?A comment regarding the height of various tube brands: A few years back, I
bought a new set of 6550 finals for a CE 100V transmitter I was restoring.
Unfortunately, they were too tall for the final cage. When I called the
company I bought them from (Antique Electronic Supply in Arizona), they were
extremely helpful and called me back after measuring the height of each of
the various brands of 6550s they had in stock. Only one of the current
manufacturers (Svetlana at that time) had the same height as the original
tubes and AES happily exchanged my tubes for a pair of those. So, if you
have problems with the physical size of any tube substitutes, it may be
worth a call to AES to see if they have a brand that will fit.
73, Floyd - K8AC
----- Original Message -----
From: "Garey Barrell" <k4...@mindspring.com>
To: "drakelist" <Drakelist@zerobeat.net>
Sent: Thursday, September 30, 2010 9:10 AM
Subject: Re: [Drakelist] 6JB6 vs.6JB6A
Gary -
I have run into the size problem also. The RCA manual specifies outline
18A and 32 for the 6GJ5 and 6GJ5A respectively. As discussed yesterday, I
have also seen 6JB6(A) that were too tall, but not of the 'four' brands.
Do you have a transmitter open where you can measure the ACTUAL internal
height of the cage. I've done it before, but can't find the info.
I have NOT run into the failure to neutralize though, but I stick to the
'four'. Some 6JB6(A) of off brands will not neutralize, and I assume the
GJ's that fail are made by the same manufacturer!
It's perhaps possible to neutralize these by adding or subtracting the
neutralizing capacitance, but I figure if they need that, then there may
well be something else that could cause trouble later. Bottom line is
these are 15 kHz tubes, NOT 30 MHz tubes.!
73, Garey - K4OAH
Glen Allen, VA
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