[Collins] "Different" 6146

[Gerald]

On Tue, 2005-07-26 at 10:24 -0700, Glen Zook wrote:
> Although I have seen various versions of the 6146
> family of tubes, I ran into a couple yesterday that I
> have not seen before.  I am working on a transceiver
> that has problems in the final amplifier so I "pulled"
> the tubes.
> 
> These tubes are marked "made in USA" but have no other
> identifying marks on them except the letters FADF.  It
> took me a few seconds, but if you take the letters and
> change them to their equivalent numbers, then the
> tubes are marked.
> 
> A = 1
> B = 2
> C = 3
> D = 4
> E = 5
> F = 6
> 
> and so on.  Therefore, FADF = 6146
> 
> The internal structure looks pretty much like most
> 6146 family of tubes.  However, this particular pair
> of tubes is pretty unstable (like 6146B tubes can be
> in circuits designed for the 6146 / 6146A / 8298).
> 
> I am pretty familiar with various versions of the 6146.
>  However, this particular version had escaped me until
> now.
> 
> 
> Glen, K9STH

Back about 1968 while on active duty, I ran into some supposed 6146
tubes made by the Electronic Tube Company. They didn't look much like
6146 inside and didn't appear to amplify at RF frequencies, at least not
in the MARS 32S I was trying to fix at the time. Their insides looked
more like sweep tubes than RCA 6146 (square bends instead of round on
the plate, and lacking the shield between the plate pin and the grid
rods up top).

The FADF marking I don't recall seeing either.

I bought RCA 6146 for that MARS rig and it went back to working fine.
-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer