[TowerTalk] Phasing 2 Verticals

[D. Scott MacKenzie]

Thanks for the help Jim:

I was looking at using a Christman feed system per OH4UN Low Band Dxing (p
11-34 3rd edition).  It looks like the simplest and best way to accomplish
the match.  I just need to get a good measurement on each of the antennas,
and then use the method shown in Low Band Dxing to establish the feed
matching. I just need to find a copy of the program FEED LINE VOLTAGE
described in the book......

I know my antenna as a single element works - worked 5A7A last night, 100W
SSB first call on 80M (I must have been incredibly lucky!) and worked 80M
DXCC on it in one season....I just want a little more oomph for the contests
on 80M, and get a bit more noise rejection off the back.  I do not have room
for a lot of RX antennas, and this looked like the simplest way to achieve
my goals....

Any recommendation would be a big help.

Scott

-----Original Message-----
From: Jim Lux [mailto:jimlux at earthlink.net]
Sent: Tuesday, November 21, 2006 9:04 AM
To: kb0fhp at comcast.net; TowerTalk at contesting.com
Subject: Re: [TowerTalk] Dumb Question


At 08:22 PM 11/20/2006, D. Scott MacKenzie wrote:
>I am trying to set up a set of 2 phased verticals in a similar fashion to
>this:
>
>http://home.comcast.net/~kb0fhp/80M_Vertical/80M_Vertical.htm
>
>With the limited space I have available, I have decided to use 1/8 wave
>spacing, with 135 degree phasing - it should give me about 3-4 db gain over
>my existing set up.  The question I have, is what is the free space length
>of 1/8 wave at 3.8 Mhz?  Can I use 125.625/f (from the loop equation l =
>1005/f)?  Or is there something else I should use?

The dipole and loop equations are estimates of the length for a
resonant doublet or loop, and take into account the fact that a
resonant dipole is 3-5% shorter than a half wavelength long dipole.

For free space:
299.8/f in MHz gives you wavelength in meters in free space.  Or,
just use 300.. it's close enough.
(78.89 m for 3.8 MHz)

Multiply meters by 3.28 to get feet. (258.8 ft for a whole
wavelength, 32.35 ft for 1/8th wavelength)

How were you planning on doing the phasing?  A tuned LC
network?  There's a fair amount of coupling between two antennas
1/8th wavelength apart.



>Sorry for the dumb question....I appreciate your help in advance.
>
>Scott