VE6AB Mobile Ops

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Past and Present HF Mobile Antennas

So here I am, having come full circle on a morning that you get to see one of my mobile HF antennas that hasn't been out in the daylight for a number of years.
I must say, I should do this more often, as I had a lot of fun operating HF mobile with this terrific and most unusual antenna on this day.

I designed and built this particular antenna for my previous mobile, and when I acquired my Avalanche as seen here, I decided that I needed to build a somewhat smaller (3" diameter) gearmotor antenna that would fit in one of the storage compartments located at the rear of my mobile as seen in the photo (key cylinder ID's the compartment) when I parked in the garage at night, or if I possibly was running with one of my monobander antennas, or just wasn't operating HF mobile at that moment.
Long story short, although this 10-80 meter antenna is a terrific performer, it doesn't store well in my Av when not in use due to its 4" diameter coil assembly not fitting through the storage compartment door.

Here is a run down on the antenna as seen.
The mast assembly including the coil is a fixed assembly in length, with the tunesleeve that includes the contactor movable with the linear actuator to select the operating band.

The coil-form is machined from 4" dia Lexan® (polycarbonate) tube.
The end-caps are machined from Delrin® (acetal homopolymar)
The wire on the coil is 12 gage tinned buss wire wound 6 tpi.
The mast as well as the coil fittings are machined from 304 stainless-steel
The TuneSleeve assembly is a build-up from flat stock 16 gage 6061-T6 aluminum, rolled to shape, and tig welded together.
The TuneSleeve has a beryllium copper fingerstock contactor surrounding the top of the TuneSleeve assembly, compressed and contacting the coil with 35 psi, allowing for a 500 watt amplifier to be used if desired.

The 12 volt 4" stroke linear actuator that is mounted on this multiband antenna and is attached to the TuneSleeve works extremely well. This style of actuator is ideally suited for this application, as the TuneSleeve requires a smooth linear operation with positional control. The other plus to this actuator is the fact that it has built in limit switches. The actuator is set up so that once the TuneSleeve reaches the end of its tuning range just beyond the 10 meter band (top of the coil), the actuator has reached the end of its travel and the limit switch shuts the actuator down.

While sourcing the linear actuator for this antenna, I was successful in discovering a company that could supply me with an actuator geared with a final drive-ratio that was required for this antenna.
In the past I have found the various motorized antennas that I have used to be agonizingly slow when shuffled between the various bands. The problem is eliminated with this antenna as the TuneSleeve moves to either end of the coil (10-80) in under 15 seconds, yet the antenna is very easy to tune. This actuator is proving to be extremely quiet, with no electrical noise from the motor coming through the receiver of my TS-480 HX while tuning the antenna.

The antenna may also be operated as a manual tune antenna by removing the actuator assembly, and re-installing the locking-knob into the TuneSleeve. Changing over is a simple operation taking only moments to remove the two fasteners securing the actuator in place on the antenna.

It may not be apparent in the photo, however the 12 volt actuator assembly is insulated from the mast assembly with a non-conductive Delrin® mount, a requirement for the actuator motor to operate correctly without it shorting out when switching polarity for directional control.

Expand the photo for a closer look.....

Here is a rundown on the whip and caphat assembly used up top.....
https://www.jerryclement.ca/HamRadio/HamRadio/i-N96p6zq