right way to test pt on bench

[mark_enger]

im wanting to test some of my power transformers, im wondering the correct way to do it should i simply hook a power cord to the black primarys and not do anything for power cord ground and cts? i was thinking i should hook a socket to the hv and the 5 volt fil and use a tube recto. hook up a socket for the preamp tubes but where can i hook the cts and the power cord ground? can i put a lug on the pts bolt and run cts and power cord ground to this or should i just make a chassis for this testing.  mark

[andrew_k]

I can't say this is the "right way", but this test rig has worked for me on a variety of PT's


What can't be seen is that this is plugged into a variac which is in turn plugged into a lightbulb current indicator/limiter. Voltages are measured across a dummy load (200W @ 8ohm)

Even if you don't want a switch, a fuse is a worthwhile addition!

[tubesornothing]

I like what Andrew did.

My quick and dirty method (and not really safe)

Wire a two prong power cord to the primary and tape it off. 
Wire a couple of meters to the secondaries (I gotta few kicking around) - tape them off.
Turn off the variac, turn the knob down
Plug into the variac
Turn on the variac, and bring the power up, check the primary and secondary voltages.

I like my variac cause it has two fuses, voltmeter and ammeter.  However, you can substitute a switchable power bar with breaker.

[PRR]

8 ohm is inappropriate for most hi-voltage windings. Fine for 6V windings.

Load isn't essential. If you get voltage out, it is probably "working".

Consider firing-up with a 12VAC (or 6VAC) source instead of a 120V source. It won't smoke so fast. Your "370VAC" winding will be 37V (or 19V), much safer to probe. If you are unsure which wires go to the wall, probing with 6VAC is safe for any winding normally found in this racket; 120V into a 6V winding causes unhappiness. Then when you know the right connections and approximate 1/10th (or 1/20th) voltages, you can confidently apply 120V and confirm.

[mark_enger]

well i made a chassis that will fit most pts and put in  sockets for 8 pin and 9 pin so i can test with a load primative but seams to work. mark