[Elecraft] TX/RX Discrepancy

[Trevor Day]

Hi again all,
I am having a problem aligning the filters.  The main symptom is this; 
I use Cal Fil in conjunction with Spectrogram to position the filter 
skirts. When I am happy with the response, I disable Cal Fil and the 
complete filter response in Spectrogram shifts left by around 700 Hz. 
This happens with both the OP1 Filter and also the standard CW filters.

Using my own K2 with identical settings, the response stays in the same 
place as I would expect.  This must be significant, and *may* be related 
to my rx/tx frequency problem, but I am starting to suffer from 
'over-exposure' to my noise generator :-))

Trev G3ZYY

In message <OlBAe4LyjtL+EwrM@trevday.eurobell.co.uk>, Trevor Day 
<Trev@secornwall.com> writes
>Just reached a useful pause point and carried out the check you 
>suggested Don.  The voltage remains stable on both pins 1 and 7 of U6 
>when I key up.  Just to check I also keyed the tx with 'Tune' and, as 
>you suggested, it does show a negative shift in voltage.
>
>The only discrepancy I have found so far is with the BFO test (p59) 
>where I can only achieve a high freq of 4916.27 instead of 4916.3.  The 
>low is 4911.87, a bit lower than it needs to be, so I *could* shift the 
>range up a bit.  I don't see this as my main problem though so it has 
>been noted rather than acted upon. (Unless anyone knows differently).
>
>Alignment continues :-)
>
>Thanks
>Trev
>
>In message <gVqLiCLdDtL+Ewsr@trevday.eurobell.co.uk>, Trevor Day 
><Trev@secornwall.com> writes
>>Thanks Don,
>>I'm just going through a full alignment; once I have finished I'll do 
>>as you suggest and let you know here.
>>Trev
>>
>>In message <DAV57fLVPS5OKVRYadw0001eeb1@hotmail.com>, Don Brown 
>><DolfinDon@msn.com> writes
>>>Hi
>>>
>>>I went out to the lab and tried it on my K2. The reference control voltage
>>>and the VFO control voltage do not change from receive to transmit on USB or
>>>LSB when keying the transmitter. You will see a shift in CW mode because the
>>>side tone is added in on receive. If the control voltages are changing on
>>>your K2 then you need to track down why. The +8 volt supply is regulated on
>>>the control board so a control board swap may help isolate a problem on the
>>>supplies if that is what is causing the frequency shift. Note you must key
>>>the transmitter, not use tune for this to work. Pressing tune in USB or LSB
>>>is the same as CW and you will get a shift in voltage.

-- 
Trevor Day