01-30-2016, 11:12 AM
I believe the Sencore PR-57 models are single unit isolated variacs. Those tend to be pricey though because they are intended to test different modes of isolation failure as well.
There's no reason you can't use a separate isolation transformer after the variac (before would work too I think). Just plug the variac into the wall, the isolation transformer into the variac, and the radio into the isolation transformer.
When I was starting out I bought something like this:
http://www.ebay.com/itm/Variac-Variable-...1872830853
A couple things I learned since then: the meter isn't useful (too small). And 20A is really overkill. One with a 5A or so rating would be plenty for radio work. Also, don't trust the dial markings - I just use my DMM to monitor the voltage.
I made an isolation transformer box using one of these that I got off of ebay for ~$50:
http://www.digikey.com/product-detail/en...ND/1118196
There are also isolation transformer boxes made for hospitals and labs that show up on eBay too.
There's no reason you can't use a separate isolation transformer after the variac (before would work too I think). Just plug the variac into the wall, the isolation transformer into the variac, and the radio into the isolation transformer.
When I was starting out I bought something like this:
http://www.ebay.com/itm/Variac-Variable-...1872830853
A couple things I learned since then: the meter isn't useful (too small). And 20A is really overkill. One with a 5A or so rating would be plenty for radio work. Also, don't trust the dial markings - I just use my DMM to monitor the voltage.
I made an isolation transformer box using one of these that I got off of ebay for ~$50:
http://www.digikey.com/product-detail/en...ND/1118196
There are also isolation transformer boxes made for hospitals and labs that show up on eBay too.
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