Leighton, I would agree with the internal issue with IC4. The circuit equivalent is enhancement-mode MOSFETs between input and output. One or two are most likely faulted to ground. The only way to tel

#qcx #qcx40 #problem

Thanks Steve. Checked for shorts on IC4 between pins and adjacent pins. The only ones at 0 ohms are pin 5 and 12 as per the intended trace on the board. No other pins show any signs of a short circuit

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18 ohms on IC4 pins 4 and 11 are not right as they are different from the other IC4 outputs. But you also say that with T1 pins 5 and 8 connected you measure 5.5K on T1 pins 5 and 8 (with IC4 unpowere

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Hi Alan, Thanks for the reply and assistance. I had a similar thought, but there doesn't seem to be a direct short to ground. These are the resistance measurements, to ground, that I have made on IC4:

#qcx #qcx40 #problem

Hi Ted, Greetings from sunny, warm NSW, Australia. :) Sorry, I should have tried to explain the fault condition. Some of the symptoms are similar to those found in the troubleshooting guides and I hav

#qcx #qcx40 #problem

Leighton, Something around IC4, C43-46 seems to be shorting to ground. Examine very carefully around pins of IC4 and everything connected to them. Measure the resistance to ground on the four capacito

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HI Leighton Greetings from a soggy Cambridge, UK. Could you describe the actual fault that you encountered? Clearly the QCX was working fine beforehand. Does the display still work? Can you still rece

#qcx #qcx40 #problem

G'day, I have built and had my 40m QCX (firmware 1.01a) on air and have had some contacts with it with great success (apart from my lack of CW skills - hi hi). I have been really impressed by it and I

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Robert Did you get your CAT issue sorted out?

#building #cat #problem #qcx

Make sure you have the correct speed on the COMM port on the PC and correct wiring on the connector — all in the manual. You can connect to the QCX via a serial terminal program such as TeraTerm. Note

#building #cat #problem #qcx

Thanks to a private reply, I think I understand the problem. My adapter is USB-RS232. I only learned recently the difference. I guess my RS232 adapter is not responding to the lower TTL voltages of th

#building #cat #problem #qcx

read section 3.77 in the online manual. Dave

#building #cat #problem #qcx

I have a USB FTDI serial interface. Don't remember the brand, but it works on other radios. I have a homebrew DB9 to 3.5mm adapter that I use on Elecraft devices. It is wired with TIP - RX from the PC

#building #cat #problem #qcx

Oops! Thanks Ron. That was my problem with PTT for the amp.

#building #cat #problem #qcx

what serial TTL interface are you using for the CAT commands and how is it connected ( signal lines)

#building #cat #problem #qcx

Hi Robert. On your second issue, please refer to pages 100 and 101 of the manual where it tells how to either modify a standard stereo cord or the QCX+ key output so amplifier keying will work properl

#building #cat #problem #qcx

My 20M QCX+ is working well, but I can't get CAT to work. Tried three different programs (N1MM, DX4WIN, TR4W), recommended settings and others as well. I finished my 50W PA and noticed that when I plu

#building #cat #problem #qcx

Alan, I'm not sure if the display still works, I unplugged power as soon as I saw smoke, and IC3 immediately starts smoking once power is supplied. I will replace Q1-3, Q6, and IC3 and then try. Thank

#problem #building

KN6HGG, I did have a dummy load attached. I had plugged the GPS in prior to plugging in power, but the lights on the GPS didn't power up, so when I wiggled the leads from the GPS, they slipped out of

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I'm guessing I should just get a new Q6 Will, And Q1-3. If IC3 is blown then it has got 12 volts through one of them. The display shows no errors? It has been known that IC3 has passed 12 volts furthe

#problem #building