[Elecraft] K2 S/N 3105 on the air -- crystal filter curves

[Thomas Martin]

Hello Dave,
there is additional loss using the 100Hz filter but in situations with lot 
of QRM I like to use it.
(For me it is like closing a window and being in a 
quiet room with the other signal being the only one there beside me.)

When calling CQ I use the 700Hz filter to be able to to tune to stations 
coming back off-frequency using the RIT.

Under low QRM conditions the 400Hz filter is the one I prefer, but under 
bad conditions switching to the 100Hz filter and switching from CW reverse 
to CW normal or vice versa will help.

Perhaps at a later time I'll play a bit with the bandwidth setting of the 
smallest CW filter to detect the bandwidth below which the filter loss 
increases remarkably. But at this time I like the settings I have.

Concerning the grounding technique used in Rev. B I remember that when I 
did this mod to an earlier K2 (Rev. A) that there is a substantial decrease 
in noise and I would recommend to do the ground wire mod to those who don't 
have it done now. 

Until now the K2 has been used only indoors under stable
environment temperature. Some tests using it under extreme temperature 
changes may follow and then there may be problems with the 100Hz filter 
being off-centre but we'll see then.
I don't know about its status but as far as I know there is some 
development going on to reduce temperature drift of PLL/BFO osc. even 
further than the enhancement achieved in Rev. B (I think this is a result 
of reports of drift occuring with the KPA100 installed) and if off-centre 
problems occur this may help in such situations too as soon as a mod is 
available. At this time my K2 only includes the K160RX option -- no 100W PA.

73
Thomas


Von:            	"Dave" <dave@astromag.co.uk>
An:             	"Thomas Martin" <df7tv@arrl.net>
Kopie an:       	<Elecraft@mailman.qth.net>
Betreff:        	Re: [Elecraft] K2 S/N 3105 on the air -- crystal filter 
curves
Datum:   	Sun, 12 Jan 2003 12:53:04 -0000

> Thomas
> 
> How do you find the performance of the 100 Hz filter settings? From your
> figures there seems to be significant additional loss on the narrower
> setting. From my own experiments, 400 Hz and 700 Hz bandwidth seems fine,
> but narrower settings seem "difficult" with off centre results and
> additional loss. This was the case before and after the crystal case
> grounding modification.
> 
> Any thoughts?
> 
> Dave, G4AON
> K2 #1892
>