Control transformers do have 3 windings on both the stator and rotor.
They are used to do offsets in a system. They are installed in the 3
stator lines between the transmitter and receiver. The 3 transmitter
stator lines would connect to the 3 stator lines of the control
transformer. The 3 stator lines to the receiver would then connect to
the 3 rotor lines of the control transformer. Reversing stator and rotor
line sets on the control transformer will accomplish the same thing.
When the control transformer shaft is turned it will offset the receiver
shaft by the same number of degrees that the control shaft has been
turned. This is while the transmitter shaft remains stationary. Once the
control transformer shaft has been locked then the receiver will follow
the transmitter position with the offset provided.
A practical use for it would be to calibrate the rotator position
indication system by just turning the control transformer shaft the
proper amount. It will then provide a permanent offset between the
transmitter and receiver.
A control transformer can't be used as a transmitter or receiver unless
you have a 3 phase signal to supply to it as a reference.
There is a difference between a transmitter and receiver. The receiver
has some damping on the shaft so that it does not oscillate by itself.
This can easily happen when there is no resistance to it's rotation as
in a compass indicator. Other than that they are much the same.
400 hz units can work on 60 hz but you have to reduce the voltage quite
a bit. They will then have much less torque. There have ben some
articles in QST? in the past about doing this.
Dubovsky, George wrote:
> If I recall correctly, the Control Transformers are the least useful of
> all the Selsyn stuff. I think they are three-phase on both rotor and
> stator, but I can't remember why. I have hooked them up using just two
> terminals on either the rotor or stator (can't remember which now), and
> all three of the other, and they _DID_ work, but with piss-poor torque -
> definitely good enough for a rotator direction indicator though.
> If the "Generators" are the same as "transmitters", two of them will
> work great together. As Jim Lux commented, TX and RX units seem to be
> identical as far as we are concerned. If all else fails, at home I have
> a copy of a Navy Tech Manual (that Fair Radio used to sell) on Servo
> Systems, and it covers a lot of this stuff; I can copy parts of it if
> you need it. Good luck...
> geo - n4ua
>>From: firstname.lastname@example.org [mailto:towertalk-
>>email@example.com] On Behalf Of Andy Bazar
>>Sent: Monday, August 29, 2005 7:40 PM
>>To: firstname.lastname@example.org; email@example.com
>>Subject: [TowerTalk] Looking for a pair of selsyns for an old Telrex
>>Hello Charles Johnson,
>>I found a wooden box full of these items while walking
>>my dogs today along the street. There are model
>>2J1G1, Selsyn Control Transformers and 2J1F1 Selsyn
>>Generators of various condition in the box.
>>I came across your note when looking for information
>>on how to connect these units and use them for
>>I will trade you a couple units plus shipping cost for
>>some information on how to use them and how to deal
>>with the fact that they are 400 cycle units if you are
>>interested. I was going to see what happened using
>>lower voltage 60 cycle on a set but won't do it till I
>>hear from you first. I suspect that might result in a
>>funeral party for both of them.
>>I presume that one way to use them is to connect all
>>the same terminals of one unit to the other unit and
>>then apply 57.5 volts ac at 400 cycles across the R1
>>and R2 terminals and find that turning the shaft of
>>unit #1 will turn the shaft of unit #2 a corresponding
>>If you are interested, let me know. I did find some
>>application information on them but nothing very
>>detailed and nothing which got into the reason why
>>these particular units were 400 cycle. I suspect that
>>would improve their resolving accuracy but that's
>>purely a guess.
>>I thought that I might be able to use them as a wind
>>direction indicator or perhaps a rudder angle
>>indicator for my sailboat.
>>Do You Yahoo!?
>>Tired of spam? Yahoo! Mail has the best spam protection around
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>>any questions and ask for Sherman, W2FLA.
>>TowerTalk mailing list
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Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
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