[GreenKeys] Teletype REC11 Rectifier "is NOT suitable for use in the signaling ... circuits of Teletype apparartus"

[Jim Haynes]

I'm not sure about the REC-11.  I know some Model 19 tables are wired to 
use the same rectifier for running the punch and for loop supply.  My 
guess is that the output voltage of that particular model might vary too 
much during punching to be satisfactory for a loop supply.  It might be
satisfactory for a local test loop but not for a situation where online
signal quality is not so good.  Maybe you could pout an oscilloscope on
the output and see how much the voltage varies as tapes are being punched.
Or connect a voltmeter to the output and hold the punch magnet contacts
closed and see how much the voltage drops.  But you probably should not
hold them closed very long since they are not meant to be run that way.