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Ham Member Lookups: 383849

 

                                  
 

                                    

My antennas today :   - home made 2 el YAGI 3,8 Mhz (total element length is about 24 m,shortened with home made coils)

                                  - home made 4 square 3,5 Mhz (wire elements with toploading 13 m high,feedpoints 2 m from ground)

                                  - home made 5 element YAGI 18 Mhz (interlaced 80 m)

                                  - shunt fed tower 1,8 Mhz

                                  - stack of two 5 elements OP DES 14 Mhz YAGIS

                                  - Rx : 200 m long beverage NO 

                                  - Active Rx loop ALA 1530 LNP

                                  - 'DO' reactangelar rx loop

 

All antenna work is just a one man (me) job.....

The 80 m YAGI is up since 15 July 2017 and is sure a winner and a keeper.

I worked more than 220 dx qso's in the first 35 days now with it.....on all continents and this in middle of summer and few activity.

Since that date i did work dx every single day ( sunrise or sunset ) and comments and reports are very promising so i

conclude this antenna works real well ......

 

 

Radiation diagram for my 2 el 80 m yagi.

Maximun gain is 6,6 dbi (free space) and F/B is 25 db.

 

Home made hi Q coils OT4A

Very high Q loading coils home made are used in order to shorten elements to a practical length of about 24 m.

High Q coils are needed to keep losses at minimum. Coil design also took into account the lack of any parasitic resonance on the

HF spectrum. Q eff,ul = around 1500 of my coils (effective unloaded quality factor at design frequency).     

See below some construction details : 

                                                                                                           

                                    

                                                             

 

Please read what Tom DF2BO (owner and founder OPTIBEAM in Germany) wrote to me after he had seen my coils: 

Hi Theo

Your coils are certainly superiour to ours.

Our coils are good, reliable and low loss, yours will have close to zero loss.

For a single personal antenna such coils are for sure the way to go, to tweak out the last per cent of

performance.

For a commercial production these coils would be too lavish, and to cost intensive.

But be assured, I love your design, the best 80m coil I have ever seen !

 

Very nice indeed to get these compliments from Tom, who's is know for very well designed antennas.

 

                 

Below some comments from Justin G0KSC ....

InnovAntennas are well known for our fantastic and super-quiet VHF/UHF Yagis..... 

but as yet, the benefits of our HF OP-DES are only enjoyed by a few.

See below the setup at OT4A and read what you are missing out on!    What a killer antenna system.....

 

Radiation diagram of my stack of the two 5 el yagi's OP -DES 20 m 13 m apart bottom one 13 m high.

                                             Maximun gain is 16,64 dbi and F/B 26db.

 

                   

Below the picture of my old antenna system, replaced since july 2017.....home made 4 element 40 m Yagi with stack of two KT34XA's....they were up in the air for more than 15 years and i certainly made lots of qso's with them....  

                                                                 

 

           

         

                                                       

 

                                                See more at http://ot4a-theo.webnode.nl

 

                                                             

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

8323819 Last modified: 2017-09-10 18:18:07, 8530 bytes

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United States Award#2118
Granted: 2016-05-15 06:35:04   (OT4A)

Endorsements:
  • 17 Meters Mixed
  • 20 Meters Mixed
DX World Award#3796
Granted: 2016-05-15 06:35:03   (OT4A)

Endorsements:
  • 17 Meters Mixed
  • 20 Meters Mixed
  • 40 Meters Mixed
Grid Squared Award#11543
Granted: 2016-05-14 06:35:03   (OT4A)

Endorsements:
  • 5 Band Mixed
  • 10 Meters Mixed
    15 Meters Mixed
    17 Meters Mixed
    20 Meters Mixed
    30 Meters Mixed
    40 Meters Mixed
    80 Meters Mixed
World Continents Award#12828
Granted: 2016-05-14 06:35:02   (OT4A)

Endorsements:
  • 5 Band Mixed
  • 10 Meters Mixed
    15 Meters Mixed
    17 Meters Mixed
    20 Meters Mixed
    30 Meters Mixed
    40 Meters Mixed
    80 Meters Mixed
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