> JE>Here's some antenna discussion fodder:
 > JE>
 > JE>A typical dipole cut for the lowest frequency you plan on working
 > JE>(ie: 80m)
 > JE>
 > JE>|-----------------------| |------------------------|
 > JE>                        | |
 > JE>                        | |  <--Feedline
 > JE>                        | |
 > JE>                     ___|_|___
 > JE>
 > JE>
 > JE>|-----------------------| |------------------------|
 > JE>         |              | |                 |
 > JE>                        | |   <--Feedline
 > JE>                        | |
 > JE>                     ___|_|___
 > JE>
 > JE>
 > JE>Above, the same 80m dipole with 40m 'tassles' installed.
 > JE>
 > JE>A 'tassle' is just a chunk of wire around 4 to 6" in length,
 > JE>soldered onto the existing dipole, at the distance from the
 > JE>feedpoint calculated for 40m, to allow for resonation at 40m.
 > JE>
 > JE>The result is a dual-band HF antenna that will not only work
 > JE>on 75/80, but 40/15m as well.  (15m being the third harmonic
 > JE>of 7MHz)
 > JE>
 > JE>Don't see why this won't work for a 40/20m situation, either.
 > JE>
 > JE>Pro's: a substantial savings on the amount of wire used for the
 > JE>dipole - only one coax run needed, if setup right no
 > JE>tuner/balun needed.
 > JE>
 > JE>Am interested in hearing from anyone why they think this
 > JE>will/will not work.
 > I thought traps were required, not just 4 to 6 inches of wire.
Conventional thinking, maybe   But, traps have historically been used - 
and, they're a compromise.
 > Interesting idea, but I've never tried it.  The only thing I've
 > done is 80 and 40 meter dipoles fed with a single coax.
Think of the RF that sees the wire - one half-wave at 75m (say, 3.9MHz) is 
idealisticly 120ft.  At 7.200, it's 65ft.  Using one dipole antenna, cut and 
install the one for 75m, and make sure it's resonate at where you want it to 
be (naturally ).
The formula I used is the old standard 468/(f) where (f) is frequency in MHz.
Then, get the 40m part ready.  You could actually use a clip-lead for 
testing.  Measure out 32.5ft each side of the feed line, attach a small peice 
of wire (say, 4" or so) and go tune up on 40m.
The theory is, that RF will seek out it's resonance point, at the closest 
point it comes to.  If there's a stopping point at 7.2MHz, and the 'tassles' 
that are cut actually do allow for resonance at 7.2MHz, then that's where 
it's going to work.
On 75m, RF is looking for a half-wave point, at/near 120ft, overall - it 
finds it, and is happy - vioila!  Dual band HF antenna with one coax, and no 
ill-effects from 'cross-over' (one antenna interfers with the other).
It's the same thing, James, as building a dipole for 160m that covers from 
1.900 to 2.000MHz.
Using the same formula, 468/2.000 = 243ft, we've got the dipole length needed 
for the high end of the band, and 468/1.9 = ~246ft for the low end of the 
band.
Wow!  3 FEET for 100kHz change?  What some people do is build TWO dipoles, 
and feed them from the same point.  What a difference, if they could just 
build the long antenna, and then put the 'resonantor' at the length needed
 > I've tried adding 20 meters, but I've never been able to get
 > it to work.
I could never get that 'cross' configuration to work here, at all!
 > Hopefully, this will be the summer
 > I get some of my HF antennas back up.
Best of luck to ya - and if you do build that thing, let us know how it 
worked out.
   73 = Best Regards
   -Jeff KA5THB
   ka5thb@bigfoot.com
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