[Elecraft] K3: best roofing filter on RTTY

[K4ia via Elecraft]

I attended Contest University at Dayton last year and the RTTY expert 
suggested he found that too narrow a filter compromised the decoding.  
It seemed to work best when the filter was a little wider.  He suggested 
500Hz and 250Hz only in the presence of strong QRM.  He did NOT like the 
dual-tone filtering in the K3 or Icom's twin-peak filter.

It is on slide 3 of the Advanced RTTY Contesting presentation available 
in the Files section on the Contest University website.

Buck
k4ia
K3# 101  KX3 #715

On 2/16/2015 12:47 PM, dmoes at nexicom.net wrote:
>
>
>
> David Moes
> VE3DVY
>
> Since I find that the 8 pole 250 Hz filter is really a bit wider I 
> tell my K3 in filter setups its 300hz It  works fine for me this way 
> including on RTTY
>
> During the WPXRTTY this weekend   I had good luck copying weak signals 
> right beside a power house signal using the 250hz filter.
>>
>> --- Original message ---
>> Subject: Re: [Elecraft] K3: best roofing filter on RTTY
>> From: Jim's Desktop <w0eb at cox.net>
>> To: <elecraft at mailman.qth.net>
>> Date: Monday, 16/02/2015  9:49 AM
>>
>> The narrowest filter I have in both receivers is the 400 Hz one.  I
>> borrowed a K3 that had a 250 Hz filter in it once and tried it on RTTY.
>> It works, but it's right on the margin of being too narrow.  If someone
>> is using one of the older Packet TNC's that have RTTY mode in them (they
>> used 200 Hz shift instead of 170 and there are still a lot of them out
>> there) it's really hard to get them tuned in with a 250 Hz filter,
>> especially in weak signal/selective QSB situations.  The 400 Hz filter
>> doesn't seem to have that limitation though it does let slightly more
>> noise in (easily handled with the DSP filters anyway.
>>
>> Jim - W0EB
>>>
>>>
>>> On 2/15/2015 11:35 PM, David Cole wrote:
>>>>
>>>> Hi,
>>>> I ordered and use the 400 for RTTY, I suspect the 250 is a bit to
>>>> narrow.
>>>
>
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