[Elecraft] K3 if isolation of softrock lite used as panadapter

[Jerry Flanders]

I assume a simple MMIC amp plus a simple resistive attenuator circuit 
will provide enough isolation and also provide for matching levels 
up/down as may be necessary. At least, that will be my first cut at 
the problem unless somebody else comes up with a better plan before 
my K3 arrives.

At down east microwave ( http://www.downeastmicrowave.com/cat-frame.htm ),
see the 
<http://literature.agilent.com/litweb/pdf/5967-6159E.pdf>INA10386 
(DC-2GHz, 24dBG, 3.5dB NF +14dbm 1dB Gain compression ) for only $5. 
Very easy to use something like this, I think.

Depending on the signal level of the K3 IF output, we might get 
enough isolation from  a resistive attenuator alone and still have a 
usable signal level on the softrock panadaptor.

I would much prefer a plug and play manufactured solution if it takes 
more than an attenuator, but not an expensive one.

Jerry W4UK


At 07:29 PM 2/11/2008, stephen pearce wrote:
>A month or so ago one of the Elecraft engineers pointed out that
>if the softrock lite rx is connected directly to the if port on the k3
>there was a significant issue with coupling of rf from the softrock
>board into the
>rx if of the k# with consequent degradation in rx performance ...
>
>Has anyone produced a design for a suitable isolation amplifier/
>coupling stage which will
>prevent this and still allow the softrock to be used (in conjunction
>with a pc) as a panadapter?
>
>Thanks
>
>
>--
>Stephen Pearce
>zl1any
>Whangarei
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