[Boatanchors] 120 - 240vac and output

[Vic Rosenthal]

George KB2Z wrote:

> Can someone in the know clear up the question of whether 240vac will 
> give an amplifier a power boost over a 120vac line?  This is assuming 
> that the 120vac is healthy and can handle the input amperage required by 
> the amplifier, (no dimming or blinking) without blowing any house fuses 
> or breakers.

It depends on the size of the wire and the length of the run from the service 
entrance.  Other things being equal, an amp will draw twice as much current at 
120v than 240.  So, to make things simple, suppose the total resistance of the 
run is 1 ohm.  If your amp draws 10 amps on 240V, the voltage drop will be 10V, 
or 4.2%.  Your HV will also drop by 4.2%.  On 120V, the amp will draw 20 amps, 
for a drop of 20V, or 16.7%!  If your amp normally operates at 2800V, it will be 
reduced by 467V, BEFORE the HV drop caused by the power supply regulation, etc. 
  This will significantly reduce the amount of power you can get from your amp.

The extent to which you will see lights dimming of course depends on whether the 
lights are on the same circuit as the amp.  Why don't you measure the actual 
primary voltage drop (you may need to use an old analog meter to avoid RF 
problems) and compute the percentage that the primary voltage is dropping.  Then 
consider that the drop will be one fourth as great on 240V.

-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco