Author Topic: Home Brew 160 meter, 3/8 wave, Inverted 'L' Project/Part 3  (Read 1287 times)

Offline JohnyMac

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Home Brew 160 meter, 3/8 wave, Inverted 'L' Project/Part 3
« on: February 06, 2018, 07:18:28 PM »

Article Three – Tuning
 
This the last article in my three part series of building a Home Brew, 160-meter, 3/8 wave inverted ‘L’ antenna and it will focus on the tuning of that antenna. 

I left the reader last at TXing and RXing on 160-meters using my Yaesu 817nd at 5 watts. I eventually got out of the Faraday Cage my Kenwood TS-590S and put the antenna to the test. Although I received a bit better report on my signal than before, now using 100 watts, the reports were still no where near what I wanted this antenna to do. My goals could only be accomplished through the tuning of the antenna. 

The VE of the New York club I belong too lives about a pistol shot away so I asked him if I could borrow his MFJ 259b antenna analyzer which he gleefully loaned to me. Once I picked up the analyzer I made my initial reading’s at the end of the coax in the shack NOT at the feed point of the antenna. 

On Figure 1.1 we see the reading’s from inside the shack at the end of the coax. Figure 1.2 shows the reading’s taken at the balun feed point at the antenna. Please note that it was 8 degrees outside and my pen kept freezing so I only focused on 160 and 75/80-meters when I gathered the readings in Figure 1.2.

Date   Dec, 27, 2017                       Date   Dec, 28, 2017      
Freq    R   X   SWR                            Freq      R     X   SWR
1.900   2   6   17.2                           1.900   35   210   17.8
3.800   70   57   2.5                         3.800   65   60   2.6
7.250   10   21   5                            7.250   0   0   0
14.275   14   22   3.7                        14.275   0   0   0
18.170   53   26   1.5                        18.170   0   0   0
21.300   59   64   2.5                        21.300   0   0   0
24.990   33   29   2                           24.990   0   0   0
29.000   18   14   2.4                        29.000   0   0   0
1.1 Read in the shack at end of coax    1.2 Read at the Balun feed point         
       
I was able to use my Kenwood’s internal tuner to tune on all frequency's except for 160-meters. I made several contacts on 75/80, 40, 20, and 18-meters. However, 160-meters, my main focus for this antenna—The best I could attain was just be able to hover at above the noise level. 

Scratching my head at this point I decided to solicited some help using eham.orgi. As always happens when you do this you open yourself to comments and advise that range across the spectrum of possibilities.  After reading the cornucopia of advise several things came to light. 

1) I needed more ground radials. One ham recommended 32, 50’ lengths of additional ground radials.
2) I needed to ditch the 4:1 balun and replace it with a manual tuner located at the feed point of the antenna.
3) Reduce the length of the antenna from 3/8 of a 160 wave (200’) to  1/3 of a 160 wave (175’) and another to 1/4 of a 160-
    meter wave (133’). 
4) Adding a capacitor to the feed point of the antenna. 
 
In short, I decided to first add more radials. Second, order a manual tuner. While the tunerii was on its way, I added 8, 50’ radials for a total of eleven radials now on the ground. 

Before the tuner arrived and after the addition of the radials I took some reading’s which I will share here.

Date   Dec, 31, 2017      
Freq         R  X   SWR
1.900   24   203   >25
3.800   38   60   3.5
7.250   67   132   6.9
14.275   33   68   4.5
18.170   86   20   2
21.300   22   20   2.2
24.990   17   13   2.7
29.000   23   20   2.2
2.2 Read at the Balun feed point         


When compared to the reading’s I got as seen in 1.1 the addition of the radials  improved  R and X however SWR worsened. So the theory that was offered of adding more radials had merit.
 
With that written It was becoming more and more apparent that my goal to have an antenna that was used for more frequency’s than 160meters was quickly waning. The big test was going to come once the manual tuner arrived which finally did on January 2, 2018. 

While waiting for the delivery of the tuner I took a piece of 1/16 x 3 x 5” piece of plexiglass  and cut a hole in it to receive a SO 239,  4 hole chassis mount in anticipation of using a jumper cable from the connector to the tuner after attaching the antenna and ground wire to the connector. Here are some pictures of the end result. 

                                             
 
 
2.3 and 2.4 SO-239 4 Hole Chassis   

Once that was accomplished I needed something to put the manual tuner into that would protect it from the elements. I had a spare plastic 5.56 Nato ammo can that was just collecting dust and screaming to me, “use me...use me”  which I did. 

Drilled two holes in the can—One sized for the jumper coax cable and one was sized for the RG-213/u coax cable. 
Well a day or two after the manual tuner arrived it was time to hook everything up and see what the readings were once the antenna was optimally tuned to the antenna.


2.5 Finished Product
 
The final optimal reading’s at 1.900 Mhz was: R = 27, X = 0 , SWR = 1.7. Okay, not perfect however much better than what I was dealing with before disconnecting the balun and adding the tuner.
 
In the shack I took additional reading’s at the end of the 100 feet of RG-213/u coax cable and the reading’s were: R = 87, X = 17, SWR 1.9.  Well within the ability to tune using my Kenwood’s internal tuner. 

That night I made six contacts on 160-meters. All contacts gave me 5/9’s and raved about my signal.  Since then when propagation allowed, I have made contacts from as far NNE as Nova Scotia WNE to Wisconsin, SSE to Louisiana, and SEE over to northern Florida and all in-between. 

As a side note, I love 160-meters! There seems to be less noise than I was expecting and much less than some other frequencies. The disappointment is that I can not presently use this antenna for some other frequency’s.
 
Once the snows melt and it becomes a bit more habitable outside, I will do the following:

1) Add additional radials as was suggested by one ham from eham.org.
2) Hookup wire jumpers from before the SO-239 Chassis to the balun and then a jumper from the balun to a manual switch then
    the coax so I could bypass the tuner and go from the balun direct into the shack and work the other frequency's with the
    tuner out of line. 
3) I have the ability to raise the antenna another 30 feet which will put it at about 130 feet high or 1/4 wave length above terra
    firma. It will involved the removal of some branches in trees that lay in the antenna’s path.   
4) Last, I would like to learn how to use the 4nec2 antenna modeling software to see what I am putting out on all of my
    antennas. 

With the 160-meter antenna project done until the weather clears. Now it is time  for me to start on my NVIS antenna project. If there is an interest I will  post my trials and tribulations on that project too. 

73

 
Footnotes: 
ie.ham.org thread                                                                             
iiMFJ Tuner
« Last Edit: February 06, 2018, 07:48:14 PM by JohnyMac »
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Offline Jackalope

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Re: Home Brew 160 meter, 3/8 wave, Inverted 'L' Project/Part 3
« Reply #1 on: February 06, 2018, 08:49:16 PM »
I'll be interested in the NVIS antenna project.  Thank you for the write up on the 160 m. antenna.  The NVIS antenna project should be a lot easier.  DX engineering has a white paper detailing a NVIS antenna which is based upon a military design. http://static.dxengineering.com/pdf/WP-NVIS-Rev2.pdf   

Offline JohnyMac

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Re: Home Brew 160 meter, 3/8 wave, Inverted 'L' Project/Part 3
« Reply #2 on: February 06, 2018, 10:10:05 PM »
Thx Jackalope. That PDF is what I will be using for my NVIS project.

When/if you get your HF out of the Faraday cage, let me know and we should try to meet up. Lets open it to anyone on UP who would like to try to make contact too.

73
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Offline Jackalope

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Re: Home Brew 160 meter, 3/8 wave, Inverted 'L' Project/Part 3
« Reply #3 on: February 07, 2018, 05:12:25 PM »
I have a radio ready to go.  I don't keep them all in Faraday cages .   

Offline JohnyMac

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Re: Home Brew 160 meter, 3/8 wave, Inverted 'L' Project/Part 3
« Reply #4 on: February 07, 2018, 06:26:30 PM »
LOL...Cool. Name a date and time. Sorry not Saturday  ;)
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Offline Jackalope

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Re: Home Brew 160 meter, 3/8 wave, Inverted 'L' Project/Part 3
« Reply #5 on: February 07, 2018, 08:44:28 PM »
Friday evening will work.  Or Sunday afternoon/evening. 

Offline JohnyMac

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Re: Home Brew 160 meter, 3/8 wave, Inverted 'L' Project/Part 3
« Reply #6 on: February 08, 2018, 09:40:03 AM »
Friday works for me. I just looked at a propagation predictor and 160 and 75/80 meter will be open at 0100 hrs UT 2/10/2018.

If 2000 hrs ET 2/9/2018 works for you, pick a channel Jackalope. This QSO is open to anybody who might like to join in on the rag chew.  :dancingBanana:

Game? 
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Offline Jackalope

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Re: Home Brew 160 meter, 3/8 wave, Inverted 'L' Project/Part 3
« Reply #7 on: February 08, 2018, 03:55:43 PM »
That works for me.  Let's try 3.960 + or -MHz.  It'll give me a chance to try the linear and auto tuner out.

Offline JohnyMac

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Re: Home Brew 160 meter, 3/8 wave, Inverted 'L' Project/Part 3
« Reply #8 on: February 08, 2018, 06:07:42 PM »
Done deal!

Unchainedpreppers forum tomorrow 2/9/2018, time 2000 hrs ET 3.960 Mhz. For you folks with just a shortwave receiver 3960 Khz.

If you are going to check in and to keep things relatively PERSEC, pls PM me your call.
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