[Kenwood] Heath CW filter in a TS-520S

[Rob Frohne]

Rob Frohne wrote:

> Hi All,
>
> I looked at the schematic and it appears that the Heathkit CW filter I 
> had kicking around would work in the old TS-520S that I recently 
> picked up.  The termination impedances look the same and the 
> frequencies are the same if I can believe ICM's web site.  I tried it 
> and it has about 30 db loss.  I kind of think that the filter has 
> something wrong with it, but I'm not sure.  Does anyone else have any 
> experience with this substitution?


Just a follow-up to this note.  I was successful by replacing what may 
have been a bad filter and tweaking the carrier oscillator frequency a 
bit for the CW and Tune positions.  This seems to be a decent way to add 
a CW filter to a TS-520S, because Heath CW filters are readily available 
at reasonable prices, and I've never seen one for the 520S for sale.  
The filter must be placed below the IF amplifier circuit board with 
short shielded cables feeding it.  The hardest part of the installation 
was unscrewing all the cabinet screws.

73,

Rob, KL7NA