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I need 60 amps for a rather large VHF solid state amp. Can I safely "stack" three 25 amp power supplies and hook the one amp to them ? If so, has anyone done this before and any advice you can give please ?

If you substitute the word Parallel for the word stack the answer is yes. Use a diode in series with each supply (at least 35 amp). If you stack power supplys then the voltage is added and the current capabilities are unchanged (creates problems but I have done it).
Ralph w5otp.

I agree with the earlier post, with one caution, make sure that all are regulated and have individual voltage and current sense systems in place infront of the diode isolators. Actually, the diodes are not necessary if all the supplies are identical and are set for the same voltage and current. What I typically do is use a small series .01 resistor on each supply and put the voltage sense for all supplies on the load side. Sort of lets them equalize.

I only want to caution that if you parallel 2 12v supplies, make sure that 1/2 of your expected current draw does not exceed the capability of the smaller supply. IE: If you put a 20 amp supply with a 30amp companion in parallel, do not expect to run 50 amp but rather look for 40 amp as safety factor since the supplies will want to equal current in each leg, with perhaps slight variation. Each will settle on about 20 amps draw, one just at its capacity and other with "reserve"... But, keep in mind a 70 amp supply probably can be bought for LESS than the cost of 2 35amp supplies!!. Good Luck. San K5YY