Category Archives: ham radio

Budget Mobile Ham Radio Install in Chevy Colorado.

My first thought was: Antenna clipped to the edge of the truck bed – easy right! How am I going to get the antenna wire poked into the bed of the truck? There is nothing back there, no holes, no grommets. For a commercial vehicle this makes sense for the eventual tool-cab or dump body – pop off the bed – no wires to deal with. I followed the existing wire loom and it travels along the frame, under the cab, and up through the firewall. So, if I wanted an antenna mounted to the lip of the bed, I was going to need a 30′ coax detour. Not to mention exposing that wire to the elements and spending 3 hours on my back with zip ties.

Plus, I have a tonneau cover. The edge of the bed isn’t exposed, and I’m not drilling a brand new hole in it. Time to re-think this whole operation.

Fender mount! Why stretch wires all over the cab when I can grab power and antenna from the same area? I did a search for these online and the premise is a metal bracket that attaches to one of the fender (or hood latch) bolts on the front of the truck. There are many available, but not for every truck, and they are not usually inexpensive. I was considering ordering one that looked like I could modify it to fit, but for $66 + shipping, that’s an expensive experiment. Instead I made my own! If you own a vise, a hammer, and a drill – you can build this.

For $8, I grabbed a flat bar of 1/16″ (or 3/32″) 2″ wide steel from the local hardware depot. Hood up, cardboard template gave me an upside-down “2” shape. I marked up the steel and into the vice it went. Hammer, hammer, hammer, fold, check fit, hammer, check fit, repeat! Making sure that the hood had clearance and that the mount would press snugly against the fender. I was able to cut a slot for the hood bolt using a grinder. A dremel could do it, or a hand drill would work here. I sanded the edges and coated with Rustoleum Flat Black Trim Paint. For the Antenna itself I now had a platform for an off the shelf trunk lip mount. I chose a Tram 3246-B SO-239 mount as I re-used the antenna from my old truck (a Diamond NR770HB). It’s close to a factory look, as this is where the FM antenna would go on older trucks. Also I chose the drivers side specifically because the ECU (PCM / Computer) is bolted to the firewall on the passenger side. I want to minimize electromagnetic interference from this, and 65 watts of EMR (electromagnetic radiation) getting into this.

The grommet through the firewall is over-sized enough that I was able to squeeze the UHF connector through intact. The Power distribution bus on these new Chevy trucks are fantastic and I had fused ground and positive wires going right to the battery using ring terminals and existing bolts. Now power and antenna were in the cab. Where do I put the radio?

In the 2014+ Colorado, there is a nice storage shelf under the rear seats in the crew cab. If I was running multiple radios, or additional equipment, I think I would take the time to route everything back here. This would of course necessitate removal of the center console to route the wiring under the carpet. In our old Blazer I didn’t take the time to do this and occasionally dragged things over the “neatly zip-tied, but totally in the way” wires running along the floor. The center console is like a sealed piece of Tupperware that’s not quite square inside, and gouging giant holes in the bottom for wires and radios would render the storage area useless. I instead turned my attention to the front seat.

My Kenwood TM-V71A roughly fit in the area, but I was worried about the seat mechanism hitting it. I picked an area of the floor that I felt would be clear, and then moved the seat into “wife is driving” mode. The radio would be crushed by one of the seat motors. “Well, maybe the radio moves with the seat?” I situated the rig against the round bar in the middle of the seat and tried various positions – it seemed to work! I then went back to the vice and fabricated an aluminum bar with tabs to bolt onto one side of the rig. Using pipe clamps I got it into position and tried moving the seat. It actually pivots a LOT more than I expected, but I was able to find the angle where: At full depth it’s tucked up into the seat, at full height it’s lightly touching the floor. I then moved the seat all the way forward and all the way back to make sure I had clearance. It worked out great! Here’s VIDEO of the seat and radio going from all the way up – to all the way down.

A nice doughnut of spare coax was made à la choke coil and everything was zip-tied up and checked again for clearance. The remote head and speaker wires were run up the side of the center console. The mic connection on this mobile rig is now in a great spot, and because the radio travels with the seat there is always enough cord!


  • Generic parts:
    • $8 Flat bar of steel
    • $4 Aluminum bar (scrap)
    • $30 Trunk Mount (Tram 3246)
    • $42 Subtotal
  • Radio Specific Items:
    • $50 Diamond NR770HB (I owned from previous install)
    • $40 Kenwood DFK-3D Remote Mount Kit (previous install)
    • $90 Subtotal
  • $130 Total

Inexpensive Charging Station

Phone Charging Station
Here’s my take on an inexpensive charging station that stops vampire power and keep our phones / bluetooth / radios in one location ready to use. The soft box was found at The Container Store. The switch is for the Belkin Remote Power Strip. These days most of the smart phone chargers suck very little vampire power, but I have a couple of hand-held transceivers from Yaesu and Icom that are the old transformer type. The power strip has a couple of outlets that are powered all the time, so I plugged one of our phone chargers in there as it’s needed the most.

Belkin Power Strip ModificationThe one dislike I had with the Belkin big ON / OFF switch is you really have to push it hard and it makes a big snapping CLICK when it goes on or off. It almost feels like you’re going to break it. I was hoping for a sexy smooth touch button. I achieved this by taking the switch apart and removing some of the CLICK plastic on both the ON and the OFF side. Notice the black arrows in the picture. Now the switch sits centered between ON / OFF and with a soft tap I can control power to my inexpensive (slightly hacked) charging station.

Setting up a Kenwood TM-V71A for APRS.

6-pin PS/2 mini din hack
Kenwood is pro APRS. Something must have been lost in the translation when the marketing guys wrote up the specs for the TM-V71A. It lists APRS, and then to the right it says: NO.

What does that mean? It certainly can transmit and receive on 144.390. So, it doesn’t have a built in TNC like its older brother the 710. So? It’s certainly an APRS capable radio. It even has the industry standard 6-pin mini din ready for packet data on the back of the rig. The TM-V71A is great for APRS duties.

Something tells me that the marketing department wants you to steer over to the RC-D710. It’s a ready to go TNC with all sorts of options that make your V71A ‘feel’ like you spent the big bucks. Well, the small bucks are okay with me. Matter of fact, with this unit connected to an Argent Tracker2 and a Garmin Nuvi 350 – it’s about $1500 worth of kit for about $600. Stay tuned as I install it over the next few weeks.

First challenge: Getting the radio to talk to your TNC (tracker).
I guess I could blame those marketing guys again, but I don’t know who messed up the verbiage in the manual on the pin-outs for the DATA jack. I opened up the manual and flipped to the section on packet operation. Easy enough, I just have to provide audio in/out, PTT and ground. Wait… What pin is PTT?

1 PKD input, 2 DE, 3 PKS input, 4 PR9 output, 5 PR1 output, 6 SQC output
Seriously Kenwood? Where did these abbreviations come from?

The description is just as confusing. For pin 3: ‘L’ is transmitted and the microphone is muted. The letter L? The low? What?!
Does that give one any indication that pin 3 is the PTT? Leading to the confusion is the ability to set the “baud rate” for the radio. (Please take note the quotes…) This had me questioning if there actually was a TNC in the radio and whether to pass audio data or digital data to the unit.
Panicked, I called Brian NJ6N for some help. He chuckled at the descriptions and pointed me to where a handy reference sheet tells us the following.

Now that’s more like it. Brian also explained that the baud rate has to do with the filtering the unit is doing. For very high data rates it skips some of the internal circuitry that could lead to some issues with received packets. For our purposes, APRS is 1200 baud and the default settings will be fine.

Cable time: Because I’m super impatient, I scrounged the house looking for a 6-pin mini din connector. “Hey, that PS/2 keyboard / mouse connector looks like it could do the trick!” Before you could say “e-waste” I had the end off a PS/2 keyboard on the desk hooked to an ohm meter. Bad news – They don’t use pin 2, and they don’t even bother to leave an un-used wire in there. Don’t bother tearing open the mouse – it also doesn’t utilize pin 2 at all. Thinking that this is the end of my experiments I slice the connector open and take a closer look. Pin 2 is there and, sure enough, nothing is connected to it. After digging a channel with a sharp knife I find there is enough there to solder. The elegant solution I came up with is to ground the pin to the outer shield and use that for pin 2 ground. A little heat shrink and we’re back in business. For those of you with patience, it looks like this cable from Byonics should do the trick.

Using the Tracker2 manual I came up with the following pin configuration:
Argent Tracker2 >>> Kenwood TM-V71A
DB9 >>> 6-pin mini
1 audio out >>> 1 data in
2 squelch input >>> 6 squelch out
3 ptt >>> 3 ptt
5 audio in >>> 5 af out
6 ground >>> 2 ground

Plugged in and ready to go:
I turned on the radio and tuned to 144.390. I specified in the menu which side my packet operations would be on. My Tracker2 blinked to confirm it was hearing packets! A quick test and I was able to send a message to K6SOA-9. Receive and transmit both work. Now, one side of the radio will be dedicated to APRS, but this is no different then the D700. A remote switch is in the works to allow me to turn off the tracker and regain the use of both A and B sides, should I need a cross-band repeat or dual receive.

12v socket and power pole additions
Next time I’ll be detailing the entire install. From hacking the existing FM antenna mount, to Garmin Nuvi 350 APRS messaging. I even tackle getting the Honda Fit amplified antenna working inside the car. As you can see I’ve added a 12v cig jack and Anderson power pole panel. Stay tuned!

Reminder – Field Day this weekend!

I’ll be over at Gilleran Park in Mission Viejo with the South Orange Amateur Radio Association. If you want to see some cool radio technology that will be used to save you during the ‘flood, fire, earthquake, etc.’ Stop by and check it out! If you’re no where near my location – use the ARRL Field day location locater and find one in your area! I’ll be teaching the educational session on APRS, making our 100 point satellite contact, and probably working late night DX on the big bands. Have tent and a Honda Fit full of equipment, will travel. :)

Icom IC-2200H cheap fan mod

Fan installed on IC-2200H

I wanted an elegant and not so permanent way to attach a 12v fan to my rig. It’s going to see use as net control and even at 5 watts – it gets hot after transmitting for a half hour. It’s also going to serve as a digipeater at an upcoming rally. I’ll show off the thermal controller once it’s built, so the fan is not running 100% of the time.

Parts: coat hanger, zip tie, $6 PC fan, $2 dust cover w/foam.
Pictures: IC-2200H fan mod here

Basically bend the coat hanger into this: |_|
Slide it into the back heatsink and tilt it forward.
Bend the ends into hooks. Hook the fan onto it.
Tilt it down and around the outside of the rear heatsink.
Zip tie it into place.
– Enjoy