[Elecraft] K2 Noise Blanker Slot as Additional IF Amplifier S tage

[Solosko, Robert B (Bob)]

Dick,
	If your filters are adjusted correctly (best done using Spectrogram, as others have mentioned), it may be that you're not tuning the CW signal to the center of the filter's band pass (usually set to 600Hz). I recently added a CW tuning indicator to my K2, and now, once the indicator shows that the CW signal is centered at 600HZ, I can switch to any of the much narrower XTAL or DSP filters and the signal is always right there. To avoid the slight reduction in signal level with the narrowest XTAL filters, I have my narrowest XTAL filter set to 300Hz and when needed, then use my narrowest DSP filter, which is set to 100Hz.

73,

Bob W1SRB

-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net]On Behalf Of Lemkes
Sent: Friday, August 11, 2006 10:58 PM
To: elecraft at mailman.qth.net
Subject: [Elecraft] K2 Noise Blanker Slot as Additional IF Amplifier
Stage


Has anyone thought of, or tried modifying the K2 Noise Blanker to be an 
additional K2 IF amplifier stage?

My problem is that when I really, really need the crystal filter, I am 
trying to copy a very weak (but readable) CW signal with adjacent S-9 QRM. 
When I switch in tighter than about 1200 Hz of crystal filtering, I tend to 
lose the target signal due to filter loss. ( Losing the target signal is not 
because the BFOs are not properly calibrated).

  When I use just the DSP filter to block the adjacent S-9 QRM, then I still 
lose the target DX due to AGC "pumping" (without the IF "roofing" filter). 
I'd really like some additional IF gain to compensate for the crystal filter 
loss.

  I would try using the Noise Blanker's U1, MC1350, as the added IF stage, 
and use U3, the Controller's decoded program lines to adjust U1's AGC input 
for front panel gain control.  I could use P1's pin 8, 8R, as power for the 
MC1350 so that it's only active on "receive".

  Any feedback would be appreciated.

  73, Dick, AD7AF

Dick and Marty Lemke
PO Box 1038
Ocean Park, WA 98640
Tel. 360-665-2438
www.lemkestudios.com 

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