RES: [Elecraft] RTTY Filter for K3 PY5EG

[Frank Lammel]

Hi Oms,

for 'each day digimode' I use mixw, for contesting N1MM with MMTTY. 
Tried also DM780. Each works ufb with the K3.

73
Frank, DD7ZT



py5eg schrieb:
> Hi Frank:
> I didn't receive yet my optional filters, but I wondering what is the
> software you are using in conjunction with the K3.
> I'm using the Mixw2
> Best regards
> Oms PY5EG
> 
> -----Mensagem original-----
> De: elecraft-bounces at mailman.qth.net
> [mailto:elecraft-bounces at mailman.qth.net] Em nome de Frank Lammel
> Enviada em: Friday, May 16, 2008 3:40 AM
> Para: dl2sca at hotmail.com
> Cc: elecraft at mailman.qth.net
> Assunto: Re: [Elecraft] RTTY Filter for K3
> 
> Hi Axel,
> 
> full ack with Joe. I use the 400 Hz 8 Pole with a DSP of about 300-350 
> in dual tone. Perfect!
> 
> 73!
> Frank, DD7ZT
> 
> 
> 
> Joe Subich, W4TV schrieb:
> 
>> After making extensive tests and plotting the selectivity curves 
>> of the 200 Hz filter in my K3, I'm convinced that it is too 
>> narrow for reliable weak signal RTTY operation, particularly in 
>> conjunction with the dual-tone filter.  
>>
>> The measured -6dB bandwidth of the 200 Hz crystal filter was 
>> 209 Hz and the composite bandwidth of the 200 Hz crystal filter, 
>> 200 Hz DSP and dual tone fitter was less than 170 Hz.  A standard 
>> 170 Hz shift 45.45 baud RTTY signal needs at least 235 Hz 
>> (170 + 3*22.7) and the dual tone filter represents a 220 Hz (two 
>> 50 Hz filters with center frequencies separated by 170 Hz). 
>>
>> After extended discussion with a well know RTTY op and K3 beta 
>> tester, I believe the combination of a 300 Hz 5-pole crystal filter,
>> 300 Hz DSP and the dual tone filter will have a composite -6 dB 
>> bandwidth of about 250 Hz - about optimum for narrow RTTY.  The 
>> currently available, "250," "400" or 500 Hz filters in combination 
>> with a 300 Hz DPS bandwidth and dual tone filter are very close to 
>> optimum.  
>>
>> 73, 
>>
>>    ... Joe, W4TV 
>>      
>>
>>
> 
>>> Hi K3-folks,
>>>
>>> What would be the best RTTY roofing filter for the K3? Is the 
>>> 400Hz 8-pole 
>>> filter too small and the 500Hz 5-pole filter the better choice?
>>>
>>> Thanks in advance for your answers.
>>>
>>> 73 de
>>>
>>> Axel, DL3ZH
>>>
> 
> 
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