[AMPS] Alpha Amplifiers

[Rich Measures]

>Ron - W4WA
>Alpha made its entry in the amplifier market in 1970. The amplifiers were 
>as follows:
>
>PA-70A  - Used a 3CX1000A7 - Air Cooled. I still have serial number 5.
>PA-70V  - Used a 3CV1000A7 - Vapor cooled tube - Had a distilled water 
>chamber.
>
>Alpha 77D - First amp. to use an 8877. Same cabinet as the PA-70 series.
>
>Alpha 77DX - Redesigned and larger cabinet styling. Single 8877. More room 
>inside.
>
>Alpha 77SX - Same cabinet styling as 77DX but used (2) - 8877's  I still 
>own two..

Did you correct the tank circuit Z problem?  If so, please describe how.  

>All the amps used an RF drive bias switching circuit wjhich had design 
>flaws ...snip...

... amen, Bob.  IMO, it is not good engineering practice to allow the T/R 
bias to switch to non-linear mode during transmit, which is what every RF 
bias switching scheem does during SSB mode.  It makes better engineering 
sense to make the T/R bias switch in unison with the T/R (RF) relays.  
Rich---

R. L. Measures, 805-386-3734, AG6K   


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