[Milsurplus] What is it?

[Hubert Miller]

Yes, but that's not how critical alarm transmitters work. You cannot have
them operate "normal off" condition; otherwise if they fail, there's no
alarm anyway.
The water alarms i have seen ( troubleshot transmission of ), the alarm
condition is sent in a data stream and, or complete failure of the signal.
Which reminds me of something. For many years, there were two-letter HF
beacons coming from the USSR. Memory seems to tell me that these were 
speculated to be river level signals, or more likely - to identify jamming
stations, for maybe propagation checks? Who knows?	

It's not a sonobuoy, but it kind of does look like the insides of those
sonobuoys surplussed back in the 1970s, doesn't it?
-Hue 

-----Original Message-----
From: Milsurplus [mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of
Robert Nickels
Sent: Thursday, June 23, 2016 11:50 AM
To: milsurplus at mailman.qth.net
Subject: Re: [Milsurplus] What is it?

On 6/23/2016 1:06 PM, Hubert Miller wrote:

> looks like free-running oscillator, which surprises me

Look again.  The crystal is missing but part of the socket can be seen in
the top view between the motor and V301.

> And no modulator? How is the normal / abnormal condition signalled ?

On/Off keying, aka "CW", by the Cramer cam switch.   My guess is that when
the alarm condition occurs, power would be applied to this device for a
period of time,  allowing it to warm up and transmit it's carrier in the
coded sequence enough times to assure it would be heard on the other end.
The receiver would have had a COR circuit connected to a counter or some
kind of display device that would tell humans which transmitter generated
the alarm.   My guess is that since there is no "condition" information the
application was one in which just knowing there was a problem was
sufficient.  In that regard it could have been a fire or burglary alarm, but
those were typically done over phone lines that may not have been an option
for a remote pumping station or something like it.

73, Bob W9RAN

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