Dear Ken, etc.,
I think there are three ways to do the project:
1. add a dropping resistor to get the primary from about 120 volts down to
100 volts. Since 9 volts @ 50 amps is 450 watts and 7.5 volts at 50 amps is
375 watts, you need to have a resistor rated for well over 75 watts, the
difference and about 5 ohms. Maybe 125 watt unit, or 5 resistors, each 1
ohm @ 25 watts in series. One of them could be adjustable for "fine tuning"
the output
2. Use a 4 or 5 amp CCS rated Variac to drop the input voltage and get 7.5
volts out.
3. Find a 4 or 5 amp CCS rated 20 volt transformer that you can wire in
backwards to "buck the line voltage"
I vote for option 2. It is fastest and easiest and if you have high or low
line voltage you can adjust as needed to get 7.5 volts at the tube socket.
Good luck, George K8GG
----- Original Message -----
From: "kenw2dtc" <kenw2dtc@comcast.net>
To: <amps@contesting.com>
Sent: Monday, June 16, 2003 10:10 AM
Subject: [Amps] transformer rating
> Hi,
> I have a 9 volt 50 amp transformer. If I bring down the primary voltage
properly to get 7.5 volts, can I still draw the 50 amps without problems?
> Thanks,
> Ken W2DTC
>
>
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