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[K2] Preamp?

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Gil G.

[K2] Preamp?

Hello,

I am curious as to how much of the time you guys have your preamp on?
Mine is on 100% of the time. I actually never had to turn it off.
I couldn't dream of ever using the attenuator…
My K2 seems to hear pretty well, but not without the preamp.

Has anyone heard of changing R76 from 10 Ohms to 6.8 Ohms?

Thanks.

Gil.

Gil.
--
PGP Key: http://keskydee.com/gil.asc

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Andrew Moore-3

Re: [K2] Preamp?

Depends on the band - although I don't venture far off 40 meters, I used to
have preamp on all the time on 40 until I read that due to noisy 40, the
noise that the preamp amplifies is much harder on the ears than copying a
reasonably strong signal without the preamp. I turned it off a year or two
ago and haven't even noticed. Of course I may be missing some very weak
signals... All depends on who/how you operate.

For higher (and less noisy) bands, I believe preamp is often preferred.

--Andrew, NV1B
maineware.net
..

On Mon, Oct 29, 2012 at 8:14 PM, Gil G. <[hidden email]> wrote:

> Hello,
>
> I am curious as to how much of the time you guys have your preamp on?
> Mine is on 100% of the time. I actually never had to turn it off.
> I couldn't dream of ever using the attenuator…
> My K2 seems to hear pretty well, but not without the preamp.
>
> Has anyone heard of changing R76 from 10 Ohms to 6.8 Ohms?
>
> Thanks.
>
> Gil.
>
> Gil.
> --
> PGP Key: http://keskydee.com/gil.asc
>
> ______________________________________________________________
> 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
>

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Don Wilhelm-4

Re: [K2] Preamp?

In reply to this post by Gil G.

Gil,

Unless your antennas are very inefficient, I would suggest that the
preamp only does damage to the dynamic range if turned on for the lower
bands (below 20 meters, 30 meters is a toss-up).

Try this test - connect the antenna and listen to band noise (no
signals). Then disconnect the antenna - if there is a difference
between antenna connected and antenna disconnected, your receiver front
end has enough gain. So turn off the preamp and try the same test
again. Similarly, turn on the attenuator and go through the same test.
At whatever settings you still hear an increase in atmospheric band
noise when the antenna is connected, that is enough front end gain. To
use the preamp when it is not needed will decrease the dynamic range of
your receiver and reduce the number of weak signals that you can hear.

Of course, if your main operating is working only extra strong signals,
then you can run the preamp on for all bands and you will not know the
difference except that your ears will suffer from the excessive
atmospheric noise that is produced.

73,
Don W3FPR

On 10/29/2012 8:14 PM, Gil G. wrote:

Gil G.

Re: [K2] Preamp?

Thanks Don and Andrew.

Interesting. I definitely hear a big difference in band noise in all three cases.
So, if the preamp only increases noise and diminishes weak signals reception, why is it there?

Gil.
--
PGP Key: http://keskydee.com/gil.asc

On Oct 29, 2012, at 8:40 PM, Don Wilhelm wrote:

> Gil,
>
> Unless your antennas are very inefficient, I would suggest that the preamp only does damage to the dynamic range if turned on for the lower bands (below 20 meters, 30 meters is a toss-up).
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Don Wilhelm-4

Re: [K2] Preamp?

Gil,

It is there when it is needed - bands with low atmospheric noise, or
attempting to use inefficient antennas.

73,
Don W3FPR

On 10/29/2012 9:08 PM, Gil G. wrote:
> Thanks Don and Andrew.
>
> Interesting. I definitely hear a big difference in band noise in all three cases.
> So, if the preamp only increases noise and diminishes weak signals reception, why is it there?
>
> Gil.
> --
>

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k6dgw

Re: [K2] Preamp?

In reply to this post by Gil G.

On 10/29/2012 6:44 PM, Ron D'Eau Claire wrote:
> I almost never use a preamp. Sure turning it on increased band noise but
> that does not mean I can hear weaker signals.

For at least one K2 owner who is nearly deaf, anything that will raise
the audio level is good. I really wish my K2 had additional audio, I
have a little RS audio amp that I use, but it's still not enough.

> Adding the preamp just cripples the dynamic range of your K2 - its ability
> to handle strong signals without causing artifacts that sound like noise
> across the band obscuring weak signals you want to hear.

"Cripples?" With the preamp, don't have any problems with strong
signals. Of course, being nearly deaf may account for that too. :-)

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2013 Cal QSO Party 5-6 Oct 2013
- www.cqp.org

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