Re: [Amps] Power Supply loaded DC output

[jeff millar <wa1hco@adelphia.net>]

just saying a 10% drop with load doesn't address all the factors

   * Output capacitance
   * Transformer winding resistance
   * Line resistance

The ARRL handbook has a graph that shows the voltage can drop to _less_ 
than secondary voltage (2067V in this case), More output capacitance 
makes a stiffer supply, less transformer and line resistance makes a 
stiffer supply. The bleeder resistor will load the output to a bit below 
the 1.414 time secondary voltage. Bringing the Amp online will further 
load the output. And finally, voice peaks on SSB will load it down the 
most. The voltage difference between idle and full load matters most in 
designing output network impedance and achieving low intermodulation 
performance. Idle float voltage matters less. The handbook also 
describes how to measure secondary resistance and how to translate 
primary resistance to equivalent secondary resistance. (Watch out for 
inductive kick when measuring the secondary, it can bite when you 
disconnect the Ohmmeter.)

jeff, wa1hco

Manuel R. Alonso / KC4MNE wrote:

> Hello Again,
>
> Trying to establish the loaded voltage output of the plate transformer that
> I am going to use with full wave bridge rectification  and capacitor
> filtering. It is the one that Ten-Tec buys from MCI Limited for the Titan
> III. I tried to get some "real life" numbers from somebody on the reflector
> but have had no responses.
>
> The transformer itself has a label with the following ratings, two 117 V
> primaries and a 2015 V secondary at 1.5A
>
> Tentec claims a 3000 V "no-load" plate voltage on the Titan III.
>
> My calculations are as follows:
>
> Actual Primary Voltage 240 V
>
> Actual Secondary Voltage w/ 240V on primary 2067VAC
>
> 2067 x 1.414 = 2923 VDC NO-LOAD
>
> 2923 less 10% = 2631 VDC @ 1.5 AMP
>
>
>
> Are these calculations correct?
>
> Thanks
>
> Manuel R. Alonso
> KC4MNE
>
>
>
>
>
>
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>  

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