[The last renewal of this page: July 25, 2009]

In my history, this is the first time to own a sedan, and thus, I finally become to built a very normal mobile station.
An outstnading feature of this mobile is to be able to work on all bands in HF, from 3.5MHz to 28MHz (50W) togther with 50MHz (50W). 144 (50W) and 430MHz (35W) FM are also available for local communication and for accessing to the EchoLink node.

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The main antenna is a hombrew, and is tuned to around 3.5MHz with a big center loading coil and a capacity hat. The total length is about 3.0 meters, and the spring base is mounted to the hauling hook of the car. The maximum hight of the antenna is reduced to 3.2 meters above the ground. With using ICOM's ATU, AH-4, this antenna works fine in all bands from 3.5 to 28MHz within SWR 1.0 to 1.3.
The left one is for 50MHz, COMET HR-50 (50MHz 1/2lambda Whip, 2.13meter long, Gain: 2.15dBi)
The right one is for 144MHz and 430MHz, COMET SB-7 (144MHz: 6/8lambda C-phase 4.5dBi gain, 430MHz: 5/8lambda 3-step 7.2dBi gain, 1.38meter long) Gain:4.5/7.2dBi)




ICOM ASTATICS X'tal microphone helps IC706MK2 to get more talk-power? DAIWA's SWR meter, CN-104 with a cross meter is modified, and the detection unit has been took off from the body to set in the trunk of a car, right after the main body of IC-706MK2. Under usage of ATU, trying to tune to different frequencies other than a proper resonance frequency of the antenna, it is essential to monitor all the time with a SWR meter with my experience. I can monitor not only the good tuning of ATU, but also I can detect ATU's malfunction caused by vibration on the vehicle or the approached object to the antenna during the drive. Illunination of the SWR meter is linked to IC-706MK2 is good for a night dirive. ICOM IC-2720D is mounted in front of the driving meter panel, and is supposed to use with the right hand. A CW manipulator, Mini-paddle of Laves Telegraficas in Spain, is set on the dashboard at the right front corner, and very easy and comfortable to operate during the drive.

The combination of a big coil and a capacity hat allows to be tuned on all bands from 3.5MHz to 28MHz with the SWR 1.0 to 1.3 using AH-4. The capacity hat is made by soldering stainless steel wire. The diameter of the acrylic case is 15cm(6.1inches), and the height is 18cm(7.3inches). The mast is a stainless steel, and is really strong and heavy. The tapered element above the coil is 1.4meter long and the diameter at the bottom is 4mm.


The antenna is large and heavy, and is impossible to support only with a spring base safely. Antenna is pulled by a stainless steel wire. A ring and a hook are used so that the wire is removable, otherwise the trunk door can't be opened.


The mountbase of the 50MHz antenna is bonded using a flat shield cable. The cable is grounded to body inside the trunk, by drilling a hole and tightened with a screw. Without this bonding, you may surely experience sudden rise of SWR due to the bad contact to the ground by screws of the mountbase.



IC706MK2, IC2720D and AH-4 are mounted on a wooden plate and fixed to the floor of the trunk. It is the closest position to the antenna. (Upper left is a wheel house, and righthand is the back direction of the car.)



To prevent RF feed back problems, thoroughgoing countermeasures are taken with cores. A control cable for AH-4 is replaced with a multi-core shielded cable.




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