[Amps] 2x 4cx1500b amp

[texasrf at aol.com]

Felipe, you can change hv as you described. The results will depend on how  
you intend to use the lower voltage. If your plan is to lower the voltage 
AND  plate current together to run less rf power, there will be no problems. 
In fact,  you will not even need to retune the amplifier if you do that.
 
The primary should be designed for the higher plate voltage and then have  
turns added to lower the plate voltage. Because of the added turns, the 
primary  loss resistance will be higher. The added loss resistance will cause 
the no load  to full load voltage drop to be worse when lower voltage is 
selected. If the  current is also reduced, the voltage drop increase will be 
lower and probably  not even noticed.
 
I have a Peter Dahl plate transformer built this way and it has served very 
 well for nearly 30 years.
 
73,
Gerald K5GW
 
 
 
In a message dated 11/30/2009 7:57:43 A.M. Central Standard Time,  
felipeceglia2 at gmail.com writes:

Hello  "Ampers",

I am willing to build a 2x 4CX1500B amp for 160 to 10m usage.  Willing to 
use a GM3SEK tetrode board for controlling and protecting  it.

As I will need to special order the HV supply transformer, I am  thinking 
about asking for a multiple voltage primary and a fixed voltage  
secondary (probably 1250v - 0v - 1250v), so it will be easier to change  
output voltage just changing the primary, instead of dealing with HV. Is  
it a bad idea?

I would like to hear from you if you have built  anything like it, or if 
you have something to say.

Also, are there  alternatives to the tetrode board?

73,

Felipe -  PY1NB



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