> For those reasons I would support 250Hz because it would meet
> the needs of more users, but would vote against 200Hz (and in
> this, I do literally mean "vote with my pocketbook").
I agree with Ian here ... a filter with a reliable 270 Hz bandwidth
would be nearly ideal for RTTY and far better than the so called
"250 Hz" 8 pole filter. I would almost certainly replace the
5-pole 200 Hz filters with 8-pole 250-270 Hz filters.
73,
... Joe, W4TV
On 7/14/2010 5:05 PM, Ian White GM3SEK wrote:
> Bill W4ZV wrote:
>>
>>
>> Gary Hvizdak wrote:
>>>
>>> If instead you think that there might be a greater demand for some other
>>> bandwidth 8-pole INRAD roofing filter, please email me (off-Reflector) to
>>> let me know that width and include your reasoning for desiring that other
>>> width.
>>>
>>
>> I'd be interested in a **true** 6 dB BW 8-pole for 200-250 Hz (Inrad's "250"
>> is actually 370 Hz BW and I don't want that).
>
> Yes, the real gap in the available range of roofing filters is an 8-pole
> with a *true* 6dB BW of 250Hz.
>
> As for the choice between 250Hz and 200Hz, I have tried both bandwidths
> by modifying a stock 200Hz 5-pole filter (with design help from Wayne).
>
> In real-life contest QRM there is no noticeable difference between the
> two bandwidths on CW, but there is a huge difference for RTTY. With
> 170Hz shift, a 250Hz filter is very close to the lower limit of usable
> bandwidth, but definitely on the right side of the line - in heavy RTTY
> QRM, a 250Hz filter can be a game changer. But 200Hz is below that
> limit, not usable at all.
>
> For those reasons I would support 250Hz because it would meet the needs
> of more users, but would vote against 200Hz (and in this, I do literally
> mean "vote with my pocketbook").
>
>
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@mailman.qth.net
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
