Reflector: K3 Roofing Filters

[Ray Coles]

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?

 

Ray Coles, C.Eng. M0XDL

10 Littlemoor Road,

Weymouth DT3 6AA

Tel: [phone]

Mob: [phone]

 

 

 

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[Bill Frantz]

I do a lot of PSK31 on my K3. I use about 2K of bandwidth when
looking for signals. When I start a QSO, I narrow the bandwidth
-- some times all the way to 50 Hz -- to limit audio overload to
my sound card from nearby loud signals. I have a 250 Hz filter
installed, and the reduction in general noise when it cuts in is
noticeable. (I am away from my radio at the moment, but I put a
fair bit of gain boost into the filter definition for the 250 Hz
filter, I think about 6 dB.) Since filter switching in the K3 is
automatic with changing the DSP bandwidth, there is no extra
work for the operator in having the correct filter in-line.

Cheers - Bill, AE6JV/4

On 8/7/13 at 3:00 AM, [hidden email] (Ray Coles) wrote:

>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?
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[Matt Zilmer]

For JT65, WSPR, etc. I just use the narrowest filter when on frequency
and the P3 to see where signals are.  In my case, that filter is the
250 Hz.

With the K3, remember that you're not selecting a filter so much as
setting a bandwidth.  Filters kick in as they're called for, and this
is slaved to the WIDTH or LO/HI control.  You can also force a filter
selection (as with the K2) using the XFIL switch, but doing so forces
the WIDTH set to the rated filter bandwidth at the same time.

73,
matt W6NIA

On Wed, 07 Aug 2013 11:00:33 +0100, you wrote:

>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?
>
>
>
>Ray Coles, C.Eng. M0XDL
>
>10 Littlemoor Road,
>
>Weymouth DT3 6AA
>
>Tel: [phone]
>
>Mob: [phone]
>
>
>
>
>
>
>
>______________________________________________________________
>Elecraft mailing list
>Home: http://mailman.qth.net/mailman/listinfo/elecraft
>Help: http://mailman.qth.net/mmfaq.htm
>Post: mailto:[hidden email]
>
>This list hosted by: http://www.qsl.net
>Please help support this email list: http://www.qsl.net/donate.html

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[Joe Subich, W4TV-4]

It depends on conditions and software.  For example JT65-HF does not
like to decode if it does not see the entire 200-2800 Hz audio spectrum
but WSJT-X seems to work fine with a restricted bandwidth.  All of the
software is designed to cope with the entire 0 - 4000 or 0 - 5000 Hz
spectrum but there are times that it is advantageous to narrow the K3's
IF to prevent one or more strong close in stations from capturing the
AGC and reducing the gain.

73,

    ... Joe, W4TV


On 8/7/2013 9:03 AM, Matt Zilmer wrote:

> For JT65, WSPR, etc. I just use the narrowest filter when on frequency
> and the P3 to see where signals are.  In my case, that filter is the
> 250 Hz.
>
> With the K3, remember that you're not selecting a filter so much as
> setting a bandwidth.  Filters kick in as they're called for, and this
> is slaved to the WIDTH or LO/HI control.  You can also force a filter
> selection (as with the K2) using the XFIL switch, but doing so forces
> the WIDTH set to the rated filter bandwidth at the same time.
>
> 73,
> matt W6NIA
>
> On Wed, 07 Aug 2013 11:00:33 +0100, you wrote:
>
>> 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?
>>
>>
>>
>> Ray Coles, C.Eng. M0XDL
>>
>> 10 Littlemoor Road,
>>
>> Weymouth DT3 6AA
>>
>> Tel: [phone]
>>
>> Mob: [phone]
>>
>>
>>
>>
>>
>>
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

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