[Elecraft] Filters for K3?

[Jim Brown]

On Mon, 28 Dec 2009 01:00:08 +0100, Martin Schmiedel wrote:

>i am about to order filters for my K3 and would like to hear from the
>group what filters i should go for.

First, bear in mind that the DSP in the K3 does the IF filtering that 
older rigs do with conventional LC circuitry, so the hardware filters 
you buy are roofing filters that simply protect the DSP from getting 
blown away by VERY strong signals. 

I'm a serious contester, and also do some DXing. Not much rag-chewing. 
I'm quite happy with the standard 2.7 kHz 5-pole, the 1.8kHz 8-pole, 
and the 400 Hz 8-pole filters. IMO, the 1.8 kHz filter is far too 
narrow for anything but contesting. It's really rather unpleasant to 
listen to, but it does help with things are really rough. For casual 
work, I'd give serious thought to either the 2.8 kHz or 2.1 kHz 8-pole 
filters. 

I have a second K3 so that I can do SO2R (single operator, two radio) 
contesting. It has only the 400 Hz filter. I'm planning to take 
advantage of Inrad's New Year's Day sale to add the 1.8kHz filter. 

Whether to use 2.8 kHz 8-pole or 2.7 kHz 5-pole?  Good question. I'd 
like to hear from those who have tried both and critically compared 
them. There IS a enough ripple in the 2.7kHz filter to cause 
significant incidental AM of a RTTY signal (you will see a wattmeter 
bounce a lot), and I'm told that the 2.8kHz filter has a lot less. I've 
been told that it's also possible to tell the K3 to TX on RTTY through 
the 1.8 kHz filter if you have one, and that this also reduces the 
incidental AM. I should try that. 

73,

Jim K9YC