On Nov 7, 2005, at 4:54 AM, Shawn Tayler wrote:
> On Mon, 7 Nov 2005 02:35:36 -0800 R. Measures <r@somis.org> exclaimed:
>
>>
>> On Nov 6, 2005, at 8:12 PM, Shawn Tayler wrote:
>>
>>> Hi Guys,
>>>
>>> Playing with my 30S-1 has gotten me thinking about a project. I've
>>> been
>>> wanting an amp for 50Mhz for a while and I have 2 4CX1500B's lating
>>> around
>>> as spares. One would make a nice amp on 6M and I think I'd like to
>>> do
>>> the
>>> grounded screen arrangement like the 30S-1.
>>>
>>> Could any of you comment on the pros and cons?
>>
>> Less power gain in cathode driven config.
>>
>>> The PS arrangement seems
>>> unusual to me with the plate supply return on the groud ie. screen
>>> and
>>> the
>>> cathode return appearing to go through the bias and screen supplies.
>>> I'm
>>> sure I'm mis reading it. IIRC the Continental 816 I maintained so
>>> years
>>> back was of a similar arrangement, 4CX15000A.
>>
>> Wasn't it grounded-screen, grid-driven, not grounded-screen
>> cathode-driven?
>>
>>> But the plate screen and
>>> grid supplies returned directly through the cathode with all kinds of
>>> bypassing.
>>
>> A seriously bypassed cathode means that it's grid driven.
>>>
>>> Comments?
>>>
>>> Shawn
>>> N7LQ
>>>
>>> --
>>> Mitchell's Law of Committees:
>>> Any simple problem can be made insoluble if enough meetings are
>>> held to discuss it.
>>> _______________________________________________
>>> Amps mailing list
>>> Amps@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/amps
>>>
>>>
>>
>> Richard L. Measures, AG6K, 805.386.3734. www.somis.org
>>
>>
>
> Hello Rich,
>
> Interesting that you say this. I was under that same impression from
> conversations through the years. I was happy to find that only the
> screen is grounded, for stability. The 30S-1 is a grid driven tetrode
> amp
> otherwise.
The 30S-1 is cathode-driven because no signal applied between the grid
and the cathode.
> I could never see how a 4CX1000A could function well in a
> grounded grid mode.
The screen grid is grounded and the control grid is at the same signal
potential as the cathode. Thus, the driving potential is applied
between the cathode and the screen, which is why the gain is roughly =
to the screen amplification factor.
>
> Shawn
> N7LQ
>
>
>
> --
> Mitchell's Law of Committees:
> Any simple problem can be made insoluble if enough meetings are
> held to discuss it.
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
>
Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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