Message:20225 In: TECH.WW

From: G8MNY
Date: Sat, 04 Apr 26 09:06:00 Z
Newsgroups: TECH.WW
Subject: Systron Donner 115 Pulse Gen
Message-ID: <56365_GB7CIP>
Path: K7EK|VE3CGR|GB7OSW|GB7BED|GB7YEW|GB7CIP

R:260404/0912z @:K7EK.#NOKY.KY.USA.NOAM $:56365_GB7CIP
R:260404/0911Z 73813@VE3CGR.#SCON.ON.CAN.NOAM LinBPQ6.0.25
R:260404/0911Z 39578@GB7OSW.#16.GBR.EU LinBPQ6.0.25
R:260404/0911Z 9309@GB7BED.#21.GBR.EU LinBPQ6.0.25
R:260404/0911Z 16479@GB7YEW.#79.GBR.EURO LinBPQ6.0.24
R:260404/0906Z @:GB7CIP.#32.GBR.EURO #:56365 [Caterham Surrey GBR]

From: G8MNY@GB7CIP.#32.GBR.EURO
To : TECH@WW

By G8MNY (Updated Aug 20)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)

I bought one of these pulse generators at a rally (it matched my RF sig gen).
It is a 19" 2U rack unit with yellow panels and side carrying handles.

FRONT PANEL
RATE DELAY WIDTH + Out Levels - Out
___________________________________________________________________
� ��Ŀ �
� � ( ) �� ( ) � �
� � (O) (O) (O) ��
� � ��
� � [ �] [� ] [ �] ( ) �� ( ) � �
� �----------------------------------------------��-----��--------� �
� � (�) 0 (�) (�) � o � (�) � (�) � � �
� ��
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Ext Enable Sync Power Base + Comp - Base
In In Out Gnd Out Out Gnd

SPECIFICATION
It generates signals from 0.5Hz - 25MHz, 8 decade variable timebase RATE.

Pulse Delays & Pulse Widths from 100nS - 5S, 8 decade variable.
As well as fixed ratio square wave (to 25MHz).

It has 3 main controls, RATE, DELAY, & WIDTH.

There are 2 inputs for triggering and pulse enable.

There is a 50ohm 2V pulse sync output for locking up to the start of the
pulse/delay.

The two BNC 50ohm outputs give +/- pulses and can be switched to complementary
(invert pulse sense). The outputs have switched & variable high power output
attenuators (2W) to give 5V, 2V, 1V, & 0.5V terminated, as well as optional DC
offset +1 to - 5V. (e.g. offset the 0 & -5V pulse to +5V & 0V)

PULSE SHAPES
Single Pulse Mode Double Pulse Mode
Sync Pulses at +2v
Repeat RATE ___�___________�___________0v ___�_____________�_________

DELAY time ��ĳ ��ĳ ��ĳ ��ĳ

WIDTH time �ĳ �ĳ ��
�Ŀ �Ŀ+5V ڿ ڿ ڿ ڿ
+ve Pulse ______� �_________� �_0v __��__��________��__��___

-ve Pulse ��Ŀ ��Ŀ ��0v �Ŀ��Ŀ��Ŀ��Ŀ��
�_� �_�-5v ��

INSIDE
There are 2 large PCBs filling the whole unit, one has the PSU for 3 power
rails 5V & �15V & all the pulse generator electronics.

heatsink
____��________.-----._
� +5V +15V -15V | DC -*� Trans- �
� V* | corr- � former �
�(�)() () () |ection �_________� V* = set +15V
� P S U | bias � '-----' � -* = set -ve pulse -5V ref
� | amps ~~~~~~~~~� 0* = set -ve pulse 0V height
� | +* 0* � +* = set +ve pulse 5V height
� Pulse Generators | +ve -ve � F* = set Max rep frequency
� | Pulse Pulse � D* = set shortest delay time
� F* D* W* | amp amp � W* = set shortest width time
� [ ] [ ] [ ] | �
� �� | -load +load �
� _�_ _�_ _�_ | DC amp DC amp �
��

The 2nd PCB has a very complex pair of current limited output amps using 16
heatsinked HF pulse transistors and 5 DC correction op-amps for each of the two
50ohm outputs.

USES
Scope calibration of attenuators as the pulse shapes have very wide bandwidth.
Coax cable testing, and demonstrating pulse shape-spectrum on spectrum
analyser, clearly shows why digital QRM is so bad!

FAULTS
Initially it all appears to be working, although a main smoothing capacitor had
been poorly replaced. Systron Donner kit often fails with main smoothing going
open circuit (been there done that!)

The -ve output occasionally has a DC fault, eventually proved to bad PCB
soldered link throughs on the +15V rail to the DC load amp, on this complex
variable/floating output amp biasing.

See my buls on "A Versatile Pulse Tester", "Spectrum Harmonic Demo circuit".
"Variable RF Attenuator" & "Systron Donner 1702 SIG Gen".

Why don't U send an interesting bul?

73 De John, G8MNY @ GB7CIP

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