[BC] Bauer/Sparta 603

[Phil Alexander]

On 19 May 2005 at 19:16, Mike Holderfield wrote:

> A little more info.
> 
> Yes both finals were in the same cavity, mounted side by side,
> with solid brass transmission line extending outward from each
> tube in parallel. The lines were shorted at the end where H.V. was
> applied. Two 3 or 4 inch diameter discs were mounted between
> the lines and variable, serving as an air variable capacitor for plate
> tuning. Above and offset from this were two more lines(pipe)
> shorted together and feeding the transmission line flange.
> Looks like something out of the Amateur Radio Handbook
> VHF amplifier chapter!

In the early FM boxes before 4CX5000's etc. started to be used
"hairpin" type coupling was fairly common. For example, the
Gates FM-1B/1C had a hairpin tank with shorting bar for rough
tuning and an output link that pivoted closer to the tank for
a loading control. Plate tuning was a large flat plate hinged 
at the top that moved in proximity to the tank coil for tuning.

The GE FM 3 kW and 10 kW boxes of the late 40's used push-pull
PA's with modified hairpin tank coils what also acted as air
ducts to the tubes which were mounted inverted. These boxes
had movable output hairpin links for loading too.
 

Phil Alexander, CSRE, AMD
Broadcast Engineering Services and Technology 
(a Div. of Advanced Parts Corporation) 
Ph. (317) 335-2065   FAX (317) 335-9037





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