[Hallicrafters] SP44/S40A advice please

[Julian Bunn]

That must be it! I should have examined the diagram more carefully ... 
it's barely readable in
my copy. The cable has certainly been cut short, which explains everything.

Thanks so much.

Julian

Chuck McGregor wrote:

> At 07:45 PM 3/2/2006, Julian Bunn wrote:
>
>> I'd like some advice on connecting an SP44 to an S40A. Both devices 
>> work well independently,
>> and are carefully aligned. But when I attach the SP44 coax lead 
>> between Pin 3 (the plate) of
>> the S40A's V2 (6SA7) and ground, it kills the performance of the S40A 
>> almost completely ... although
>> I can still tune some very strong signals, and pips appear on the 
>> SP44 and move as I tune the
>> S40A.
>
>
> Julian-
> There is supposed to be a 50Kohm 1/2 watt isolation resistor between 
> the end of the cable center conductor and the plate of the S40 mixer.  
> Originally, that resistor at the end of the cable  was covered by a 
> brass shield, as shown in the manual.  If the cable was cut short, 
> that changes the capacitive loading on the SP44 input transformer and 
> you will need to realign it.
>
> --Chuck N7RHU
>