wrote in message
...
I'm not a ham operator! But I figure you guys can explain what an
Isolation Transformer does.

I came up with one at an estate sale this weekend of a former TV
repairman. Among the 1970s vintage test equipment and color bar
generators was this xfmr. This unit says "Isolation Transformer 5
Amps, 600 Watts" on one side and "Isolation: Primary 120 VAC,
Secondary 120 VAC" on the other. It's about 8" square and as you can
imagine, quite heavy.

I was guessing it keeps voltage spikes out of the equipment that's
plugged into it, but then I saw some old posts in this group which
mentions grounded chassis.

Do people who have fairly modern ham equipment still use these things?

They are useful for older equipment where it is convenient to have the 120V
supply "floating" above ground. In other words, there is 120VAC potential
across the transformer, but neither leg has potential from that leg to
ground. They are used on the bench where "hot" chassis poses a shock
risk/hazard. They are also handy where "leaky" bypass capacitors across the
AC line cause GFIs to trip (as in radios such as R390A). I have a 1KVA unit
and used it quite often. It does little for shielding against spikes or
other line noise.

Good find.

Barry - N4BUQ