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uBit-x CW gone #ubitxcw

 

Hi Folks,
I was tuning up my u-Bitx by shorting the cw, which usually gives me about 9 watts and all of a sudden it stopped.
The SSB still works fine, showing about 5 watts on the meter.? Anyone know what might have blown out?
Andy KM4TRT
 

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It depends on the band your on what the output is .. did you use a diff band ?


On Jun 6, 2022, at 12:29 PM, KM4TRT via <garello@...> wrote:

Hi Folks,
I was tuning up my u-Bitx by shorting the cw, which usually gives me about 9 watts and all of a sudden it stopped.
The SSB still works fine, showing about 5 watts on the meter.? Anyone know what might have blown out?
Andy KM4TRT
 

Check the solder joint on the cw pull up resistor. Oh and check your key and wiring too.?

Note the ubitx makes cw transmit by leaking 45 MHz RF direct through the last mixer. I am doubting likely failure of the few parts on the board.?

Curt
 

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Curt this statement you wrote is incorrect:
Note the ubitx makes cw transmit by leaking 45 MHz RF direct through the last mixer.
On CW transmit the clock #2 to the first unbalanced mixer before Q90 is at the operating frequency and the other two clocks (#1 & 0) are turned off during CW transmit. This is per the circuit description for the UBITX on HFSignal¡¯s website.
I would check if you are getting DC bias voltage to R104 from pin 13 of the Raduino when you close your CW key. Also clean the contacts of your key they could be dirty giving the key input to the Arduino a false level.


Skip Davis, NC9O?

On Jun 6, 2022, at 16:14, Curt via groups.io <wb8yyy@...> wrote:

Note the ubitx makes cw transmit by leaking 45 MHz RF direct through the last mixer.
 

Andy,

Skip's recommendations are good to follow.? To restate what he said,?CW is generated when the Nano sets the first LO (CLK#2) to the RF value (either the dial frequency or the Dial frequency +/- the side tone dependent on the software installed) and shorts the first mixer diodes to allow the signal to get through.? If you have a v6, you can set the mode to CW and key the mic to get CW.? If this works, the key/paddle input has a fault somewhere.

If you do not have a v6, verify that there are 5volts when the CW key is up and zero volts when the key is down.? You should be able to measure this at the key.? You can then trace it to the Raduino and then the Nano.

We need to know your version because there are slight differences in the mixer unbalancing.? v4 unbalancing is different from v5, and the key circuits are different from v6.

Assuming a v6 here is the first mixer where the 5volt CW-KEY signal from the Raduino unbalanced (shorts) the diodes in the ring mixer to pass the CLK#2 signal to the LPF that then goes to the transmitter amps.



Checks would be to verify that you do get 5volts on R104 on the CW-KEY side.? Then you can verify with an oscilloscope that you are getting the signal at TP1 on the board.

73
Evan
AC9TU

 

Thanks guys.? I believe it's a V4.? No key to clean as I just plugged in a double ended cable and shorted the end.
I will do the voltage checks as you suggest.?
Andy KM4TRT

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