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DU1IST Philippines flag Philippines

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Page managed by DX1J Lookups: 159872


Luzon Island IOTA: OC-042

DU1IST's Home Call is JF1IST.


Log Search: ClubLog


Nao Mashita, 8-2-4-2A Akasaka, Minato-ku, Tokyo 107-0052, JAPAN
107-0052 東京都港区赤坂8-2-4-2A 間下 尚彦
My ANT YouTube:
My Shack (Operate Room)
Our family: Biketa Ⅱ and Gonta

160m GP,   Support Tower 28mH,   KOHJINSHA VERSA Beam:  Model KA1-435X、KA1-206X

This is quite new antenna VERSA KA1 which was developped by Kohjinsha Co.,Ltd.

VERSA can cover 8 ham bands (40m, 30m, 20m, 17m, 15m, 12m, 10m & 6m) by one antenna.

All frequencies are adjusted by motor drive copper elements with digital control in order to get the best performance.

Excepting 40m band, the antenna works as a full size YAGI beam. 40m band is performed with center loading coil  equipped into AEU (Adjustable Element Unit). It enables to shorten approximately 30% length of element. This is new technology of adjustable antenna in the world.

This antenna is great product which took 2 years development period to enable the best performance of adjustable antenna system by JH1ECG and their group.


Versa KA1-435X  made by Kojinsha

Duo band antenna, i.e. 5 element for 40 meters and  30 meters, has a 23.5 meter-long triangular cross section truss boom.
Priority is given to 40 meters with "Long John" type element settings. The 40 meter elements are shortened by 25 percent with a center loading device while 30 meter elements are full-sized.

It has been approximately 45 years since I was licensed as JF1IST. When I was young, I experienced to build a 47 meter-high guy supported tower and mounted a full-size 3 element 75 meter-band antenna on its top and thought then that I could handle the huge antenna work because of my young physical strength. Since then, a great progress has been achieved in the function and structure of antenna systems thanks to high technologies and now I was able to obtain my dream antenna, the Versa antenna.
Element lengths of this antenna mounted on the tower can be adjusted even for a few millimeters remotely from the shack.
Decades ago, it required considerable physical effort to make adjustments of element lengths of large antennas at their tips and it was rather difficult tasks to complete satisfactory calibration with regard to F/B adjustments. With this Versa antenna, however, it is feasible to achieve adjustments of its pattern such as F/B ratio satisfactorily if a remote transmitter is located a few kilometers away. Adjustments of the antenna was done alone by myself this time. I believe that I attained excellennt antenna patterns on 40 meter band from its CW band low edge through SSB band high end. In the past, I used a 5 element full-size 40 meter Yagi the boom of which was of the same length. The new duo bander which has 25 percent shorter elements for 40 meters is completely as good as the 5 element full size in its performance of both reception and transmission. I believe It is more advantageous and enjoyable in that the Versa can be adjusted to your satisfaction. When I am getting older, I almost gave up handling large antennas. Now with the Versa antenna, I can challenge again to enjoy my ham life for a longer period.

2. Tower bridge for maintenance work of KA1-435X
Using the bridge, it is convenient to move elements of the antenna for adjustments in an easy and safe manner.

EF-405XXLJ  5 element full-size yagi for 40 meters  Boom length:23.5m
The antenna is designed to achieve superb front-to-back ratio.
Its driven element is designed to 7.200MHz and the box at its feeding point contains a couple of variable inductor coils which function to add element lengths. The box also contains another variable inductor coil which is used to adjust impedance.  Utilizing CPU linkage, it can maintain, by step motors, SWR of 1:1.1 at 7.000 MHz through 7.200 MHz  synchronizing with transceiver's frequencies.
The hot dip galvanized triangular cross section truss boom, made of lightweight steel pipes, is 23.5 meter long and weighs 98kgs.
1. Tuning circuit box

With the diven element being tuned at 7.200MHz, a couple of variable
inductor coils ( i.e right and left ones,) are provided to add extra length
for the element to cover up to 7.000MHz.  3 turns of the variable inductor
coils, which are generally available on the market, are utilized for this
purpose while the remaing turns of coils are shorted and unused. The other
variable inductor coil, positioned horizontal, is for impedance tuning.
Approximately 50 % of the coil is utilized.  Behind this variable inductor
coil is located a 50 ohm 1:1 feeding balun.
2. Control box
The CPU enables the antenna to be tuned instantly to a transceiver's
transmitting frequency with a linkage to its VFO through the CI-V control.
Whenever the control box is switched on, the calibration will take place to
achieve stable operation of the antenna with preset data at every 25KHz
between 7.000MHz and 7.200MHz .
Boom lock device:
In a country where there are a lot of typhoons, it is important to prepare to protect antenna systems.
The auxiliary crank-up tower, located 7 meters from the principal crank-up tower, is equipped with a V-shaped device to lock the truss boom, in order to be prepared to avoid strong wind damages to  the antenna or a rotator.
My house (DU1IST)
Security Guard dog for DU1IST. You can trust the brave. (Biketa Ⅱ 7-months-old  Gonta 5-years old)
80m 75m Delta loop ANT
Beverage EU 400m, USA JA 350m
160m: GP

8361183 Last modified: 2017-09-30 23:34:48, 8773 bytes

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