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#QMX #Finals...did I kill it?
#qmx
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Hello all! I have a QMX rev. 1 low band that has faithfully served me on 19 POTA activations, almost 1,000 QSOs and, recently, I was successfully using for my first 4 JS8Call contacts. After using it at new ham's house this morning to show him how to adjust for a resonant antenna length (using the QMX's SWR sweep function), it now puts out 0.2 watts...and ONLY 0.2 watts...on all bands. Everything else is in the green on the diagnostics. This is my first kit rodeo and I assembled it 7 months ago. That's my first though (Factory reset did not change the issue). |
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Mordan42, How is it doing on receive? Check C510 and C526 to see if they are damaged. If either have cracked or have been overstressed by high RF current, output power will be very low. JZ KJ4A? On Thu, Feb 29, 2024, 10:24?PM Ham Radio <bernard.murphy@...> wrote: Digikey has BS17s in stock ?for 0.59 each.? Buy 10 and you will have spares … |
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OK. How are you measuring output power? Can you measure current drawn from the power supply while transmitting? On Fri, Mar 1, 2024, 5:18?AM mordan42 via <mordan42=[email protected]> wrote: Receive looks okay. Waterfall was showing incoming FT8 signals. I'll check anyway, thanks! |
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On Fri, Mar 1, 2024 at 05:49 AM, John Z wrote:
?Yes, I can. I'll do that Sunday or Monday morning and post the results here (at work today, usher in a wedding tomorrow morning). The diagnostics on Putty were showing 0.2 watts, and the Kenwood AT-230 was showing about a quarter watt. I know signal was getting out because this was first observed during a JS8 heartbeat signal which received acknowledgements from the Southeast and Midwest states, even with the tiny power... |
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GIUSEPPE
good morning everyone, a similar problem happened to me with the high band qmx, after 10 hours of transmission and in wspr 10 mt, it went from 5W to 0w, the RF no longer comes out, I replaced the bs170 mosfets and nothing has changed , how can I access PUTTY to control the qmx, I don't know how to do it.? Thanks 73 Giuseppe iu8eun Il Ven 1 Mar 2024, 13:00 mordan42 via <mordan42=[email protected]> ha scritto: On Fri, Mar 1, 2024 at 05:49 AM, John Z wrote: |
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My QMX is reading <.5w on all channels in the Putty diagnostic.? I have a QRP power meter that outputs to my DVM and that showed the QMX at almost 4w on 20m!? Below is the schematic for the QRP power meter.? My cheapo SWR/Power meter shows about the same.? It's a rainy day here in Mobile, AL and I'm gonna reflow all the toroids and transformers.
-- Bill Harbour K4VIB |
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I think we have different root issues, Giuseppe...I do still have RF coming out, it's just a tiny fraction of what it was.
If you're running a windows OS, go to Start button, Run Program, and type 'putty', then hit run. It should have Putty already on your computer.? Then when it pulls up the window to determine which port you want to access, select 'Serial' then type COM* where * is the number for the comport your QMX registers when plugged into your computer.? I'm not very good at explaining things, and I'm not a computer geek, sorry if this doesn't help. |
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GIUSEPPE
Thank you very much for the help, I had 6w on 20,17e 15 mt and 5w on 12,11 and 10 mt, I tried to transmit with the qmx connected to an ammeter to measure the absorption, in TX it absorbs 190 mA and RX 90 mA, therefore 100 mA it absorbs when I transmit, I don't know what it could be, according to you I should replace the c510 and c 526 capacitors, I don't know.? Thanks anyway, I'll try PUTTY.? 72 Giuseppe iu8eun Il Ven 1 Mar 2024, 13:18 mordan42 via <mordan42=[email protected]> ha scritto: Good luck Bill! Let us know how it goes, please. I've been putting out 3.5w on 20m and 5.5w everywhere else for 5 months or so of regular operation, so seeing 0.2w really bummed me out ?.? |
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It would take more RF power than the radio can develop to hurt those capacitors it seems. The ESR (equivalent? series resistance) is quite low. ?The possibility of cracked capacitors or defective solder joints remain. JZ On Thu, Feb 29, 2024, 10:32?PM John Zbrozek <jdzbrozek@...> wrote:
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