[Elecraft] P3 "spurs" that move with tuning - resolution.

[Geoffrey Mackenzie-Kennedy]

Fred,

Delighted to hear that you have got rid of those "spurs" !

My hunch is that the steady carrier, which you were seeing 15 kHz down or so 
on all bands, originates in the P3 rather than the K3.

73,

Geoff
LX2AO


On May 08, 2012 at 00:03 + 0200, Fred Jensen wrote:

> Original post:  While tuned to 3533, the P3 reported an S9 signal, narrow 
> and essentially a steady carrier down frequency 15 KHz or so.  It moved 
> with the VFO A cursor such that I couldn't tune to it.  I found similar 
> "signals" on other bands.
>
> Geoff and I have been conversing about it off-list and the final 
> conclusion was that I had finally calibrated my K3 S-meter with my service 
> monitor, and then tried to calibrate the P3.  I was able to do so, however 
> I had to run the "P3 Gain" way way up to get -73 dBm on the P3 for the S9 
> signal.  K3 is S/N 642 and did not have the IF level mod. It does now, the 
> P3 gain is back in reasonable territory, K3 and P3 agree on signal 
> strength, and all the "spurs" are gone.
>
> My theory is that with the P3 gain so high, it was seeing miniscule 
> leakage of internal K3 signals.  Moral appears to be, if you're going to 
> use a P3, you need the IF level mod [K3BUFFKIT] or something like that if 
> your K3 doesn't already have it.  The kit replaces a single SM resistor 
> [R8 on the RF board].  If I can do it, anyone can.
>
> Elecraft sent both SM and leaded resistors, I chose old school.  I found 
> R8 very easily, grabbed it with a small locking surgical clamp, and it 
> immediately broke off leaving the two pads.  I formed the resistor leads, 
> soldered the one end into the via, and then tacked down the other end.  By 
> far the hardest part was getting the K3 out of the shelf, a dozen cables 
> disconnected, and then reconnecting everything [correctly] in back again. 
> It took several tries, and I kept wondering why is it called "wireless?"
>
> Incidentally, I have a small stock of surgical clamps of various types, 
> they are most useful electronic tools.
>
> 73,
>
> Fred K6DGW