[1000mp] QSK investigation (somewhat long)

[Tod - ID]

For those who have been following this thread:

I have been experimenting. Let me begin by stating I have an FT1000MP and my
findings may not apply to the FT1000 Mark V or the Field (I think they do,
but I cannot be certain since I do not have either of them.)

Try the following experiments:

1. Set the Mode to CW and turn off the DSP.
2. Turn on the Break-In button ( under the sub VFO knob).
3. Turn the internal keyer off. (This should allow you to key the radio as
though you were using a straight key.
4. connect the radio to a dummy load
5. Adjust the RF gain control to reduce the RF gain. Adjust it so that the
S-meter indicates S9.
6. Set the audio volume control to 12 o'clock.
7. Set the band to 20 meter CW and the RF Power to minimum.
8. Push in the VOX button. When you key the radio there should be a
noticeable delay between the time when you release the key and the muting of
the receiver is ended.
9. Set both IF filters to 2.4 kHz.

10. Key the radio and you should hear a very gently 'poof' when the receiver
is no longer muted. 

I have 2.0 kHz, 500 Hz and 250 Hz filters in both IF's. You should use what
ever you have for the balance of the experimental steps.

11. Set both IF filters to 2.0 kHz and repeat step 10. The 'poof' should be
a little more pronounced.
12. Set both IF filters to 500 Hz and repeat step 10. The 'poof' is gone and
is replaced by a definite 'pop'
13. Set both IF filters to 250 Hz and repeat step 10. The 'pop' becomes very
sharp compared to the 500 Hz 'pop'.


14. Leave the IF filters set for 250 Hz or the narrowest width you have.
Turn the RF gain fully counterclockwise. The S-meter should indicate S9+60.
Turn the audio gain fully clockwise. Repeat step 10. The 'pop' is still
there even though the RF gain should have cut out any signal. 

15. With everything as in step 14 ,set the IF filters for 2.4 kHz and repeat
step 10. The 'pop' is very apparent.
16. With everything as in step 15 turn on Menu 9-1 and reduce the IF gain to
0. Repeat step 10. The 'pop' will not have changed. (Restore the IF gain to
its original value before turning off Menu 9-1 so that you don't think you
destroyed your radio because you ran the experiment).


The next statement is 'conjecture' and deserves to be critiqued and improved
upon.

I am guessing that the following may be true:

1. That the audio stage needs to be turned on more gradually than it is
being turned on. If this stage could be turned on a little more gradually
the pop would disappear or at least be reduced.


Anyone else want to run the experiment and make a guess? Does someone who
REALLY knows about receivers (and maybe has a Service Manual) want to
suggest what is the cause of the 'pop'?

Tod, KØTO