HOW TO LOWER HV Supply

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flintstone mop:
I would like to lower an HV supply from 820vdc to around 600vdc. It's a Heathkit HP23A. I do not want to use a Variac. Regulation goes out the window.
A supply I built sags under full load from a 6146 final and 6550 mod pubes.
It's using a voltage doubler. I see some 100k resistors that prolly could be reduced to 47k and (lower voltage??) Shortcut engineering happening here

Fred

flintstone mop:
I guess this post can float down the log.........It just hit me that if I throw a choke in the P.S. at the input to the filters instead of the capacitors that it would knock the HV down the 100 or so volts that I'm looking for. I forget what a choke input vs capacitive input does to HV.... there was a magic number that a good Ham friend of mine told me that would be the reduction in HV with a choke inpoot.
Have a Great New Year
Fred

WQ9E:
Hi Fred,

As long as the choke is of sufficient inductance and the load on the supply is sufficient to keep the filter acting as a choke input then the magic number is about .9 times the transformer secondary.  However, as I recall doesn't the HP-23 series of supplies use a voltage doubler circuit?  Someone with more knowledge of this will have to chime in on conversion to choke input.  The other problem is that, depending upon what you are powering, you will need to draw a fairly significant idle current to prevent the choke input filter from acting like a capacitive input filter.

Rodger WQ9E

flintstone mop:
You have a good point Roger about loading. I could juggle the values of the bleeder resistors.
You are correct on the voltage doubler diodes to get the 820vdc.
I'll have to stare at the scheezo some more

Fred

WQ9E:
Fred,

I pulled my HP-23A manual and I don't see an easy way to get to 600 volts.  If you are not using the low voltage or bias outputs then you could probably series the 2 secondaries and end up with about 500 DC volts under load with a standard capacitor input filter (The two secondaries in series would add up to 407 volts and you could expect to get around 1.22 times this voltage as loaded output with reasonable sized capacitors).  Is 800 volts too high for the safety of components in your intended circuit?

Rodger

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