[Milsurplus] What is it?

[Robert Nickels]

On 6/23/2016 7:54 AM, n2lxm at juno.com wrote:
> Looks like a VHF Beacon Transmitter. The motor would drive the disk to 
> send out a preset message or code that planes could home in on.

In the combined opinion of W9RAN and WD8INC that is close - but it's 
neither military nor Russian, nor most likely aviation-related. The 
missing crystal would confirm the output frequency but while it is 
likely VHF, even though the inductors in the PA area looks more like UHF 
to me.    The PA tube is almost certainly a 6360 since the balanced 
inductors and butterfly caps make it obviously a push-pull output stage, 
and the recessed socket mounting would be to accommodate the height of 
that tube, which is the only dual tetrode I can think of that fits what 
we see.

The application?   We believe this is an early industrial telemetry 
transmitter that transmits a unique identifier when triggered by some 
external event.   The markings around the edge of the cam switch may 
indicate "bits" that can be programmed by the user to create a unique 
pattern.   There is no modulator, the carrier is on-off keyed (OOK) just 
like modern-day temp sensors and RKE keyfobs do.  Since the 6360 can 
deliver 12 watts or more output up to 200 Mhz, this suggests that it was 
used in an application that required covering significant distances.  It 
would most likely be used at a location where AC power would be 
available to support this power level.

We've seen remote monitoring like this done on dams and weirs, 
irrigation systems, and valves, but a good bet would be that this device 
was used to monitor wastewater lift stations.   A typical city would 
have dozens of them, scattered over a distance of up to 10 miles, so 
having the unique identifier and sufficient power would be a must.    
These systems were also an early application for telemetry and SCADA 
because the cost of failure is high enough to justify such an investment.

73, Bob W9RAN