Sweet photos of the insides of this Heathkit! It's really neat to see all of the old components and a tube!
I had the honour to start building an AC Voltmeter Heathkit when I was an artist in residence at Evil Mad Scientist (part 1, part 2). It was very interesting to build it, especially since Heathkits are recalled as legendary. It was cool having all of the wires being attached in 'mid air', compared to kits now where everything is on a pcb. Was definitely surprised at the amount of solder needed, since the 'lugs' were giant, as well as the leads from the components. Sometimes the instructions were confusing — but it's not like they could go and edit the documentation, since it's printed on real paper!
One of the pieces was missing, so we designed and laser cut a replacement part. People have actually downloaded the part from Thingiverse, so maybe there are other people out there who were also missing it (though unlikely)!
Noticed the 'mighty' capacitor in your GD-1A. There were also huge capacitors in the AC-VM, the metal enclosed one took up a lot of space. Why were capacitors so big back then? Were they made by hand or something?
Okay, that too. But in order to measure the change in current through the resonant circuit, or voltage change created by a changing current flow, you need current to flow through the circuit under test. The flow was created because the circuit was radiating RF.
I built a few Heathkit devices, including a color television, an oscilloscope, and a printer. Heathkit did an extraordinary job of design in putting together their kits. The assembly documentation was second to none. The color television had at least 5 or 6 manuals, covering the assembly of the circuit boards, the mechanical assembly of the unit, tuning the varius stages, and adjustments to the set. It was a marvelous way of gaining experience in assembly and testing of complex devices. I don't think there are any equivalent systems today that even come close to the experience Heathkit provided.
As a power RF specialist I depedn on my trusty grid dipper. Mine happens to be an Eico 710. It's basically similar to the Heathkit shown but a bit more compact. I carry it in a canvas case originally made for a "brick" cell phone. The instrument and its coil set (The coils live in a mahogany block drilled to accept the pins.) fit perfectly. There is even room for a spare tube, a BNC coil adapter, and the Manual which fits in its own zippered compartment. I previously owned a solid state immitation "grid" dip meter, but it was almost useless so I traded it.
In addition to analyzing resonant circuits, the GDO can test transmission lines for electrical length and measure the distance to shorts or opens. As a wavemeter it detects RF leakage. Amazing versatility for an instrument with just one triode section. I won't leave home without it!