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Heathkit IG-42 Laboratory Generator – First Look


Heathkit IG-42 Laboratory Generator – First Look

A friend and colleague of mine asked me to take a look at his Heathkit RF Signal Generator: IG-42.  The only information I got from him about it was that he had inherited it from a good friend, and had not had much luck using it.

Here we will make our initial inspection of the unit, and try to get a feel for what work might be needed to restore it to a useful condition.

Front View as received

The front panel is in pretty good shape, with just a few flaws:

There is some writing or marks above the meter.
There is a paint chip or scrape to the left of the frequency pointer.
All of the controls are functioning, nut the knobs on some are loose.

Front Panel

The cabinet has a pretty good sized dent on the top left side, and it is generally dirty and looks like it might have an oily residue on it.

Cabinet Top

After pulling the cabinet off, we find that the chassis is a bit dirty on the inside, with some pitting in the plating over most of the chassis.  Someone has fashioned a screened compartment for the amplifier tube out of what looks like brass.  They did a pretty nice job. The electrolytic can has some corrosion on top.

Top View

The Audio Amplifier and Regulator tube compartment has many paper capacitors which should be replaced.

Top View 2

The Audio Amplifier and Regulator tube compartment has many paper capacitors which should be replaced. 

Audio and Regulator Tube compartment

The function and meter switches are in the same compartment.

Function and Meter Switches

It looks like most of the coupling capacitors are all on two terminal strips – maybe to make troubleshooting easier?

Terminal Strips J & K

The generator uses a selenium rectifier – we may want to replace this, I’ll have to look into it.  But it has survived 40 or 50 years already…

Selenium Rectifier

The oscillator section and attenuator sections are very nicely shielded.  This should make for a good non-leaky system for the bench.

Rear View – Oscillator Compartment


Coarse Attenuator

The oscillator is a little cramped…

Coarse Attenuator

 The oscillator is a little cramped…


The fine attenuator is located inside the oscillator compartment.

Fine Attenuator

And, there is a nice line filter to keep squigglys off the line…

Line Filter

And, it even came with a schematic…

IG-42 Schematic

Here is the checkout as it happened…



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