Re: [Amps] AMPS

["John Vickers" <wa4tt@nlamerica.com>]

> Rich writes:
>
>> K-202 looks like it's a grid shutoff.

Joe answers:
>
> There is no K-202 on the schematic or parts list of the PA-374, PA-76
> or PA-78 amplifiers on the BAMA site.  Those are the only amplifiers
> produced by Alpha to use the 8874.  In all three cases the grids of
> the 8874 are connected directly to the chassis.
>
> Which amplifier/schematic are you looking at?

>Rich writes:
>> I was looking at Alpha's diagram.

> Joe answers:
> Apparently not the diagrams provided to BAMA by Alpha (W0UN and AE0Q).
>
>> Rich writes:
>> The Q1 is a TIP-147 and is rated at 5A.  Q1 appears to carry grid
>> current. Is this true?

> Joe answers:
> If you read the explanation, Q1 and U1 are an "adjustable zener" that
> provide bias.  Looking at the schematic they are in the cathode circuit.
> The only transistor in the grid circuit is Q6 (page 31, lower left
> corner) used in the grid current sensing circuit.
>
> If you bother to read the rest of the manual, you will find the G3SEK
> board is designed for use with the grids bolted directly to the chassis.

I was preparing to order the Herring, someone mentioned earlier, for dinner. 
But the awful stench of rotting "Mullet" blowing in from the West Coast has 
me thinking steak and potatoe instead. :>)
3's from Jihad John, WA4TT

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