[ARC5] AM linear amplification

[Kenneth G. Gordon]

On 20 Dec 2016 at 16:27, AKLDGUY . wrote:

> Many thanks to those who have replied so far, all with interesting aspects.
> Use of a very large tube in order to get a worthwhile power output while not exceeding plate 
> dissipation and Class B operation are of particular interest to me.
> 
> I'm familiar with the 813 class of tube, being the owner of a RCA ET4332-B transmitter at one 
> time which used a pair of them, and although they're sometimes available at swap meets here, 
> the building of a 1500 volt power supply is a bit further than I want to go (no suitable power 
> transformers).

Got any microwave ovens around your neck of the woods?
 
> Class B is interesting. It's not widely known that the 807 / 1625 is capable of Class B zero bias 
> operation, with screen grid connected to control grid*. This configuration eliminates both the 
> negative grid supply and the screen supply. A pair of these tubes requires about 5.5 W of drive 
> power*, which the BC-230 can easily deliver.
> 
> *RSGB Communication Handbook, Fourth Edition, 1968, page 9.21-22

That is VERY cool. I had completely forgotten about that!!!! Thank you for the reminder.

> I'll look into this aspect. I had forgotten about 807s in Class B.

My preference is push-pull Class B. For a single-band, that isn't all that difficult to 
implement...and it has other advantages...

Besides, it is symetrically pleasing...at least to me... :-)

Ken W7EKB

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