Rare 1973 Heathkit BUILD! Pt.5

Just a point that instability in amplifiers is often due to commoning of power and signal ground paths. -You did follow the recommended ground tie points for components in the signal chain? When this arises it can seem that switches and pots are faulty - a tiny change in resistance can cause oscillation to break out.

Looking forward for part 6. :-)

Heathkit - Griefkit. Never works the first time - but that's how we all learned electronics troubleshooting in the day.

Bruce Davis

I think the Noise switch is operating perfectly :)

Great to see your IT-12 passed the "magic smoke test" when first turned on. You're right when you say it wound't be a proper Heathkit build if it worked the first time. Where would the fun be in that? Looking forward to the troubleshooting video where "you'll figure it out kid". :-) Thanks for sharing!

David Blake

Having to wait for a new body, and then go through all the thumb sucking and learning to walk and talk phase is a real pain though. Plus, unless you're a Tibetan lama you don't even get to keep your stuff. Of course if Tim Burton is right you might have to spend 120 years haunting the old lab first. It's all in the handbook.

I’m very impressed that it (almost) works from first power on, with 40+ year old parts. Hopefully the troubleshooting is easy. I’m looking forward to part 6 of 3 :-) Ewen

Ewen McNeill

At the exorbitant premium I paid for that piece, it wasn't positive entertainment for me lol. Sure, it had the NOS Telefunken tubes but I couldn't justify either leaving it on my shelf or the amount of work to get it going. I do admire your drive, energy and interest - very very much so. Keep up the great work and so glad you have a plan for yourself and Franlab both.

There's actually a TRX Bench YT video on an IT-12 repair/testing. Didn't look at it until you finished yours :) But could be good reference material with regards performance?

No worriekrrrkkrrrkkrrkrrrk - Just kidding :) Great to see it is lighting up and doing at least basic stuff. The mechanical chassis layout seems really quite complicated. Seems like they designed one bit and then hung stuff around. Did the kit acquired more functions over the time they produced it?

The turn on moment!!!!!

Working or not, it's good entertainment.

Fran Blanche

And How!

Fran Blanche

I've been electrocuted dozens of times.

Fran Blanche

I bought a NOS unbuilt Dyna PAS 3 on Ebay about 5 years ago. When I discovered I couldn't solder to the PCB, I took a deep breath, assessed my interest level and probability/annoyance of working around oxidation issues, and put it up for sale a few years later. I believe you have more energy and patience.

the noise switch should place some B+ to the tip of the probe via a resistor so you can test "noisy" components.

William

You need a 42k resistor. That replaces anything from 1R0 to iM. Seriously, as a safety tip I'd be inclined to insulate the metal case of the probe. When working on exposed live equipment, especially vacuum tube gear, you really don't want to be holding earthed metal in your hand.

Around 1974, I had a serious Heathkit addiction. The signal tracer was among my favorite – oooohhh magic eye tube! I also built: IO-102 'scope, VTVM, transistor tester (wasn't sure why, but had to have it...), handheld LED calculator (terrible battery life), desktop calculator (cool display), and a 13" color TV. Everything worked great, except for an operator oops whereby Johnny Carson was standing on the right side of the CRT. A quick twist of the yoke and fixed. 😊 I'm pretty sure I still have the signal tracer, and I remember packing the 'scope up before we moved recently. I used the signal tracer about 15 years later (as in 1989) to fix some rather expensive gear, so it more than payed for itself many times over for just that one repair. Thanks Fran for the great vids and the trip down Heathkit memory lane with the signal tracer build! I'm just about to turn '65 and have enjoyed little SMT kits lately (my vision's pretty good, but I still bought a stereo microscope for that stuff). Still need to setup a new "lab" at the new house so I can do that and my own RF projects. I have my HF station up and running at least. 😊 Thanks again!

I really like watching this build, Thank you Fran

Dane

Well Fran, you said that building this would give you a "Buzz" you got one :-) Thanks Fran, good work.