40m OCF DIPOLE

Version 4

 

Version 4 has the same feedpoint split and leg lengths as used in version 3.1 and 3.2.

 

CHANGE:  I have re-designed the feed method.

 

New:  I have built a 4:1 Guanella on two "-43" Toroids, placing one transformer on each core.

 

SAME:  I have used the same 1:1 Guanella (CMC Choke) which is 2x 9 turns of RG-174 on a "-43" Toroied.

 

LENGTH:  About 66 ft. 

 

FEEDPOINT SPLIT:  17.4% / 82.6%

 

WEIGHT:  Unfortunately the weight has increased significantly.  This version weighs 440 gr. (14 oz.), including 11m (35 ft.) of RG-174 coax.  For comparison, Ver. 2 weighed 335 gr. and Ver. 3 weighed 360 gr.

 

RESULTS:  The excellent SWR curves of Ver. 3.1 have been maintained, while eliminating the problem of the apparent resonance frequency being dependant on the length of the coax.

 

 

SWR CURVES:

How do you like them apples?

NOTES:  

  • The antenna was mounted on a Spiderbeam 12m telescoping fiberglass "Spiderpole".  
  • The feedpoint was 10m (33 ft.) high.
  • The long end was 4m (13 ft.) high at its far end.
  • The short end was about 8m high at its far end.

SWR CURVES BY BAND:

[ click on image to enlarge ]

COMMENTS:

THIS ANTENNA:

  • IS RATED FOR 100 WATTS OF TYPICAL AMATEUR RADIO SSB AND CW OPERATION.
  • may be used on 40/20/15/10/6m  WITHOUT  the need for an antenna tuner.
  • may be used on 12m WITH a matchbox, but I recommend reducing power to 75w.
  • has met all of my original design goals EXCEPT for weight.
    • I will address the weight issue in Version 5.
  • is finished.

 

WARNING:

 

DO NOT ATTEMPT TO USE THIS ANTENNA ON 17m

UNLESS YOU REDUCE POWER TO ABOUT 50w.

 

DO NOT ATTEMPT TO MATCH THIS ANTENNA ON 50m

UNDER ANY CIRCUMSTANCES;

THERE IS A VERY HIGH RISK OF BURNING UP

THE 1:1 GUANELLA CMC CHOKE IF YOU TRY TO USE THOSE BANDS!