HF Mobile
The rig is a Kenwood TS 480 SAT with the optional 500 hz CW filter installed. I use a set of Begali Traveler Light Paddles, located just in front of the arm rest. They are vertical and can be moved from the back cup holder to the front cup holder. The arm rest slides front to make working CW more comfortable.
The RF section is under the front seat. There is a matching transformer (28 ohm to 50 ohm UnUn) at the base of the HF antenna but the SWR gets a little too high on the band's edges, on 40 meters that is. The rig's ATU keeps the rig from going into SWR protection. The antenna I use on 20 meters is well below 1.5 to 1 SWR across the entire band, CW to the top of the SSB portion. For VHF and UHF I use the TM 733A dual band radio.
The control head for the TS480 is mounted on a block of wood. The wood is pushed into the compartment that was used to store the CD's for the CD player. No holes were drilled in the car and it looks like it was made to fit. A pair of #12 wires run from the RF decks direct to the terminals on the battery. This line is fused at the battery connection.
The antenna is a dual band hybrid vertical which consists of the following:
1" x 5' copper mast covered with black shrink tubing.
B&W Hy Q coil with a movable tap for 40 meters which is resonant at 7.180 mhz.
By moving the tap I can go anywhere in the 40 meter band or any frequency from 10 to 40 meters.
The whip on top of the coil is six feet long for a total antenna length of twelve feet which includes the coil form that is 1 foot long.
Under the 40 meter coil is a 20 meter resonator which is mounted at a 45 degree angle. The 20 meter resonator is a modified Hustler 80 meter resonator rewound to resonate on the 20 meter band. This resonator will now cover the entire 20 meter band with an SWR of less than 1.5 to 1. I have provided instructions, on the bottom of this web page, for modifying an 80 meter Hustler Resonator to work on 20 meters.
Comparing my little low profile 40 meter mobile antenna to the antenna pictured above right, I increased my ERP by 6 DB. That is equal to going from 100 watts to 400 watts. To run a 400 watt mobile amplifier, it would create an additional current drain on the car's electrical system by 70 amps. That is over and above the current drain from your HF radio. By improving the antenna's performance by 6 DB there is not only no additional current drain on your car's electrical system but your receive signal also increases by 6 DB.
A matching transformer / UnUn is located at the base of the antenna to provide a low SWR at the resonant frequencies of the two bands. The UnUn is designed to match 28 ohms to 50 ohms.
I always wanted to try 160 meters mobile. I put the Kenwood TS 480 SAT in the car and made a 160 meter resonator to fit on the mast shown in the picture. I have checked into the 1900 group (1900 khz) on Weds. evenings while driving home from the club's station. I have gotten favorable results. I am located in Bethlehem, PA and I was 20 DB over S9 into Maryland.
The coil is not a high Q coil. I used 1 ½" PVC and wound the coil using #18 enamel wire. This is not a very efficient system, but neither are most of the commercial mobile 160 meter antennas.
If you would decide to build one of these coils, don't expect to go too far from its resonant frequency. The 2:1 bandwidth is in the order of 5 khz.
This setup was done mostly for an experiment. The results were interesting.
Shown to the right is the 160 meter coil. The actual coil length is 7 ½ inches long and wound with number 18 enamel wire. The coil form is 1 ½ inch PVC.
If you have a screw driver type antenna, this coil can be placed between the top whip and the top of the screw driver’s coil. By moving the adjustable coil on the antenna you should be able to work the entire 160 meter band.
Hustler Resonator modifying instructions, for 20 meters:
First you must acquire a Hustler 80 mobile resonator. Remove the shrink tubing and all of the enamel wire from the form. Rewind this form with 37 turns of 14 gauge enamel or bare wire. You can use 14 gauge THHN house wire if you don't have any enamel wire. Replace the shrink tubing and extend the whip to a length of 27 inches. Check the SWR, and adjust the whip for a resonant frequency near the center of the band. You should be able to cover most of the band with a very low SWR. Efficiency of the antenna system will be improved over the standard and the Hustler KW resonator..
Updated version using a smaller coil form (8 Feb 2018)
20 meters:
Coil form: Hustler RM-40
Whip taken from SF-2 VHF (2 meter) mobile Hustler antenna.
Re-wrap the coil form with 21 close spaced turns of #14 enamel wire centered on the form. This comes out to 8.8 uh.
Allen 10-32 set screws are used for the adjustable whip.
Adjust for 14.200 MHz
Expect full band coverage staying under 1.5 to 1 if matched properly at the base of the antenna.
This resonator is over 3 db better than the RM20 low power Hustler resonator. That equals double your ERP over a 100 watt transceiver and 3 db gain in receive without additional current drain off of the car's electrical system.
Here is my original article that shows how to modify a Hustler Resonator titled, "Hop Up Your Hustler". This article shows you how to, not only make the 20 meter resonator, but also give the needed information on how to make a Hy Performance 15 meter resonator.
The above updated version uses a longer whip then was used in the original, "Hop Up Your Hustler" resonators.
Shown to the left is an 80 meter Hustler resonantor rewound to resonant on 20 meters. I have since made another modified resonantor using a 40 meter resonator instead of the 80 meter resonator. Use the same coil form to make a 15 meter Hy Performance resonator.
Pictured is the original resonantor that the, "Hop Up Your Hustler" article describes.
This is the finished modified 20 meter resonantor.
The heat shrink can be purchased from Amazon.com .
I used a Brother P Touch to make the labels.