This is almost ok, but using 468/f is a typical length for a half-wave
dipole including the shortening due to end effect (-5%).
At 7.15 the wavelength is 983.571/7.15 = 137.56 feet. In your coax with
VF=0.6779, this would be 93.25 feet.
So a quarter wavelength line would be 0.25*93.25 = 23.31 feet and
a three quarter wavelength line would be 0.75*92.25 = 69.94 feet.
When I modeled this in EZNEC, with 3/4 wl line between the verticals and
a 3/4 wl line to the Tx from vertical #1, the beam goes to the SW. With
5 ohms of ground loss, the gain is 2.56 dBi and the F/B is 8.8 dB. Feed
Z is 86.2 - J 50.02 ohms or a 2.48:1 SWR at 7.15 MHz.
Let me know if you need more info.
73, Terry N6RY
On 2012-05-02 8:44 AM, Bob Ad5vj wrote:
> My first Rodeo on phasing, need confirmation please.
> I am working on 2 34' phased verticals spaced 34' for 40 meters pointing in a
> NE/SW line.
> SW ant we call #1
> NE ant we call #2
> I am wanting ONLY NE direction.
> Using my MFJ-259B I have determined the length of coax I have (RG-11) to
> measure 106.2' to the fault.
> Physically measuring the coax it comes to exactly 72'.
> Dividing 72/106.2 I get a measured velocity factor of .6779 according to the
> MFJ manual.
> (468/7.150)/2 =32.7' per 1/4 wave
> 32.7' X 3 = 98.1818
> for 3/4 wavelength
> 98.1818 X .6779 = 66.55'
> So this should be the physically measured coax length for the 3/4 wavelength
> going to the #1 vertical.
> Then I do the same for a 3/4 coax wavelength from #1 to #2 antenna.
> Does that sound right?
> 73, Bob AD5VJ
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