The 18HT is a very good antenna ..over the years I've had then in a
single/dual and triple combination.....The key to the performance are
the grounding system and the radials....Take GREAT care in the design of
such ...radials are a pain in the butt but are very necessary.... After
driving 4 ground rods at the 4 corners of the base of the antenna I left
enough of the rods so I could heat and bent the top 4 inches over to a
90 degree angle, I then took 4 layers of copper strapping 3 inch wide
then bolted it to the rods...so now I have a heavy copper ring
surrounding the antenna...in addition the strapping was brazed to the
rods...and the joint of the rod and the copper strapping was sealed with
Epoxy putty, so ZERO water/dirt etc can get to the joint and weaken its
properties......then the fun begins ... I installed 70 radials, 1/4 WL
for 40 and 80 meters, then another 140 radials of random length for the
other bands....Installation of the radials was easy...we made a jig for
each length then ran layers of wire between then cut them as
needed....we use #18 stranded bury able coated...For the radial
attachment, a hole was drilled and a copper bolt and nut secured the
wire to the copper strapping..(Copper bolts/nuts found on Ebay)
The radial wire as it passed from the bolt across the strapping was
soldered ...then a 1/2" generous layer of canning wax/paraffin was
dribbled on the entire radial-strap to water proof it and keep the junk
out....
The ant was easy to tune with the stubs for the bands .. and I must say
the tower works!!!!! I have a 40 and 80 bazooka at 130 feet and a full
wave loop at 150 feet .. the HT18 usually is better than all into Europe
etc and hears into VK/ZL that are not noticeable on the wires....
Good Luck and have fun...
Bill Winkis - KC4PE
http://www.kc4pe.com/amateurshack.htm
On 3/28/2011 9:49 PM, r miles wrote:
> Tnx guys. It came from Fl& a few guys think it was a homebrew spark gap
> arrester to drain the static off.
> .........
> Think I've got a plan for the concrete.
> .....
> Tnx fast replies........
>
> K9IL
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