[Boatanchors] 1625 tube, 807, 837

[Mark Foltarz]

Yup, I believe that was a "Lakeshore Products" device.  

I don't think it was the 837 however. 

I recently had to look up specs on the 837 for a TBW transmitter I put on the
air. 

I was suprised to see how weak the 837 is compared to the 807 - much less power
from a 837.

So far I have only seen the 837 used in the ART13, TBW and the GO9.

Strange how the 837 cost $12 as compared to the $3.50 that a 807 cost in the
1950's.  

As far as my own experiences with the venerable & plentiful 1625, even as
recently as last year I was given a container of at least 25 NOS in the box. 

My DX100 will NEVER be for want in the modulator.. HI


de KA4JVY
Mark


--- Glen Zook <gzook at yahoo.com> wrote:

> Actually, in every 807 tube that I know of the
> supressor grid is connected internally in the glass
> envelope to the cathode.  It is the 1625 that in some
> brands the supressor grid comes out of the glass
> envelope and is connected by a separate wire to the
> cathode.  It is these 1625 tubes that could be
> modified to use in ground-grid linear amplifiers (as
> you described) and not any of the 807 tubes.  Since
> the supressor grid cannot be isolated the 807 cannot
> be used in a grounded-grid circuit.
> 
> There were circuits for these published in various
> ARRL publications and at least one commercial linear
> amplifier manufacturer furnished one model of their
> linear amplifier that used the modified 1625 tubes. 
> This linear was also available using, if I remember
> correctly, the 837 for the amplifier tubes.
> 
> 
> 
> --- Vic Rosenthal <vic at rakefet.com> wrote:
> 
> More 1625 trivia: one other difference between the
> 1625 and 807 that should be noted is that the 1625 has
> its supressor grid internally connected to the 
> cathode, whereas it goes to one of the base pins in
> the 807.  This means that you cannot use an unmodified
> 1625 in a gg amplifier.
> 
> 
> =====
> Glen, K9STH
> 
> Web sites
> 
> http://home.comcast.net/~k9sth
> http://home.comcast.net/~zcomco
> 
> 
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