In a message dated 97-06-04 01:54:50 EDT, Joseph.F.Nemecek@twa.com (Nemecek,
Joseph F.) writes:
> Thanks for the information, Ed. It brought to mind a question I've had
> for some time. Has anyone come up with a good indicating system for a
> prop-pitch motor? Every installation I'm aware of, the ham coupled a pot
> to the mast and read the position with an ohm or milliampere meter in
> the shack and a piece of card board marked up with headings. Has someone
> disigned an interface box to go between a prop pitch and a standard
> Hy-Gain indicator, for example?
The most common technique that I've seen is to use selsyns for the
indicator system. You can still pick them up at flea markets for five bucks
or so. The trick is getting it to turn 1:1 with the mast. There are a couple
of ways of coupling them.
I recently ran across someone who uses little selsyns used by
railroads. Apparently they are plentiful and reasonably priced.
I just got an email from Dave, W6NL/ex-W6QHS where he says:
"BTW, my recommendation to Glen was to make an interface box to work
with
any standard rotator control box. I use relays and a transformer at the
tower base, but that's a separate issue. There's an example of a good
use of a potentiometer sensor by KD5UO in the ARRL Microwave book.
An interface box could even mimic the slow start/stop provided by
some control boxes, and it need not be a giant project. Just a thought..."
You might want to contact him for further info.
73, Steve K7LXC
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