There are at least two approaches:Hi.
How would you modify a linear 15VDC 30A unregulated supply into regulated 14VDC 30A ?
That would require about 93% efficiency and you're not likely to get there.How would you modify a linear 15VDC 30A unregulated supply into regulated 14VDC 30A ?
A synchronous buck converter with some pretty fancy MOSFETS in parallel with some high current Schottky rectifiers might get the job done. I'm pretty sure it would cheaper to bin the unregulated supply and buy what you need.That would require about 93% efficiency and you're not likely to get there.
What is the ripple on the unregulated 15VDC?
Perhaps in the neighborhood of beefy paralleled pass transistors...What kind of answer were you expecting?
A DVM won't tell you much about ripple voltage. If it's a couple volts above 15V, that makes what you're trying to do easier, but you're not likely to get 30A unless the unregulated supply current rating was conservative. With many unregulated supplies, the unloaded voltage is higher than the nominal rating and the voltage will drop under full load.It is a non-regulated linear supply
If you put the DVM in the AC mode it should give the average ripple voltage.A DVM won't tell you much about ripple voltage.
Could you simply mention them @nsaspook ?Is the supply a simple, big-iron, 50-60hz transformer (not likely today) type? If so then AC side voltages adjustments are possible.
Variac or even a simple light dimmer on the AC input side.Could you simply mention them @nsaspook ?
Curious
Oh, so obvious...Variac or even a simple light dimmer on the AC input side.
View attachment 269848
No hum reports when transmitting with battery.Did the Transmitter have hum-issues when it was new ?,
or did You build it from scratch ?,
how old is the Transmitter ?, it may need a complete rebuild.
You are trying to fix what You "think" is the "problem"
before You actually know for a fact what the source of the "problem" is.
Don't think you're special, this type of repair pursuit is ubiquitous with all types of complex machines.
To fix this type of problem there are 2 approaches,
the "Shot-Gun" approach,
replace every Capacitor in the Transmitter, if that doesn't work, replace all the Resistors too,
and the "Methodical" approach,
which requires a thorough understanding of the operation of all sections of the Transmitter,
and requires the appropriate test equipment, and experience with it's use.
by Jake Hertz
by Jake Hertz
by Aaron Carman