[HBR] Capacitor question

[Shoppa, Tim]

> I see a wide variety of 3-section air variables on ebay these days.
> I see a couple that have attractive gear drive systems on them.
> (see 370590238594 for example)

> I was wondering how hard it is to take plates out.  The capacitors
> I see appear to have slots in the axle into which the plates fit
> and have a small bakelite piece which drives all of the rotors at the
> same time.

> How hard is it to remove plates?

It's straightforward but with close plate spacing and 3 sections would require a lot of care. It is a lot easier (hint hint) starting from a single-section unit with wider plate spacing.

The types of caps where it's super easy: Single section. Here you disassemble the shaft and remove the unneeded sections and spacers, then reconstruct with the original spacers and put in a few handy extra spacers you have from previous cap reconstructions.

For something like this, if you needed to just remove a few plates, you could go in with a Dremel or other good cutter and remove the plate or fraction of a plate you didn't need. But to turn this into a HBR tuning cap you'd have to remove 80% or more of the plates. What you picture is a nice cap suitable for a lot of homebrew uses... but is not a good cap for a carbon copy clone of the HBR-14 or -16 say.

Some scandalous comments follow below:

The original HBR design put a lot of attention on tracking RF and LO sections.

This was back when the creme de la creme in any receiver was such tracking using a single tuning knob, it was an attempt to prove "this is as good as any commercial receiver".

Unless the goal is to build a carbon copy of the HBR-14 or -16 or similar....
I see no reason why a new construction HBR-inspired receiver would do the same. A separate "preselector peak" control, there's nothing at all wrong with that, and it lets band-imaging techniques come in too (techniques common on the good old Drake and other well-respected vintage  receivers).

Tim N3QE