PG505: Difference between revisions

PG505 (view source)

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 |discontinued=(?)
 |designers= |manuals=
-* [[Media:070-1583-01.pdf|Tektronix PG505 Manual]] (OCR)
+* [[Media:070-1583-01.pdf|Tektronix PG505 Manual 070-1583-01]]
+: '''''See erratum'''''
 }}
 The output section is isolated from chassis ground and can float up to ±200 V.
 {{BeginSpecs}}
-{{Spec | Period          | 10 μs to 100 ms in decade steps, one custom position, variable control ×1 to ×10 }}
+{{Spec | Period             | 10 μs to 100 ms in decade steps, one custom position (≥10 μs), variable control ×1 to ×10 }}
-{{Spec | Pulse width     | 50 ms to 5 μs in decade steps, one custom position, variable control ×1 to ×10 }}
+{{Spec | Pulse width        | 5 μs to 50 ms in decade steps, one custom position (≥5 μs), variable control ×1 to ×10 }}
-{{Spec | Rise/Fall times | 1 ms to 1  μs in decade steps, variable control ×1 to ×20 }}
+{{Spec | Rise/Fall times    | 1 ms to 1 μs in decade steps, variable control ×1 to ×20 }}
-{{Spec | Amplitude       | ±4 to min. ±80 V into 4 kΩ  }}
+{{Spec | Amplitude          | ±4 to min. ±80 V from a 4 kΩ source, floating up to ±200 V to chassis ground (with grounding strap removed, see note) }}
-{{Spec | Trigger output  | min. +4 V into 10 kΩ / 3 V into 600 Ω, same duration as output }}
+{{Spec | Duty cycle         | min. pulse width to 99% }}
+{{Spec | Input              | Delay, 0 – 10 V; Ext. Duration, ≥0.5 V (TTL) active; ≥10 kΩ }}
+{{Spec | Gate input         | +5 V to inhibit free-running rate generator (rear interface only) }}
+{{Spec | Trigger output     | min. +4 V into 10 kΩ / 3 V into 600 Ω, same duration as output }}
 {{EndSpecs}}
@@ Line 23: / Line 27: @@
 {{Documents|Link=PG505}}
 {{PatentLinks|PG505}}
+===Notes===
+* '''''Manual erratum:''' In manual 070-1583-01, Fig. 4.3 Output Delay Range Check (p. 4-5), the PG 505 connections are drawn correctly but the connector labels are swapped – the left connector fed from the FG501A via the BNC "T" is the Delay/Duration input, not the output.''
+* The PG505 is shipped with the output connector ground connected to chassis ground through a removable ground strap.  This must be cut/removed to float the output, in which case output common remains grounded through a 100 kΩ resistor (R545).  The manual says this resistor may be removed but doing so causes unspecified "degradation of performance".
+==Operation==
+The main controls are a pair of concentric switches for pulse period and pulse duration, with the latter mechanically limited to prevent the duration range to be set higher than the period range.
+In the leftmost position of the duration switch, the output is locked in its "on" state so that the amplitude can be set conveniently with a DC voltmeter attached to the output.
+The second-rightmost position of either switch is reserved for a custom period or duration that is defined by an optional, customer-installed capacitor for each.
+Two pairs of test point lugs on the circuit board (near the cam switch cover) are provided to install these capacitors.
+In the rightmost position of the period switch ("OUTPUT DELAYED"), the rate generator is disabled.
+The signal on the Delay/Ext Duration input, assumed to be a positive-going 10 V ramp, is compared to the setting of the Output Delay potentiometer.
+When the ramp reaches the threshold, an output pulse of the set duration is triggered.
+When the duration switch is put in the rightmost position (which mechanically forces the period switch to the same), both the rate and duration generator circuits are disabled.
+In this "EXT DURATION" mode, the output simply follows the Delay/Ext Duration input
 ==Rear Interface==
@@ Line 28: / Line 50: @@
 * B24: Ext Delay In (9A/9B ground)
 * B24: Ext Gate In (9A/9B ground)
+Family key: Signal source (between pins 23 and 34)
+==Internals==
+The rate generator (free-running, discrete) and duration generator (a Fairchild 9601 TTL monoflop) are operating on the chassis-referenced power rails.
+A small toroidal transformer couples the generated pulse to the output section in the form of differentiated positive and negative pulses.
+On the floating side, a Schmitt trigger section restores the square pulse, which steers the output of a pair of current sources via a diode bridge into one of four switch-selected capacitors to create the variable rise and fall time.
+The output amplifier has a dual FET ([[2N3958]]) source follower input, with the switching threshold set by the Delay potentiometer.
+Two half-wave rectifiers, fed by the series-connected floating 25 V mainframe transformer windings, produce an unregulated floating supply of about ±65 V, from which regulated +48 V, +20 V, –10 V, –10 V, –20 V, and –48 V are derived.
+Depending on the selected output polarity, either +48 or –48 (less an adjustable component) V is referenced to output ground.  The push-pull output stage therefore has about 96 V supply available.
+The output is short-circuit protected by a fixed 4 kΩ series resistor.
 ==Prices==
@@ Line 33: / Line 68: @@
 |-
 ! Year
+! 1974
 ! 1975
 ! 1980
+! 1982
 |-
 ! Catalog Price
+| align="right" | $265
 | align="right" | $295
 | align="right" | $550
+| align="right" | $840
 |-
 ! In 2024 Dollars
+| align="right" | $1,700
 | align="right" | $1,700
 | align="right" | $2,100
+| align="right" | $2,700
 |}
 ==Pictures==
 <gallery>
+Tek pg505 front1.jpg
+Tek pg505 front2.jpg
+Tek pg505 rear.jpg
+Tek pg505 top.jpg
+Tek PG505 circuit_board.jpg |
+Tek PG505 output.jpg        | Output connector – not ground strap (to chassis lug)
 Tek pg505 1.jpg
 Tek pg505 2.jpg
 Tek pg505 3.jpg
 Tek pg505 4.jpg
 Tek pg505 5.jpg
 Tek pg505 6.jpg
 Tek pg505 7.jpg
-Tek pg505 front1.jpg
-Tek pg505 front2.jpg
-Tek pg505 rear.jpg
-Tek pg505 top.jpg
 </gallery>
 ==Components==
 {{Parts|PG505}}