[Elecraft] K3 Roofing Filters

[Edward R Cole]

Ray,

short answer:  Use the SSB bw filter for JT65.

The sw looks at up to 4-KHz bw, if available, and the narrow band 
feature of this mode is accomplished at the digital level in the sw 
(inside the computer).  Narrowing bw below this just limits the 
number of signal the sw looks at.  JT65 and MAP65 both have sw 
features to limit the decoding bw window if you are operating in a 
crowded band.

That happens to me a lot as I am the only AK station QRV on 2m eme 
(if you want eme WAS on 2m you have to work me - KL6M is working on 
curing IM issues and should be on 2m-eme soon).

So I often have several stations calling me on JT65 and may be only 
spaced 10-20 Hz apart.  JT65 provides the ability to narrow the bw 
which I often set a 20-Hz.  If you are running JT65HF I am not 
familiar enough what the HF environment is like to know if this 
situation happens much on HF.  Narrowing the radio bw does not aid 
JT65 in decoding.

73, Ed - KL7UW

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Date: Wed, 7 Aug 2013 11:00:33 +0100
From: "Ray Coles" <raycoles96 at gmail.com>
To: <elecraft at mailman.qth.net>
Subject: [Elecraft] Reflector: K3 Roofing Filters

Since this subject is current (and likely always will be!) I have to ask the
learned brethren which filter does experience show to be best for use with
JT65 mode. I currently only have the standard issue 2.7KHz filter, which of
course works OK for everything (except I suppose DSB and FM). If I used CW I
would definitely choose a narrow-band filter, but the waterfall display used
for JT65, PSK31 etc. might lead me to rely on a 2-3KHz filter for these
modes, even though the signal bandwidths are much narrower. My question is:
is anyone using narrower roofing filters and tuning across the waterfall to
squeeze the most out of those DX data stations? Or am I being dumb?


73, Ed - KL7UW
http://www.kl7uw.com
dubususa at gmail.com
"Kits made by KL7UW"