"I suggested to the original poster that he make it a swamped class AB1
amplifier. He will get plenty of drive with a 50-ohm swamping resistor.
The only tuning he needs is a small coil to balance out the input
capacity of the tubes."
This is the direction I'm taking. I'm amazed it's so much simpler than what
I've been trying so far.
73, Roger
AI7RR
On Mon, Jul 27, 2015 at 8:58 PM, Vic Rosenthal <k2vco.vic@gmail.com> wrote:
> I suggested to the original poster that he make it a swamped class AB1
> amplifier. He will get plenty of drive with a 50-ohm swamping resistor.
> The only tuning he needs is a small coil to balance out the input
> capacity of the tubes. That should be unconditionally stable, as long as
> he bypasses the screens properly.
>
> 73,
> Vic, 4X6GP/K2VCO
> Rehovot, Israel
> http://www.qsl.net/k2vco/
>
> On 28 Jul 2015 04:14, donroden@hiwaay.net wrote:
>
>>
>> REPLY:
>>>
>>> I see a potential problem with that. Having only the single
>>> variable capacitor will case a phase shift when adjusting it. By
>>> comparison the bridge neutralization circuit with it's two voltage
>>> dividing caps will not.
>>>
>>> I think. :-)
>>>
>>> 73, Bill W6WRT
>>>
>>
>>
>> I used SK-630 sockets on four 4CX250Bs on six without
>> neutralization.
>>
>> I think the secret to a stable six meter amp is well RF grounded
>> screens.
>>
>>
>> Don W4DNR
>>
>
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