Hi Breck –

Out of the dozen or so R390As that I have had I never encountered a filter failure. However, in everyone of them, I replaced the 3TF7 with a 50 ohm Dale chassis mount resistor, right near the socket. 73 – Mike

Mike B. Feher, N4FS

89 Arnold Blvd.

Howell NJ 07731

908-902-3831

-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of B. Smith via Milsurplus
Sent: Wednesday, July 24, 2024 3:16 PM
To: [email protected]
Subject: Re: [Milsurplus] R-390 vs. R-390A, was R-808 versus SRR-13 resolution

When working on the R-390A be sure and replace C553 on the IF deck. This cap blocks DC to the mechanical filter which may be destroyed if it fails or leaks. I would put that task #1 on any inspection and especially prior to resale.

k4che