View Single Post
  #1   Report Post  
Old October 8th 07, 06:01 PM posted to rec.radio.amateur.antenna
Bob D. Bob D. is offline
external usenet poster
 
First recorded activity by RadioBanter: Jul 2006
Posts: 41
Default Tweaking 80 meters on multi-band dipole

I have a multi band dipole with traps/loading-coils. I would like to raise
the resonate frequency of the 80 meter band by 200 KHz. Can I simply shorten
the 80 meter part of the dipole by the proportionate part of 200 KHz?



I.E. - ¼ wavelength at 80 meters = 66.9 ft.



200KHz/3.5MHz = .057



66.9 ft x .057 = 3.8 ft.



If I shorten each leg of the 80 meter section of the dipole by 3.8 ft, will
that raise the resonate frequency reasonably close to 200 KHz? (If this were
a simple monoband dipole, I would not hesitate to lope off the 3.8 ft. But
with the coils, I'm not sure what the effect will be.)



BTW, this is a Delta Alpha DX-LB plus. I realize shortening the 80 meter
section will also affect 160 meters. This should not be a problem because I
want to raise 160 also.


--
Bob D. ND9B