Pictures of the modifications to the 37 MHz DB201 ground plane antenna to 29.56 MHz

  1. Ken Noblitt N5UA making initial measurements on the radiating element

  2. Additional measuring - showing detail of the new solid radiating element extension

  3. Chuck N5UN starting the bending of the new solid radiating element using a tower guy post as a mandrel

  4. Continuing the bending

  5. Bending the solid radiating element extension is hard work!

  6. Almost bent to the correct dimensions

  7. The new solid radiating element after bending and installed for a fit check

  8. Sleeve installed for a fit check on new solid radiating element splice

  9. Sleeve after final mechanical fastening

  10. Another sleeve for a different splice location after final mechanical fastening

  11. The splice between the new solid radiating element and the main radiating element tube

  12. The radiating element spacer installed - it is made of outdoor grade PVC pipe

  13. The base of the antenna showing the jumper cable installed and also 2 of the 3 radiating element splices

  14. The assembled antenna set up for testing

Final test data for the antenna after fine tuning of the ground radial lengths

VSWR measurements

29.0 MHz  1.5:1

29.56 MHz  1.1:1

30.0 MHz  1.25:1

For operation at 29.56 MHz, the length of the radiating element to the ground radial base
should be 92 inches and the length of the ground radials should be 128 inches.

Modification of a DB201 ground plane antenna to 6 meters

For operation at 52.525 MHz, the length of the radiating element to the ground radial base
should be 50.5 inches and the length of the ground radials should be 73 inches.

Modification of a DB212 folded dipole antenna to 6 and 10 meters

Here's the information to either shorten a lower than 50 MHz DB212 to 6M or to lengthen a higher
than 30 MHz DB212 to 10M:

10M (29.6 MHz) 94 inches

6M (52.525 MHz)  51 inches

Refer to the picture below of a DB212 antenna.  The measurements above are  for the distance between the
2 arrows.  Both the top half of the dipole and the bottom half of the dipole should be to the same dimension.

These dimensions were determined by calculating the approximate lengths and then fine tuning when the antenna
was mounted about 15 feet above the ground to it's lowest point on a Rohn 25 tower.  Note that these antennas
are designed to be mounted to the side of a tower or a pipe for proper loading/tuning.

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This page was last updated on 13 January, 2008 11:39:15 -0600 by webmaster xanaduu

All photos by Chuck Adams.

All contents copyright 1997 - 2008 by Charles P. Adams, Fort Worth, Texas USA.   Texas flag