Hello again Mike, Thanks for the question,
I have had as many as 4 of the directional Hi-Z and a new undisclosed
design experimental Low impedance element arrays running at one time for
comparisons. Some over 1000 feet apart.
From the plots of Eznec there is scant 1.4 dB RDF difference betw
Wonder why the TOGA map shows all that below the equator activity and 2 that
show the equator of the others do not.
Seems strange to me.
Lee K7TJR
_
Topband Reflector Archives - http://www.contesting.com/_topband
Hello JC and others,
I must take a little issue on being able to measure the vertical arrays.
While it may be true that it is hard to measure, you can indeed see the pattern
quite well by looking at different stations and switching around the compass.
It does not take long before you can obse
Greeting top-banders and Ed,
You could simply disconnect the elements from your Hi-Z amps at each
element. This will tell you if the noise is being generated in the system or
coming in the air.
My guess from experience something some distance from you is following your
power wires.
Good luck
These two sites are also gone now. Hauled away for scrap. Acres of stainless
mesh wire ground plane as well.
http://www.k7tjr.com/fps118_oth_radar.htm
Lee K7TJR
_
Topband Reflector Archives - http://www.contesting.com/_topband
Ken, did you remember the 180 degree phase inversion needed on the Waller
flag.
It will act like a very large signal level single loop if not.
Lee K7TJR
_
Topband Reflector Archives - http://www.contesting.com/_topband
Hello Gary and all, The answer to your question depends on how quiet your
location is. If you have an extremely quiet location I would go with another
section of tubing for 23 feet overall with the Hi-Z. If your location is
pretty normal for noise then 18 feet or so will be fine with the Hi-Z
arr
John, do your NEC4 numbers take in to account the signal that actually
arrives at the element insulators and the amplifiers with their inherent
input capacitances as a load on the element source capacitances. Or are you
using NEC gain numbers to get the 0.5 dB per foot?
Lee K7TJR
>>>A while back
Thanks John, I have been faced with this capacitive loss thing for a long
time. It became quite necessary to reduce it to make my all active HI-Z 8A
array work well. Especially with the early Hi-Z amps with 6dB loss.
Here is a list of elements of different lengths and their subsequent output
source
Hello Gary,
Spray painting the elements is no problem. As far as mounting the amps to
the elements I would not recommend that. It likely could compromise
performance. It would be much better if you could take a steel post like a
piece of rebar and provide a second place for the amps to moun
Yes Ed, You have the right numbers. It won't matter which windings are first
or last. You can even wind 4 then wind 1 more and use it as an autotransformer
where the 1 turn is added to the 4 for 5. Any of these will work fine at these
TOP Band and higher frequencies. This ratio is not perfect
Actually there is a reason or two to match the feedline impedances when
using these active antennas.
There are amplifiers in most of these systems that rely on their matched
impedances to produce their best IMD capability. It may not matter in some
areas of the world but in others with high
Paul, I suggest you talk to Gary KD9SV as he built a Hi-Z around his TX
antenna.
Incidentally the ground radials under the Hi-Z is not a good idea. I suspect
you would have to use NEC4 to see the real effect of the radials. I have not
made a test myself to see how close radials could be. Disc
101 - 113 of 113 matches
Mail list logo
