[hpsdr] Ozy.

[Sheldon Hands]

After cutting some new slots for the revised board arrangment I posted 
earlier the 10mtrs spurii is back.
I have found how the problem occurs but am totaly lost as the the root 
cause.

The spurii appears and the noise floor jumps around 10dB when the body of 
the Merc BNC makes contact with case. A test lead or long screwdriver 
between the body and case  has no such  effect. The BNC jack on Merc shows 
zero ohms to the case.

It looks as if the problem area is the pre-amp as switcing the attenuator in 
(i.e preamp off) considerably reduces the spurii.

Provided the BNC Jack is floating with respect to the rear case cover 
everything runs ok !

Shel CT1IZU 


 1244154014.0