Tuning the 80/40/20 Fan

 I built the 15/10/6/2 fan last fall in the basement.   Fine tuned it then dragged it to the top of the hill and put it up and when it was lit up it behaved exactly like it did in the basement.    Based on this I tried the same approach with the 80/40/20 fan and set it up just outside the house a few feet above the ground.   When I strung the antenna up the tuning changed dramatically much to my surprise.    

Below is the 80/40/20 fan dipole after if was strung up at its operating position BEFORE it was tuned. 

Below is the 80/40/20 fan dipole after if was strung up at its operating position AFTER it was tuned. Might I add it took hours and multiple trips up and down the hill.  

Played around the next day a bit more and ended up with....

LESSON LEARNED    as I moved the antenna up and down the impedance changed and the 1:1 match was skewd +/- 150 KHz.  

Putting the Nano VNA to good use!

 The problem with the 80/40/20 antenna and the lack of ability to tune the 80 meter segment was a result of a bad IFL.   No big surrprise when its nearly 500' between the radio and the antenna.   

First I terminated the IFL that runs between the house and each of the 4X1 switches.  

Its about 100' to each 4X1 switch.    So there was no problem between the house and both switches.

Terminated the 80/40/20 fan dipole IFL at that runs to the top of the hill...

Terminated the 15/10/6/2 IFL that run to the top of the hill ...

NEW RULE...Before using any IFL new or in use terminate and sweep.     

Fall Antenna Work

 Put a solid 4 days in working on antenna projects a couple of weeks ago!  

1.  Took down the 80/40/20 fan dipole from the top of the hill.   It wasn't performing as well as I  expected and it wouldn't tune to anything but 3.740 MHz on the 80 meter segment.   
2. Tuned the 80/40/20 fan just outside the house then hung it up just behind the house. 
3. I swept the IFL to both 4X1 switches as well as to a couple of chunks then went to the top of the hill ( separate blog entry ).
4. Tuned the 80/40/20 fan in its operating position.    

All those activites entailed many many many trips up and down the hill.   

Another build....15/10/6/2 Fan Dipole / Vert

 Built this in my basement...

worked this guy from my basement ....

Folded it all up an lugged it up the hill for install.

Here it is mounted. 

2nd build this week ,  didn't like how the first fan turned so scrapped it and started again.   

The 15m element is attached to the rope.   The 10m and 6m segments hang below.  The 2m segment is a vertical dipole.  The antenna is completely built inside ready to go up the hill.  Installation time ... 10 min.   

I fussed over this thing with my NanoVNA and below is the results " In the Basement "  and then after it was installed "Up the Hill Outside".

15m in the basement

15m installed outside on top of the hill

10m in the basement 

10m installed outside on top of the hill

6m in the basement 

6m installed outside on top of the hill

2m in the basement 

2m installed outside on top of the hill  ,  see ***** below 

1-150MHz sweep inside

1-150 MHz sweep installed outside on top of the hill. 

******  the LDF4 run between the house and antenna is around 500' there is another 40ft of RG59 after that.   The IFL routes through a 4X1 switch that isn't spec above 6m so that is what I suspect is the problem with the 2m segment outside.   I have a direct IFL that I will switch to when the weather improves....probably May!  ******

  

Throw out the previous test ... 20m 1/4 Vert vs 20m Fan Dipole 24h WSPR

 The results of the previous test were inconsistent with what I was expecting.  Poking around I determined that the IFL was bad.    Its only a little over 100' but the RG214 has been buried for 20+ years and has been dug up and weed whacked a few times I am surprised it lasted that long.  

Replaced it with 40' of RG214 + 60' of smaller diameter hard line.   Probably less then a db loss across the HF spectrum ...more then acceptable. 

The results were more inline with what I was expecting.   The Vertical is just up behind the house with a tilted GP towards the W SW.  The Fan Dipole is at the top of the hill with  EU and AUS off the broad sides and nulls towards AS and somewhere mid S Atlantic.   The nulls off the end of the dipole are quite apparent and the low throw and tilted GP of the Vert stand out. 

The Fan is best towards EU and AU ,  the Vert is best towards AS.  The low throw of the Vert does give it a 360 degree DX advantage over the dipole.     Both antenna work very well and both have certain advantages  but overall we are talking a 3 db difference for the most part.  

Spots Map Green=both  Blue = Fan Dipole Red = Vertical 

Simultaneous Spots 

Top 10 DX Spots for each antenna ,  LDP Fan Dipole , IMI Vertical 

Added about a 1' chunk to the 80m segment of the 80/40/20 fan dipole.  Below is a comparison of the antenna before and after the addition.   Not allot of change ,  especially with the 80m band.  Next up adding a few feet to the 80m segment!          

    VSWR             VSWR After 1' added to        VSWR After 5' added to 80m  

  Original                     80m segment                     segment  2" removed 20m       

                                                

 80m 

Freq     

3.7             3:1                          3:1                                          3:1                                                            

3.75           1.5:1                       1.5:1                                       1.5:1

3.8             1:1                          1:1                                           1:1                     

3.85           1.5:1                       1.6:1                                        1.5:1

3.9             2.5:1                       2.3:1                                        2.2:1                       

40m

Freq         

7.0            1.2:1                    1.3:1                                            same

7.05          1.2:1                    1.3:1                 

7.1            1.5:1                    1.6:1 

7.15          1.6:1                    1.9:1

7.2            1.9:1                    2.2:1

20m

Freq     

14.0            2.2:1                3.1:1                                    >3 wont tune                        

14.05          1.7:1                2.3:1                                    3.2:1

14.1            1.2:1                1.6:1                                    2.1:1                         

14.15          1.2:1                1.6:1                                    1:1        

14.2            1.6:1                2.1:1                                    2.3:1 

Just had to sweep it with the Nano VNA

500 kHz to 60 mHz

80m

40m

20m

Sure looks like the 40m segment is a wee bit long.   80m is sure narrow band would really prefer it closer to 3.5 MHz  20m is anyones guess.   The IFL is 500' long and because of this I get allot of standing waves created on the IFL which makes it a little difficult to judge resonance.   One way of "tuning " the antenna is to add or remove IFL....doesn't make it resonant just makes it load better.

Ultimate goal is to get the desired freq under 2:1 VSWR keeping in mind a 2:1  VSWR equates to a 1 db loss in TX Power.  

So the plans is ....#1 lengthen the 80 segment then test again #2 depending on the results after lengthening the 80m segment I may want to shorten the 40m a bit.   #3 look at 20m after wrapping up the first two steps.  

20m Fan Dipole vs 1/4 Vert

 Comparing  these two antennas it was alot closer results each having its own advantage.  

The 20m Fan Dipole is at the top of the hill runs from about 260 deg to 130 deg favouring EU and AUS,  40 and 220 deg broadside.   The 1/4 Vert with 8  radials is just behind the house on the side of the hill with a GP tilted towards 200 deg.  

The fan Dipole is LDP ,  the Vert is IMI.  The fan favours EU and the Vert favors in the direction of AUS.  

The reason being is that the vert is shadowed by a big hill looking toward EU and the ground plane is tilted towards AUS.   The fan Dipole has clear LOS both directions.    

Looking out greater then 3800 km ...simultaneous spots 

and less then 3800 km...simultaneous spots