[Elecraft] IF Output Buffer Gain Mod

[Don Nelson]

Ken K3IU wrote:
> G'morning:
>
> Tomorrow I am going to make this mod on the K3 of a friend. To try to 
> see what difference it makes, I though I'd look at the IF signal on a 
> scope before and after. I have looked at the output on a modified K3 
> (mine) and it looks like about 2.5 mV (P-P).
>
> Does that look about the right order of magnitude???
>
> Thanks...
>
> Ken K3IU
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>   
Ken,

I have already made this modification to my K3. But I have not tested 
it. So your email triggered a curiosity to check it. Since the test gear 
is in the basement and the K3 is here in the shack, I thought of 
connecting my FT817 and listening to the IF output. The IF center 
frequency is 8.215 MHz more or less and so you can listen above the IF 
and below the IF to what stations are transmitting. The FT817 was chosen 
because it is highly portable and tunes to 8.215 MHz easily. You could 
do an A/B test on signal level. There were a lot of signals on 20m and 
so I had a lot to hear. If you put the K3 on say 14.350 MHz, for 
example, then a signal at 14.325 MHz is going to be 25 KHz above the 
8.215 MHz IF or 8.240 MHz out of the IF output. This is because the IF 
signal is inverted and goes up in frequency as you go down, in this case 
down from14.350 MHz. The signals are going to be LSB for the same 
reason. You could tune for WWV at 10 MHz to have a stable signal for the 
before/after test.

By the way, this is an odd and awkward way to add a sub receiver to the K3.

Don, N0YE