Ever wondered where some of the kit projects get their inspiration to strive for clear instructions, excellent documentation, and an overall fantastic DIY experience?
Heathkits were electronics kits popular in the late 1940s and 1950s. We have a mint AC Voltmeter kit that we will be building up over the next few days! We plan to document the experience and share it with all of you! Read on for more delightful photos and descriptions!
This Heathkit is for building an AC Voltmeter. Since the kit has been around for many years, some of the components may not work. Let’s get started and open up the box!
Here are all the contents of the box. Everything that we will need will hopefully be in here. It even comes with solder! Since solder does go bad over time, we’ll be using some more modern solder.[Editor's note added: "More modern" in this case means recent-vintage solder of the same type and manufacture, which we happen to have in the lab.]
One of the neat things about a kit of this age are all the historic elements to it. This kit uses tubes, referred to as electron tubes on the boxes. The one on the left is a 6AW8A by Radio Corporation of America (RCA) made in Harrison, NJ. The one on the right is an EF184/6EJ7 by International Electronics Corporation (IEC) made in Melville, LI, NY (although on the tube it says made in Great Britain!)
The tubes inside are gorgeous. We don’t often have the opportunity to see these any more because they have been replaced by smaller solid-state devices. With that said, tubes were the key factor to bringing radar, television, broadcasting, sound recording, and much more to where it is today. Their exterior is made of glass with electrodes extending from the bottom.
This is a very old electrolytic capacitor! It is enclosed in a metal casing with its name and details embossed on it. Here’s what it says on it:
- CODE MFD. W.V.
- (semicircle) 80 150
- (square) 40 150
- (triangle) 20 150
- FOR 85°C OPER.
- GI 24066
I looked into this a bit more and found that the GI most likely stands for General Instrument. Wasn’t able to find any datasheet however.
More of the parts included with the kit. They are vintage and really colourful, check out the domino capacitors! Domino capacitors were used in the 40′s and 50′s, and you could determine their value by using the coloured circles. They are also known as Mica capacitors!
Here’s the pack of resistors with additional precision resistors. The precision resistors are the ones in the coloured shell. They are used for the turning knob, which will be discussed later!
Have you ever seen one of these? It’s a crystal diode! These crystal diodes are extra special because they are made of Germanium rather than Silicon. Germanium diodes are still used today because they have a different forward voltage. Cool eh!
Here is what Heathkit is known for- its instruction manual! It includes an envelope that you can send to request replacement parts, tips on how to solder, and fold-out pages of illustrations to follow. Here is a photo set of the instructions.
Since this kit is for an AC voltmeter, there is a very nice panel display that will be mounted on the front of the enclosure. Check out that vintage font! There is a clip on the back of the display between the two terminals. This has to be removed before use.
To wrap it all up, the Heathkit also comes with a sticker to identify your kit’s model and series number! This definitely adds an authentic touch.
After some assembly, the 4 lug terminal plug has all of its components added to it. It seemed throughout the instructions they kept changing their mind if they wanted to solder some of the leads to the lugs, so they are left unsoldered for now.
Getting the dial assembled was quite the challenge. The first part was to insert and tighten it all correctly so that the knob lines up with the lines. Afterwards several components have to be threaded through the lugs on the different decks.
One of the resistors, the precision 2.162K ohm, that had to be attached was actually missing. However thanks to the heaps of vintage components here, we found a similar one! The one we found was 2.15K ohm, making it within the tolerance of the original resistor.
Next up was starting to assemble the transformer box, with the capacitor. Except there’s kind of a big problem… the piece doesn’t fit the enclosure or the capacitor!
The instructions clearly do not show this predicament. Hmmm…
It’s definitely good to know that our Heathkit building experience is the real deal by having to find replacement parts, and in the case of the plate we will be making our own part! We can even complete the mail-in form for a replacement part and see what happens! Coming up in the next part will be more assembly, possibly testing the vacuum tubes, and more.
While looking around the internet for more information about Heathkits, there were a few really nice sites out there. Check them out:
You can look at more photos of the Heathkit on these sets: