[Elecraft] K3 Purchase and Accessories Questions

[Jim Brown]

  On 9/30/2010 10:45 AM, Don Cunningham wrote:
> I use the 400hz 8 pole filter for RTTY, for PSK 31 you will probably want to
> see the whole range of avaliable stations, so the SSB filter would be better
> in my mind.
Not necessarily. While using a wideband 2.7kHz IF and letting the PSK31 
decoding software do the filtering in DSP is certainly the most common 
way to work PSK31, you can gain a lot of signal to noise ratio by using 
a very narrow IF filter. This would be especially useful under tough 
noise conditions or heavy QRM.

It's also important to realize that the optional filters you buy are 
ROOFING filters that protect the IF from overload by strong signals in 
its passband, which can be QRM or QRN (either local noise or static 
crashes).  IF filtering is provided by DSP, so you can set anything you 
want by turning a knob. Seasoned operators have generally settled on the 
stock 2.7 kHz filter, the 1.8 kHz filter for serious SSB contesting or 
DXing, and the 400 Hz filter for CW. Those who are even more serious 
contesters also use the 250 Hz filter for CW and RTTY.  That's the 
collection I use.

Filters are easy to add later if you only have one RX, so 2.7 kHz plus 
400 Hz is a really good starting point. If, however, you have the Sub RX 
installed, you want to do it right away, because it is a real PITA to do 
ANYTHING inside the radio, even something as simple as changing filters. 
That's because the sub-RX is a real "shoe-horn job."

73, Jim K9YC