40 meter noise level and K2

[dw-4]

I'm sure this question has been asked a ton.
It seems that the noise floor on 40 meters is much greater than on the
higher bands for my K2.

I'm guessing this is just the characteristic of 40 meters.
But I thought I would post the question anyway.

Thanks
N1BBR :)
--
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[Don Wilhelm-4]

Yes, that is true.  Turn the preamp off for all bands below 20 meters
and your ears will be more comfortable and you will hear signals just as
well.

73,
Don W3FPR

On 9/18/2012 8:45 AM, dw wrote:
> I'm sure this question has been asked a ton.
> It seems that the noise floor on 40 meters is much greater than on the
> higher bands for my K2.
>
> I'm guessing this is just the characteristic of 40 meters.
> But I thought I would post the question anyway.
>
> Thanks
> N1BBR :)

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[dw-4]

Hi all,
I never used Spectrogram for setting my K2 band-pass filters until a
month ago.
I used to set the pass-bands by using the S-meter with a fixed frequency
signal source.

I followed these steps:
1) Zero beat to get a maxed S-meter reading.
2) Dial frequency down until the S-meter drops one LED,  and record the
count.
3) Dial frequency up until the S-meter drops one LED, and record the
count.
4) Adjust the pass-band so that the count is equal in both directions.

I ran the K2 this way for about 3 years, and this month I thought I
would try resetting the pass-bands with Spectrogram.  I’m pretty sure I
was super careful to follow the directions.
But now I’m not sure If I should re-do them again using my old method
because the up/down count is no longer equal.

For example:
With zero beat @ 704031mhz, I adjust RF gain for an S-meter reading of
7.
When I adjust the frequency dial up to 704046 (15 counts) , the S-meter
will drop 1 LED.
When I adjust the frequency dial down to 704006 (25 counts), the S-meter
will drop 1 LED.

Is my assumption that the up/down count should be equal wrong?
Perhaps the pass-band characteristics are such that best setting is not
in the center?
Am I missing something?
Thanks
N1BBR
--
 [hidden email]

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[Don Wilhelm-4]

dw,

You are missing one very important point - you should be using a
broadband noise source when viewing the filter passband response with
Spectrogram.  The presence of any signals will confuse things and not
give you a good view of the filter passband.

If you do not have a broadband noise generator (Elecraft N-Gen or
equivalent), you can use broadband "antenna noise"  Turn the preamp on
and make sure there are no signals within the received region.

Spectrogram will show you the entire filter passband.

For a more complete explanation, see my webpage article on K2 Dial
Calibration.  Part 3 of that article deals with setting the K2 filters.

73,
Don W3FPR

On 10/3/2012 8:17 PM, dw wrote:

> Hi all,
> I never used Spectrogram for setting my K2 band-pass filters until a
> month ago.
> I used to set the pass-bands by using the S-meter with a fixed frequency
> signal source.
>
> I followed these steps:
> 1) Zero beat to get a maxed S-meter reading.
> 2) Dial frequency down until the S-meter drops one LED,  and record the
> count.
> 3) Dial frequency up until the S-meter drops one LED, and record the
> count.
> 4) Adjust the pass-band so that the count is equal in both directions.
>
> I ran the K2 this way for about 3 years, and this month I thought I
> would try resetting the pass-bands with Spectrogram.  I’m pretty sure I
> was super careful to follow the directions.
> But now I’m not sure If I should re-do them again using my old method
> because the up/down count is no longer equal.
>
> For example:
> With zero beat @ 704031mhz, I adjust RF gain for an S-meter reading of
> 7.
> When I adjust the frequency dial up to 704046 (15 counts) , the S-meter
> will drop 1 LED.
> When I adjust the frequency dial down to 704006 (25 counts), the S-meter
> will drop 1 LED.
>
> Is my assumption that the up/down count should be equal wrong?
> Perhaps the pass-band characteristics are such that best setting is not
> in the center?
> Am I missing something?
> Thanks
> N1BBR

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