[ARC5] Plate impedance...

[Kenneth G. Gordon]

On 14 Dec 2008 at 20:25, w7qho wrote:

>     Anyone know what the plate impedance is of a pair of 1625 
>     at, say, 7.0 Mhz, a plate voltage of 550 VDC, and a plate 
>     current of about 150 mA?
> 
> Presume you mean "what load impedance reflected to the plates of the
> 1625's would result in a DC component current of 150 ma.

Yes. Something like that...

>  A rigorous
> answer to this would require knowing the operating conduction angles
> and access to constant current curves for the tubes.  An approximate
> answer would be 550 divided by 0.15 as mentioned by Robert.

That is for DC. For AC, one formula used is plate voltage divided by 
twice the plate current.

>  See pubs
> like Eimac's "Care and Feeding of Power Grid Tubes" for more.

Thank you. I have that here. I'll dig it out and re-read it.

> Note
> that command sets operated as designed don't have enough PA drive for
> true class C operation.

Thank you, Dennis. Yes, I knew that.

Ken Gordon W7EKB