Hi Doug
Yes, as I mentioned, there is no effect in the Drake transmitter. To quote
Garey some years ago:
NO modifications are needed to either the T-4(any) or the TR-4(any) to
> use the 6GJ5s.
>
> Pin 3 in the Drake 4 Line transmitters is the cathode of the final
> tubes. Pin 8 in the transmitters is grounded at the socket.
>
> With 6JB6s, K is connected internally to Pin 3, and G3 is connected
> internally to Pin 8.
>
> With 6GJ5s, K AND G3 are connected internally to Pin 3, AND there is
> _NO_ connection to Pin 8.
>
> So everything works the same, except G3 is connected directly to K
> rather than via a 15 ohm and 3.3 ohm resistor.
>
> The only difference is the interelectrode capacitance, which is small
> enough (0.5 pF) that the neutralization circuit is able to take care of
it.
I stocked a lifetime supply of these tubes NOS at $2 and $3 ea some years
ago.and they are to me, indistinguishable from the JB6s.
John k5mo
At 02:25 AM 9/30/2010, Douglas wrote:
>Date: Wed, 29 Sep 2010 20:49:08 -0500
>From: "Curt" <rhule...@comcast.net>
>Subject: Re: [Drakelist] 6JB6 vs.6JB6A
>To: <drakelist@zerobeat.net>
>I'll never again buy vacuum tubes off of the internet, after buying from a
>regular "store" on the auction site two "matched" 6JB6s, both soft as
>pillows and useless above 40M. Of course, everything there is always
>"as-is". I'll also never buy anything from a big tube seller in
Florida >who
>is a small-time liar and crook. Only bonafide companies for me, the
>products are no more expensive, and at least its a big outfit ripping me
>off.
>Good to know that a 6GJ5 is equal to a 6JB6, surprised had never read that
>before. Unfortunately, maybe most tubes sold are pretty much worn out.
>Even most of the companies selling tubes draw the line at providing much
>warranty for sweep tubes ( 10 days conditional from the outfit I use a
>lot ).
>Curt KB5JO
------------------------------------------------------------------
A 6GJ5 is not quite equivalent to a 6JB6.
There is a pin difference. That caused problems with National transceivers
such as the NCX-5 and the NCX-3 that used 6GJ5's. The 6GJ5 internally ties
its suppressor grid to the cathode, the 6JB6 does not. The Nationals used
one base pin as a tie point, that had to be separated out when tube types
were swapped. Since I don't know how the Drakes are wired, I'm not sure if
a similar problem exists. There are other minor differences between the tubes.
73,
Doug/WA1TUT
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