I have mine at the 70 foot level and it work good. Try it you will like it.
JIm
At 07:31 AM 5/28/98 -0600, T A RUSSELL wrote:
>
>On Wed, 27 May 1998 22:22:22 -0500 Tom Champlin <w0hh@ix.netcom.com>
>writes:
>
>
>>.....snip.... I have a 40-2cd in the basement I never
>>finished, because, frankly the thing needs to be up at about 140' to
>>have any real gain.
>>
>>Tom W0HH
>>
>
> WRONG !
>
>This kind of thinking results from the misconception that DX signals
>ONLY propagate at the lowest angle that will link two distant locations
>in
>the minimum number of hops. Most propagation programs list the
>waveangle that corresponds to this minimum number of hops.
>
>In actuallity, the ionosphere will support much higher waveangles.
>Several factors can combine to produce the strongest signal at
>waveangles higher than those corresponding to the minimum number
>of hops. These include absorption in the D layer (which is higher
>for low angles since they spend more time in the D layer), LOW
>ANTENNAS at the DX end (which radiate more energy at HIGHER
>angles), and DUCTING effects and E-layer effects which take high
>angles and bend (refract) them to lower angles aimed at the F layer.
>
>It is fairly easy to determine the highest angle that will propagate:
>Simply observe the closest stations that are heard via ionospheric
>refraction. Knowing this SKIP distance, and the height of the ionosphere
>will yield the highest angle supported by the ionosphere (see graph of
>waveangles vs. distance published in ARRL Antenna Books and other
>sources).
>
>>From 40 years of DX and contest experience, and discussing antenna
>performance vs. height with station owners having more than one 40M
>beam, my opinion is that 80 to 100 ft is optimum on 40M during the
>late afternoon and evenings. Higher antennnas (140 to 200 ft) pay of in
>the
>early morning, especially just before sunrise and just after sunrise on
>the
>LONG PATH to Central Asia and the SKEW PATH to SE Asia (from eastern
>USA). Everyone I know with both high and low 40M beams uses their
>LOW antenna for the evening opening to Europe and Africa.
>
>Even if you can't get a 40M beam up at 80 ft, it is still beneficial.
>Did you
>ever hear A22MN on 40M? His big signal originated from a 40-2CD at
>50 ft.
>
>By now, most readers are tired of hearing me tell about how my 40 ft high
>TH7 is often my BEST antenna during daylight hours on the high bands.
>You need BOTH high and low antennas to cover ALL of the waveangles
>supported by the ionosphere and the LOW antennas will OFTEN outperform
>higher antennas when MUF's are higher than the band in use.
>
>de Tom N4KG (with 20 antennas on 7 towers from 40 to 140 ft)
>
>
>
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