[Drake] Drake 2-C question

[Dennis Monticelli]

I confirmed 6BZ6 in my very early R4-B (#7011).

Dennis AE6C

On Mon, Nov 16, 2009 at 2:50 PM, Garey Barrell <k4oah at mindspring.com> wrote:

> Ron -
>
> I've run into this before.   There are at least two versions of
> schematics for the 2-C, 0007 and 1000, but both show 12BZ6.
>
> If you have priced the 12BZ6 lately (or back in the late 60's) it's
> always been an expensive tube, and difficult to find.
>
> The second (1000) version of the 2-C is dated 8/67 and still shows
> 12BZ6, and the first R-4B (7000) is dated 9/67, and shows the 6BZ6.....
>
> Likewise, the TR-4 had the 12BZ6 up to 27000 (9/67), then 6BZ6 from
> 27500 (4/68).
>
> By the way, there is at least a couple of R-4/As out there with 6BZ6s
> even though the chassis says 12BZ6!  Very easy to move the filament wire
> from 12 to 6!
>
> If the "only working band" happens to be 3.5 to 4.1 MHz, keep in mind
> that the 2-C, like the 2-B, is an 80M receiver with a crystal controlled
> converter in front!
>
> 73, Garey - K4OAH
> Glen Allen, VA
>
> Drake 2-B, 4-B, C-Line&  TR-4/C Service Supplement CDs
> <www.k4oah.com>
>
>
> bonddaleena at aol.com wrote:
> > Hi. I received an e-mail from a chap that had recently acquired a 2-C
> > receiver. It 'kinda' works on one band. In suggesting some of the usual
> > suspects, a strange fact has emerged.
> > His radio uses a 6BZ6 tube as the RF amp. My radio has a 12BZ6. He sent
> > me a pix of his chassis and it is indeed stamped "6BZ6".
> > My info and schematics indicate a 12BZ6 was used there. Now the
> > filament transformer does have a center tap, so it's possible that
> > Drake made a running change.
> > My ser # is: 085X and his is: 163X.
> > He is going to measure the fil voltage and get back to me.
> > If Drake did indeed switch to the 6BZ6 later in production, what would
> > be the reason?
> > Cost, performance, heat, availability?
> >
> > This one's got me scratchin' my gray head...
> >
> > thanks!
> >
> > ron
> > N4UE
> >
> >
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