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A systematic approach to operate 70 MHz from 3A/Monaco - 3A/OH5ZA

  
SP6MLK
15.04.2016 21:55:14
moc !!!
wydawało się ze wiecej już sie nie da ale jednak !



Grupa: Administrator 

Lokalizacja:: Kłodzko JO80IK

Posty: 39331 #2269881
Od: 2013-10-18
A systematic approach to operate 70 MHz from 3A/Monaco - 3A/OH5ZA

3A/Monaco is considered to be a difficult VHF-location,
first of all due to geography, with fairly high surrounding
mountains in a wide sector “screening” much of Europe
from direct low-angle skip.

I arrived here (actually at Beausoleil, France) a few days
ago at about a 50 meters crawling distance from 3A-soil.
This is a social visit, with very few private time slots, so
the outcome of VHF-activity may be very low, but a pile
of tools and antenna hardware has been purchased, adding
to 19 pcs of 100 cm 3.2 mm AlMgSi bent at a 90 degrees
angle at 35/65 cm to fit in the suitcase. The best product
(nr. 817791-1164) for making AlMgSi element extensions
is the Carrefour brass 6 square mm 2 x 6 "Connection strip"
(Barrettes de connexion / Verbindungsstellen / Aansluitstrip),
we call them sugarcubes in Finland, when cut off in pairs.
Only one barrel with 2 screws is needed, e.g. to make a
70 MHz director with two 3.2 mm welding rods, with one
shortened for the right total length.

Before the trip I studied the skyline with Streetview from
the most Southern 3A-areas. That seems to place 1800 m
mountaintops at about 8 km distance, which would mean
a cut-off of the lowest 10 degrees to the Northerly horizons.

For VHF meteor-scatter a good take-off angle would probably
be about 11 degrees for the lobe maximum, which on 70 MHz
for a horizontally polarized antenna would mean about 6 meters
height over flat ground or Mediterranean waters. The search is
on for such a spot. The height of the antenna is very critical.
If one puts it at 12 m height, there will be a deep null in the
radiation pattern at 11 degrees take-off angle and a maximum
at about 25 degrees, which will shorten the meteor-scatter
range enormously. Then there is also a take-off maximum at
6 degrees, but it will hit the mountains. For 50 MHz these
heights must be multiplied by 1.4 x to get the same angles.


We have a brandnew IC-7300, and hopefully it can be driven
with a USB cable for digimodes. Only got one hour to play with
the new rig before packing for this trip.


Will be continued …. (steno, to save time for hardware) ...


Cheers/73, “Zaba” OH1ZAA (3A/OH5ZA)




_________________
Life above 50,000 MHz
73! Stanisław Kłodzko JO80IK
IC-7300 + IC-9700 + (2m - 9el + 250W),
(70cm - 21 el + 250W), (23cm - 55 el + 150W)

  
Electra28.03.2024 12:11:11
poziom 5

oczka

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