[Dept. of Computer Science]

Precise 630 Signal Generator

Our Department and University.
See my radios too! (Here is the next item.)

Data for this object
Type Precise 630, Signal Generator
RF Bands .3-1, 1-3, 3-10, 10-30, 30-100 Mc.
AF Bands 20-40, 40-200, 200-2k, 2k-20k Hz.
Cabinet Metal, 28x23x12cm, carrying handle on top.
Tubes 6X5GT (EZ35), 6SN7GT (ECC32), 6AU6 (EF94),
6C4 (EC90), two dial lights.
Controls RF tune, AF Tune, RF Band, AF Band,
Output, Mode (CW/AM/Ext. Mod/Xtal/AF),
RF level, AF level.
Produced By Precise Development Corp., Oceanside, N.Y.
(USA), July 1953.
Condition Very good; it is in regular use on my workbench.

Usage of a Signal Generator

Despite the suggestion implied by the name of this object, it is far from a precision instrument. In contrast, it is a portable cheapo that could be carried by repairmen to the costumer's home so it had to be light and no large investment should be required.

But even then, as a tool for testing and repairing old radios it comes very handy; it generates AF and RF unmodulated signals, as well as modulated RF signals. Here are some of the things I use the generator for:

(1) The AF signals are used to see if the AF section of a radio works; the signal is then connected to the control grid of the ouptut tube or the pre-amplifier.
(2) I also use the AF signal for my homebrew
RC meter.
(3) If a radio is silent I feed a strong modulated RF signal to the radio to find out if it is really dead or just a little deaf.
(4) If the radio is really dead I feed a modulated signal of the Intermediate Frequency to the antenna terminal to find out if the silence is due to a failed local oscillator. If the oscillator is the cause of problems, an IF signal fed to the antenna is audible in the speaker.
(5) If the local oscillator is defect I feed an unmodulated RF signal to the mixer to replace the oscillator and find out if repairing the oscillator will bring back sound.
(6) With a modulated signal at the intermediate frequency the IF transformers of a radio can be adjusted.
(7) To receive Single Side Band stations on a BFO-less receiver like the Pye, I generate the IF and feed it to the radio together with the antenna signal.

Some things I don't do with this generator:
(1) Test LW reception; this (American) generator doesn't cover the Long Wave frequencies.
(2) Adjust the Local Oscillator and Radio-Frequent circuits; because of the limited precision of the generator I prefer to use broadcast stations for this purpose.
(3) Check for distortion in audio circuits; the shape of the output of the generator is way too irregular to allow for this application.

Gerard Tel, gerard@cs.uu.nl