[R-390] A Few Questions for the Group

[Jim Brannigan]

> Hi all
> I am getting ready to dig deep into the R390A that I have and I have a few
> questions for the group.
> 1. Has anyone changed the tube type and circuitry to support  quieter
> tubes as described in ER magazine #26 June 1991 ? I.E. Change most of the
> IF tubes to 6JH6's. Change the RF amp to a 6GM6. Change most of the mixers
> to 6HA5's.
I am very reluctant to try and re-engineer the RF paths in Collins radios.
They were designed to work as a system and changing one part up-sets the
gain balance of the whole unit.
If the receiver noise is greater than atmospheric noise or greater than the
first RF stage with the antenna disconnected, the problem can be fixed
within the R-390A design parameters.

Jim