[Premium-Rx] Racal RA6830 digital noise

[Carcia, Frank A. HS]

Hi All,
My worst offender has been on the bench for a while now collecting dust. A
couple weeks ago I bought some nice ferrite sleeves that fit over miniature
coax.

They are about an inch long. Dallas L. and I both agreed the digital noise
was getting into the first IF. He had good luck putting a transformer in
line with the coax that feeds the IF input of the board.  

I cut off the connector at the input of A11 and slipped 2 sleeves over the
coax then replaced the connector. The digital noise is just above the noise
floor above 25 MHz. with no screws in the module mounts and no cover. I can
reduce it further if I squeeze the sides of the radio. I suspect this will
be the fix once I install all the hardware and the case. The O.D. of these
sleeves is small enough to easily fit between modules. 

The old coax connector had less than perfect shield termination. Racal uses
a nice double shielded coax but broken strands don't help.      fc