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good morning everyone, my QMX also no longer works, I replaced the two power boards and it only turned on for a few seconds to be detected by the PC, then it turned off and never turned on again. How

Hello Graham There is no wait for QDX kits. I had just forgotten to remove the message on the shop page. I've removed it now. All QDX kits are shipping normally within 1 business day. Assembled

Hello Nick Where and how are you measuring this? Not right! Hardly even possible :-/ I'd suggest a factory reset but you've already done that. So how are you measuring Clk2 and ARE YOU SURE

Opps, that is prebuilt IF desired. 73, Cliff, AE5ZA

If I may make a suggestion, try a N7VE SWR bridge. the design provides at least a measure of safety for the finals, then when your Antenna tuner is adjusted to satisfaction, switch the bridge out of

Hi Peter IC7 and IC9 are the two unidentified chip supplies on the VCC (+5V) rail. Apologies for the confusion, the PCB CAD library for these op-amps doesn't seem to label the IC at the power

BE SURE you have a dummy load or an antenna connected. Then use ever QRP watt meter you have. My dummy load has a SWR meter built in. 73, Cliff, AE5ZA

There have been a lot of discussions about protecting the BS170 power amplifier transistors from our bad SWR mistakes.? Zeners and TVS diodes get a lot of consideration. BS170s cost about $.40 each

New Guy trying to learn.? When using PuTTY transmitter test on my QDX, pressing "t" key shows transmitter is turning on. Where/how do I test transmitter power out? Thanks from VE7DHJ, Joe, in

shame the drawing clip is truncated as the Vdd bus to the right continues with two devices called out. Get a clean copy like in the manual and a magnifier. -- Allison ------------------ Post online

I managed to destroy 2 MPU’s for my QCX. Both were entirely my fault but they don’t give you a 2nd chance. The slightest moment of short circuit or a little bit too high voltage and it is done

Razvan, That can work save for its limited to one frequency and can induced a negative going voltage that the 74AC08 will not like (may trigger die level

Just finished building my QMX, apart from a bad joint on the VOL encoder it worked first time. It took a week to build, one step each day. Philip G7JUR

OK, I admit I am a bit of a nerd, but I can't resist just reading circuit diagrams trying to understand all the nuances of a design. I was recently scanning the QDX (Version 4) circuit diagram.? For

Thannks Ryuji! Youg got me right. This is what I wanted to know. 73 de dl2arl

Thank you for the response Jerry. I followed the advice and desoldered one lead of L14. However, even after doing so, when I power up the QDX, it still doesn't turn on :(

That's good news. Auto tuners are not a good idea with QRP rigs like the QMX, QDX etc. The tuning process goes through a number of trial settings that will give very high SWR values and may damage

QMX update. I removed one turn from L510 and 513, 30m power improved but 20m no change. New version of T501 built and certainly helped except 20m. New version L401 built and a huge improvement, all

I'm not sure if that was the case with earlier firmware but mine does have that option in QMX.

Thanks for all the tips. I spent a good part of the day today just inspecting my work, trying to make sure I had to cold solder joints again...I managed to get another 0.5 watts out so now it's up to