Connie,
What you are missing is you need to constantly bleed off static that is
induced and charges up a dipole or other antenna like it was a
capacitor. The static can come from wind vibrating your wire or beam
antennas, or from induced charge from a passing storm.
This is discharged continuously if you have a high ohms resistor in each
half of the dipole to earth
The commercial products you list may have either gas tubes that only
discharge when a certain high voltage is exceeded, or may be spark gap
types, that again only break over and conduct when a high voltage has
already run down to your radio.
Thus you need as much of each type as you have antennas.
Disconnecting a feed line is fine, but putting it in drawer just invites
a fire burning up the dresser.
Consider that a typical lightning bolt is 10 miles long, If you only
disconnect the cable and put them nearby, the lightning can jump the
distance across your shack easily.
A feed line needs to be disconnected outside the building and the free
end plugged into a panel of grounded (both sides) antenna jacks for the
most protection.
Some measure of protection is afforded if you run feed lines inside a
tower or mast, and ground the base of the tower or mast with copper
braid or strap of copper or aluminum to 8 foot ground rods driven
entirely into the ground.
You need to get some heavy copper wire no. 6 as a minimum to lay in a
trench between your station ground and your tower ground to force them
to the same voltage in case of a nearby hit. The copper does not have
to be buried deep, as it is acting as a conductor for current between
station and antenna pole.
Aluminum is a great conductor but can't be buried in some soils. Thus I
mention copper wire to bury, and aluminum flashing for above ground use
like bonding tower to ground rod. You may have to put anti oxidants on
dissimilar metals being joined to lessen those metal differences.
Check the ARRL Handbook and the RSGB Handbooks for more on antennas and
lightning protection.
Conduit to enclose coax cable run from tower or mast to station should
be used to form "a waveguide beyond cutoff" to oppose lightning currents
following the shields of the coax to the station.
Baluns may improve receiving, but don't do much for transmitting.
Have a central antenna feedthru panel on an outside wall of the shack if
you can. This would be an aluminum plate with coax and other
connectors, and grounded to an 8 foot ground rod. Antennas and rotor
cables should come thru the same protection panel.
Look up "Lightning Protection for the Ham shack" on internet.
You will find lots of references. Look for those of some of the big
lightning protector manufacturers. They will have the best info.
You may not be able to afford the top of the line procedures, but
implement as much as you can now, and allow for extra antennas etc.
later at your feed thru panel. Some of these are installed right in the
wall, or you raise a window and permanently fit the metal plate between
sash and sill.
Gl,
Stuart Rohre
K5KVH
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|