[Elecraft] Fw: K2 low sensitivity on 15 and 10m?

[Dave]

On further investigation, the cause seems to be the band pass filters going
off align. Re-aligning on 28 MHz gives me a sensitivity of 0.16uV (without
pre-amp) and 0.1uV with pre-amp. Some months ago there was a modification
for the four band K1 board to replace the trimmers due to temperature
drift... I wonder if this is also a problem with the narrower (A to B mod)
filters in earlier K2s? Mine is  noticeably warm having been switched on all
day in a warm shack.

Dave, G4AON
K2 #1892

----- Original Message ----- 
From: "Dave" <dave@astromag.co.uk>
To: <Elecraft@mailman.qth.net>
Sent: Monday, May 26, 2003 8:45 PM
Subject: K2 low sensitivity on 15 and 10m?


> In an idle moment, I decided to check the signal to noise ratio of both my
> K1 and K2 on all their bands... for some odd reason, my K2 is below par on
> 15m and 10m. The pre-amp offers no real improvement. These figures have
> probably always been the case, the list is as follows:
>
> 160m to 20m <0.14uV
> 17m 0.25uV
> 15m 0.45uV
> 12m 0.15uV
> 10m 0.32uV
>
> Levels in pd, 400 Hz bandwidth on CW, no audio filtering. Pre-amp off. For
> comparison, the K1 has a sensitivity of 0.11uV on 15m. The higher
frequency
> band pass filters have been reduced in bandwidth as per the "A to B mods".
>
> Does anyone else with a decent signal generator have comparison figures? I
> suspect my K2 isn't as good as the rest and the pre-amp increases the
> background noise but makes hardly any improvement in signal to noise
ratio.