Yesterday (8/28/14), I did a lot of testing on the repeater's power supply.  It works!  And in my usual style, I have lots of data:

KF5KYT loaned me a nice 1200 watt variable autotransformer which made testing much safer for both me and the power supply.  This allowed me to gradually ramp up the AC input voltage while taking measurements so I could see impending trouble before something blew up.  Never do that to a switching power supply, but for a linear like this, it's a good way to prevent the old & rusty giant capacitors from shorting, exploding, etc.

The first test measured open circuit voltage and the temperatures of the capacitors and transformers.  I spent several hours ramping up the power, 5 volts at a time to allow temperature increases to normalize through the massive chassis.  At each 5-volt step, I also measured input & output voltages.

During the ramp up, temperature changes looked fairly normal, but one capacitor (the oblong one) showed up to a 22.0°F temperature increase over ambient.  It was still well within normal limits, but may need to be addressed.  I plan on measuring the ESR (equivalent series resistance) of all the caps to further discover potential issues.

Satisfied that the PSU could handle full voltage, I did another ramp up with a ~40 watt load.  In this case, it was as 12 volt flood light bulb like you'd find on a tractor.  Hey, it's not a laboratory grade load, but it was convenient and good enough.  For this test, I only spot-checked temperatures but I also measured input & output current as well as voltage.  Input AC current measurements were only good to ±0.1 amps because I used a clamp meter.

Here is the setup:

Power Supply Test Setup
Power Supply Test Setup
(click for a large view)

There is an audible 60 Hz AC hum from the main transformer.  Nothing weird though.  Here are the test results with the 40 watt load:

PSU Load Test
PSU Load Test Data


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