[Elecraft] K1 band pass filter alignment

[Don Wilhelm]

Alexey,

Using the noise source or "dead band noise" with the K1-4 is problematic 
for the 15/17 meter and 20 meter bands.
The real world situation is that it is possible to tune the 15/17 meter 
Pre-Mixer bandpass trimmers to the region of 29 MHz rather than 23 MHz.  
The usual result is that 20 meters cannot be tuned properly (and the 
frequency that 15/17 meters is tuned to is incorrect).

The way to avoid that situation is to use a known signal source when 
tuning 15/17 meters.

The manual states that the initial position for the Trimmer capacitors 
is to be with the slots parallel with the long side of the board.  The 
final adjustment ot the trimmers will be no further than 20 degrees away 
from that position.  If the 'peak' occurs further away from that range, 
it is at the wrong point.

Using a signal source of a known frequency will avoid this problem, but 
using a wideband noise source can certainly produce this false response.

Note that this condition does not occur as readily with the 2 band board.

73,
Don W3FPR

Alexey Kats wrote:
> Greg,
>
> You can use XG2 kit from Elecraft as a signal source for K1 on 80m,
> 40m and 20m bands (it'll also give you a chance to adjust S-meter as
> well). 80m might be a little problematic if you selected 80kHz tuning
> range because it is close to the upper end of the band, but you should
> still be able to use it unless your VFO is misaligned.
>
> Or you could use N-gen kit too, but  be careful with it - it's easy to
> adjust all filters on receive so it will look like you reached the
> peak, while in reality your IF will not align properly with center
> frequency of crystal filters. This is because it produces relatively
> strong noise signal. If that happens (the giveaway is that you can
> hear noise generator, but nothing from the antenna) - move all
> adjustments for the problematic band to their neutral positions and
> start over.
>
> But the easiest method is to use another QRP rig or a signal generator
> as a signal source.
>
>   
>