[Johnson] Relay Voltage ID

[Kevin Ward]

Try to get a good look at the coil assembly.  You may have to remove it
or the contact assembly to do so, but look for a number stamped in the
end or the core.  If no number, check to see if there is a thick metal
D-shaped ring at one end of the core.  The presence of such a ring
indicates an AC coil.  Reassemble the relay and connect the coil to a
variac, preset to zero output.  Slowly bring up the voltage until the
relay pulls in smartly.  Now you're in the ball park. 

The absence of a D-ring indicates a DC relay.  Use a variable DC supply
as above. 

That coil resistance seems very high.  If you hadn't said it was an open
frame relay I might have guessed you  had a plate relay there, in which
case it would probably have a very low coil current draw.  Plate relays
are usually small. 

One more thing.  Some DC relays have a biased core; that is, a
magnetized core which predetermines the polarity of the applied coil
voltage.  Such relays will have some marking of the coil terminals, like
a + and -, or a black or red dot on the positive terminal.  Also,
anything steel will be attracted to the core. 

Good luck in the contest OM.

Kevin N2IE