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

[Paul Birkel]

Well, there's nothing about the physical appearance of the transformer
that's unusual (e.g. the expected dual-design of a ferro-resonant core with
a magnetic shunt) -- the laminations are the usual alternating Es with all
windings concentric in the usual "bobbin" configuration.  No name plate.
However there are some printed-on marks:  "P. E. CO.  Galion, O.  JUN 1957"
and the Teletype PN = 6500006.  All shellac-dipped (same for the choke).
It's all really an attractive example of industrial design of the first-half
of the last century.

That information corresponds to your historical observations.  I don't know
what to say; right manufacturer, wrong apparent design, right application.
Wish that I could find a circuit diagram explaining the usage/physics :->!
I'd say that it's a resonant circuit, just not ferro-resonant.

The accompanying oil-filled capacitor is a bit better marked:

    GENERAL ELECTRIC
    CAT  2 3 F 3 6 4
    10 u f  1000 VDC OR
    440  VAC  60 CYC
    71B1BG106K

According to
http://www.americanradiohistory.com/Archive-Catalogs/GE/GE-BT-250-A-Manual-1
948.pdf on page #21 it lists IC59 (see Fig. 13) as:

    Low-voltage Rectifier Filter.
    Pyranol, 10 mfd +-10%, 1000 VDCW.
    G-E Cat. #23F364, or equivalent.

Unclear what to make of the absence of the PYRANOL marking given everything
else marked on it.  Note that the referenced GE broadcast transmitter manual
dates almost a full decade earlier (1948) than this REC11 (1957).  GE may
have changed their "formulation" for this part in the meantime.

Mine is in quite fine shape.  Although EPA regulations apply regarding
proper disposal of PCB-contaminated materials/liquids, in the absence of
evidence of leakage (or imminent leakage) there doesn't seem to be any legal
requirement for replacement.  I was unaware of the likelihood of PCBs in
fluorescent lamp ballasts.  Something else to pay attention to when I get to
the point of replacing all of my legacy fixtures in the basement.

I imagine that others of us have similar oil-filled capacitors lurking in
heavy-iron equipment.  What have folks been doing about that?

I see that my filter-output capacitor is actually 200 MFD 200 VDC (SEP 13
1957), which is much better than the schematic/design-spec of 110 MFD.
Nice.

(Note that the accompanying documentation cited earlier identifies an almost
identical "REC19 Rectifier" designed for 25 cycle input.  According to
Wikipedia, at least in North America that would have been a special design
for industrial customers near Niagara Falls.)

-----Original Message-----
From: Jim Haynes [mailto:jhhaynes at earthlink.net] 
Sent: Monday, November 20, 2017 9:06 AM
To: Paul Birkel
Cc: greenkeys at mailman.qth.net
Subject: Re: [GreenKeys] Teletype REC11 Rectifier "is NOT suitable for use
in the signaling ... circuits of Teletype apparartus"

If there is an oil-filled capacitor then the REC-11 probably incorporates
a constant voltage transformer.  You might look on the name plate to see 
if the thing was made by North Electric Co. or Power Equipment Co. of
Galion, OH.  (North acquired PECo).  That was Teletype's favorite supplier
for rectifiers, and they were experts in constant voltage transformers.

They work on a principle sometimes called ferro-resonance.  However that
term has a completely different meaning in the electric power industry,
so constant-voltage transformer is a better term.  Constant voltage 
transformers are frequency sensitive, so they are rarely used in military
equipment which might have to be powered from a generator set in the 
field, hence not very good control of frequency.  Also you see speed
governed motors rather than sync motors in military equipment for the
same reason.

The Model 19 as used in the field by the military typically had a power
supply with thyratron tubes to regulate the voltage.  And some later ones
had magnetic amplifier control (saturable reactors)  I once had a
Western Electric power supply for a Model 19 that used a saturable
reactor, and used a couple of VR tubes as the voltage reference.