"Thyractors" on the DEC LT33 modified ASR33 Teletype

[vrs]

> I am currently modifying my Teletype ASR33 into a LT33 according to the
DEC
> specifications to work with my PDP-8/L. Does someone know what is a
> Thyractor (GE 6RS20SP4B4) ? Some kind of voltage clamping device ?.
> How could I make one, using, for instance a pair of thyristors or a pair
of
> zenner diodes ?

thyractor:
    "A marketing name by DAVIS, the thyractor was a combination of a low
loss choke (the reactor) and a thyristor."

I know NTE still markets a replacement for the 6RS20SP5B5 (but not the 4B4).
Unfortunately, I don't have the detailed specs for the 4B4.

On the other hand, I think it is just a handy voltage clamp to keep the
semiconductor circuits from seeing the inductive spikes from the TTY.
Shouldn't be too hard to come up with something else that would work.

    Vince