[BC] Re: Copper program Loops

[Thomas G. Osenkowsky]

Bob raises excellent advice here. At one new NCE install
in CT we suffered three blown PGM output modules in
R-60 consoles by driving underground copper pairs
directly with only 111-C's at the tx end. Great freq response,
however whenever there was lightning in the area the
surface mount 5532's got zapped. Placing two 111-C's
at the send end solved those failures. As a matter of fact,
the AirTools profanity delay got zapped too before I used
coils at both ends. The run was direct and under 1000 feet.

Tom Osenkowsky, CPBE

> A word about driving those long loops. Whatever you use to drive long, un
> amplified telephone circuits care must be taken in choice of driver
> amplifier. I would use a good quality low impedance driver for these
> circuits. I would not try to drive them with a typical analog console with
> mere 5532s in the output stage. They will run out of current in a hurry
and
> will have slew limitations too. You are driving a big long inductance with
> distributed capacitance and older consoles had good totem pole push pull
> discrete transistor drivers that could do the job nicely.