[Elecraft] KSYN3A tuning noise on 40m

[Guy Olinger K2AV]

As has been stated here before, operating a K3 rx with the input
unterminated is an invalid test. The rx will never be used this way to
routinely listen to "nothing connected".

Terminate the antenna connector with 50 ohms to make any test of this sort.
Also remember that 40m band noise anywhere covers up a lot of rx internal
noise. Terminated noise readings as a possible impact on received signals
start to make sense on 10m and above.

73 Guy

On Monday, May 4, 2015, Arie Kleingeld PA3A <pa3a at xs4all.nl> wrote:

> Hi all,
>
> I just installed two new KSYN3A's in K3 #1255. I found high tuning noise
> on 40m.
>
> First case:
> On 40m S-3 tuning noise in the MAIN RX while tuning the MAIN RX
>
> To reproduce:
> mode: SSB, normal bandwidth
> freq: 7000 -7200
> no antenna connected
> pre-amp off
> att off
> full RF gain
> AGC-S
> VFO tuning noise reduction Mod has no effect.
>
>
> Second case, with SUB RX on:
> Listening on MAIN RX
> Same tuning noise audible on MAIN RX while tuning the SUB RX
>
>
> Third case, with SUB RX on:
> Listening on SUB RX
> SUB RX has no tuning noise, neither tuning the SUB RX nor tuning the MAIN
> RX
>
> (I switched the two SYNT3A's, main to sub, sub to main: NO difference)
>
>
> Can anyone confirm this, or is #1255 unique in this?
>
> 73
> Arie PA3A
>
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