Need assistance with Screwdriver Antenna

[K6WML]

I inherited part of a screwdriver antenna from a friend after her father passed away. I've got the main antenna, but could not find the mount or any method of attaching coax. Three wires come out of the base, two for screwdriver power and one for ground. The screwdriver portion works.
It looks like the antenna must have mounted on a conical shaped mount, as the signal gets fed to the antenna through a 3/4" copper pipe which is tapered on the inside.
Any information on building/buying a mount ant building a matching circuit would be greatly appreciated.

73s, Will
K6WML

 

[prcguy]

That's either a home made unit or I've seen some on Ebay that are made from Home Depot type components. Either way the entire antenna is hot with RF including the motor and turns counting pulse wire. I don't know how that version mounts to anything using what looks like copper plumbing pipe, you'll have to figure out a good method for that and I would be a little concerned about using it mobile without bracing or guying due to the copper pipe.

Anyway the typical way to decouple the motor and pulse wire are to wrap about 6 turns through a large #31 mix ferrite bead about 1 1/2" long and maybe 1" in dia with the ferrite as close as possible to where the wires exit the antenna. The red and black wires are usually the motor and you can connect 12v if you haven't already to see if the coil or coil shorting mechanism moves up and down. There are wiring diagrams online that show how to wire a momentary rocker switch to run the antenna up and down and I would also put a small circuit breaker in line with a current trip value slightly above what the antenna draws when it starts to hit the up and down stops.

To test it you could temporarily get a copper pipe to threaded pipe flange adapter and a pipe floor flange then mount that to some wood to hold it up with a few ground radials and a 6 to 9ft whip on top and fire it up. On the lower bands like 40 and 80m the match will be a bit high due to the low impedance well under 50 ohms and on 20m and above it should match up just fine.

If the antenna works and is useable and you operate on the lower bands you can buy or make a 50 to 25 ohm transformer that will greatly improve the match on 40 and 80m or better yet get one that has a 12.5 and 25 ohm tap and run the lower impedance on 80m and medium on 40 then run straight through for 20m on up. You can also make a shunt matching coil to smooth out 40 and 80m but they can be a little finicky. Sometimes connecting about 500pf across the base of the antenna to ground will also help match it on 40 and 80m but the transformer is the best method.