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@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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