K6ACJ HF MOBILE ANTENNAS

Antenna experiments are continuous beginning with the Hustler HF Mobile antenna, fiberglass whips, Ham Sticks, quarter wave antennas and a BuddiPole.   

The first photo (click to expand) illustrates the size of the 100 mh silver plated coil for 80 and 40 meter operation and one section of bottom mast with the quick disconnects in clear view.  Similar coils are available from QST advertisers  but this coil and mast were hand made with the help of a friend. 

If you build your own coil, you will most likely dream up many methods to tap or short the turns.  For this application, I use a very heavy braided strap from a stand off on the base to a type of clip that presses between the coil turns at selected points.   

For 80 and 40 meter operation, I might put as many as three sections of 33" mast below the coil and 120" whip above for maximum signal. Bandwidth is about 40Khz on 80 meters but with the LDG auto tuner, bandwidth increases substantially.   The antenna does attract a few visitors and others with strange comments , that will happen. 

Operation on 20 through 10 meters is possible with a 16 foot vertical and either the LDG Auto-Tuner or the larger SGC500 auto tuner.   

Since I often park along the ocean, the breeze can be pretty strong making the gutter mount necessary to hold the assembly stable.  The Hustler heavy duty ball mount was never intended for this load so I'm maxed out.  However, this combination is giving excellent results so that is about the end of my experiments for a while.
 

When using antenna resonators, the LDG tuner will fine tune the match to the transmitter and increase the useable bandwidth.  This is desireable on 80 and 40 meters. 

The mast shown here is using two sections of 1" X 30" stainless steel tubing.  Each end has long brass inserts machined for 3/8"X24 threads. Hustler Quick Disconnects connect each 33" section together with the resonator and whip. 

The entire antenna is easy to take down in less than a minute and easily stores inside.  Only the ball mount remains for the ride home.

The gutter mount material is a plastic cutting board available from a kitchen supply store for $2 .  When in motion with smaller antennas, it holds the antenna vertical to control sway and keeps the SWR stable. This is a good reason to have a LOCK control on the auto tuner, it keeps the tuner inactive during those moments when the antenna is detuned by nearby objects.

The detailed photos show how the plastic is threaded and tapped for 3/8 - 1-1/2" stainless steel screws.  The last photo shows how the outside screw acts as a hinge point while the two inner screw pull the halves together.  What is not seen is a thin 1/2" plastic bar that drops down into the VW rain gutter for additional support. 

Currently, Radio Shack supplies the SS 102" whip until I can find a commercial quality replacement.  A surplus knock-down 120" mast is often used but only while at-rest.

Radials

I went to the trouble of making ground plane radials from steel tape measures and was dissappointed about a couple of items.  First, although it was easy to modify the steel tape measure for a large alligator clip, the electrical resistance of the tape was much higher than expected.   I measured .5 ohm resistance from end to end across the 16 foot tape.   Secondly, I did not notice any difference when receiving from 20 through 10 meters and could not measure a transmitting difference.  Maybe my expectations were too high or the improvements are more obvious below 20 meters.