[Elecraft] TX/RX Discrepancy

Sun Jan 26 12:21:05 2003

Hi All,
Just to let you know that I have eventually found the fault which was 
causing my frequency difference problems and problems with CAL FIL.
The fault eventually turned out to be a defective J310 FET at Q24.  It 
was allowing a couple of volts to appear at its gate when in Tx mode 
which was sufficient to alter the bias on D37 and shift the BFO when 
transmitting. For reasons I don't understand (as I am not familiar with 
the way the firmware works) this also had an effect upon the audio 
response when in/out of CAL FIL.   In any event, not having a J310 to 
hand I replaced it with a 2N3819 and all my problems disappeared!

Hopefully the next fault won't be as elusive :-)
73
Trev G3ZYY

In message <[email protected]>, Trevor Day 
<[email protected]> writes
>
>Hi Francis,
>Its the latter; the settings set by CAL FIL remain and if I make a 
>change, exit CAL FIL and then return, the settings are as I had left 
>them.
>
>The problem is that the filter performance set (and seen with 
>spectrogram) when in CAL FIL, change when I exit CAL FIL.  The audio 
>pitch also changes confirming the different filter response.  But, when 
>I re-enable CAL FIL, the pitch changes back and the settings are where 
>I left them!
>
>I am convinced that this has something to do with the Tx/Rx difference, 
>but haven't found what is causing it yet.  The problem lies on the RF 
>Board.  I have exchanged everything else with parts from my working 
>unit.
>
>Thanks,
>Trev G3ZYY
>
>
>In message <000e01c2c317$c0c51200$[email protected]>, Francis 
>Belliveau <[email protected]> writes
>>Trevor,
>>
>>I'm a bit concerned over how you describe this new symptom.  I believe that
>>you must change to another filter in order to get the new setting to stick.
>>Is the setting failing to stick or is the setting value staying and the
>>spectrogram result not holding?
>>
>>Fran
>>
>>_______________________________________________
>>Elecraft mailing list: [email protected]
>>You must be a list member to post to the list.
>>Postings must be plain text (no HTML or attachments).
>>See: http://mailman.qth.net/mailman/listinfo/elecraft
>>Elecraft Web Page: http://www.elecraft.com
>

-- 
Trevor Day