K3 PREAMP2

[briancom]

I use an SDR based panadapter (ROCKY) on the subrx.

I've noticed the following on all bands 15-6 when switching in preamps.

Noise floor no preamp = x
Noise floor with preamp 1 = x to x+1 dB
Noise floor with preamp 2 = X+10 to X+15 dB.

Would have expected the noise floor with preamp 2 to be about x.

What's going on?

73 de Brian/K3KO
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[Don Wilhelm]

Brian,

Since the IF takeoff point in the K3 is before any filtering or
processing, I would expect the band noise floor to rise with the preamp(s).

If you are referring to the receiver noise level with the antenna
disconnected, then you have a valid point and I have no suggestions to
offer.

73,
Don W3FPR

On 6/22/2017 5:46 PM, brian wrote:

> I use an SDR based panadapter (ROCKY) on the subrx.
>
> I've noticed the following on all bands 15-6 when switching in preamps.
>
> Noise floor no preamp = x
> Noise floor with preamp 1 = x to x+1 dB
> Noise floor with preamp 2 = X+10 to X+15 dB.
>
> Would have expected the noise floor with preamp 2 to be about x.
>
> What's going on?
>
> 73 de Brian/K3KO
> ______________________________________________________________
> 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
> Message delivered to [hidden email]
>

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