[Boatanchors] High Voltage 400 Hz Supply

[Phil]

Well,  How about a vacuum tube amplifier fed with 400 Hz from an audio 
generator.  You could decouple the plate of one of the vacuum audio 
output tubes with a capacitor to remove the DC component.  (BE SURE TO 
PUT A LOAD RESISTOR ON THE OUTPUT TRANSFORMER SECONDARY TO PREVENT 
DAMAGING THE OUTPUT TRANSFORMER).  IF your amplifier doesn't have enough 
output to produce 300 Volts RMS on the plate, then an audio output 
transformer connected in reverse to the secondary to step the voltage up 
may do it!  Again, you can use a digital DVM to calibrate the output as 
most will measure accurately at 400 Hz (both of mine do well throughout 
the entire audio range and even higher).

73 de Phil,  KO6BB
http://ko6bb1.multiply.com/ (OTR Blog)
http://www.qsl.net/ko6bb/  (Web Page)

RADIOS:
Grundigs: Satellit 750 (2011), S-350 (2006)&   G6 (2011).
Kenwood: TS130S Transceiver (circa 1980).
Radio Shack: DX-380 digital portable (circa 1990).
Yaesu: Two FT-8800 Mobiles, VX8R Quad-Band (circa 2010).
Zenith: Royal-7000 Transoceanic (circa 1969).

ACCESSORIES: MFJ 1040C Pre-Selector, W9GR Audio DSP.
ANTENNA: 88' Long Ladder-line fed dipole, Apex at 35 feet.

Central California


On 1/10/2012 4:57 PM, David C. Hallam wrote:
> I am considering various ways to build a HV 400 Hz supply to calibrate
> AC VTVM's.  Current requirement is obviously low and I need variable
> voltage up to 300VAC,  So what I need is some type of an inverter to
> convert from 60 Hz to 400 Hz and a transformer to step up to 300V.  As I
> see it, the inverter needs to have a voltage variable output, or can
> accept a variable line input from a 120V 60Hz variac, or I need a 400 Hz
> variac to put on the output.
>
> Since this will have very limited usage, cost is important.  Any
> suggestions on how to do this at low cost?
>
> David
> KW4DH
>