[Central-Electronics] Use of Russian 1625s in P&H ElectronicsLA-400B amp?

[Jim Candela]

Cal,

   I think it all depends on whether the suppressor grid wire can be reached 
inside the socket. I presume the amp is grounded grid. Also consider the 
EL-38 which can be used as-is except for the 6v filament. Here is a post 
from Colin, K7FM, a fellow CE man on this list:

"A final note on this issue: 1625's are 807's with 12.6V filament, all other
parameters are the same.

73's
Sam  HS0ZDY"

Almost - but not quite

Some of the 1625 tubes were manufactured with a wire connecting the
suppressor grid to the cathode - external to the envelope, but inside the
socket.  The enterprising amateurs discovered this and found how to
disconnect this wire from the cathode for true grounded grid.  The 807's did
not have this feature.  A judicious hacksaw to the base at just the right
point allowed extraction of the suppressor wire.  No more difficult to do
than a root canal.  With glee, the amateur would get on the air saying he
was using modified 1625 tubes.

So, some 1625 tubes could be used in grounded grid (such was the case with
the P & H linear), whereas none of the 807's could be used in such a
configuration.

If 6 volt tubes were desired, the 837 could be used, as it had a separate
suppressor.  However, it also had less dissipation.

73,  Colin  K7FM


----- Original Message ----- 
From: "C Eus" <catman351 at gmail.com>
To: <central-electronics at mailman.qth.net>
Sent: Tuesday, March 16, 2010 12:55 PM
Subject: [Central-Electronics] Use of Russian 1625s in P&H 
ElectronicsLA-400B amp?


> All:
> First off, I'm glad to be here and I am looking forward to operating 
> Vintage
> SSB using a recently acquired CE 20A.  I also acquired a P&H Electronics
> amplifier that uses four modified 1625s.  However, I would like to know if
> anyone has attempted to modify the Russian 1625s found at various
> suppliers.  Any comments appreciated and thanks. Cal, N6KYR/4
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