[time-nuts] Spectracom 8140T distribution amps

John Ackermann N8UR jra at febo.com
Sat Apr 22 10:07:39 EDT 2006

Does anyone on the list have any specs or manuals for the Spectracom
8140 distribution amplifiers?  While I'd like schematics, I'm
particularly interested in how many of them you can put in a single chain.

For those who aren't familiar, these are part of a frequency
distribution system where there is a master coax line that carries 10MHz
on top of 12VDC.  You attach multiple 8140T boxes along this line (with
BNC tees) and each one provides a single output, usually a sinewave but
there were versions that did frequency conversion, output a square wave,
etc.  There was also a multiple version (8140M I think) that provides
three square wave outputs and can be externally powered.

These make a nice way to route signals around the lab.  They were
designed to work with a box (just plain 8140, I think) that took a
single input and could drive up to 4 strings of amps.  Also, my 8164
WWVB-disciplined oscillator has an option installed that put 12 volts on
its outputs.

Right now, I'm driving it from my slightly modified HP 5065A Rb
standard; I tapped the signal off before the divide-by-2 (later model
5061As and 5065As used a 10811A oscillator followed by a divider to
maintain a 5MHz output) and used a mini-version of the TADD-1 amplifier
with an injector circuit to put 12 volts on the output.  The original
5MHz is still available and doesn't seem to be affected.

Anyway, I'm just wondering how many of these amps I can string together;
right now I have 8 and it seems to work OK but I'm not sure if I'm
stretching things.



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