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K3 Filter for PSk and RTTY question

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KD8NNU

K3 Filter for PSk and RTTY question

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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Matt Zilmer

Re: K3 Filter for PSk and RTTY question

Hi Don,

I use the 250 Hz filter for all low-bandwidth data mods and it works
fine. In fact it's usually overkill, however it's worth the
protection against the receiver blocking with nearby strong signals.

The 1.8 KHz filter is what I normally use for voice-bandwidth data
like MT63. It's about minimum bandwidth (in my case) for use with
SSB. Normally, I use 2.8 KHz with SSB receive, holding 1.8 in reserve
against QRM nearby the frequency.

The 2.7 or 2.8 KHz filter is used for TX. This can't be changed and
is perfectly fine for TX in all modes except AM and FM. For data
modes, the quality of the output signal is determined by the source
(sound card for example). The bettery quality sound card - more bits
and more range - the better the TX quality.

If you're using one of the K3's internal data modes, the quality of
the output is determined by the DSP. No worries there either.

73,
matt W6NIA

On Fri, 28 Jan 2011 12:33:35 -0500 (EST), you 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
>
>
>______________________________________________________________
>Elecraft mailing list
>Home: http://mailman.qth.net/mailman/listinfo/elecraft
>Help: http://mailman.qth.net/mmfaq.htm
>Post: mailto:[hidden email]
>
>This list hosted by: http://www.qsl.net
>Please help support this email list: http://www.qsl.net/donate.html

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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Jack Brabham KZ5A

Re: K3 Filter for PSk and RTTY question

In reply to this post by KD8NNU

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, [hidden email] 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
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>