PTS Frequency Synthesizers

© Brooke Clarke 2012 - 2022

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.

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.