[Elecraft] K3 Filter for PSk and RTTY question

[Jack Brabham]

Don,

I have the Inrad 8 pole 500hz and also the 8 pole 250.    Either is a 
big improvement over the 1.8, which was previously my narrowest filter 
for PSK, RTTY, and CW.     The 250 is about the narrowest usable filter 
for RTTY and works great for PSK.   The 500 will support the 500 hz data 
modes like Olivia ,etc., and is a good all around, day to day,  
data/digital/CW filter.

The 500 is very versatile and I use it a lot for casual work, however in 
RTTY contesting I use the 250 almost exclusively.    The 250 is also 
particularly good at isolating a weak PSK31 station in the presence of 
"QRO" PSK signals near by.

None of these have any impact on TX bandwidth.    On PSK, if you set up 
as recommended with 4 bars of ALC you will have a very clean signal.

73 Jack KZ5A
K3 #4165





On 1/28/2011 11:33 AM, goldtr8 at charter.net wrote:
> Dear All,
>
> I am debating if I should get a narrow filter for PSK and RTTY work.
> Currently the most narrow filter I have is the 8 pole 2.1.
>
> I am thinking about an Inrad 8 pole 500 hz to add to the K3.  I am not
> having problem, however, the more I use these modes I find that you will
> have very close signals for PSK and I am wondering if this will help in
> pulling weaker signals in, instead of depending so much on the DSP.
>
> I also want to know will this filter also be in use when in TX mode to
> help limit the bandwith.  I wonder this as I worry about bumping up the
> power as signals are so close and I do not want to interfer with others.
>
> I am asking because I am hoping users can give their experience working
> these modes before I purchase the filter.
>
> I dont want to make the same mistake I made with the 2.1 filter for SSB
> where I now wish I would have purchased the 1.8 filter.
>
> Anyway I will appreciate any and all feedback.
>
> Thanks
> Don
>
> Don
> KD8NNU
>
>
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