[AMRadio] New Year's Resolution-Getting Back on AM!


ARS W5OMR ars.w5omr at gmail.com
Mon Dec 25 20:41:10 EST 2006


On 12/25/06, Bob Scupp <k5sep at yahoo.com> wrote:

> Thank you for the warm welcome and information on AM
> activity.

> Everyone with comments is always welcomed.

Good to see you again, Bob. Been a while.

> Actually I have a G5RV antenna. I seem to remember it
> is for 10-80 meters. I was originally thinking of
> using the tower I mentioned to hold the center feed of
> an inverted V, with the broadsides facing
> East-West(?). The ends would maybe about 15-20 feet
> above ground. However, being out here in the country
> with no strict municipal or other restrictions, I can
> also experiment with other antennas.

> I have never been on 160 meters. Sounds like another
> band on AM to experiment with.

I ran, for the longest time, an inverted Vee on 75m, because of my
'restricted' space.  Until a year ago (or more, now) when I used
another lenght of wire, attached one end to the existing 75m Inv Vee,
and then closed in the bottom of the antenna .  That made it a loop,
with another ~120' of wire, in addition to the 120' of wire that was
up there.

What I wound up with was a full-wave Delta Loop installed in a
Vertical Plane, and it works great.  I am constantly amazed by the
signal reports I get from that antenna.
I think the biggest gain I got, was when I switched from coax to
ladder-line for feed-line to the antenna.  It just got that much
better, when I closed in the loop.

The actual formula for the loop length is 1005 / f(MHz) but when you
feed it with 50' of 450 ohm ladder line, a lot of sins are forgiven.
;-)

Although I don't think it's high enough, 60' is a good enough start
for a center-support for the 450 ohm ladder-line and loop feed point.
(not to mention, it's better than nothing ;->)

 1005 / 1.9 = 529' of wire.  Typically, that would work out to around
176' per leg.  So, you can't make it a perfect triangle.  So what?
Stretch it out as far as you can, and feed it at the top of the
antenna.  The antenna would work on 160m, it'd be 2 wavelengths on 75,
and would exhibit even more gain on the higher bands.  As long as you
have a good wire-tuner from the rig to the feed-line, you'll be great.

> I agree with you in that the early predictions for
> Cycle 24 looks like it is going to be a whooper!
> Scientists are predicting a peak around 2010-2011 of
> 160 for a sunspot peak. I guess my timing is about
> right on.

For the higher bands.  Nothing more for the lower bands, but more noise ;)

> Again Jim thanks for the advice.

Jim's a good source, Bob.


--
Operating your AM rig without a scope
is like driving our car at night without headlights.(~K4KYV)

73 = Best Regards
  -Geoff/W5OMR-
 Merry Christmas!



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