[GreenKeys] Testing 255A Relay

[John, W9DDD]

Hi Tom and Paul

Tom the 314 is a sealed unit with mercury wetted contacts.  Can't see 
what is happening.

Paul if you had a 255 or 215, you would be able to hear the clickety 
click of the signal as the armature fluttered back and forth.  (No I 
haven't learned to decode baudot that way yet.)

Short of having a real test set, the best you could do is Tom's method 
with a battery and VOM.  Some test literature I've seen actually used 
low voltage 50-60 Hz as the test signal.  If I can find it again, I'll post.

Do you have  spare 314 or 255 to swap out?  ( I have spares)


On 2/7/2023 7:59 AM, Tom Hunter wrote:
> 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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The above comments or recommendations are SWAG. Use at your own risk.

John, W9DDD