[ARC5] Brass tubing and knob.

[Kenneth G. Gordon]

I might also suggest, if it hasn't already crossed someone's mind, that the 
larger the knob you can install on the adapter, the easier it is to do 
fine-tuning.

It acts sort of like a bandspread.

I buy the biggest Radio Shack knobs that they sell. They all have brass 
inserts, and are fluted. They are pretty nice knobs. They sell them in pairs.

Ken W7EKB