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My Mobile Radio Installation
Page Four


This page continues what we started on page 1, 2, and 3 -- links to those pages are at the bottom of this page.

Okay, now, I have:

  • Assembled the GeoTool stake hole mounts, one with  a VHF connector, one with a NMO connector.
  • Drilled 5/8-inch holes in the bottom of both rear stake holes and sanded the paint from around the holes.
  • Installed power lead from the battery to the cab of the truck, ready for the rig.

This photo shows the stake hole mount in place, shimmed, and ready for the antenna.

Note that you have ready access to the mounting bolt -- the GeoTool mount slides down inside the stake hole, push it all the way down until it hits the bottom of the stake hole bracket -- then, reach in with the mounting bolt and thread it into the threaded bottom of the mount, through the hole you drilled in the stake hole bracket.  Rick includes several flat washers -- you want your mount to stick up just a hair above the top of the bed side rail -- add as many washers as you need to raise the mount -- I did not use any -- put the toothed lock washer between the head of the mounting bolt and the sheet metal and tighten it down TIGHT.  You can easily get a ratchet handle and a socket in here to tighten the mount.  Below is an exterior view of the NMO mount, installed.


You can see the black vinyl shim on the bottom side of the stake hole.  Also -- I almost forgot -- go to an auto supply or electrical supply shop and get a tube or can of anti-oxidant grease.  This is grease the conducts electricity.  Before mounting the GeoTool mount, smear this anti-oxidant grease around the mounting hole, where you sanded off the paint.  When the mounting bolt and washer are tightened, smear a gob of grease over the bolt and washer -- this will keep the assembly from rusting and ruining your ground connection.

Update, 6 February 2006After completing this installation 10 days ago, I began to have problems with my HF antenna, a Yaesu ATAS-120.  The antenna's operation was erratic.  As you see, I use a Yaesu FT-857D transceiver -- it has a setup routine in which you tell the transceiver that it's connected to an ATAS-120 and the transceiver then automatically tunes the antenna as you change bands.  After a couple of days, the transceiver would not recognize the antenna.  I went through a lot of troubleshooting and found the problem -- poor grounding.

I used an ohmmeter to check for continuity between the antenna connector where the ATAS-120 screwed onto the GeoTool mount and the mount -- no continuity.  There was no continuity between the antenna connector and the truck body.  Thus, the outer shell of the coax and the antenna were not connected to ground at the antenna mount.

The GeoTool stake hole mount is aluminum.  The body of the truck is steel and the VHF Type M mount used to mount the ATAS-120 is stainless steel.  Oxidation had developed between the Type M VHF mount and the aluminum GeoTool mount and there was no connectivity between the antenna connector and the body of the truck.

I fixed this problem as follows:

  •  Get some anti-oxidant grease used by electricians for connecting dissimilar metals -- electricians use this stuff when they are connecting aluminum wiring to copper wiring.  It is sold under various names, Penetox-A being the most popular.  I found a similar product at Lowe's -- ask for "anti-oxidant paste" or "anti-oxidant grease."
  •  I used my Dremel tool with sanding drum attached to sand every place where there was metal-to-metal contact.  I ground off oxidation and coatings down to bare metal on:
    • The nut that holds the Type M connector onto the GeoTool stake hole mount.
    • The area on the stake hole mount where it contacts the Type M connector mounting nut.
    • The base of the GeoTool mount that contacts the sheet metal in the bottom of the stake hole.
    • The toothed lock washer that contacts the bottom of the stake hole sheet metal and the area of the bolt head that contacts the toothed lock washer.
    • Look at your installation -- wherever there is metal-to-metal contact, use a Dremel tool or 240-grit emery paper to sand down to bare metal.
    • Because aluminum oxidizes almost instantaneously upon contact with air, the instructions for Penetrox-A recommend you apply a coat of Penetrox (or other anti0oxidant grease) to the area to be cleaned, sand the metal with the grease applied, then apply more grease and tighten the connection.  This procedure keeps the aluminum coated with anti-oxidant compound while it is being sanded and, thereby, prevents instant oxidation -- which would negate what you are trying to do.
    • Here is a website describing the procedure:
  • I then applied a coat of anti-oxidant paste to each metal surface and bolted it all back together.
  • The antenna worked perfectly.

These photos show where I sanded to bare metal and applied anti-oxidant grease.  In each of these photos you will see small reddish-brown arrowheads -- >>>>>>   and     <<<<<<  -- these show the metal-to-metal points where I sanded both surfaces and applied anti-oxidant compound -- these photos were made before the grease was applied.


In the left photo, I applied grease under the nut that secures the VHF connector to the GeoTool antenna mount -- stainless to aluminum
contact point.
In the center photo, I applied grease under the big brass nut that comprises the NMO mount and that secures the NMO mount to the GeoTool antenna mount -- brass to
aluminum contact point.
In the right photo, I applied grease to
the point where the lock washer
contacts the bottom of the stake hole
sheet metal, and, I applied grease between
the lock washer and the head of the bolt --
bare steel to bare steel contact.  I used two GeoTool
mounts, one for VHF/UHF antenna and one for
the HF antenna -- apply anti-oxidant compound to
both mounts

While you are looking around at your installation, you will notice that the sides of your truck bed are hollow -- there is sheet metal that makes up the inside wall of the bed and sheet metal that makes up the outer wall of the truck -- and a big space in between. I crawled under the truck and ran the tape of a tape measure from the front of the bed, through the hollow in the bed wall, over the wheel well, and back to the stake hole.  Then, I taped the end of the coax to the steel tape measure and pulled the coax through the bed wall to a point under the truck, behind the cab.  I had already drilled a 1-inch diameter hole in the floorboard of the cab, directly under the driver's seat.  I cut a slit in the carpet above this hole and plugged the hole with a 1-inch diameter plastic hole plug from Home Depot.  I then drilled two 1/4-inch diameter holes in the plastic hole plug -- the two coaxial cables coming from the antennas go through these two holes (tight fit) and into the cab.  The next two photos show the details of this installation.

This photo was taken while I was lying on my back under the cab of the truck.  The two black cables are the antenna leads coming from the back of the truck.  In the center of the photo is a round black object -- that's a plastic hole plug that is stuck into a 1-inch diameter hole that I drilled through the floorboard of the cab, under the driver's seat (actually, I used a 1-inch BluMoly hole saw).  BE CAREFUL AND DON'T CUT THROUGH A WIRING HARNESS.  After I popped the plug into the hole, I drilled two 1/4-inch diameter holes in the plastic plug -- these holes were just a bit too small for the coax so I widened them with a rattail file -- two strokes of the file per hole was enough.  The photo below shows these two cables coming up into the cab.

The photo below shows the coax from the antenna coming up through the hole in the floorboard, through the carpet, and into the cab.  The driver's seat is slid full-forward in this picture.  The power cable is just out of sight to the left.  After this photo was made, I cleaned up the mess, installed coax connectors on the ends of these two cables, laid the rig on the floor, and attached the power and antenna cables.


Mounting the radio front panel

Now, let's look at how I mounted my radio.  The Yaesu FT-857D is like most mobile radios these days -- the front panel separates from the body of the radio.  I don't have photos of the front panel and the rig separated -- may put some up later -- but here is how I did it.  Yaesu sells as an extra accessory a "separation kit" -- this contains cables to connect the front panel to the radio body and a mounting bracket to mount the front panel to whatever.  With the radio mounted under the front seat, I needed to mount the front panel somewhere.

I searched and searched and finally found my solution -- a gooseneck mount used for mounting satellite radio control heads in cars.  Here is a photo:

What you are looking at is: (1) gooseneck, the long black thing; (2) lower left corner, a bracket that the gooseneck screws into, the bracket has a foot that mounts to the bolt that holds the front seat onto the floor; (3) right side of photo is a plastic bracket that mounts onto the end of the gooseneck.  This link will take you to the place where I bought the gooseneck mount -- as I recall, it was under $20.00.  If you have a car audio shop nearby, they may have these in stock.

Here is the gooseneck with the front panel, mounted in the truck.

The front seat mounts on rails that are attached to heavy steel brackets that are bolted to the floor, front and rear.  I  loosened the mounting bolt under the right front corner of the seat, slipped the foot on the gooseneck mounting bracket under the bolt, and tightened the bolt.  I attached the front panel's mounting bracket to the mounting bracket that came with the gooseneck and popped the front panel onto its mounting bracket.  The cables that go to the radio under the seat are secured to the gooseneck with nylon cable ties (I have since replaced these white ties with black ones).  Run the cables under the seat to the rig and dress them and secure them in place with nylon cable ties.

Here's what it looks like from the driver's seat.

The speaker is the Yaesu M-100 mobile speaker.  I put pieces of industrial strength Velcro on it, top and bottom, and forced it under the dash in the space between the ash tray and the front edge of the bezel around the shift lever.  I plan to make a small slit in the carpet and run the speaker lead under the carpet.  When the front seat moves forward to provide access to the area behind the seat, the seat forces the gooseneck forward -- this is not a problem as I don't move the seat full forward too often.  This is a 15-inch gooseneck.  If I do this again, I'll get a 19- or 20-inch gooseneck for a little more flexibility in positioning the front panel.   The mike lies on the seat next to the driver.

So -- now it's past midnight, 3-4 February, and I did not intend for this to be so long.  I'll post this to my website now and come back later to edit it, add a few more photos, and generally clean it up.

I hope something here is useful to you.

Page 1 of my mobile installation
Page 2 of my mobile installation
Page 3 of my mobile installation
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