[Amps] grounding grids

[Roger]

Fuqua, Bill L wrote:
> Let see. RF plate voltage is proportional to RF plate current,,,,RF cathode current is proportional to plate current....RF voltage across the cathode drive impedance is proportional to RF cathode current and the cathode drive impedance which is equal in magnitude to the tubes input impedance, if everything is matched. The RF cathode to grid voltage is in phase with the RF plate voltage The grid-cathode RF voltage is 180 degrees out of phase with the RF plate voltage. 
>
> Sounds like negative feedback to me.
> And it is. That is why a small additional resistance in series with the cathode improves IMD and decreases the gain.
>   
and should reduce the need for carefully balancing the tubes.

73

Roger (K8RI)
> 73
> Bill wa4lav
>
> ________________________________________
> From: amps-bounces at contesting.com [amps-bounces at contesting.com] On Behalf Of Gary Schafer [garyschafer at comcast.net]
> Sent: Thursday, July 30, 2009 12:09 AM
> To: dezrat1242 at yahoo.com; amps at contesting.com
> Subject: Re: [Amps] grounding grids
>
>   
>> -----Original Message-----
>> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
>> Behalf Of Bill, W6WRT
>> Sent: Wednesday, July 29, 2009 10:29 PM
>> To: amps at contesting.com
>> Subject: Re: [Amps] grounding grids
>>
>> ORIGINAL MESSAGE:
>>
>> On Wed, 29 Jul 2009 21:35:47 -0400, "Joe Subich, W4TV" <lists at subich.com>
>> wrote:
>>
>>     
>>> Unfortunately, as shown by others this is not accurate and since
>>> the negative feedback varies significantly from band to band the
>>> floating/bypassed grids simply can't work as Heath claimed.
>>>       
>> REPLY:
>>
>> Also, that isn't true negative feedback anyway. It is just gain reduction.
>> True
>> negative feedback means taking a sample of the output, inverting the phase
>> (if
>> needed), and feeding it back to the input.
>>
>> 73, Bill W6WRT
>>     
>
> How then would you account for the reduced IM products of a tube operated in
> GG verses the same tube operated in a standard grid driven configuration?
>
> 73
> Gary  K4FMX
>
>
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
>