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Re: More on troubleshooting.

 

Andy,

C42 is the bypass cap and you should not get any RF there.

Shake T1 and T2 and see, if there is a short or bad solder then you might get a clue.

The tx amp stage R46 may be open - in which case the TX gain will be reduced severely but not affect the RX.
If C44 is open then you will have the same problem. Check r45 also.
Switch off power when checking these resistors.

In my experience slight overheating of these resistors makes them go open. This could have happened during manufacture.

Cheers
Raj

At 18/06/2017, you wrote:
Hi all,
I put my board back in the Bitx40 and took more measurements.
Again I can get the 12 MHz with audio modulation on transmit thru the xtal filter and thru the amp
to C51 at 200 mv,
Also get it on all the diodes on the T1 side. ~250 Mv to 300Mv depending on the diode.
But on the T1 side, and C42 it drops to a questionable 100Mv and doesnt amplify, unlike my friends board that tracks straight through. It would seem that it's T2, but the receive side is so good I'm puzzled.
If it were 10db down as Jerry suggests, wouldn't that affect the receive also?
Would one bad diode make this effect? I guess I would have to remove the diodes to check them, as they all measure .470 but are intertwined.
Andy
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