[Milsurplus] Re: More Russki Radio...

[Michael Tauson]

Hi, Dave,

In a word, ick!

I like using auto inverters but you're right.  There's more than one
kind.  The ones like you have, I usually put a small toroidal 1:1
transformer in line to float the output and use the inverter ground as
... ummm ... ground.  While I wind 1:1 out of pure laziness, the
isolation transformer offers an opportunity to diddle the output
voltage a bit.

Memory serving from when I wanted to see why they were the way they
were, they used part of the output winding to provide feedback to the
oscillator.  This made them cheaper for the Chinese to produce but
messed up the output as you noticed.  One thing I did notice is that
the inverters marked "30 watts" and the ones marked "50 watts" seem to
be identical.  I don't know if the first group is conservative or the
second optomistic, or if there really is a difference.

The other group of inverters already do float the output so they're
not an issue.  These tend to be a bit more expensive but they're also
better designed.  Here again, though, ratings can be misleading.  I
have one that claims to be a 150 watt inverter but, in the small
print, that turns out to be a momentary rating with a continuous
rating of 100 watts.  I had one previously that also claimed to be a
150 watt unit and it really did have a 150 watt continuous rating.
(That one got "borrowed".)

Isn't this fun?

Best regards,

Michael