[GreenKeys] Testing 255A Relay

[Tom Hunter]

Paul,

I put one of my 255A Polar relays on the bench to go through a test on it.
Pins 1 and 5 are numbered on the bottom. You can count down to the rest.
The two coils on mine (pins 2 & 7 and and 3 & 6) each measured 128.6 ohms.
Pin 1 shows continuity to the frame and  armature.  Pins 4 & 5 show
continuity, each to a stationary contact. Pin 8 is not connected on mine.

When I tested the contacts with an ohmmeter and moving the armature by hand
they barely worked. A piece of bond paper cured that problem.

A 1.5 V D cell was on one winding was enough to cause the armature to move.
My relay is out of adjustment so I could only get it to move one way. If
your relay is in adjustment reversing the polarity of the battery should
get the armature to move the other way.

The attached illustration is from the New RTTY Handbook. I could send you
the adjustment procedure  from the same source if you need it. It worked
for me on the 255A I am using with a military Dovetron.

I am posting this to the group in the hope it may help others.


Tom N3CRK
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