Crystal filters

[ac0h]

Hello all,

I'm at the end of my yearly K2 alignment and have come to the crystal
filters part.

Currently I have CW filters of 1.5K, 750, 400, and 250 with a side tone
of 600Hz.

On SSB I have OP1, 2.1, 1.8 and 1.6. I'd love some spectrogram screen
shots showing how people have theirs setup. Mine are all pretty much
centered between 300Hz and 2500Hz. I know Don, W3FPR says move the -3db
low end "shoulder" of the bandpass to 300Hz but a screen shot would be
helpful.

I'm going to setup and use my RTTY filters for digi modes and need some
guidance on suggested bandwidths and center frequencies.

Thanks.

--
R. Kevin Stover, ACØH
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[David Pratt]

In a recent message, R. Kevin Stover <[hidden email]> wrote ...
>I'm at the end of my yearly K2 alignment and have come to the crystal
>filters part.

Kevin - I would be interested to know the reason for the need to do an
annual alignment of the K2.  Do you find that the alignment drifts from
one year to the next?

73
--
David G4DMP
Leeds, England, UK
------


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[ac0h]

Hello David,

No, as far as I can tell the alignment of the K2 doesn't drift at all.
The annual alignment is just my way doing preventative maintenance and
staying on top of things before a problem does rear it's ugly head.

This year I discovered some dust in the rig. I think it's caused by the
two 80mm computer case fans I've got on the KPA100 heat sink. They draw
air across the sink and exhaust straight up. Some canned air and a fine
brush and she's cleaned.

Never would have found that if I didn't open the case up once a year.
While I've got it open I just check stuff.

73

David Pratt wrote:
> In a recent message, R. Kevin Stover <[hidden email]> wrote ...
>> I'm at the end of my yearly K2 alignment and have come to the crystal
>> filters part.
>
> Kevin - I would be interested to know the reason for the need to do an
> annual alignment of the K2.  Do you find that the alignment drifts from
> one year to the next?
>
> 73

--
R. Kevin Stover, ACØH
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[David Pratt]

Thanks, Kevin.  I was a bit puzzled about the alignment bit.  I don't
have the KPA100, but I do nevertheless open my K2 occasionally to check
the internal SLA battery I have fitted.

73

David

In a recent message, R. Kevin Stover <[hidden email]> wrote ...

>
>No, as far as I can tell the alignment of the K2 doesn't drift at all.
>The annual alignment is just my way doing preventative maintenance and
>staying on top of things before a problem does rear it's ugly head.
>
>This year I discovered some dust in the rig. I think it's caused by the
>two 80mm computer case fans I've got on the KPA100 heat sink. They draw
>air across the sink and exhaust straight up. Some canned air and a fine
>brush and she's cleaned.
>
>Never would have found that if I didn't open the case up once a year.
>While I've got it open I just check stuff.
>
>
>David Pratt wrote:
>> In a recent message, R. Kevin Stover <[hidden email]> wrote ...
>>> I'm at the end of my yearly K2 alignment and have come to the crystal
>>> filters part.
>>  Kevin - I would be interested to know the reason for the need to do
>>an  annual alignment of the K2.  Do you find that the alignment drifts
>>from  one year to the next?

--
David G4DMP
Leeds, England, UK
------


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[Bill Coleman-2]

On Feb 28, 2009, at 11:41 AM, R. Kevin Stover wrote:

> I'm going to setup and use my RTTY filters for digi modes and need  
> some
> guidance on suggested bandwidths and center frequencies.

First thing to consider is if you have enough BFO bandwidth to go with  
standard tones. I opted to use 1500 Hz as the center frequency for my  
RTTY tones (eg 1415 mark, 1585 space). My thinking is that this would  
allow me to use the DSP and have the signals centered in the passband,  
since you can only adjust the frequency center on 100 Hz boundaries.

I had to make a minor modification by adding a couple of pF to the BFO  
crystals to get enough range.

I've set my filters to OP1, 1000, 500 and 300. 1000 makes a pretty  
nice filter for tuning, 500 is great for crowded contest conditions.  
300 is for when the going really gets tough.

The K2 is a good radio for RTTY, but it isn't great. Biggest  
limitation is that the KPA100 can't take the full duty cycle, so you  
have to back off. I run about 50 watts with supplemental cooling on  
the heat sink. Second limitation is that the frequency display doesn't  
correct for the mark frequency, so you have to do it in your head.

Bill Coleman, AA4LR, PP-ASEL        Mail: [hidden email]
Web: http://boringhamradiopart.blogspot.com
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901

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