Need suggestions on a Variac

[rockpassion]

Hello all,

I am in need of buying a variac to use on my very old IPC AM-1026 amp restoration.  What size and make is recommended.  I am not looking to spend hundreds of dollars but I also do not want something that is too limited.  I guess my budget is $50 to $150.

I look forward to your suggestions.

Thanks

Richard

 

[Maxwell_E]

There are always great used ones on eBay. Sometimes the little carbon brush can wear down, becoming bigger and contacting several coils at once. I have an old Power Stat thats rated for 10 amps that I picked up for cheap and I had to disassemble it and file the brush back to a point. I don't have much experience with the newer ones, although they look slick with their output meters and multiple outlets.

 

[Grainger49]

If you can get to a Ham Fest you will find a number of them there.  What you need is one that has meters for voltage and current.  That way you can bring up the voltage and watch for a surge in current.  A surge indicates a short that is going to mess up the whole works. 

Bring it up in several steps.  Say start at 40V and leave it sitting for 5 minutes.  It forms the capacitors.  Then go to 80V, slowly, and let it sit for another 5 minutes.  Then slowly to 110V.  If it is an old amp it isn't quite designed for 120V or higher that we all have coming into our houses today.  That is why I also suggest buying a higher voltage for all the capacitors.  We run over 10% higher voltage today, the caps need to be 10-15% higher too.

 

[rockpassion]

Grainger,

What about current rating?  Should it be 5, 10, 15, 20 amp.  And is there a make that I should look for.  I definitely am sticking with US made such as Powerstat or Staco. 

Thanks again for your help.

Richard

 

[STURMJ]

You need to consider what you are using it for (how many amps do you need). and don't forget to consider you circuit breakers rating (usually 10A).

 

[2wo]

5A is probably all you need, have a look at the fuses on the gear you want to test.

If I found a good deal on a 10A, I would buy it, but that's just me ...John

 

[Grainger49]

Look at the fuse on your amplifier.  Whatever that is you need that or more.  5A is usually enough.

 

[4krow]

  G, I had some of the same questions and appreciate your information. Current AND voltage meters sound to be a much better indicator than current or voltage alone. Also, the ham fest idea is great. I have only been to one in Arizona years back, and was very impressed by these guys and their equipment.

 

[Grainger49]

The one I have does either current or voltage.  So I can measure with my meter how the voltage is coming up and watch with the meter set at current for any sudden increases.

 

[4krow]

Sudden increases are a bummer, except in the stock market.

 

[adamct]

...or one's paycheck...

;D