component layout is impossible within a given chassis size dimensions, and so the inductor is split into two.

author: p.larner
author_rank: Frequent Contributor
timestamp: January 18, 2024, 04:22:29 pm
content: read about someone talk about adding coil for the higher bands,any idea what thats about?,was in relation to a pi tank cct

author: fourfathom
author_rank: Super Contributor
timestamp: January 18, 2024, 08:03:19 pm
content: Generally if you need to add inductance this will be for a lower-frequency band, but it's all going to depend on the antenna, the cable length, etc. Any matching network (TEE, Pi, L, etc.) will need to cancel the antenna/cable reactance and transform the result to something near 50 Ohms to keep the transmitter happy.

author: Andy Chee
author_rank: Super Contributor
timestamp: January 18, 2024, 09:12:25 pm
content: Quote from: p.larner on January 18, 2024, 04:22:29 pmI have read about adding coils for "top band". Don't mix up the terminology "top band" with "higher" bands.Top band refers to the 1.8MHz 160m band. Adding a coil is invariably required due to the large inductance required to achieve tuning for 1.8MHz.The name is no longer correct insofar as dictionary definition and EM spectrum physics is concerned, nevertheless the name has stuck. The name comes from early radio days, where they once believed in an upper limit for practical radio frequency communication ("top of the radio band").
SGC  Auto tuners - Page 1
Forum section: electronics / rf-microwave

author: cleanworkbench
author_rank: Regular Contributor
timestamp: January 15, 2024, 10:24:28 am
content: Have SGC USA gone out of buisness ?.

author: Flux-Sucking Shunt
author_rank: Newbie
timestamp: January 15, 2024, 01:16:03 pm
content: Yes.They've been a zombie company for years. They stopped answering their phone middle of last year, and the website domain expired late last year. It's since been snapped-up by a cyber-squatter.

author: cleanworkbench
author_rank: Regular Contributor
timestamp: January 15, 2024, 02:02:24 pm
content: Ok , any ideas who may sell a eeprom chip for 1.8 to 30 Mhz for the SGC 239 ? as my board needs one .

author: Flux-Sucking Shunt
author_rank: Newbie
timestamp: January 15, 2024, 02:19:08 pm
content: Unfortunately I don't. But you might start asking on ham-specific boards like QRZ or eHam.You also might start going down this list (sorted by last review date) and see if any of the general repair shops can help:https://www.eham.net/reviews/view-category?id=26&sort=-lastrevGood luck!

author: cleanworkbench
author_rank: Regular Contributor
timestamp: January 15, 2024, 03:28:53 pm
content: Thank you .

author: ZigmundRat
author_rank: Regular Contributor
timestamp: January 15, 2024, 04:56:35 pm
content: Did some looking around, and at the schematic. There is no separate EEPROM. It apparently uses the internal EEPROM of the 68HC11 processor. At least it appears to be socketed. I could not find any evidence that anyone has dumped it or replaced it. So maybe your best option would be to look for awhile and find a blown up donor unit. I know that’s not too much help, sorry.

author: edtyler
author_rank: Contributor
timestamp: January 16, 2024, 06:28:31 am
content: It's even worse than you might imagine. The EEPROM on these tuners is protected and cannot be examined using conventional (jtag) means.That said, there are other likely causes for not tuning, like the SWR detection diodes, etc.What is the problem you are seeing?Dale
Replacing questionable Samwha HV caps for Rubycon in a HF Amp - Page 1
Forum section: electronics / rf-microwave

author: kj7e
author_rank: Frequent Contributor
timestamp: January 15, 2024, 03:15:20 pm
content: So I have a perfectly good working OM Power 4001A HF amplifier. Its very nicely made with the possible exception of the HV filter caps, which are Samwha HC series 450v 330uf parts. I know Samwha has a very questionable reputation for quality and certainly not on par as Rubycon. So I am contemplating replacing the Samwha caps with some Rubycon HXH series which on paper appear to be vastly superior with ripple current capacity and longevity.Here is a link to the OEM Samwha's;https://www.soselectronic.com/en/products/samwha/hc-330uf-450v-85degc-hc2w337m30050ha159-128956And the proposed Rubycon's;https://www.digikey.com/en/products/detail/rubycon/450HXH560MEPASN30X55/20370926Anyone have issues with Samwha caps?Edit, adding the datasheets.
fitting a balun - Page 1
Forum section: electronics / rf-microwave

author: p.larner
author_rank: Frequent Contributor
timestamp: January 11, 2024, 07:40:09 am
content: i am build ing an l match atu,i have a 1-1 balun should i fit it on the radio side or antenna side of the atu?

author: Andy Chee
author_rank: Super Contributor
timestamp: January 11, 2024, 07:44:44 am
content: Antenna side
Phase noise contribution when upconverting with mixer instead of multiplication - Page 1
Forum section: electronics / rf-microwave

author: prutser
author_rank: Regular Contributor
timestamp: January 07, 2024, 02:19:24 pm
content: I have a DDS signal which I want to have a a higher frequency. On option is multiplication (either with or without using a PLL) but this increases phase noise with 20log(N) which is about 6dB for doubling. Another option is using low phase noise oscillator, upconvert and filter. I am trying to find out what the phase noise contribution is when upconverting. I expect it to be betther than multiplying. Any information, pointers where to look ?

author: A.Z.
author_rank: Super Contributor
timestamp: January 07, 2024, 04:02:07 pm
content: why don't you revert your approach ? I mean, something like thishttps://www.eevblog.com/forum/rf-microwave/how-are-the-adf-synths-so-good/msg5235924/#newwill work in the GHz range with good stability, now let's say you downconvert it to get down to (say) 100MHz, any drift or phase shift will then be downscaled...

author: prutser
author_rank: Regular Contributor
timestamp: January 07, 2024, 06:47:28 pm
content: Actually I am looking at an LMX2594, but I want it to use in integer mode to avoid integer boundary spurs. Was planning to use the pfd at a high frequency somewhere between 220 and 250MHz and to use a "fine grained" reference (a DDS is a nice option). An AD9951 is reasonably priced, but doesn't go high enough, for that reason I considered multiplication or upconversion. Another option is the AD9910, but it's getting pricy. I am also considering another PLL as reference for the LMX2594 (e.g. LMX2582) but I didn't do any calculations yet, to see if I will obtain the desired output resolution of the main PLL (~ 1Hz resolution at an output from 10Hz - 12GHz)
Hairpin Match Calculator - Page 1
Forum section: electronics / rf-microwave

author: k6sti
author_rank: Contributor
timestamp: January 07, 2024, 12:38:47 am
content: I've written a hairpin match calculator:http://ham-radio.com/k6sti/hairpin.htmYour antivirus software may inhibit downloading the file. First pass the file URL (http://ham-radio.com/k6sti/hairpin.zip) to VirusTotal (https://www.virustotal.com). It will check the file with dozens of antivirus programs and report the results. Once you're satisfied the file is safe, temporarily disable your antivirus software, download the file, and then reenable it.Brian

author: vk4ffab
author_rank: Frequent Contributor
timestamp: January 07, 2024, 06:14:14 am
content: Quote from: k6sti on January 07, 2024, 12:38:47 amThere is really no reason to be using http anymore when Lets Encrypt give out free SSL certificates. The anti virus is borking because because of the lack of SSL.

author: RoGeorge
author_rank: Super Contributor
timestamp: January 07, 2024, 07:01:14 am
content: Using SSL also means one is now dependent on yet another 3rd party, plus the browser asks SSL authorities for certificate validity, which means they can deduce your traffic.
Attenuator Question - Page 1
Forum section: electronics / rf-microwave

author: Randy222
author_rank: Frequent Contributor
timestamp: January 04, 2024, 05:25:44 pm
content: Rather basic question, but I perhaps don't know the real answer.Let's say I have a 50ohm -3db attenuator "A", and it has a flat 1.2 VSWR (0.816% reflected)Does -3db (-50%, or 0.5 factor) add with the fwd loss factor of 0.99184 ?Eg;10v(rms) into 50ohm (2watt) as source, insert the "A" device, I should expect to see 2w x 0.5 x 0.99184 = 0.99184w in my ideal 1:1 antenna?

author: pienari
author_rank: Regular Contributor
timestamp: January 04, 2024, 09:14:58 pm
content: I think it is correct.You can use this calculator.https://www.random-science-tools.com/electronics/dBm-Watts-volts.htm

author: Randy222
author_rank: Frequent Contributor
timestamp: January 05, 2024, 04:02:06 pm
content: Quote from: pienari on January 04, 2024, 09:14:58 pmThanks, but that calc is not for real power calculation using attenutaion and VSWR.

author: ejeffrey
author_rank: Super Contributor
timestamp: January 05, 2024, 04:14:40 pm
content: Most attenuators are not accurate enough to worry about an additional <1% loss either way. If you care about that you probably need a traceable cal, in which case you will have the exact S21 at least for the test fixture used for calibration.I'd guess that the nominal value of attenuators is generally based strictly on the resistor values, ignoring the additional loss from reflections.In the real world, the output match of your amplifier is at least as bad so you will have a frequency dependent standing wave with more than 1% ripple anyway.

author: Randy222
author_rank: Frequent Contributor
timestamp: January 05, 2024, 05:30:33 pm
content: Quote from: ejeffrey on January 05, 2024, 04:14:40 pmTrue, that's all the real math stuff.But in general, VSWR loss is in addition to attenuation, in terms of rated attenuator.In other words, if I tell you the DUT (attenuator "A") is -3db with 1.2 VSWR (f=0-6GHz), that -3db is independent of the VSWR factor. I mean it should be, there's no real SWR at 0Hz.This is why VSWR(f) is important. A spec of "-3db 0-6GHz" is an incomplete spec of the device. I see many time spec sheet that says "-3db VSWR<1.2 0-6GHz". Somewhat better, but we don't know if that means it runs near 1.2 the whole way, or if 1.2 is just a peak in a very narrow band and then runs 1.05 on eitehr side. This is why I like to see VSWR chart before buying.

author: pienari
author_rank: Regular Contributor
timestamp: January 05, 2024, 06:48:23 pm
content: You are right but sometimes you have to use what have in hands.Like my new Diconex 17-0694 1500w 50ohm dummy load.800w module was much better vswr curve but it got burned .