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Tom It has been done before http://qrp-labs.com/faq.html#fry 73 Alan G4ZFQ

Just completed mods to U3s and mistakenly applied 12v supply to 5 v bus. Pinned the ammeter, hard. Replaced synthesizer and eprom. ?QLG1 GPS not flashing. Only thing not replaced is the display

Received my two cases in the mail today.? Put my 40m QCX into one of them.? It was quick and easy to do.? I am very impressed with the fit of everything - couldn't be better.? This is a really

Kevin I think the manual could benefit from a lot more clarity in what steps to take before switching to WSPR - and plugging in the external GPS.? Don't plug in the GPS in the CW mode !? I recall a

Jim very nice and thanks for explaining receiver use.? curious if you are using an exotic soundcard or just an ordinary PC installed one?? on receive the bandpass filter is intended to prevent the

After my power supply experiment mishap - got a spare IC and a 'reserve' kit from the store.? found it only needed a replacement controller, and I am back on the original, reliable power supply -

I think I have it figured out. The header on the U3S' main board normally used to connect to the relay switched LPF board does the job. The pin labeled "RFI" refers to RF *Into* the low pass filter

Well all the chips came in so I started to t-shoot again and found that I had no signal on pin 8 of IC3, or pin 10 either. ?Checked the 3.3v to IC1 and it was there so I swapped it out with one from

Thanks, Paul (and others) – I have been leaning toward the new caps. I have looked the board over and seen no mechanical anomalies, have checked all and reheated a few solder joints (the audio pot

I just had the same problem with little or no audio after the change. I replaced C21 with a 1uf electrolytic and C22 with *.1uf* electrolytic cap. Worked fine and no chirp. Don't know if the

Tx for your replies. I was talking about receiving, my bad. I have the U3S, with Rx module , OXO,GPS and a few other things.? . For testing the BPFs I used a 50ohm load on the output and connected

I've just finished the OCXO module kit and want to start the final test (calibration) phase. My U3S setup includes the Switched Relay board and 5W PA board.? To calibrate the OCXO I believe I need to

I had a volume problem too where the volume remained at full bore irrespective of the potentiometer setting. Resoldering its legs into the board fixed the problem. Even under magnified examination the

I'm driving a small speaker directly with mine. It's one of those designed to be used with a cell phone. ?I've plenty of volume with this setup. 73 Howard

David, As Jim was talking about receiving I was assuming he was actually referring to the RX module being used with the U3S, although he did not specifically say that. 73 Alan G4ZFQ

I had those batteries on hand from a previous QRP project.? The 5 place battery holder is from Parallax.? https://www.parallax.com/product/753-00007

I forgot to mention, when I tightened the screw holding the pc board in place, the board warped enough to undo a connection to the pot.? I could loosen the screw and get audio back. Dave, KI4PSR

I had a similar problem, once I put the QCX in a case I lost audio.? Turned out to be the volume pot solder connections to the board.I removed the pot, placed bare wires in each of the solder points,

By the way, I reduced the RX current by about 12 mA just by replacing R48 (270 ohm) with 820 ohms. The backlight was too bright for me anyway.? Karlis YL3JG

Hi. From memory, the U3S has low pass filters, not bandpass filters. If that's correct you can transmit a signal on any band lower then the one the filter is designed for. Along with a lot of