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

[David Wise]

I'm having trouble believing that a 1.1% difference
is enough to mess up the operation.  That's probably
within the normal tolerance range.

It's possible that something else was marginal in such
a way that your 6082s were barely in regulation
and the reference shift pushed them out, but in that
case I think you'd have gotten the same hum by just
cranking your variac a few degrees.

Is it really that touchy, or is there something
deeper going on with the device physics?  Just curious.

73,
Dave Wise

> From: Rodney Bunt [mailto:rodney_bunt@yahoo.com]
>=20
> For 5651A
> Description    Vmin  Vreg  Imax Imin  Reg
> Gas Regulator  107   85.5  3.5  1.5   0.1
>=20
> For 5651
> Description    Vmin  Vreg  Imax Imin  Reg
> Gas Regulator  107   87    3.5  1.5   0.1
>=20
> So for 5651A there would be 172 v Across the two VR tubes not=20
> 174 v for the 5651. =20
>=20
> --- DAVID MEDLEY <davidmed82@msn.com> wrote:
> > I am presently working on an early R-390 radio serial #99.=20
> This radio is in wonderfully good
> > condition considering its age. I have replaced all the=20
> tubes with NOS and when I fired it up
> > there was a loud tuneable hum on all stations. The problem=20
> turned out to be that I had replaced
> > the 5651 tubes in the VR with 5651A tubes. Restoring the=20
> 5651s the radio works great. Can anyone
> > explain this phenomena for me?