Ideal HF mobile antenna for icom706?
Mark Marriott
I would be interested in hearing ideas/experiences etc for mobile hf mobile
antennas for the icom706mk2. Specifically, does anyone have experience
using the icom solution... the AH3 and the AH2b whip? How would this
compare to using a screwdriver type such as the HighSierra hs-1500? I would
plan to mount the antenna on the trailer hitch on a toyota 4runner.
Thanks,
Mark Marriott
WA6JIQ
Palo Alto, CA
N8BLK
In article <6cd619$lq1$1...@nnrp1.snfc21.pbi.net>, "Mark Marriott"
<mma...@pacbell.net> writes:
>I would be interested in hearing ideas/experiences etc for mobile hf
>mobile antennas for the icom706mk2. Specifically, does anyone have
>experience using the icom solution... the AH3 and the AH2b whip? How
>would this compare to using a screwdriver type such as the HighSierra
>hs-1500? I would plan to mount the antenna on the trailer hitch on a
>toyota 4runner.
Well let's first look at the cost, the combination you're suggesting is
over $900, while one can order a DK3 from W6AAQ for $150 minus
the whip which goes on top (Most Radio Shacks have a CB whip
in stock which can be cut down), even the BB3 and High Sierra
1500 go for about $600 dollars less.
Second, assuming you want a decent signal on 75 meters and 40
meters, the screwdriver type antennas once again will definitely
outperform the SGC duo, despite the advertising. Of course, it is
your money and your signal. There is no free lunch, a base loaded
whip remains a base loaded whip, no matter how good the antenna
tuner is, and a center loaded whip, which the screwdrivers in some
way implement will outperform a base loaded whip while mobile
on the lower HF bands. Above 20 meters, and possibly on 20
meters, there may be no difference in signal on a field strength meter
or any other way you want to make measurements.
Now, admittedly the SGC will supposedly tune up the whip without
the operator having to listen or pay attention to swr, while the
operator does have to tune one of the screwdrivers for a good match
from inside the vehicle, but I can get pretty close to where I should
be just by listening for an increase in noise on the receiver and then
tune up for a good match quickly, your milage may vary!
-art clemons-
Bob
Hi Jesse. I would think that the Icom antenna your talking about would be just
about the worst performing antenna you could possibly get and it would cost you
around $900. The screwdriver mobile antenna is the best mobile antenna you can
get. It requires no tuner. At the mobile antenna performance competitions the
scewdriver antennas are at the top of the list. They have a remote control at
your radio that allows you to tune it for the lowest SWR. They cost around $300
with mount. There are several manufactures of these antennas. You should be
well satisfied with the screwdriver antenna. And I'm sure you would be very
disapointed with the performance of the Icom antenna. Especially If you were
planning on using it on 75 meters and 40 meters. Just imagine putting a 8 foot
whip on your house and try working all the frequencies with it. I speak from
experience. I tried using a 20 meter whip on 40 and 75 with a antenna tuner and
I couldn't hear hardly any thing. I don't know of any one dissatisfied with a
screw driver antenna. The mounting of the antenna is the only problem. They are
a heavy antenna and require special mounting. Just make sure who ever you get
one from shows you how to mount it or has a mount that will work with your
vehicle. I hope this helps you out. I do enjoy HF mobile. I have worked the
world on 20 and 10 meter mobile.
Bob W7CTW
W6KKT (Jesse) wrote:
> On Tue, 17 Feb 1998 15:17:50 -0800, "Mark
> Marriott" <mma...@pacbell.net> wrote:
>
> >I would be interested in hearing ideas/experiences etc for mobile hf mobile
> >antennas for the icom706mk2. Specifically, does anyone have experience
> >using the icom solution... the AH3 and the AH2b whip? How would this
> >compare to using a screwdriver type such as the HighSierra hs-1500? I would
> >plan to mount the antenna on the trailer hitch on a toyota 4runner.
> >
> >Thanks,
> >Mark Marriott
> >WA6JIQ
> >Palo Alto, CA
> >
> Hi Mark, since the 706 doesn't incorporate a built
> in antenna tuning unit, you should consider the
> "screwdriver" type systems, especially if you plan
> 75m operation. In my opinion, they are the best
> compromise for all band mobile operation.
> Good luck, Jesse, W6KKT
W6KKT (Jesse)
Phil Wheeler
I agree with Jesse's remarks.
One thing, tho. If you plan to operate only 20 m and above, then you
can use Hamstick-types or a Hustler setup and you will NOT need an
antenna tuner (I find those antennas to be broad enough and efficient
enough for SSB operation on those bands).
For 40 and especially 75, the more efficient antennas (like the
screwdrivers) are definitely required.
Phil
W6KKT (Jesse)
Hi Phil, a electrical 1/4 wave hf mobile antenna
that produces close to 50 ohm base impedance (no
matching) I would look on with suspicion. Several
things can cause the high base impedance. Both are
not good.
1. coil loss resistance (low Q coil)
2. The automobile body is approaching 1/2wl
resonance, causing the feed-point impedance to
rise. Kind a like a L on its side,very close to
ground.. This would also contribute to a higher
take off angle. This happens frequently on 10m
when using a 8' whip.
On 10m & above, a simple solution for higher base
impedance, is to cut the whip to 100 degrees
(instead of 90). This will raise the base R close
to 50 ohms with a +J reactance. The reactance can
be canceled with a simple series or parallel
capacitor. Very efficient and works really well.
73, Jesse, W6KKT
Bill Clarke
For several years I ran 75 meters with an ICOM 730 and a
735. I used the KW Hustler coils. Had two. One set for the
country hunters and another set for the part of the band all
my friends were on. Worked great and not nearly as costly as
screwdrivers and bug catchers.
There is a limitation however (nothing is free) and that is
narrow bandwidth. I found I could keep the rig very happy as
long as I stayed 15 kcs + or - from the resonate point. The
other limitation is the need to stop and change coils to
QSY.
I am thinking of getting a new 706 MkII or a used 706 for in
my travel trailer and will probably use the same set up as I
did in my van - the Hustler system.
Bill W2BLC
N8BLK
In article <34F0A8A7...@mindspring.com>, Bill Clarke
<billc...@mindspring.com> writes:
>For several years I ran 75 meters with an ICOM 730 and a 735. I used the
>KW Hustler coils. Had two. One set for the country hunters and another
>set for the part of the band all my friends were on. Worked great and not
>nearly as costly as screwdrivers and bug catchers.
Let's see, W6AAQ's new book with shipping Cost $10
plus all new components to build a screwdriver antenna plus
an electric screwdriver without the battery pack comes to less than
the cost of two KW Hustler coils.
Incidentally, you'll be saddened to discover that most people who
test the KW coils on a field strength meter discover that they perform
even more abysmally than the supposed 400 watt Hustler coils on
75 meters, and that's not a good description, since the screwdrivers
for example well outperform the Hustlers of either stripe. Yes, the
Hustlers give a match on 75 meters, and they do radiate, but so
does a dummy load with three foot wires attached to both sides,
only if I had to bet money, I'ld bet on the dummy load with the 3 foot
wires winning in a field strength test.
-art clemons-
Curtis M LaFon
W6KKT (Jesse) wrote:
Hi Jesse,
I ran across an article on an antenna such as you describe, longer than 90
degrees.
I thought it was 112 degrees though. I included the antenna as one in my
antenna program. I hope I did not goof by making it 112 degrees. The
program is available for download at my site.
--
73, Curtis ..N5HDQ.. http://wf.quik.com/n5hdq
------------------------------------------------------------
Gray Frierson Haertig wrote and Curtis plagerized:
Eat a prune.
Unbunch your shorts.
Ignore posts that make you angry.
W6KKT (Jesse)
>For several years I ran 75 meters with an ICOM 730 and a
>735. I used the KW Hustler coils. Had two. One set for the
>country hunters and another set for the part of the band all
>my friends were on. Worked great and not nearly as costly as
>screwdrivers and bug catchers.
>
>There is a limitation however (nothing is free) and that is
>narrow bandwidth. I found I could keep the rig very happy as
>long as I stayed 15 kcs + or - from the resonate point. The
>other limitation is the need to stop and change coils to
>QSY.
>
>I am thinking of getting a new 706 MkII or a used 706 for in
>my travel trailer and will probably use the same set up as I
>did in my van - the Hustler system.
>
>Bill W2BLC
Hi Bill, the KW75m Hustler coil has a lower Q than
the standard coil. On 75m the Hustler systems
average about -3db compared to the better
"screwdrivers".
73, Jesse, W6KKT
W6KKT (Jesse)
Hi Curtis, I seem to recall the 10m mobile whips
were between 9-9.5' and required 100pf for 50 ohm
resonance..
I would think the 112 degrees would give you a
higher radiation resistance than 50 ohms.
73, Jesse, W6KKT
Gary Coffman
But that's still better than nearly everything else except
the Bugcatcher. And a Hustler is often mechanically
more practical than a screwdriver or Bugcatcher.
And as an aside about screwdrivers, have you heard that Yaesu
has come out with a screwdriver antenna for their new FT-847?
They claim it covers from 160m to 70cm and is autotuned by the
rig using phantomed power down the coax. Waters and Stanton
(http://www.waters-and-stanton.co.uk/) have a description of it
on their website in the "Latest Hot News" section.
According to their blurb, the screwdriver section is 18 inches
tall, and is topped with a 19 inch whip. Somehow I don't think
that particular screwdriver is going to be a good low band
performer. :-)
Gary
Gary Coffman KE4ZV | You make it |mail to ke...@bellsouth.net
534 Shannon Way | We break it |
Lawrenceville, GA | Guaranteed |
W6KKT (Jesse)
Perhaps, but the "Bugcatcher" (no cap hat) will be
5db better. For me -5db is way too much of a
penalty when all it takes is replacing the Hustler
coil, which has high loss resistance,with a High Q
coil. At resonance, a 75m hustler system base
impedance will measure >30 ohms. Replace the coil
with a "Bugcatcher" or any Hi-Q coil and that
resistance drops at least in half. Enough said.
>
>And as an aside about screwdrivers, have you heard that Yaesu
>has come out with a screwdriver antenna for their new FT-847?
>They claim it covers from 160m to 70cm and is autotuned by the
>rig using phantomed power down the coax. Waters and Stanton
>(http://www.waters-and-stanton.co.uk/) have a description of it
>on their website in the "Latest Hot News" section.
>
>According to their blurb, the screwdriver section is 18 inches
>tall, and is topped with a 19 inch whip. Somehow I don't think
>that particular screwdriver is going to be a good low band
>performer. :-)
>
>Gary
>Gary Coffman KE4ZV | You make it |mail to ke...@bellsouth.net
>534 Shannon Way | We break it |
>Lawrenceville, GA | Guaranteed |
Hi Gary, right on. Yaesu has never built a
efficient mobile antenna system. In fact, the
Japanese are relatively new to mobile operation.
Two years ago K6UMB and myself were t;he first
U.S amateur stations to work 75m ssb mobile to
mobile with Japan. They build good transceivers ,
but inefficient multi-band mobile antenna
systems. Also, their mobile transceivers have way
to many "bells & whistles" and knobs and switches
for mobile operation.
One can increase their 75m mobile signal by 2db
when using the Hi power 75m hustler coil by
replacing the stock coil wire with #14 teflon,
close spaced and readjust the top whip for
resonance. This will give a little higher SWR due
to less coil loss resistance.
73, Jesse, W6KKT