What about QRO Plate Chokes??

[KM1H]

Dont be surprised if you wind up using a vacuum relay to bypass L2 on the higher bands.

[K1JJ]

Speaking of QRO plate chokes, does anyone recognize this one? It's not in the greatest shape but probably could be repaired with a little glue and tape. It has "9308" stamped on it.

Impressive looking, but I've tried a few of those in the early days for HF QRO and every one went off like a howlizer..

I think the distributed capacitance or potential for multiple series resonace situations of those pie-wound rat nests is way too high for HF use. It's more suited as a BC/VLF choke device.

T

[N2ZD]

I like the idea of using glass.

It would be easy enough to cut the ends off a Pyrex test tube from a scientific supply store...after two or three broken ones- LOL.

  Old thread revival, but here is some good info, cut the glass under water (carefully!!)

[Opcom]

Glass would be the most elegant, but the Teflon is here. I do have to cut out L2 due to a resonance at 22 MHz of all places.

About glass, I was told to cut it with a hot wire, but that might not work well on Pyrex. Why is it better to cut glass under water?

[Opcom]

.

[KM1H]

Ive seen curved untempered auto glass cut with high pressure water and by sandblasting so anything is possible I guess.

Carl

[W2VW]

This choke looks like the same type as the one used in the Harris AM-7224.

http://cgi.ebay.com/HARRIS-RF110A-High-power-RF-plate-choke-Assy-/150581415140?pt=LH_DefaultDomain_0&hash=item230f5a0ce4

It has a ferrite core which increases the inductance at low frequencies. The ferrite mix is doesn't do much at the higher frequencies. Less coil needed. Supposedly works from 1.6 to 30 megs without self resonances.