[Elecraft] 2.7 vs 2.8

[Edward Cole]

When I ordered my K3, I opted for the 2.8 KHz 8-pole filter assuming 
it had a better filter shape.  Since I bought the aux Rx it got one, 
too.  I left room for a narrower SSB filter in the main radio (2.1 or 
1.8 will be the question).  I bought the 400-KHz for CW and man is it 
sharp!  I wanted the wider SSB bw for using it with wide spectrum 
display sw (WSJT, ARGO, SpectraJT) on my computer (for weak-signal 
work: 600m and eme). Doing causal listening on 20m phone the DSP 
controls work well.  I tend to make a small shift and narrow down to 
2.0 KHz.  NR is working nice, too.

On my FT-847 I only had the stock SSB filter and DSP.  I used the NR 
there quite often, but the K3 NR seems less distorting.  The filters 
on the K3 run rings around the Ft-847 (no surprise).

I ordered two 13-KHz FM filters (extravagant) to get an even wider 
spectrum display using sw (Linrad).  This will be used with both Rx 
locked to one VFO for dual-polarity diversity Rx on 2m using two 
converters locked to the same LO. Linrad calculates the polarization 
angle of the 2m signal when dual Rx is used.

I have wondered about getting the 200-Hz CW filter, but will see how 
well the DSP+400 Hz filter do.

73, Ed - KL7UW
--------------------------------------------------------------------------------
Message: 31
Date: Mon, 12 Apr 2010 06:23:51 -0600
From: "Bill VanAlstyne W5WVO" <w5wvo at cybermesa.net>
Subject: Re: [Elecraft] 2.7 vs 2.8
To: "David Ferrington, M0XDF" <M0XDF at Alphadene.co.uk>,  "Bob Garceau"
         <rgarceau at snet.net>
Cc: elecraft at mailman.qth.net
Message-ID: <1C1781E7080B4D238DE2054A04AD9DF2 at BILLHP9250>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
         reply-type=original

I think David has hit upon the crux of the matter with the tag line in his
sig: "There is no pillow so soft as a clear conscience." Will you be able to
tell the difference in actual single-receiver operation between the 2.7 kHz
5-pole and the 2.8 kHz 8-pole filters? Almost certainly not. But will it
make you feel more comfortable, knowing you have the better 8-pole filter in
all slots? Undoubtedly, based on reading between your lines! Is it worth the
cost differential? For you, sure, probably.

If and when I decide to buy the KRX3, I plan on replacing the 5-pole 2.7 kHz
filter in my main K3 with the 8-pole 2.8 kHz, along with an 8-pole in the
added KRX3. In the meantime, I'm finding the 5-pole filter works very
adequately. (I already have the 8-pole 1.8 kHz filter installed for narrow
SSB work, however, which works great in crowded bands.)

Bill W5WVO


73, Ed - KL7UW, WD2XSH/45
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