Dear Boris,
The closer you look at power supply chokes, the worse the situation
appears.
Firstly, the sheer weight of copper and iron is daunting.
Secondly, the cost of copper approaching that of gold nowadays
makes winding them a mortgage-qualifying event.
Thirdly, the total amperage through them, considering the peak
talk power and the bleeder resistor load, etcetera, etcetera, means
for the average 3KW amplifier a hunk of metal equaling, if not
surpassing the weight of the anode iron. Where ya gonna put it?
Resonant chokes are not a simple deal either. Their resonant
frequency is determined by their inductance and the paralleled
capacitance, and that's the rub, because you just can't pick a cap
off the shelf and hope it will work with a particular choke to achieve
resonance at let's say 120 Hertz right off the bat.
A manufacturer of commercial chokes talked with me about this. His
suggestion was to design the choke/cap circuit, do the math for
120Hz resonance, and find a suitable cap at the exact value, oil-filled,
plenty of overhead voltage capability and buy a crate full so when the
choke is wound the winder can use the sample capacitor as the test
jig to measure 120Hz resonance, and there will be exact spares on
hand when the caps periodically burn out.
All this for right around 1400 bucks for a two-amp, 9 Henry, 6KV
resonant choke that would tip the scales at 845 pounds, delivered.
I went to the C-input design.
Hal Mandel
W4HBM
[snip]
I don't like the need for big chokes.
[snip]
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