Mobile HF

This page is dedicated to my adventures in Mobile HF.

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Watts have been added to the mobile station! I finally got a mobile amp, Ameritron ALS500M.


Here's the amp installed in the back of the Turbo Brick.  The amp sits on a shelf bolted to the vertical divider and is also screwed to the sidewall.  There is a 1" foam block under the amp and an adjustable strap to retain it in position.  This allows the amp to be easily moved if needed.







Rear view of the installation.










Here's the latest installation, I bought a second Base Quick Disconnect and installed it on the Safari van.  As much as I like this antenna, I'm not buying two. (sorry Charlie*)

The brackets were pretty much a duplicate of the Volvo, though I elected to flip the bottom one as the heads of the allen screws were hard to access when the base was installed.

I still have to wire and tune the antenna, that has to wait until out 100° plus days leave us.





     * apologies to Starkist®











I decided I am really serious on the Mobile HF thing, so a serious antenna was needed.  Many were considered and few met my requirements.  They were size, cost, ease of tuning and most importantly performance.  Looking over the offerings I settled on a Hi-Q antenna.  After seeing one in the flesh I had to say the machine work was top notch and the enclosed, constant size of the antenna coil sold me.  A couple units from another source I saw were, IMHO, testimonies to the glitzy machining art, something that did not appeal to me. 

The model I selected was the HiQ-3/80RT, not because of its impressive low price, rather its size and coverage.  I had to have some 75/80 meter coverage while mobile.

Here's a shot after the installation and first on air test.  The top of the coil is right at 5'10" and the combined height is 13'4" The arrow shows the tip of the whip, which is easily removable without any tools.  A storage tube on the ceiling of the interior will keep the 7'6" whip out of the way when not in use.  I just have to remember I can only go where semis can go... 

Saturday the 4th I went to a star a party near Superior AZ.  Listening around on 20m I heard some activity from up north, so I tuned up on a nearby frequency being careful to crank the power down to about 7-8 watts.  I rolled back on frequency and replied to the gentleman who came back and gave me a good clear signal report.  After a minute or so I realized I had not brought the power back up!  Lets see, Lloyd Minister, Saskatchewan on 8 watts?  Damn, what an antenna!!!  Thank you Charlie Gyenes W6HIQ





Lower BracketThe first step of the installation was the lower bracket.  This was formed up from .125" mild steel and curved to fit the profile of the body.  Sandwiched in between the bracket and coachwork is a thin sheet of silicone rubber.  A metal backing inside the body helps strengthen the mount.  The top two bolts actually pass through a multiple layer of the body as there are several panels coming together at the window opening.  A flat braid ground strap is attached to the inside plate and connects to the body.  Stainless hardware used throughout.  Finish by Krylon.  I'll pull it apart and powder coat it when the weather gets cooler.  It was 112F the day I did the installation!







Here is the initial test fit and gratification shot of the antenna.  I plan to temporarily use the ATAS bracket for a mid point support.  Later this year I will re-make the mid point bracket.  It's that cooling off thing again...


Here we have some construction details of the mid bracket.  Made from 1/2 plastic and using a 1" PVC electrical conduit strap.  The two ears on the bracket help keep things together.  The right picture shows the bracket drilled and tapped, ready to install.

Detail shots of the finished bracket after installation.

I am waiting for a Turbo Tuner to arrive to complete the istallation.


             Shunt Coil Installation





Well it cooled off enough to play in the driveway.  I made a shunt coil to help with the 80m end of things to avoid the complications of a tuner while driving.

I took a 3/4 grey PVC electrical conduit union and chucked it on a mandrel in the lathe and threaded it to 8tpi.  This gave me a nice spacing on the coil when I used 12ga bare copper wire.  I pulled the ends through holes into the middle of the coil and that keeps the wire tightly wrapped on the form.

I then adjusted the coil by shorting and then made the adjustment permanent with a solder bridge.









I then wrapped the coil with red Rescue Tape to keep it clean and dry.  1.08 SWR with the RigExpert Antenna Analyzer

The Turbo Tuner is wonderful.  I can use the built in tune function of the Yaesu FT857D and keep my attention on the road while tuning.  I have checked the tuning using the Rig Expert and I am getting wonderfully low SWR readings when it is done tuning.

The only thing I have to learn is to turn off the Tune function before switching bands.  The tune function will commence if you change bands with TUNE showing on the display.  Other than that it is flawless and simple.

I had considered a screwdriver controller like HiQ's DC Controller, but the only thing that held me back was having a chart to show what position number was for which frequency.  The additional $100 was well spent in my mind for safety and convenience.






Yaesu ATAS 120 Screwdriver Antenna.

My first foray into the world of HF Mobile was with the Yaesu ATAS120 screwdriver antenna.  I had no idea how much I would us the HF side of things and elected to go with this antenna because of its small size and it was plug an play with my Yaesu FT857D all mode transceiver.  I learned a lot about screwdriver antennas over the year I used the ATAS.

Here's an "action shot" of the antenna.  This is up on Mt Lemmon north of Tucson AZ.  Shown is Bob Harbour KE7FEF 

The whip on the ATAS is about the same height as the main body.  Small but relatively effective, my best contact was Japan on 20M earlier this spring.







The Yaesu 857D was selected for size, price and the performance it seems to regularly deliver.  It has not disappointed me so far.  There are a few things I don't like about it, mostly menu related, but overall I am happy with the purchase.


Installed antenna....


Here is the current installation as of 9/2010.  Installed is the FT857D remote head on a flexible stalk.  In the dash above the fuse box is a DR-235 Alinco 220mhz radio.  On the dash is an amplified speaker and Large FT meter from LDG.













Here is the main body of the FT857D in the RR trunk area.  The unit sits on rubber pads and is positioned to get good airflow.  Hanging onthe sidewall is a MFJ power Booster.  A remote control up front allows me to turn it on and off.  The diplexer on the wheel arch is to split the 6meter away from the rest of the HF output.  There is a separate 6meter base loaded whip on the roof.  The blue zipper bag contains all the tools and remote head cords needed for the two radios.  I can always find the face plate cord....









Last updated  9/3/2010