Tektronix 5T1A Instrument Reference Book page 11

TYPE 280 TRIGGER COUNTDOWN UNIT
The Tektronix Type 280 Trigger Countdown Unit allows
timing systems to be synchronized on frequencies up to 5
gigacycles. The Type 280 can be used to lower the fre-
quency of the triggering signals to within a range of 15
to 45 megacycles. This permits the triggering circuits of
timing systems to lock in solidly with a much higher input
signal frequency.
INPUT IMPEDANCE is approximately 50 ohms.
Type 280 Trigger
connected for use with
Timing Unit
EXTERNAL
—
Dual-Trace
Sampling
TRIGGER
Plug-In
Unit
INPUT
G3
c
INPUT
@)
Attenuator
ae
if required
aA
Connector
Signal Source
GR 874T
ee
hun
(50 2 Output Z)
Connector
30 Mc -5 ge
SYNC
INPUT
50 mv -4¥ a
Connector
Sync Output of Signal Source peuletospeok
INPUT FREQUENCY is from 30 megacycles to 5 giga-
cycles.
INPUT SIGNAL RANGE is 50 millivolts to 4 volts, peak
to peak.
OUTPUT REPETITION is continuously variable from 15
to 45 megacycles.
FAST RISE TRIGGER OUTPUT (terminated in 50 ohms) is
150 millivolts, with
less than 0.4-nanosecond
risetime, decay-
ing with 2-nsec time constant, (for use with Type 511, 5T1A,
or 3177).
Countdown Unit
Type 661 Oscilloscope
Typical application of the Type 280 and Sampling Oscillo-
scope is in microwave research and design.