PTS Frequency Synthesizers

© Brooke Clarke 2012

PTS160 Frequency
          Synthesizer
Background
Description
    Photos
Model Numbers
Related
Links

Background

Programmed Test Sources makes a number of frequency synthesizers that can be remotely controlled. There are a number of variations all based on the same modular design.

Description

This was purchased on eBay for a very reasonable price.  It turns out because it has no output.
I've heard from another PTS 160 owner that the internal 10 MHz oscillator may not be working and using an external oscillator may fix it.

Power Supply

The power supply has outputs of +5 (5.367) and -12 (-12.39).

Function

PTS 160 Functional Schematic

SGA

The SGA module contains a 10 MHz oscillator and has provision to use an external 5 or 10 MHz input.  It Generates outputs of: 10, 18, 20, 22, 33 MHz and a comb (picket fence) of frequencies between 10 and 140 MHz with a spacing of 10 MHz.

SGB

Uses the comb output of the SGA module and generates outputs of: 14, 16, 33, 112 and 113 MHz.  The outputs of the SGA and SGB modules supply the reference frequencies used by most of the outer modules.

DM

The Digit Module is used for all the decades starting from 100 kHz and down to the lowest step size.  The lowest step size module is the first in the chain and is fed by the 14.0000000 MHz reference.  It has an output of 14.n00000.  Where n is the value between 0 and 10 of the switch or remote input for that decade.  The next highest DM module has an input of 14.x0 and an output of 14.nx where n is the input control data.

DMA

This is always the 1 Mhz decade.  It works like the DM module but has an output that's in the 140 to 150 MHz range. It feeds the Intermediate Mixer (IM) module.

SO

The Step Oscillator contains a VCO that tunes in 10 MHz steps over a range of 160 MHz (100 & 10 Mhz dials).  It feeds two mixers.  One of the mixer outputs is passed through a 505 MHz narrow band filter (black box in photos with tuning lock nuts) to the IM module.  The IM module combines the 505 MHz signal and the 140 to 150 variable frequency from the DMA module to generate a signal in the range of 355 to 365 MHz which is fed back into the other mixer in the SO module generating an output of 0.1 to 160 MHz.  This signal is fed to the Output Amplifier (OA) module.

OA

The Output Amplifier module contains a filter power amplifier (+13 dBm max) and a variable attenuator.

Photos

Fig 1 Front Panel
PTS 160 Frequency
                Synthesizer
Fig 2 Top Inside
PTS 160 Frequency
                Synthesizer A1 is the Output Amp (OA)
A2 is the Intermediate Mixer (IM) module
A3 is the Step Oscillator (SO) module
100 MHz is really the SGA
10 MHz is really the SGB
1 MHz is the DMA
100 kHz and 10 kHz are DM modules
More DM modules could be added to get finer frequency steps.
Fig 4 Rear Panel
PTS 160 Frequency
                Synthesizer
Fig 3 Bottom Inside
PTS 160 Frequency Synthesizer
Fig 4 SGA PCB
PTS 160 S2N1X SGA
                PCB
The problem is with the xtal oscillator.
It's powered by the -12.4 DC rail and when the voltage
is between 12.5 and 14 there's an oscillation around
500 kHz, far from the expected 10 Mhz.  Maybe the
McCoy crystal is bad.  Need to check my parts bin.

-------------------------
The McCoy 10 MHz crystal in the Crystal Activity
Meter
shows good operation at 10.00 MHz.
PTS 160
                Crystal from SGA PCB tests OK
Fig 5 SGA schematic (the 10 MHz oscillator part)
PTS 160 SGA 10
                MHz Oscillator schematic


Q5 and Q4 are the comb generator who's output
is at the junction of R22, R23 & R24.









Q6 is a buffer amp for the 10 MHz output.






Q7 is the 10 Mz oscillator and acts as a doubler if
the input is 5 MHz.

Model Numbers

1st Three Digits

The digits after PTS are the upper frequency limit in MHz, so the model number PTS 160 S2N1X has an upper frequency limit of 160 MHz.

1st Letter

The first letter after the upper frequency digits describes the method of setting the frequency, the output location and cabinet style.

Letter
Control
Output
Cabinet
M
Switch & Rem
Front
Rack
S
Switch & Rem Rear
Rack
D
Keyboard/LCD & Rem
Front
Rack
R
Remote only
Rear
Rack
B
Switch & Rem Front
Bench
U
Switch & Rem Rear
Bench
V
Remote only Rear
Bench

Resolution Character Code

Code

0
na
1
100 kHz
2
20 kHz
3
1 kHz
4
100 Hz
5
10 Hz
6
1 Hz
7
0.1 Hz
H
DDS 0.1 Hz
J
DDS 1 Hz
K
DDS 0.1 Hz
8
na
9
na

Internal Frequency Standard Code

Code
Type
/day
/year
O
OCXO
3E-9
1E-6
T
TCXO
1E-8
2E-6
N
None

Power Supply Digit

Frequency can be anywhere between 50 and 400 Hz.

Digit
Voltage
1
120
2
120/220
3
120/240
4
na
5
120/100

Miscelaneous Options Code

Code

A
Prog Atten
C
Comb output
D
1 MHz input
E
Extra 10 MHz outpts
F
Filtered Comb or Int Aux Freq
FM
Filtered Comb & Dual 10 Mhz out
G
GPIB
L
Delta Output
M
Dual 10 MHz out
O
No Options
P
90 deg Phase shifter
Y
Phase Rotation

Rack Slides
X-6
Rack handels removed
X-8
DDS-TLU overrange
X-26
DDS load strobe

Related

Time and Frequency
HP 8648A Signal Generator

Links

Back to Brooke's Products for Sale, Test Equipment, Microwave Test Equipment, Military Information, Electronics, Personal Home page

page created 4 July 2012.