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G8MNY  > TECHNI   07.03.19 08:03l 102 Lines 4411 Bytes #999 (0) @ WW
BID : 61511_GB7CIP
Read: GAST
Subj: Systron Donner 115 Pulse Gen
Path: DB0FFL<OE5XBL<F1OYP<IR2UBX<IW8PGT<CX2SA<OK2PEN<GB7CIP
Sent: 190307/0656Z @:GB7CIP.#32.GBR.EURO #:61511 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To  : TECH@WW

By G8MNY                                (New Jul 13)
(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 & side carrying handles.

FRONT PANEL
        RATE       DELAY       WIDTH      + Out    Levels   - Out
 ___________________________________________________________________
³ ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿ ³
³ ³                                       ( )    ßß     ßß    ( ) ³ ³
³ ³     (O)         (O)         (O)              ßß     ßß        ³ ³
³ ³                                              ßß     ßß        ³ ³
³ ³ [ Ü]      [Ü ]     [ Ü]               ( )    ßß     ßß    ( ) ³ ³
³ ³----------------------------------------------ßß-----ßß--------³ ³
³ ³ (ú) 0     (ú)       (ú)      í  o      í    (ú)  í  (ú)    í  ³ ³
³ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ ³
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Ext     Enable      Sync    Power    Base    +  Comp  -    Base
    In        In        Out              Gnd    Out      Out   Gnd

SPECIFICATION
 It generates signals from 0.5Hz - 50MHz, 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 & pulse enable.

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

 The two BNC 50ê outputs give +/- pulses & 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 ___³___________³___________0v     ___³_____________³_________
 
DELAY time     ³ÄÄij       ³ÄÄij                 ³ÄÄij         ³ÄÄij

WIDTH time         ³Ä³         ³Ä³               ³³  ³³        ³³  ³³
                   ÚÄ¿         ÚÄ¿+5V            Ú¿  Ú¿        Ú¿  Ú¿
+ve Pulse    ______³ ³_________³ ³_0v          __³³__³³________³³__³³___

-ve Pulse    ÄÄÄÄÄÄ¿ ÚÄÄÄÄÄÄÄÄÄ¿ ÚÄ0v          ÄÄ¿ÚÄÄ¿ÚÄÄÄÄÄÄÄÄ¿ÚÄÄ¿ÚÄÄÄ
                   ³_³         ³_³-5v            ³³  ³³        ³³  ³³

INSIDE
There are 2 large PCBs filling the whole unit, one has the PSU for 3 power
rails 5V & ñ15V & all the pulse generator electronics.

          heatsink
 ____ÞÞÞÞÞÞÞÞÞÞÞÞÞÞÞÞÞÞÞ________.-----._
³     +5V  +15V  -15V | DC  -*³  Trans- ³
³         V*          | corr- ³  former ³
³(ú)()   ()     ()    |ection ³_________³    V* = set +15V
³           P S U     | bias  ³ '-----' ³    -* = set -ve pulse -5V ref
³                     | amps   ~~~~~~~~~³    0* = set -ve pulse 0V height
³                     |    +*        0* ³    +* = set +ve pulse 5V height
³ Pulse Generators    |   +ve     -ve   ³    F* = set Max rep frequency
³                     |  Pulse    Pulse ³    D* = set shortest delay time
³ F*    D*    W*      |   amp     amp   ³    W* = set shortest width time
³ [ ]  [ ]  [ ]       |                 ³
³ ÄÅÄ  ÄÅÄ  ÄÅÄ       | -load     +load ³
³ _³_  _³_  _³_       | DC amp   DC amp ³
ÀÄÄÅÄÄÄÄÅÄÄÄÄÅÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ

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

USES
Scope calibration of attenuators as the pulse shapes have very wide bandwidth.
Coax cable testing, & 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 soothing 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 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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