[GreenKeys] 28ASR slow release relay

[w9ddd at tapr.org]

I have the LESU 15 (28G).  It seems similar to the 13.  The SR relay sits between the line shunt relay and the line (polar) relay. I was surprised to see a test button mounted on the same plate.

So I've printed the WD for LESU 15 and LESU7/184.  Laid them on the table to see what I needed to change.  Immediately ran into the SR relay confusion.  Seems like it's only activated in the KT position of the K-KT-T switch.  

Thinking it may only be important if you're hooked into an circuit where you don't want a unintended break.  In which case I don't need it.  But I'm always curious about the original purpose of things.

John, W9DDD


> On Aug 8, 2020, at 2:42 PM, Jim Haynes <jhhaynes at earthlink.net> wrote:
> 
> Without knowing what it's wired to I couldn't offer a guess.  However
> I can think of a couple of applications - in FAA machines they were on
> a separate panel in the base of the machine.  One use is as an open
> line detector, or break detector.  Normal marking signals hold the relay
> in, and slow release keeps it from dropping out on signal pulses, but
> a break or open line lets it release and give an alarm or prevent
> transmitting or whatever.  Another use is as a busy line detector, where
> the spacing contact of the polar relay operates the S-R relay and it
> stays pulled in during transmissions but drops out when there is a steady
> mark on the line.
> 
>    ---
> 
>    "Ya can argue all ya wanna, but it's dif'rent than it was."
>    "No it ain't! No it ain't!  But ya gotta know the territory."
>        Meredith Willson, The Music Man