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Transformer Terminal Designators

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korneluk

korneluk

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Joined 2005
#1
On an interstage transformer secondary, i.e. UTC A-19, what do the G and F terminal designators stand for?
TYVM,
 

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#5
B is B+
P is Plate
G is Grid (pushpull grids)
G is Grid (pushpull grids)
F is either ground or bias reference point if fixed bias is used
F is either ground or bias reference point if fixed bias is used

Plate current: 8mA rated (stay around 6mA for best performance IMLE)

Primary Z: 15K
Secondary Z grid to grid: 80K

Approximate ratio: 1.0 : 1.15 + 1.15

40Hz - 20kHz +/- 2dB (often better)

http://www.bunkerofdoom.com/xfm/UTC_1960_WEB/036.jpg

Bunker of Doom has all the skinny on these and a lot of other transformers.
 
#7
DF96 said:
Could be. If it was intended for driving zero bias Class B DH P-P outputs then that would make sense.
Click to expand...

It's a phase splitter IST. For driving Class B2 triodes (especially) or even pents, you want a voltage (impedance) step down ratio to minimize the driving impedance. This one has a voltage step up of 2.31 : 1 (whole sec/pri).

It's also specced at 15dbm, and that translates to 31.62mW -- way too low to drive Class B2, triode grids. That won't even do for pentode loads, as, for example, Class AB2 operation of the 807 (not a particularly hard load) needs 100mW of grid drive.
 
#10
It was one of a series that were designed for driving typical pentodes in P-P class A or AB1. I have one or two lying around from the series that I pulled from commercial audio equipment built in the late 50's or early 60's. I think mine are for driving 600 ohm twisted pair lines.
 
#11
No class B due to very limited power handling.. These could used with pushpull 2A3/45/6L6/EL34/EL84 and all sorts of other types. It is a very generic pushpull driver transformer. I'm quite familiar with a number of the members of this family. Common in pro communications, recording and broadcast gear.
 
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