[Amps] WTD: 5CX1500A Datasheet

[Richard]

>
>-----Original Message-----
>From: Bill Coleman <n2bc@stny.rr.com>
>To: AMPS <amps@contesting.com>
>Date: 03 April 2002 02:04
>Subject: [Amps] WTD: 5CX1500A Datasheet
>
>
>>Thanks to all who aimed me at the Svetlana info - I should have mentioned
>>that I already had this in my first post.  The Svetlana datasheet is rather
>>abbreviated.
>>
>>Anybody got an old Eimac datasheet, ...

€  The Eimac data sheets do not have a constant current curve graph for 
the rated screen potential of 750V.  If you like, I can scan the 8-pages 
and e-mail them to you in jpeg format.  However, to me, the important 
items are 75pF input; c. 3.1A of peak-emission at 750 screen V; 0.2pF 
feedback; appros. ­120v of bias; 250mA of ZSAC; and extraordinarily low 
IMD at a screen-I of 60mA (AŘ), or 30mA using 50wpm dits.  Since the 
plate-modulated rating is 3500V/7000V-peak,  If I were designing a SSB 
5cx1500 amp,. I would use an anode supply of c. 5500V no-load, 750 reg. 
screen V, and a 50-ohm grid termination mounted close to the grid.  
Neutralization may not prove to be necessary, but I would neutralize 
because the 75pF grid will muck up the input match above 10MHz.    
Driving P is c. 150W pep for a 50-ohm grid term.  With a 200-ohm 
grid-term., c. 38W.  With a 200-ohm grid term., neutralization is 
probably good engineering practice - unless one needs a VFO.  
-  To protect the screen from all Murphy-esque possibilities, I would 
obtain the screen V from a string of zeners mounted on a perf-board.  
(c.40), 20V, 5w zeners should work well.  Zener bias needs to come from a 
1500V or more source limited by a series R that limits current to c. 70mA 
under normal conditions.  [note -- in the real world, zener diss. ratings 
should be divided by 1/3]. 

have fun

-  R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K, 
www.vcnet.com/measures.  
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