[time-nuts] HP ET2702 5 MHz distribution amplifier
daun at yeagley.net
Thu Jun 30 21:56:31 EDT 2005
The "ET" designation was generally used for production test, special demo boxes,
or other similar uses. My guess is that it was an "in house" unit, and using
what was called the "next bench syndrome" may have indeed been the inspiration
for the regular production amps.
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
Behalf Of Bob Voelker
Sent: Thursday, June 30, 2005 4:15 PM
To: time-nuts at febo.com
Cc: pickypicky101 at yahoo.com
Subject: [time-nuts] HP ET2702 5 MHz distribution amplifier
Does anyone have any information, specs, or
history of the HP ET 2702 5 MHz distribution
I suspect that it is a very rare unit,
based on the "ET" model number prefix.
Could it be the predecessor of the
HP 5087A distribution amplifier?
I have neither the HP 5087A nor its
manual, so here are notes on my
ET 2702 for comparison:
-One 5 MHz input and ten 5 MHz outputs,
all on rear panel.
-Front panel has 13 labeled holes for
inserting a screwdriver to adjust the
gain of each of the 13 amplifier
-Front panel pushbutton power switch has
a guard to prevent accidental shut-off.
-Cabinet almost same size as HP 5087A,
except for being 5 inches high.
-Traditional 1960's HP blue color scheme
-Serial number plate on rear does not
use the usual HP 1960's or 1970's-on
format. The number suggests 1968.
-Components inside are date-coded 1968.
-Inside, there are 13 unmarked, seemingly
identical, fully-shielded amplifier
modules of roughly 4 x 2 x 2 inches in
-Architecture consists of the output of
the first amplifier driving the parallel-
connected inputs of two following
amplifiers, and these amplifiers in turn
each drives five amplifiers, providing
ten outputs that go to the rear panel.
-Each fully-shielded amplifier module has
two parallel-connected SMB input jacks,
one BNC output jack, and one gain-adjust
-Each amplifier module contains two
cascaded 2N708 NPN BJT common-emitter
amplifiers with the collector of the
second stage loaded with a tuned-primary
transformer. The transformer's secondary
-The PCB inside the amplifier module is
labeled "05060-6023", suggesting that it
might be related to the HP 5060A cesium
Thanks for any info,
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