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From: =?iso-8859-1?Q?Tom_Gruis=2C_EdD=2C_K=D8HTF?= <donnatom@netins.net>
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Date: Mon, 20 Mar 2006 22:33:18 -0600
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Subject: RE: LF: Decca SG
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Good evening de EN31do. A.k.a., Des Moines, Iowa, USA area!

Very interesting reminiscences! I have quite a few tube manuals, both
receiving and industrial, and started in broadcasting in 1952.

If memory serves correctly, there was a tube type 42 that was also a =
beam
power tube, one of many to be sure but the 42 is an older one. I'm about =
to
"sign off" for the night or I would go check it out.

I remember seeing an aeronautical HF transmitter using three 6V6s and a
6SJY. The 6V6s were for the crystal controlled oscillator, power =
amplifier,
and modulator with the 6SJ7 as a speech amplifier. I think it was made =
by
Bendix.

The 6V6 was a smaller version of the 6L6. The 6L6 came regularly in both
glass and metal but it was quite rare to find a 6V6 metal version. I did
come across one or two and I think I replaced the glass one in my olde =
Globe
King with the metal tube. The industrial version of a 6L6 was a type =
1622.
In those days when I was the chief (usually pronounce that "only") =
engineer
I used the industrial versions for all the tubes I could and had very =
few
failures and cleaner tests. Examples: 12AX7 was 7025, 12AU7 was 5814, =
and
off the top of my head those are only a couple of the many equivalents,

The 2E26 was, I believe, developed for FM broadcast band transmitters. =
It is
a smaller version of the 6146. Both of these were great tubes.

Popular power tubes for VHF and some low UHF were the 832-A and the =
larger
829-B. These "bottles" had two (2) power tetrodes in one envelops.

Oh - my first 175 KHz transmitter, ca. 1965 or so used a 12AT7, 9 pin =
twin
triode, as a VCO and "power" amp. This was replete with a 12AX7 into =
6V6-GT
modulator.

GN ES 73

Doc.

-----Original Message-----
From: owner-rsgb_lf_group@blacksheep.org
[mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Costas Krallis
SV1XV
Sent: Monday, March 20, 2006 21:46
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: Decca SG

At 20:41 20/3/2006 +0000, you wrote:

> I think what Costas was getting at is that the 6L6
> was the grand daddy of all beam power tetrodes including
> the 807, 6146 etc. Yes the 807 has higher voltage and
> frequency rating than the 6L6 but both valves share
> a common architecture.

Yes, this is the meaning of my posting. In addition,
6L6 and 807 have the same design approach with
long internal wires etc. 6146 was designed as an
RF amplifier and is much more compact.

Regarding power levels, the 6 W stated for 6L6
is for class A audio. You can get much more from
a class C circuit. Maximum plate dissipation is
30 W maximum for 6L6CG. Strangely, 807W is rated
at 25 W and 6146B at 20W. The data is from Sylvania.
Of course at 30 W dissipation a 6L6 would not
last long! 1987 ARRL handbook rates 6146 at 25 W
max plate dissipation.

My first HF transmitter had a 6L6 delivering 15-20 W
CW on 7 and 10 MHz.

Regards,=20

Costas


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