I disagree with the note below - get a 100 miliamp meter and make a shunt
out of 12 gauge wire - start with about a foot - apply a known load and
check calibration - make the shunt longer or shorter as required.
Note - if "shunt" doesn't mean anything to you, I mean to take a length of
12 gauge wire and connect it across the meter terminals (like a short
circuit) - you want to make a 1000 to 1 divider so you don't need much
resistance.


"Grant Erwin" wrote in message
...
Brad H wrote:
I need to replace the selenium rectifier stack in an old battery
charger to bring it back to life. The battery charger is rated at
7.5V-80Amps dc and 14.5V 50Amps DC. It is set up with multiple primary
windings selected by a switch. I verified that the transformer is
good.
Does anyone have a recommendation for a good replacement rectifier
diode set that will handle this current? Will I have to use separate
diodes and build it to get 80Amp capability?
The amp meter is also shot, and I might entertain replacing that if its
cost effective. Any ideas on a small 2" x 2" panel mount 80A dc meter?

Whatever you do it won't be cheap unless you get incredibly lucky. And you
will also need luck to find a drop-in panel meter.

Other than that, it should be easy to find a rectifier and meter for your
ratings, just watch ebay for awhile. Not too many buyers need those specs.
When you get your rectifier, take the time to find the actual datasheet,
download it, and read it for the manufacturer's suggestions on mounting
especially heat sinking, and use new heat sink grease. If you have to
retrofit a new panel meter with a slightly different footprint it isn't
too hard to cut out panels with a jeweler's saw, or else make a bunch of
punches along your profile and then use a small sanding drum in a Dremel
tool (or carbide burr in a die grinder, or...) to clean up. You can also
chain drill, although I hate drilling sheet metal.

GWE