Hello John, Funny how you find KNOWLEDGE in the most unlikely places! First of all Phenolic is available from most any plastic supply store ie: Cadalliac Plastics, A-1 Plastic here in the Houston area.
If you have any friends in the machine shop business, check and see if they do Broaching. IF so then go see them with a piece of Delrin (round stock) and see if they will Broach you a 1/4" square hole thru the middle. Then you can simply drill and tap holes on the Square sides for Set Screws and you have your very solid Union which is RF proof. For the "True" Home brew "ARTIST" you could buy either Delrin or phenolic, Drill say a 3/16" hole thru the middle then with a small SQUARE File which they sell at the hardware store, you could make your own. Alot of work but would save you some bucks if that is what you are after. Just a few ideas from, "Down By the River"! Take care John, Tony/W5OD River House Radio
