This past weekend I installed my first ham radio, a Yaesu FT-2800M.  An early birthday present, Dad gifted me the unit with a mag-mount antenna.  The plan was to put it in my 1999 Ford Ranger truck.  I began thinking about where/how it would mount.  There were not many options and I did not want to drill any holes in the truck if I could at all avoid it.  I decided the best course of action was to make my own mount that would fit on the transmission hump between the gear shift and the split bench seat.  I took a few measurements and built this box:

I left the back open in case I needed place to hide a filter (for alternator whine).

Next I bought a cheap floormat ($1.58) from the Walmart and glued it to the bottom of the box.

The box was designed to fit pretty tight, I thought this would help just a little more.  I hit the box with some spray adhesive:

Then cover it with some auto carpet remanent I picked up for $8.00.  I have enough carpet from that reminent to do 5 more boxes now, but I digress.  I’ve never done auto upholstery before, so my carpeting job on the box is fairly mediocre, mainly because I didn’t read up on how to incorporate hiding the seams into my box design. (A goal for next time) Here is the carpeted box:

The radio on the mount:

Next step was to find a place where I could run the power cable and the antenna cable through the firewall.  I popped the hood and immediately noticed a metric ton of corrosion on the battery terminals.  I guess I had been neglecting some of my maintenance duties.  After cleaning the terminals I noticed one of them was in really rough shape and needed replacement, so I went to the auto parts store and bought some new terminals.  I had mental tug of war and returned twice to the store before finally deciding on the heavy duty gold plated terminals.  Yea I know, I’m probably the biggest sucker ever… but they did have extra cable mounts that the others didn’t have that would make my install go easier.  I like simple. 

I’ll bet I looked for a solid hour, maybe even 90 minutes for a place I could run cable through the firewall on my truck.  I contorted myself into some very uncomfortable situations looking for that “simple” place to run the cable through.  I had almost given up and decided to check the passenger side one more time before resigning myself to drilling, and there it was.  It was almost as if it had materialized moments before I knelt down, and now it was staring me right in the face.  Unbelievable.  I popped the rubber plug out and ran a wire snake through the hole.  It came out just under what might be the blower motor for the air conditioner, but who knows… I’m not a mechanic.

I secured the power and ground cables carefully keeping them away from hot or moving parts.

The only concern I had with this path was the possibilty of picking up some noise from the windshield wiper motor, but that has not been a problem.  I posted the mag-mount on the roof, passenger’s side:

I secured the antenna cable along the chassis, again taking care to keep it away from hot or moving parts.

I pulled the power and antenna cables through the firewall hole:

Then I cut the grommet and pulled the cables through it, and put it back in place.

The cables are not as hidden as I would like them, but they will do.  From the passengers seat they are not visible.  There is not a place to zip tie them, and an adhesive cable fastener doesn’t hold well on the slick plastic surface of the air vent.  I’m still mulling this one over.  They do tuck well under the transmission console, however.

The finished product:

That’s it for now, I’ve got to run for a net check-in.

73,

Michael KJ4DXZ

4 comments

… or wire splitters

I use the automotive connectors….spread for the wires to fit like the pictures. I wouldn’t pump big amperage through them but they make nice splitters. Spread them with a pointy object.

Then solder them up and shrink wrap tubing.

Ideas?
email me
Mike N4MAA

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How to do them:

Tools I use and a drop of super glue holding the red and black insulators together not a tiny roll pin that can slide out. My friend Jim G. says get the real crimpers! Well I did and they are the way to go.

Notice the Red PP has a raised space and the black PP has a slot, both are tapered. The Red slides into the Black slot and add a drop of super glue to make sure they don’t go any where.

Strip about 1/4″ maybe 5/16″ of insulation off, insert wires into contacts and crimp. Make sure they are facing the right direction, not twisted, and not squished too wide.

They fit in exactly as you see them and click when you insert them into the insulators if you have done it correctly.

You can get as fancy as you wish (below)

Ideas?

Mike N4MAA

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By Jim KB1MVX

I recently installed a new transceiver in my truck. On the first day of using the new radio I got reports that I was transmitting very noticeable alternator whine. I could also hear it on receive and when the radio was quiet. I checked the diodes in the alternator, verified I had good grounds, and I even ran the truck with the alternator removed to be sure that the whine was indeed from the alternator.

The alternator produces AC, which is rectified into DC. The problem is the rectification is not perfect. The DC output will have a small AC signal riding on it. That AC signal will have 9 cycles for each revolution of the alternator. Suppose your engine is idling at 600 RPM and the drive pulley ratio to your alternator is 1:3. At that engine speed your alternator is turning 1800 RPM, which is 30 rotations per second. Each rotation gives you 9 cycles of AC. Do the math and you get a 270 Hz sinusoid (not a perfect sinusoid but close enough). Cruise down the road at 2000 RPM and you get a 900 Hz sinusoid riding on your DC power supply.

I tried an off the shelf filter from Advance Auto. It did very little so I decided to build a filter. The first filter I built worked VERY well. The problem is that not everyone has the tools required to build that filter so I decided to figure out a filter design that could be built in less than an hour by anyone with basic tools, have a cost under $20, and handle a current of at least 20 Amps.

Parts List:
1/2″ Quick Link (Lowe’s) $2.98
6x3x2″ project box (Radio Shack) $3.79
20′ roll 12 gauge red hook up wire (Radio Shack) $4.99
4700 uF 35V capacitor (Radio Shack) $5.29
18″ of black 16 gauge wire
Electrical tape
GOOP or similar glue
3 zip ties
Total: $17.05

Directions below:

1/2″ Quick Link will be used as the inductor core. A fellow ham, Dave KC1LT, suggested using a shackle. I went to get a shackle and came across this quick link. I went with the quick link to make more efficient use of project box space.

Beginning the winding
Wrap the hook up wire around the closed side of the quick link starting from the left as shown. Leave about 9″ of wire free on the left end. Try to keep the winds as close together and tight as possible. On the last layer space the winds so that you have 9″ of wire left on the right end. Use all 20′ of wire.

Above is the finished wrap

Wrap the coils in electrical tape and close the quick link. About 1.5″ from the right end of the inductor strip 1/4″ of insulation off the red wire and solder in the + lead of the capacitor. Make sure you observe the capacitor polarity. In the picture you can see the negative arrow on the capacitor pointing down. Solder the 18″ piece of black wire to the negative lead of the capacitor. (Above)

Cover the solder connections and capacitor leads with electrical tape. Drill a 3/16″ hole in both ends of the project box for the red wires. Drill an 1/8″ hole in one end of the project box for the black wire. Run the wires through the holes. Put a zip tie on each of the three wires to limit how far the wires can be pulled out of the box. Make sure to leave a little slack in the wires inside the box. Using GOOP or some other thick strong adhesive, glue the capacitor and inductor into the project box. Leave the cover off until the glue dries.

+12V Side with the capacitor to radio
Black Ground +12V to battery

Measured Filter Response:

I made this measurement using a low frequency signal generator and an oscilloscope. At 25 Hz the filter has better than 30 dB of attenuation. In other words for frequencies above 25 Hz the noise power has been knocked down by more than a factor of 1000. I am new to practical electronics. By answering basic questions and making suggestions several folks contributed to this. In particular Dave KC1LT was very helpful. I hope this information is useful. If you use this design to build a filter or if the information presented was useful please email me and let me know it was worth the effort to put this together.

73,

Jim
KB1MVX

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