At 09:48 AM 11/21/2006, D. Scott MacKenzie wrote:
>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've got an excel spreadsheet that can do the calculations for you,
if you have the Z measurements.
>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@earthlink.net]
>Sent: Tuesday, November 21, 2006 9:04 AM
>To: kb0fhp@comcast.net; TowerTalk@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
>
>
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