[aprssig] APRS HF Mobile Antenna Suggestions

Fri Oct 10 19:13:26 EDT 2025

Take a look at the Tarheel line. Pricy but compact and generally fewer
issues than an ATAS. If you don't mind a little inconvenience a  wolf river
coil and 102” whip will out perform them all. I run a little tarheel 2 on
one side of the truck and a wolf river coil on the other side with a 102”
whip. The wolf river runs circles in both receive and transmit. The Tarheel
will fine tune the SWR on the Wold River antenna by adjusting it up and
down. Pretty cool.

KJ7AZ

On Sun, Oct 5, 2025 at 9:54 PM Stephen H Smith via aprssig <
aprssig at lists.tapr.org> wrote:

> On 10/5/2025 8:37 AM, Arte Booten wrote:
>
> Hi all,
>
> I'm retiring next year and will be living in a Class A Motorhome - roughly
> the size of a bus. I already have a Yaesu FT-991A 160M-70CM principally for
> HF & C4FM and two 2M/70CM FM antennas.
>
> Ideally, I'd like an all-HF-bands antenna rather than have to climb the
> ladder to change hamsticks though I don't intend to operate HF SSB while
> driving - too many potential distractions.
>
> What's worked for you. Equally pertinent - what didn't? 73
>
> [On the road in Grand Junction, Colorado, returning to Michigan after a
> week in Los Angeles.]
>
>
>
> Assuming you are going to use the FT-991, I think the "no-brainer" choice
> (assuming you don't need 60 and 80 meters) is the Yaesu ATAS-100 or
> ATAS-120 mini-screwdriver mobile antenna.  The FT-991, like the FT-857 and
> FT-891, can completely automatically control the ATAS.   Just select the
> band/frequency 40M-through-70cm and hit the TUNE button on the radio.  No
> separate control cable for the screwdriver motor is required -- the motor
> control voltage is sent up the coax to the antenna.
>
> When the ATAS is hard-mounted on a substantial sheet metal mass like the
> roof of a vehicle (not on a crappy gutter clip or trunk-lip mount) it works
> amazingly well, even on 40 meters. It tunes onto 30 meters very well for HF
> APRS operation too.  (I have mine in the center of my Jetta TDI's trunk
> lid.)  It's no taller than a common 2M 5/8ths wave - about 56-60 inches
> depending on what band it is tuned to.  (Gets longest on 40 meters; shorter
> on the higher bands.)   You might need one of the motorized tilt-over
> mounts to lay it flat while enroute if mounted on the roof of a Class A.
>
> The ATAS base is a PL-259 connector; you will need a mount with an SO-239
> socket; not an NMO.   I have multiple heavy-duty Larsen NMO mounts (that
> are made of stainless steel-not the usual brass) on my car.  I then use the
> Tram NMO-to-SO239 adapter.  Note that the Tram is the only such adapter
> that is cylindrical (not tapered) and fully supports the entire base of the
> ATAS which is almost 2" diameter around the recessed PL-259 connector.
> (There are a lot of other NMO-to-SO239 adapters out there but they all
> taper to a smaller size at the SO239 end only suitable for supporting
> lightweight VHF/UHF whips with PL-259 bases.)
>
> As for the other post about using the SGC-230 Smartuner:
>
> Normally the Smartuner is used with at least a quarter-wave of wire at the
> lowest frequency of interest, like the back-stay of a boat.   It WILL tune
> into a 9' solid CB whip even on 75M, but will be hideously inefficient on
> the lower bands (40-60-80 meters).   The tuner's internal L-network has to
> configure to such an extreme matching ratio with such a short radiator that
> most of the TX power is dissipated in the tuner - not delivered to the
> whip.    SGC used to offer a 9' fiberglass whip with two concentric
> copper-tape helical windings that was far more "tuner-friendly" than a
> simple 9' solid stainless whip.  It was dramatically more efficient on the
> lower HF bands.  Alas, SGC no longer exists.
>
> For any kind of a end-fed whip to work efficiently, you MUST have an
> effective ground.  This means connecting the ground terminal of the SGC or
> similar tuner to a substantial metallic mass.  At least the vehicle body.
> If you are only operating in camp (not mobile), consider the LOG
> (loop-on-ground) ground.  Instead of just stretching a straight wire
> outward from the ground terminal of the tuner, you stretch 40-50-70 feet of
> wire outward from the tuner ground terminal, form a roughly circular or
> elliptical loop on the ground and bring the far end of the wire back to the
> tuner ground terminal. This DRASTICALLY increases the coupling to earth
> ground compared to a straight wire without having to drive ground stakes
> into the ground.
>
>
> One final comment:    I considered the FT-991 for my "Studio B" radio
> trailer setup.  It looked appealing due to it's "DC-to-light" band
> coverage, it's built-in sound card, the continuously-variable DSP IF
> filters (nice for digi-modes including my HF APRS-over-VARA operation), and
> it's ability to directly control the ATAS screwdriver antenna.  My radio
> trailer is intended to be powered by batteries and solar power.
>
> I rejected the '991 because of it's rather high power consumption on
> receive:  nearly 3 amps while most HF rigs (FT-857, FT-891, IC-706, etc)
> consume only about 1 amp on receive.  If you are boondocking on
> battery-power-only, this is a major issue.  The ultimate power conservation
> setup would be an FT-818 "porta-luggie", with an external
> 5-watt-to-100-watt amplifier.  If you can tolerate the tiny front panel of
> the FT-818, it draws less than 300mA on receive. It's actually essentially
> an FT-857 minus the 100-watt-output PA.  It has the same 160-thru-UHF
> coverage as the FT-857 and looks essentially like an FT-857 to CAT control
> software. However the '818 lacks the auto control for the ATAS screwdriver
> -- the FT-857/897 and the FT-891 do have the ATAS control capability.
>
>
> ------------------------------
>
> Stephen H. Smith    wa8lmf (at) aol.com
> MS Teams::        WA8LMF
> EchoLink:  Node #  14400  [Think bottom of the 2-meter band]
> Home Page:          http://wa8lmf.net
>
> Live APRS Mapping on HF & VHF
>    <http://WA8LMF.net/map> <http://WA8LMF.net/map>
>
> "Studio B" Ham Shack on Wheels
>    <http://WA8LMF.net/Aliner> <http://WA8LMF.net/Aliner>
>
> -- APRS over VARA  --
>    <http://wa8lmf.net/VARA/APRSoverVARA>
> <http://wa8lmf.net/VARA/APRSoverVARA>
>
> ----   Sent from my Panasonic Toughbook mobile laptop
>
>
> -
>
>
>
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