Anyone familiar with this HV transformer?

[KG4DAG]

I have this transformer that I'd like to use someday in a power supply
for an HF amp.. No markings except T-201, .... 0, H, M, L on a tapped
primary and 1370, 2000, 3450 ... 0 ...3450, 2000, 1370 on a center tapped
secondary. It weighs 35 lbs and looks pretty useful. It all seems to ohm out
OK with nothing shorted or open...















So... Is anyone   familiar with this beast and do you think I can get an ampere or 2 out of it?
Will it run a 4-1000 deck? 

Thanks!

[W7TFO]

I'd say that is a bit light for your expectations.  What is the rule, 10 Watts to the pound or some such dictum.

The similar transformer in a T-368 weighs in around 100lbs, and that is good for running a pair of high-level modulated 4-250's.

No where near enough scrote for a 4-1000.

73DG

[KG4DAG]

Ok.... maybe some 813's.... he he   

[w8khk]

A sealed transformer like that one should last a long time if it is not abused.  I have a 220 pound plate transformer from a Temco commercial transmitter that will do 2KW continuously without getting warm.  Same style enclosure and terminals.

But your transformer is obviously designed for higher voltage and less current, based upon the engraving and size/weight.  In order to get the most benefit/efficiency, try to come up with a plan that uses most or all of the windings, to distribute the copper losses as much as possible.

It is not obvious whether the primary is designed for 110 or 220.  (Would not be 120 or 240 for that vintage, obviously.)  I would start testing by putting about 100 volts across the two high voltage terminals, using a variac or powerstat with a 60 or 100 watt light bulb in series.  Then you can measure the voltages on the various windings and calculate what input voltage would produce the rated output voltage.  The primary appears to be a tapped affair, with 0 and L at the ends of the winding.  Powering smaller segments of the primary will obviously produce larger voltage on the secondary.

If I were to guess at a good application for this transformer, to get the most capability using the rated voltage out, I might use a center-tapped full-wave solid state rectifier stack with choke input and a moderate sized filter cap.  Then feed the primary in a manner to produce around 3KV DC, to power the final RF stage of a plate modulated AM rig.  As for tubes, Eimac 4-65s or 4-125s could easily produce 350 or more watts input in intermittent duty.  Monitor temps, it might even work in old buzzard mode.  I think the key here is to choose an arrangement that works at the higher voltage and lower current, and the 4-65 is very efficient in this configuration.  Hope this is somewhat helpful....

Rick  W8KHK

[kb3ouk]

I'd say that is a bit light for your expectations.  What is the rule, 10 Watts to the pound or some such dictum.

I thought that was just for mod iron?

[KG4DAG]

Putting a variac on is a good idea..... I'll see what I get and go from there..

OK 100 V in the secondary gets 1.605,  2.648  and 3.80 on the primary   
calculator time....  ratios of 62.3,  37.8 and 26.3

120 * 26.32 = 3156    12V across the pri gives 310V    155  0   155 on
the sec...  11V gives 286V    143  0  143


Looks like a 110V transformer.

[WBear2GCR]

for safe testing a variac with ideally a 10vac filament transformer connected to the primary is nice... the secondary voltages are not too high, and if set at 10 volts the ratios for the secondary are easy to figure. Of course you can use any other low voltage transformer, and obviously a 12.0vac to be equivalent to a 120vac, etc...

                   _-_-bear

[w8khk]

120 * 26.32 = 3156    12V across the pri gives 310V    155  0   155 on
the sec...  11V gives 286V    143  0  143

Looks like a 110V transformer.

Yes, I agree.  But the output voltages appear to be labelled referenced to the zero center tap, and the total secondary winding is actually double the labelled numbers, as follows:

Apply 110 volts across 0 and L, the entire primary, and expect to get 1370 on each side of center tap.  Total secondary voltage is 2740.  Calculate 110 * 26.3 (lowest ratio) = 2893.  Rated 2740 is based on  I2R losses in transformer.

Next apply 110 volts across 0 and M, for the intermediate voltage.  Expect to get the rated 2000 volts each side of center tap, or 4000 volts total secondary.  Calculate 110 * 37.8 = 4158 total secondary, slightly higher than the rated 4000 volts because of transformer losses.

Finally, apply 110 volts across 0 and H, the shortest portion of the primary.   Calculate 110 * 62.3 = 6853 unloaded volts.  This is very close to the 3450 rating each side of center tap, total is double this, or 6900 volts.

So a possible application might be to use the entire primary, driven with a variac, to allow up to 2740 volts across the entire secondary, with a bridge rectifier to provide up to 3KV for use with 4-65 or 4-125 tubes, or use a center tapped full wave rectifier to obtain closer to 1200 - 1500 volts for 813, 811, etc.  The transformer looks like it might function well for a final or a modulator, as long as the current drawn is moderate, and the duty cycle is intermittent.

Some resistance checks on the secondary would be helpful in estimating the voltage drop in the secondary, and the power lost in heating the transformer secondary.   Also, some tests under a resistive load would help to determine the regulation expected, as well as transformer temperature rise over time.  The absolute first test would be to apply 110 volts across the primary, (with or without the protective light bulb in series.)  Let it run for a while, there should be no noticable hum, and no significant heating.   If the transformer exhibits a  loud hum or rapid heating, the transformer probably has some shorted turns and should go to the transformer graveyard in the sky.