The Heathkit IG-18 Sine-Square Audio Generator

In this video, we'll take a look at a piece of vintage Heathkit test
equipment, the IG-18 Sine-Square Audio Generator. I'll discuss the
history and features of the instrument, and we'll look at the front
panel controls and inside circuitry. I'll discuss the restoration of
this particular unit, and say something about the circuit design it
used. We'll see a demonstration of the generator in operation, and
then wrap things up with a summary.

[@davewhittaker9547]

Great video Jeff; very clear and concise. Thanks for creating and posting it.

[@reinaldomaldonado4969]

Thanks for the video. I bought and assembled this audio generator in 1986, and it still works like the first day. I am trying to repair a Heathkit IO-4210 oscilloscope, with problems with the power transformer, by the high voltage coil.

[@ticklemeelbow]

may seem like a silly comment but I've had luck removing tape residue with Ronsol Lighter Fluid. Dab some on a q-tip and rub gently. It dissolves the adhesive with out damaging the paint. This will also work to remove adhesive, such as stickers, from paper, such as record album covers. love your videos. thanks so much.

[@wa4aos]

Hi Jeff, Thanks for another EXCELLENT review of Heath gear. Your videos are well done, explained very well and helpful to those of us who enjoy using this vintage test gear. vry 73, Glenn WA4AOS

[@thetrafficshop]

Awesome review. You have an extensive knowledge on this topic. Thanks again.

[@cheezhead6007]

Very thorough ,,wonderful job my friend

[@TechBrant]

Excellent video.

[@judges69]

Thank you for the info, I just bought one in good condition.

[@JohnHoranzy]

Thank You for posting.I inherited one of these from my late Uncle who was a Ham Radio Operator. So this is worth fixing up. There seems to be a a large amount of ringing from the edge of the square wave spilling over to the Sine wave and both signals look like fuzzy caterpillars.

[@jefftranter]

I'd start checking the power suppy voltages and filter caps.

[@JohnHoranzy]

Thanks for showing me the potential of this Sig Gen. It turns out that there is lots of HF line noise coming through the AC mains from 2 switching power supplies and a plug in power block from an LED lamp. They are all plugged into the same power strip. All the fuzz goes away when these are turned off. There is still about 5 Mv noise at 65Khz and 3.4Khz. Switching power supplies were just theoretical things when the Coast Guard taught me to maintain its Navy hand me down Avionics from WW2. So setting up my lab is a learning experience. The Rigol DS1054Z is an amazing scope for being able to catch all this.. There is a 1.5Hz amplitude modulation on the sine wave with the multiplier knob in the X1 position but that should be easy to trouble shoot. There is also a small bit of distortion at the bottom of the sine wave but that is probably an alignment exercise. Now I Have to figure out how to get clean power for my equipment. I will not be working on RF or Audio, just digital and CNC equipment but it is still good to know ones equipment limitations. This mostly taught me about how dirty mains power is and that it needs to be constantly taken into account. Up next is an EICO VTVM my father built and a Heathkit RF Sig Gen buried somewhere in storage.

[@captlarry-3525]

All the gear in this I series is great stuff... very reliable and just plain good. If you have a receiver that uses a 50 KC IF Filter... like National or Hallicrafters, or Drake from the 1960's..( Drake 2B, National NC-270, Hallicrafters SX-117 You are going to need this for it's frequency accuracy, stability, and calibrated output. I have all 3. If you want to KNOW what the frequency response of your AM transmitters so-called Hi-Fi Mods really are.. you are going to need this. I am amazed at how many hams do "hi-fi" audio mods to thier transmitters.. but have No Way To Testing the Results... which explains some of the horribly goofy values of caps I see suggested !

[@charleshoward9944]

Thanks for the video. I have one of these and I am having the same problem with oscillation. Can you do a video on how to calibrate the unit. Thanks....

[@randomscience4k]

Hi Jeff, I got one of these off eBay for like $38 and it kinda works fine. After powering ON the voltage takes a few minutes to stabilize. I think its probably due to the 35V caps and the other that probably needs to be replaced. But the RMS Voltmeter glass on the panel was slightly and the meter hairspring was damaged. I tried to resoldering it, it was a real pain but even then the meter showed open circuit. I had a few panel meters used to show voltage on these old servo voltage stabilizers that I collected a while back. But I need to find the resistance of the original RMS meter to install the new meter mechanism on the Heathkit. Could you please let me know what is the resistance of the panel meter? The new meter coil I've shows a resistance of 395 ohms.

[@jefftranter]

The meter in my unit has a resistance of 1381 ohms.

[@randomscience4k]

@@jefftranter Thanks for the info! So, I added a 1000ohm resistor in series with the new meter(put the new meter assembly inside the old meter case such that it looks like the original). But even then the voltage reading on the meter never goes beyond the 2V range. I do get 9.5V at 10V sine range and fine tune to highest setting. So voltage output is fine.its the meter that is faulty. What do you think I should be potentially looking ?

[@darrenclark6552]

I don't suppose you have the schematic?

[@noritasorenson8400]

Can these instruments be used medically?

[@jefftranter]

I can't think of any obvious medical uses, but they were not certified as medical devices and I would not want to use equipment of this age for any medical purpose as it may not be safe, either due to the original design or component failures due to age.

[@boycoter]

je devai achetre en 1977 le reveil les radio jai achetre heatkit metaldetector et bingo il a narche des la derniere soudure et rebingo t