A couple of Heathkits I am working on

So I was given a Heathkit C3 Condenser Tester yesterday in really amazing condition. It works but I'll recap it and replace some out of spec resistors. The precision caps in the condenser "meter" section have drifted.

I also have a NOS AA32 that I've been meaning to build for a few years now. Well, since winter is coming and cash for other builds is nowhere in sight, I'll be starting this soon, too.

Wow...
In the box...
Very cool...

scott2000 said:

Wow...
In the box...
Very cool...

Click to expand...

Yup, still sealed from 1966. I got it a few years ago and debated whether I wanted to break the factory tape until I opened it to actually build it, but I couldn't NOT open it, and it's like a time capsule. All of the manuals (that were in color) looked like they were printed yesterday. All the metalwork is mint. One of the dual concentric post is a little stiff but I'll fix that.

I started a Mouser BOM for the parts I am going to replace with new. Should be a fun wintertime build, and since cash is tight it'll take time to do it all.

If you have not already discovered Bob Putnak's web site, you must give this a read:
https://tubesound.com/rc-testers/

Here's a picture of my old Heathkit test equipment, with a couple decades of assorted old computer gear (including a heathkit 16b computer from the 1970s based on old DEC LSI 11/2).

JR

This was my first foray into electronics in 1970 when I got back from Viet Nam - it was going to take me to rock 'n roll stardom. 
When I blew the output transistors after a few months, it taught me a hard lesson about what "factory authorized repair" means, and that's when I decided to educate myself. I modded it with a line level output between the preamp and the amp, and used it to make (poor quality) recordings of our gigs.

I still have it. I should probably power it up (gradually) to see if it can still reform the electrolytics - it's been a few years.

Ive got the exact same Heathkit cap tester , still works too ,just remember while testing for leakage there may be high voltages on the terminals . I also fitted mine with a three wire mains connection for safety.

Tubetec said:

Ive got the exact same Heathkit cap tester , still works too ,just remember while testing for leakage there may be high voltages on the terminals . I also fitted mine with a three wire mains connection for safety.

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It MAY have high voltages on them?  Oh, it will. As much as 450! 

So I discussed the idea of a 3 wire cord for this with an engineer friend and decided against it in this case. His point was that since there IS live high voltage on the front terminals, having the case actually grounded could lead to a serious shock for the user if they were touching it.

I'm going to wire mine properly with a polarized 2-prong cord so the hots are switched. This unit, like many old units switches the neutral ON/OFF instead of the hot, and I will be replacing the death cap with a safety cap.

That Heathkit cap tester is a gem and in mint condition, I have a similar one but its made by EICO, its been a long time since I've used it because I replaced it with a Sencore LC102. I always treat cap testers with the utmost respect, I certainly don't want to get zapped.

Ok the two wire mains connection may be slightly safer in the event of user error/stupidity or with ancient fuse board type mains installations , in the event of a fault in the equipment itself modern mains safety systems wont provide much protection if theres no ground wire. Its a slightly unusual situation in this case I agree , but a metal box connected to the mains should always be grounded so in the event that the case ends up at mains potential the ELCB cuts the power in milliseconds, I guess we'll have to agree to disagree on this one 

The only real usage for one of these units in the modern setting as far as I can see is the leakage test for capacitors , a modern multimeter will give better results on resistance and capacitance measurements.
Touch proof 4mm binding posts or shrouded 4mm sockets might be a worthwhile addition along with  insulated HV croc clips and leads.

Tubetec said:

The only real usage for one of these units in the modern setting as far as I can see is the leakage test for capacitors , a modern multimeter will give better results on resistance and capacitance measurements.

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Yes, thats the entire purpose of these units nowadays, when testing electrolytics its usually best to just replace them instead of taking them out, testing them and putting them back in, but sometimes if you have a fault in an equipment and you replace the caps its good to test the old caps to corroborate if they were leaky. Also, mica caps are ok to test and put back in, aswell as some poly caps. In tube equipment you really need to apply the full rated voltage to a cap to check if its leaky.