[Elecraft] 100 Watts or 500 Watts

[Vic Rosenthal]

For linear purposes, 813's work in grounded grid with the screen tied to the control grid 
and grounded. You can also make a class AB1 amplifier with a 'grid circuit' consisting of 
a big 50-ohm dummy load. And then there is the G2DAF circuit, in which the screen voltage 
is derived fom the drive -- but I only recommend this one for SSB if you have a means for 
checking IMD; it may require some careful adjustment.

I'll put up the report on my amp soon. I need to redraw the schematics which are a 
horrible mess at present.

On 12/22/2010 8:30 AM, Dale Parfitt wrote:
> Hi Vic,
> Dave Ishmael has a single 813 amplifeir in this month's Electric Radio. Please do publish
> your amp for all of us to look at. I still have an 813 and socket I have had since I was a
> kid- maybe it's time to build an amp for my Atlas 350XL.
>
> Dale W4OP
> ----- Original Message ----- From: "Vic K2VCO" <vic at rakefet.com>
> To: <elecraft at mailman.qth.net>
> Sent: Wednesday, December 22, 2010 11:14 AM
> Subject: Re: [Elecraft] 100 Watts or 500 Watts
>
>
>> I just finished building a grid-driven amplifier using two 813 tubes. With a 3 db
>> attenuator at the input, it requires between 16 and 40 watts of drive on 160 through 10
>> meters respectively, for 800 watts output (only 700 on 10). Without the attenuator, it
>> would need 8 - 20 watts drive.
>>
>> And this is a class-C amplifier designed for CW only! If it were a class B or AB linear,
>> the drive requirement would be even lower.
>>
>> Grounded-grid is not the only way to design a tube amplifier. Although a traditional
>> grid-driven circuit is a little more complicated, it's one way to get more gain.
>>
>> I am going to put some pictures and schematics on my web site soon, not that I think
>> anyone will want to duplicate it!
>>
>> On 12/22/2010 7:50 AM, Ron D'Eau Claire wrote:
>>> Even the Elecraft 100 watt amps are integrated with either the K2 or K3
>>> control logic so they cannot be used as a stand-alone amplifier with other
>>> transmitters.
>>>
>>> The only reason I have ever seen from the FCC for the amplifier
>>> certification and 15 dB gain limitation is to discourage the CB
>>> 'bootleggers'. Certainly building a stable, clean amplifier that would take
>>> even a few milliwatts to 1000+ watts is a straightforward design exercise.
>>> There's no real problem with using more than one stage of gain if there was
>>> no 15 dB limit on the system gain.
>>>
>>> Ron AC7AC
>>
>> --
>> Vic, K2VCO
>> Fresno CA
>> http://www.qsl.net/k2vco/
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-- 
Vic