[r-390] 5651 tubes - specs....

Thu, 12 Sep 2002 21:13:40 -0700 (PDT)

David,

I feel that I am telling you something you already know, David,  but....

For 5651A
Description    Vmin  Vreg  Imax Imin  Reg
Gas Regulator  107   85.5  3.5  1.5   0.1

For 5651
Description    Vmin  Vreg  Imax Imin  Reg
Gas Regulator  107   87    3.5  1.5   0.1

So for 5651A there would be 172 v Across the two VR tubes not 174 v for the 5651.  

There is a "HUM Balance" control R-614 (500k), did you check this, and adjust for minimum AC
output on the 180V at J601 ???

Rodney
VK2KTZ

--- DAVID MEDLEY <[email protected]> wrote:
> I am presently working on an early R-390 radio serial #99. This radio is in wonderfully good
> condition considering its age. I have replaced all the tubes with NOS and when I fired it up
> there was a loud tuneable hum on all stations. The problem turned out to be that I had replaced
> the 5651 tubes in the VR with 5651A tubes. Restoring the 5651s the radio works great. Can anyone
> explain this phenomena for me?
> Dave
> 
> 
> end
> David Medley
> Tucson AZ
> 
> 
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