[Elecraft] K3 Filters for digital work

[Bill Frantz]

I have a 250 Hz filter I use for PSK and RTTY. It helps when 
there is a strong nearby station that overloads the AtoD 
converter between the K3 and my computer. During a RTTY contest, 
I found it helped, but the dual frequency DSP RTTY filter was 
more than enough for most contacts.

When I use the filter with PSK, I lose the computer waterfall 
and the computer noise reduction because of the narrow 
bandwidth. I use full bandwidth to scan for signals and the 250 
filter after establishing contact. Usually a narrow filter works 
better than the computer noise reduction.

I would worry about 200 Hz for RTTY. While the deviation is 
nominally 170 Hz, there is energy out wider than that which may 
be affected by the skirts of the 200 Hz filter.

IMHO, RTTY is like AM -- a classic mode which uses more 
bandwidth than necessary, but is nice to keep around for 
nostalgia and to relive history.

Cheers - Bill, AE6JV

On 11/27/13 at 9:58 AM, recordupe at verizon.net (Dave Barr) wrote:

>Which two of the 200/250/400 and 500 hz filters are best for 
>digital use, primarily RTTY, both contests and dx.  I 
>understand that for JT-65 and PSK the standard ssb filter, or 
>even the AM filter is useable.  I am concerned that the 200 hz 
>might be too narrow for RTTY.  I work some CW but almost no ssb.

-----------------------------------------------------------------------
Bill Frantz        | If the site is supported by  | Periwinkle
(408)356-8506      | ads, you are the product.    | 16345 
Englewood Ave
www.pwpconsult.com |                              | Los Gatos, 
CA 95032