I guess CSVHF has already tested the Arrow at UHF - oops!
How I read Kent's data is that adding either an 8-32 nut to lenthen the elements #1, or insulate them #2 improves gain about 0.3 dB over the standard antenna #4. I'mnot sure what torquing means other than maybe consistent tightening each element. Obviously it does not show any difference with #4. #6 merely shows that using the diplexer adds some loss which is normal for any such device, though 2.4 dB seems a bit high (but maybe not for its small phycial size -compare its insertion loss with a Comet 416 diplexer).
In my opinion it is not fair to compare diplexer loss with antenna gain measurements. All diplexers have some losses as do repearer duplexers. One can merely compensate Tx power for this. Rx performance is harder to compensate but a preamp will help.
73, Ed - KL7UW
At 07:00 AM 12/28/2008, Gary "Joe" Mayfield wrote:
http://www.csvhfs.org/ant/CSANT06.HTML
Man; that is some good info. I have nothing but respect for Kent, wa5vjb. Would someone please clarify some things for me?
- Arrow Antenna w/8-32 nuts on elements ~7.3
- Arrow Antenna w/plastic inserts on elements ~7.3
- Arrow Antenna w/star washers on elements ~7.1
- Arrow Antenna w/o Diplexer ~7.0
- Arrow Antenna w/"torqued" elements ~7.0
- Arrow Antenna w/Diplexer ~4.6
I assume number 6 is the dual band Arrow "out of the box", and that number 4 is the dual band Arrow "out of the box" bypassing the diplexer. Is this correct?
Does everyone else read this as insulating the elements, and/or lengthening the elements only buys you at most .3 dB, or were those tests run with the diplexer in line?
It seems improving the 2.4 dB of insertion loss of the diplexer would be a better strategy (although not necessarily easy in the space available) than attempting to modify what is very mechanically sound antenna.
73, Joe kk0sd
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Jim Leder Sent: Sunday, December 28, 2008 8:06 AM To: Amsat Subject: [amsat-bb] Re: Fw: ELK or ARROW
Is it really worth it for .3 DB gain? Seems you would be better served by not using the diplexer.
Reference http://www.csvhfs.org/ant/CSANT06.HTML
I continue to be amazed how people can judge by just looking at imagined numbers. Seems that practical hands on experience has no bearing on how good
or bad the Arrow or the Elk antenna is, but just conjecture over assumed specifications makes them less than a 'Ford or Chevy'?
If you need a handheld satellite antenna, you have pretty much 3 choices: -The 'bad' Arrow -The equally 'bad' Elk -make your own Arrow clone, which according to the numbers is far superior (what's that they say about imitation?)
I have an Arrow and have 'field tested' the Elk. I stuck with the Arrow. My OPINION, it's better. Others disagree. I contemplated building an Arrow clone, as there are several websites that tell you how. Are they better? Perhaps, but I got to think that a DB or 2 won't make that much difference.
Believe what you want, but I believe the Arrow works just fine the way it it is.
Jim Bob Buckeye AKA**** Jim Leder**** K8CXM since 1961 IBM retiree since 1999
There are 10 types of people in this world -- those who understand binary and those who don't.
----- Original Message ----- From: "Jim Jerzycke" kq6ea@pacbell.net To: amsat-bb@amsat.org; "Gary Joe Mayfield" gary_mayfield@hotmail.com Sent: Saturday, December 27, 2008 11:42 PM Subject: [amsat-bb] Re: Fw: ELK or ARROW
Or you can just lengthen them 1/4" on a side with a threaded spacer.... Jim KQ6EA
--- On Sat, 12/27/08, Gary "Joe" Mayfield gary_mayfield@hotmail.com wrote:
From: Gary "Joe" Mayfield gary_mayfield@hotmail.com Subject: [amsat-bb] Re: Fw: ELK or ARROW To: amsat-bb@amsat.org Date: Saturday, December 27, 2008, 8:17 PM Has anyone played with insulating the Arrow elements from the boom? It shouldn't be too hard to do.
73, Joe kk0sd
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Jim Danehy Sent: Saturday, December 27, 2008 8:33 PM To: amsat-bb@amsat.org Subject: [amsat-bb] Fw: ELK or ARROW
there is the old adage that you get what you pay for . . . why buy a poorly designed antenna that does not work very well
?
If you have a 5 element yagi that only produces 4 dbi
you are not getting
what you paid for . . . most 2 element yagis would out
perform that
statistic . . . a 5 element yagi should be at least 9
db + or 10 db dbd
(dipole ) not isotropic . . . . there is something
that is called
MERCHANTABILITY . . .i.e., an IMPLIED WARRANTY that
you are getting at
least the minimum for your money . . . 4 dbi for an Arrow is way off base . . . so it is not
just ; you can not
afford a Cadillac but you are not even getting a Ford
or Chevy . . i.e.,
the gain of a 5 element yagi on 435 mhz . . . that is
the issue, not cost
alone . . . . . . same comments apply to the ELK but I
have attempted to
make the point that there is a minimum performance for
a certain number of
elements that is pretty OBJECTIVE and when it is not
met . . . . well
that is my point . . . these two antennas have shown
to some testers that
they do not measure up to the minimum EXPECTATIONS . .
.unfortunately that
is acceptable to some . . . . then it becomes
acceptable to many . . .
and objectivity is abandoned . . .
Jim W9VNE
----- Original Message ----- From: "Trey Brown"
To: "Jim Danehy"
Sent: Saturday, December 27, 2008 6:39 PM Subject: Re: [amsat-bb] ELK or ARROW
Thanks for the comments. Realize, though, that not
everyone wants or
can afford to have the Cadillac.
On Sat, Dec 27, 2008 at 4:06 PM, Jim Danehy
jdanehy@cinci.rr.com wrote:
the Arrow antenna has been critiqued by Kent
Britain, WA5VJB
http://wa5vjb.com/references/Cheap%20Antennas-LEOs.pdf
he says that some have measured the Arrow for
gain on 435 mhz @ 4 dbi
(isotropic) . . . . and that further analysis
showed that for the
element lengths used on 435 mhz that it peaks
at 457 mhz and not 435 mhz
. . . Kent is a well respected VHF/UHF antenna
person who has plenty of
credibility . . .
Kent opines that the Arrow, as built does not
have its elements
insulated from the boom. It uses dimensions
for insulated elements . . .
so much for the Arrow . . . .
Now for the ELK : a local friend of mine owns
an Arrow and he uses it
successfully. He bought an ELK and attempted
to compare the Arrow and
the ELK . . . . he could not make an across
town QSO on 435 mhz from his
second story window with the ELK , so he sent
the ELK back for a refund
.
I have worked and exchanged QSLs with several
hundred satellite users .
. .the majority of the folks that have worked
and QSLed me (close to 250
- ) have been using either the Arrow or ELK
based upon the information
on their cards. So they are popular. Are they
optimum ? A lot of
anecdotal information would seem to say NO . .
.
Thirty-five years ago I worked Oscar 6 with a
homebrew 2 mtr yagi that
probably was worse than either the Arrow or
Elk but I worked YV and KL7
from Indiana on CW with about 15 watts to the
3 elements which my XYL
waved around at my directions . . . not any
more . . .what do I use
these days : a pair of circular polarity yagis
on 10 foot booms
manufactured by M Square . . . .
Folks ask what should they buy ? Maybe a Ford
or maybe a Chevy . . .
neither is a Cadillac . . . .
Jim W9VNE
Sent via AMSAT-BB@amsat.org. Opinions
expressed are those of the author.
Not an AMSAT-NA member? Join now to support
the amateur satellite
program! Subscription settings:
http://amsat.org/mailman/listinfo/amsat-bb
-- Trey -- N5THX
They who can give up essential liberty to obtain a
little temporary
safety, deserve neither liberty nor safety.
- Benjamin Franklin
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb