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Nice work, Klaus I stole your photo, which is 84.2dB better than mine, and put it on my new article see https://qrp-labs.com/qmx/qmxrev2.html - with all due credit to you of course :-) 73 Hans

Dear friends, I have replaced the broken IC402 and my QMX is up and running again. As mentioned I have also implemented the modification by adding a small 1N4148 between G and S of Q508. I had some

Schottky diode has lower drop out voltage but also lower max reverse voltage. So it all depends on what is needed. HNY -- 73 Bojan S53DZ

Hi Rick, These are roughly the values that I also had after the build. After a bit of tinkering, I get 4.5 to 5 watts on all bands. What I have observed is a noticeable RX insensitivity on the 10m

Bob, as I understand it there are both Analog and Digital formats, so it may be possible to accomplish one formatting or another to accomplish SSTV. Justin

Adrian, What part are you thinking of using? A 1N5711 for example will not be able to handle the current peaks, but it has a nice low capacitance. A rectifier for a power supply could handle

Hi Adrian I don't know of any reason why not Schottky. I haven't tested it. Any other views on this? 73 Hans G0UPL http://qrp-labs.com https://www.buymeacoffee.com/g0upl [email protected]>

Tnx Hans, will do the mod ASAP. A quick question: would there be any reason for which a Schottky diode wouldn't work (even better) in this scenario? I honestly can't see one and I have a whole bunch

Fixed, thanks Dav 73 Hans G0UPL http://qrp-labs.com https://www.buymeacoffee.com/g0upl dafydd.walters@...> wrote:

Minor edit to the description on the web page is needed: Currently: "*TRANSMIT:* During *receive*, the "RX: signal is at DC Ground potential, as is the Q508 source" This needs to say "during

Thank you very much for your advice Hans, I will install the diode as you described. Giuseppe iu8eun Il Gio 4 Gen 2024, 10:46 iu8eun Giuseppe Coppoletta <iw8rsb@...> ha scritto:

Giuseppe iu8eun

Hi all I have written an article about the recommended PCB Rev 2 modification that prevents potential destruction of IC402 (74CBT3253 BPF MUX) due to large parasitic oscillations. See

Rich, Where in that do you discern the temperature at the die within the package? I fear your complicated experiment will only produce confusing results. A better approach might be to measure the

"A fool can ask questions wise men cannot answer." I'll take that challenge. What can a bunch of amateur radio enthusiasts do to learn more? How about an experiment!? Who’s got a thermal

Hello Mike, Have you tried measuring output on a dummy load and with something else other than the diagnostic screen? I would look closely at T507 (the SWR bridge binocular core) for cold joints,

I just had the same exact problem. Voltage was at 0.6V on receive and would jump to 10.7V on transmit. No output on any band and the SWR looked very strange into a dummy load. I found that T507 was

I have just finished assembly of my 20-10M QMX. Although it's always terrifying when power is first applied, no magic smoke was released this time. All went well but the output on some bands seems

Here, here on not unsoldering (or otherwise removing) components without good cause! Some measurements can be done in situ. There are some knowledgeable people around: I hope you get some useful

I don't recall seeing it listed, but I also don't know how the signal is encoded, so I will ask.? Can the QDX do SSTV?