[Milsurplus] Opinion on transformer ?

[howard holden]

I use a 110-220V 150VA step down/isolation transformer (not an 
autotrans) backwards in a voltage "doubler" to power a Millen 90800, 
which uses a 6L6 oscillator and 807 amp. AC in is 120.5V, pretty normal 
for here in NNV, Ac out is just over 220V, DC out with a 20 ma bleeder 
current is 578V, so Seth's formula is pretty spot on. With about 100 mA 
(80 on the 807, 20 on the 6L6)load the voltage drops to 540. The output 
capacitance is effectively about 50 uF (100 uF per cap). I draw screen V 
(just a few mA) from the midpoint of the two caps. You will have more 
drop than that, as your trans is not as high on the VA rating and with 
phone you will be trying to pull more current. Can't give an opinion on 
the usefulness for AM as I almost never run phone.


73, Howie WB2AWQ





On 2/6/2019 2:34 PM, Seth Taylor wrote:
> Take rms voltage. Double. From Shay's curves, multiply by 1.3. 180 x2 = 360 x 1.3 = 468.  Use at least 60 mfd effective capacitance on output.
>
> ST. ARRL Tech Advisor
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