On 10 Jul 2005 21:53:28 -0700, "Blue Dawg"
wrote:
Richard, are you saying to go buy two identical antennas and mount them
the same sans coax...

Hi Cliff,

Put them back about ¼ wave, and tune them about 3-5% lower in
frequency = Two element yagi. If you want to chip in two more, you
can build them as directors.

73's
Richard Clark, KB7QHC

Your SWRs are great (as the antenna is setup now) dont bother fixing them.
A good antenna, maybe with some gain, usually only has a bandwidth of the 40
channels. The SWR will be maybe 2:1 at ch1 then go low to 1:1.4 at ch20 then
back to 2:1 at ch 40..will work just fine. Actually your SWRs sound too good
to me, for antennas with loading coils.

If you change the antenna the SWR WILL change so you will need to tune it
up. You want more gain, in some direction, right? well you're going to loose
gain in all the other directions. Focusing the signals by setting up the
antenna like in a beam makes the antennas SWR curve narrower, 2:1range may
only go from ch10 to ch 30. And the SWR will go up, so you need the gamma
match you see on the driven elements to fix the problem.

Apparently Peneterators are 12 ft long, with a load in the center (a lousy
compromise). There would be a matching coil at the base probably too whether
theyre 1/2 wave or 5/8th antennas. A real 5/8th antenna will be 21 ft high
with no loading coils, dont skimp on heighth .

If they are 5/8th antennas and you have mounted these base to base then you
have made an Extended Double Zepp which has gain of maybe 4-6db (2.5-4X
signal gain) and can focus the signals on the horizon (I assume these are
mounted vertically not horizontally out from the sides of a tower). you
would need to put the base to base mount at least 40ft off the ground, one
pointing up/one down.

Adding a director or reflector will not do much for you, since you already
have pretty good antenna (assuming its working right!) A Zepp antenna (end
to end 5/8th antennas, 42 ft long) is a great vertical if high enough and it
puts you power on the horizon.



"Blue Dawg" wrote in message
oups.com...
I am running a President Grant am/usb/lsb and on Channel 1 the SWR is
1:0.08, on Channel 40 it is 1:1.45 and on Channel 19 it is 1:1.09. It
really isn't worth doing an adjustment on this antenna setup is there?
The antenna is a single Yagi beam made up of two Tram Penetrators
(Monkey Made's). I think that it is sold as a 1/2 wave antenna and
have heard that it is a 5/8 wave. This antenna can be set for 10 meter
usage also. It really looks weird up there without a reflector on it.
I may put a reflector on it but am stumped as to length of the
reflector (ging to be made of 1/2" electrical conduit). I can't find
the formula for the length taking into consideration of the diameter of
the reflector. I believe that the 'stand-by' one should use 468/f.
Using 27.185 (Chl 19) the length should be 17.22 feet. Only thing is
the length of the driven element is less than 12' because of the
antennas having the centerload coil in them.

What do you think?