[Antennas] Best 'no radials' HF vertical?

2002年8月16日 20:35:51 +0100

Subject: RE: [Antennas] Best 'no radials' HF vertical?
Hi all..
 Did anyone mention the Force 12 Sigma-5 ?? It covers 20m and up. Capacity
hat loaded vertical dipoles are efficient. You can see it at
http://force12inc.com/sigma5info-003.htm . I use homebrew wire versions for
160 and 80m. They're at http://www.iol.ie/~bravo/ if you're interested..
 73 es happy hunting..
 John EI7BA
> Hi Jim:
>> Since you have identified your space limitation and the desire have
multiband capability, considering a "radialess" vertical makes sense. You
are clearly aware of its limitations, so it is just a matter of picking the
best offered.
>> I have (and still do) own the MFJ 1796 and the Cushcraft R-7 (preceeded
the R-7000) which both utilize the end fed window theory of operation. The
one thing I take away from using both of these antennas is that more metal
is better. The MFJ-1796 at 12 feet tall was not as good as the R-7 at 20 or
so feet. So, if you are not limited vertically, I would line up the
contenders and select the tallest one offered.
>> While I am not familiar with the trapless model you mentioned, this
should be a plus if it was not significantly shorter than the others.
>> One last observation. Cushcraft has had a history of providing little
or expensive support for those needing part replacement on their antennas.
Either they want you to purchase half the antenna to get at a single part or
want way to much money for the part desired. The R-7000 and R-7 both had a
tendency to burn out traps (although this was probably due to owners trying
to run power with SWR readings that exceeded 1:1.5) and this lead many users
to realize that Cushcraft was not as supportive to their customers as they
could be.
>> Good luck.
>> Ron W7MRR
>>>> --- On Fri 08/16, Jim Shaw wrote:
> From: Jim Shaw [mailto: [email protected]]
> To: [email protected]
> Date: 2002年8月15日 21:05:43 -0700
> Subject: [Antennas] Best 'no radials' HF vertical?
>> > Because verticals with 'no radials' are sometimes an emotional topic, I
> > have
> > been hesitant to ask for feedback on them. However, due to a sudden
> > decrease in my already limited space for antennas, I am now seriously
> > contemplating the acquisition of a 'no radials' vertical antenna in
order
> > to
> > remain on the air until I can move to a new QTH with more space.
> > Hopefully,
> > I can obtain a vertical that covers all bands, including WARC, from 40
> > thru
> > 10 M and will take the full legal power limit.
> >
> > From what I can tell, there are three commercial possibilities: 1) the
> > Cushcraft R8, 2) the Hy-Gain AV-640, and 3) the Hy-Gain DX-77A. In
order
> > to
> > familiarize myself with what kind of performance I might expect, I
> > obtained
> > the publication "HF Vertical Performance Test Methods and
> > Results" by N0AX
> > and K7LXC published in 2000 and obtainable via
> > http://www.championradio.com/forsale/ . This report compared the
> > Cushcraft
> > R8 'no radials' vertical to the Butternut HF6V, MFJ 1798, Force-12 ZR-3,
> > Diamond CP-6, Hustler 6BTV, Force-12 V-3, and Gap Titan. In addition,
> > from
> > my own personal experience, I've used the Cushcraft R-4 (the very first
> > commercial 'no radials' HF vertical?) as a 'backup' antenna for nearly
15
> > years.
> >
> > I had pretty much settled in on the R8 because, among other things, it
> > uses
> > fewer traps than the Hy-Gain DX-77A. Also, its 'counterpoise' elements
> > are
> > only 4 feet long thus I could install it in a space no wider that 9 feet
> > by
> > 9 feet. However, recently, I noticed that Hy-Gain now offers a new, 'no
> > radials' vertical' - the AV-640. This new AV-640 not only has 'no
> > radials',
> > it also has 'no traps'! I downloaded the manual and found that it
> > contains
> > a nice 'theory of operations' discussion and the design makes a lot of
> > sense
> > to me. But, I'm no expert on this topic.
> >
> > So, assuming you were limited to putting up a single 'no radials'
> > vertical
> > and wanted to operate high power on 40 thru 10 M, which one of these
> > three
> > verticals would you choose and why? Or, is there a better alternative
> > possible within my limited space that I have not considered?
> >
> > 73 de Jim [email protected]
> >
> > - - -
> >
> > Your moderator for this list is:
> > Larry Wilson KE1HZ [email protected]
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> >
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