First place to look from what I read is T507 and the solder connections. The heavy wire and ground plane make soldering difficult. If you didn't scrape the enamel off before soldering you will have difficulty burning it off. Takes lots of heat, but don't wreck the board either.
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On Jan 15, 2024, at 18:46, Larry VE7EA <
lagagnon@...> wrote:
I recently finished building the QMX kit, 20-10m version, Rev 2. The receiver works great on all bands, and all systems function well
except transmit.
I have built 4 other QCX Mini kits successfully and yes, I suspect toroid shorting or lack of continuity in the Tx circuit somewhere but would like some hints as to where to start.
(PS: all Tx testing was done with a 50 ohm dummy load/wattmeter).
These are my symptoms:
- If ¡°Protection Enabled at SWR 3¡± and transmitter is keyed "S" immediately appears and no output - all bands
- If "Protection Disabled" quick key down at low voltage (9v on a 12v wiring) and test with nearby receiver shows extremely weak signal on 20-17m and slightly stronger signal 15-10m but QRP wattmeter reads nil
Given the lack of power out on any band I suspect problem lies before the band filters, and possibly around T501. However, if there is little to no power out why is the SWR circuit even involved?
Thanks for your attention.
Larry VE7EA
