TM 11-6625-2980-14
To use this feature, place the DD 501 in the delay
interval mode of operation by moving the wire strap as
shown in Fig. 1-5 or changing connections, depending
on the DD 501 available. Connect the PG 508 and the
DD 501 as shown in Fig. 1-6. Use ten inch (Tektronix
Part Number 012-0208-00) or shorter cables for
interconnecting the two units to reduce delays.
Make certain the PG 508 TRIG/GATE IN input
impedance is set for 50 n. (See External Triggering and
Gating discussion and Fig. 1-2.) Set the controls of the
PG 508 for the desired output waveform with the PG
508 in FREE RUN. Do not use the SQ WAVE mode.
Place the PG 508 in the + SLOPE, SYNC GATE mode
and set the TRIG/GATE LEVEL control at the 2 o'clock
position. Select EVENTS + SLOPE, START + SLOPE
and place the EVENTS and START LEVEL controls at
the 2 o'clock position on the DD 501. The three TRIG'D
lights on the DD 501 and the TRIG'D/GATED light on
the PG 508 will be off until the DD 501 is triggered.
Upon receipt of a trigger, all lights will illuminate. If not,
check the setup and slightly adjust the LEVEL controls
as necessary.
Set the EVENTS DELAY COUNT on the DD
501 for one less than the desired number of counts up to
PG 508 repetition rates of about 20 MHz. See below for
further information. If necessary, a single trigger may be
obtained by rotating the DD 501 START LEVEL control
through the 0 position, with no external trigger applied. A
single trigger may also be obtained by using the
TEKTRONIX manual (One Shot) Trigger Generator,
Tektronix Part Number 016-0597-00. All other DD 501
and PG 508 operating controls function normally.
Due to propagation delays in the PG 508, DD 501
and the interconnecting cables, one or more pulses in
addition to the desired number are generated when the
PG 508 repetition rates are set between 20 MHz and 50
MHz. These extra pulses are consistent for any given
frequency irrespective of the desired EVENTS DELAY
COUNT setting. To determine the number of extra
pulses for a given PG 508 period, set the PG 508 and
the DD 501 controls as previously described. Now adjust
the PG 508 TRIG/GATE LEVEL or the DD 501 EVENTS
LEVEL for the same number of extra pulses at DD 501
EVENTS DELAY COUNT setting of zero and nine.
Fig . 1-7 . Typical propagation delays using PO 508 with DD 501 In counted burst mode at 50 MHz repetition rate .
1-7
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