ja3nep and wh2j amateur radio

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Let' enjoy 160m band QRP outside!!

How to make a small 160m band vertical antenna
with valiable coil and easy to adjust SWR

DE　JA3NEP／WH2J
Shinzo(Ozzy)Ozone

Attached book of JA CQmagazine
on march 2011/By JA3NE

Abstraction

There are many Ham radio operators who are interesting in 160m band operatin at mobile operation, but one of big problem is that operators need long element (About 80meters length for 1/2 lambda dipole antenna on 160m band). So many people have to give up 160m band operation, especially JA stations who have not big house and small land, like my house, Hi.)

I sometime enjoy portable operatin on 40m and 30m bands with my bicycle and at hotels. but I strongly want to operate 160m band at resort hotels which have small balcony.

So I designed 160m band vertical antenna with 5m length fishing rod and radials with FT-817 5w QRP tranceiver.

Consist of antenna system

This antenna system is very simple which is consist of 5m length fishing rod, coil, 3.3m length coxial element(3C2V), big coil at a bottom and a valiable coil which is easy to adjust resonant frequency and counterpoise. I use manual antenna tuner between a bottom of antenna element and counterpoise for the best matching.

Block diagram

←Alminum top element

←Top Coil

←3.3m 3C2V antenna element

←Variable L

←Bottom coil
←Antenna tuner
←CP
←5m coxial cable

←FT-817 tranceiver


Coil for JA's 1.9MHzband	Coil for 7/10MHz bands with capacitance hat



Bottom coil, valiable coil and antenna tuner on a chair	Counterpoise on a balcony

Fishing rod with top coil and hat

How to make a bottom coil

I first rolled corrugated paper on a plastic bottle(7.5cmφ, you can use proper size of bottle) and then rolled 2mmφ tinned wire on a bottle. I was solidify tinned wire on bushes then pour epoxy adhesive material into bushes) and then removed coil of 2mmφ tinned wire with corrugated paper from a bottle and then take away corrugated paper. It is very easy way to make a big and strong structure coil.

Procese of coil making

Wind 2mmφ tinned wire on a bottle which is very strong stucture.

Bottom coil in a box

How to make a valiable inductance coil

It is very difficult to find a valiable inductance in Japan, so I designed valiable coil which is like a iron spring

It is consit of enameled wire, F connector of 3CFV, long volt and nut, plustic case,
enameled wire for valiable inductance, INSULOK and cable tie .
Coil is elastic lile a rubber band. Please refer pictures as follows.

I rolled 2mmφ enameled wire on a plastic bottle(about 10 times on a bottle).
and then remobed enameled wire from a bottle.
I fixed nut with adhesive material on a plastic bottle. So I can change inductance when I adjust length of volt.


3CFV coaxial connector	Long bolt and nut


Coil like a spring	Long nut on a bottom of case



Case with nut	Coil with F connector and long bolt



Close up of coil, F connector and bolt whici is fixed by epoxy adhesive material



Strectched coil which is less inductanace	Shurinked coil which is much more inductance than left one



Variable L in a PET bottle	Variable L with fishing rod at balcony of the hotel


How to make a top coil and capacitance hat for 160m band
I rolled 2mmφ enameled wire on a plastic bottle about 123 turns and then 28 turns of spiral coil which is 65mmφ diameters coil. And then attached with punched thin alminum board on the bottle.


Punched alminium thin board for capacitance hat	Coil for 160m band with taps for 80m 40m and 30m bands



Coil for 40m/30m bands	Coil with INSULOK



3 screws for capacitance hat for 160m band	Coil and capacitance hat

Top element
I adjust element length with 2 diameters alminum pipes which pipes change resonant frequency widely.

2 alminum pipes with black clump	Fishing rod and almimum element


Manual AT tuner


SWR meter and AT tuner	Inside of SWR meter and tuner



Coil and SW with VC	SWR circuit(front of box)


Variable coil, AT tuner with SWR meter

Setting antenna and adjustment
I attached top element, top coil, 3.3m coxial element, side of fishing rod and then installed valiable L, bottom coil, CP and AT tuner. . Adjust frequency about 1.910MHz by top element and bottom coil and then adjust frequency 1.9075MHz to 1.9125MHz for Japanese domestic operation frequency by valiable L exactly.



3.3m 3C2V antenna element	2 of CP(40m lengh)



2 of 5m CP for 7/10MHz bands	Antenna with hat and top coil


AT tuner and CP for 7MHz band	Adjust SWR by valiable coil



CP, bottom coil for 160m band and AT tuner on a chair
Efficiency of antenna system and receiving noise

Efficiency of Antenna system is very important for QRP operation. I have to be resonate antenna system by top element coxial element bottom and valiable coi and CP and then impedance matching to SWR 1:1. Above anetnna system has very narrow band width(about 10KHz widths with SWR 1:1.5) and this antenna has very low noise. I think that antenna with narrow band width is one of good BPF for noise supression.


Result

I operated 1.9MHz band and 7MHz band in Okinawa Island southern part of Japan. Many stations called me on 40m band. I contacted with station of Kyushu Island from Okinawa on 1.9MHz band. But my power surply was out of date after above contact was end. On the other hand, I contacted with 10 stations on 40 meters band at the hotel beside Biwako lake in Shiga prefecture and 10 stations on 160 meters band within a hour. I was very happy to contact with above stations with small antenna and QRP without JA2, JA6, JA8. I have to do operation maxuimam 2 hours a day because my XYL don't like operation for my Ham radio at resort hotels everywhere. But above negotiations is very usefull to keep good relationship between the two.

FT-817 and key	SSB operation



CW operation


Conclusion
I am operating from 1.8MHz to 10MHz band as similar antenna system at my home. My antenna system for 7 and 10 MHz band is that I install 10m long fiber rod with capasitance hat, antenna element, variable coil and CP system at the rooftop of my house. VC is for 10MHz band resonant. Additinal element to Groud level for 80m band and 160m band with bottom coil and CP system, and then connect with CG5000 automatic antenna tuner which works 800W.



10m long fiber rod with capacitance hat	Change frequency (７or１０ＭＨｚband) by banana chip



Valiable coil and VC for 10m band CG5000 is under a black	Bottom coil with another manual ntenna tuner on the ground

I enjoy Ham radio from QRP operation to 1KW one I contacted with ZL8X on 160 and 80m bands on Nov.2010 above antenna system with FT-1000MP MARK5, bearfoot 200W. Finaly I am very happy to contribute my experience for your ham radio life.