[Elecraft] K3 Softrock Lite

[Don Wilhelm]

Jerry,

I would not advise connecting the Softrock without isolation in any case 
- I believe the biggest problem is that the Softrock LO signal can be 
coupled back into the K3 and can cause spurs on the *transmitted* 
signal.  This is one you cannot evaluate with the K3 receive.  A 
spectrum analyzer at the K3 output would be required for a good 
investigation of your question.  On receive, the normal K3 filters and 
the DSP may be quite able to reject the Softrock LO signal.

Take a look at Larry Phipps website www.telepostinc.com for his LP-PAN 
project.  Larry has measured the LO of the Softrock at -40 dBm which is 
an S9+30 signal.  I do not think one would want to inject such a strong 
signal into the K3 IF - at least 20 dB of isolation is needed.

73,
Don W3FPR

Jerry Flanders wrote:
> Hi, Jo
>
> Did you have to get the KXV3 before using it with the K3, or did you 
> find another way to interface the softrock to the K3?
>
> Since the K3 roofing filters (centered at 8215) do not pass much of 
> your LO freq of 8204 KHz, I am guessing that you would not have seen 
> much effect of the moderately weak LO signal at all in the K3 - did 
> you try it before you added the additional isolation stage?
>
> Jerry W4UK
>