I have made three different style of burners, just testing and everyone has a better idea. I will put them here as I can get pictures of them and have the time.
Burner at 5 lbs propane pressure
To make this burner I used an 8x3/4 inch pipe nipple, 5x1 inch pipe nipple, 11/4 inch section of pipe 5 inches long and a 3/4 to1 inch bell end reducer.
Plus the stainless steel burner flare
There are four slots under the slidding choke sleeve, each slot is 1/2 inch wide by 2 1/2 inches long. The slidding choke is held in place by a 1/4 inch thumb screw and can be adjusted up or down.
The accelerator (where the propane is injected) is made from 6 inches of 1/8 inch heavy wall pipe with a 9mm mig welding tip threaded in the end to act as a gas orifice
The accelerator enters the back of the burn tube through a 3/4 X 1/4 bushing that has been braze welded to the 1 inch pipe. It is held in place (centered) by a 1/4 x 1/8 inch bushing that has been drilled out with a size Z drill so when it is screwed in it clamps the accelerator in place.
Burner at 2 lbs propane pressure
Burner at 10 lbs propane pressure