[GreenKeys] Testing 255A Relay

[Nick England]

One caution about the 314A. Do not operate or test with the base up. The
mercury-wetted contacts may short. Hold base down for several seconds
before operating
https://www.navy-radio.com/manuals/tty/570-303-106-6412.pdf
The 314A can be operated vertically with base Dow. Also in the horizontal
position with the orientation mark up.

On Tue, Feb 7, 2023 at 9:20 AM John, W9DDD <w9ddd at tapr.org> wrote:

> 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
>
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> >>> 1998-to-2001 greenkeys archive:
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>
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-- 
Nick England K4NYW
www.navy-radio.com
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