[ARC5] 12 V Power pentode.

[Dennis Monticelli]

I should add that the 12HG7 and 12GN7 bring the suppressor grid out to
separate pins (in fact two of them) to insure these grids are cold for RF.
It is a key reason why I employed them.

Dennis AE6C

On Sun, Apr 10, 2016 at 2:53 PM, Dennis Monticelli <
dennis.monticelli at gmail.com> wrote:

> Gentlemen,
>
> The video amp power pentodes have significant plate dissipation
> capability, especially those designed for color TVs like 12HG7 and 12GN7.
> They can handle some serious power.  I know because I have built
> transmitters with them.
>
> The 12HG7 is 10W plate dissipation and the 12GN7 is 11.5W.   The 12BY7 at
> 6.5W is a relative lightweight.
>
> Of all the octals mentioned in this thread only the 6F6 can claim to be in
> the same league with its 11W plate rating.  However, it's plate current vs
> grid voltage curves are significantly inferior.  The HG7 and the GN7 will
> run rings around it in class C where peak cathode currents really matter.
> I know this from experience not just IV curves.
>
> If Ken's application is RF then there is the added advantage of plate to
> grid isolation in favor of the TV tubes.
>
> BTW, I have seen 12HG7s in larger diameter envelopes than the standard 9
> pin bottle, giving the appearance of better heat shedding.
>
> Dennis AE6C
>
> On Sun, Apr 10, 2016 at 2:21 PM, Leslie Smith <vk2bcu at operamail.com>
> wrote:
>
>>   Hello All,
>>   The 1941 RCA handbook (May 1, 1942) lists the 12A6 as a "beam power
>> amplifier"
>>   I was surprised to see how many "beam" tubes were used, and how few
>> "pentodes" (as distinct from 'beam' tubes) were used as power amplifiers.
>> Even the 12AQ5 is a beam tube.
>>
>>   I don't know much about 'tubes' or the history of 'tubes' but it seems
>> to me that the 12A6 (or 25A6) was the 'grandfather' of  the beam 'tubes'.
>>
>>
>>    73 de Les Smith
>>    vk2bcu at operamail.com
>>
>>
>>
>> On Mon, Apr 11, 2016, at 04:26, Dennis DuValll via ARC5 wrote:
>>
>>
>>
>> Ken,
>>
>> How about the 12A6?
>>
>> Dennis D.  W7QHO
>> Glendale, CA
>>
>> ****************
>>
>>
>>
>>
>>
>>
>> On Apr 10, 2016, at 6:03 AM, Phillip Carpenter <carpenterpa at tds.net>
>> wrote:
>>
>> Ken,
>>
>> All I could come up with was the 12BY7 9 pin miniature and the 25A6 octal
>> which has a 25 volt filament.
>>
>> Respectfully,
>>
>> Phillip
>>
>> Sent from my iPhone
>>
>>
>> On Apr 9, 2016, at 11:47 PM, Kenneth G. Gordon <kgordon2006 at frontier.com>
>> wrote:
>>
>> Does anyone here know of a power-pentode, which is 1) not a beam-tube, 2)
>> has a 12.6 V filament, and 3) might have an octal base?
>>
>> #3 isn't all that important: I can build an adapter. But #s 1 and 2 are.
>> And #1
>> is of prime importance.
>>
>> I can't think of any.
>>
>> Anyone?
>>
>> Kenneth G. Gordon W7EKB
>>
>> "Courage is being scared to death but saddling up anyway."--- John   Wayne
>>
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