Category Archives: Ham Radio

Mobile HAM radio in the truck

I’d noticed that as the summer had come on and the trees had leafed out, my ability to reach some local 2M repeaters was impacted, using my 5W HT and a roof mounted magnetic antenna. For example I was having significant issues accessing the Durham “TV Hill” repeater (fine in the winter), though the newly reinstalled OCRA 70cm was fine, albeit configured much higher and sitting much closer to Chapel Hill. So I decided to install a standard mobile rig. I’d wanted a Kenwood 710G but they are just too pricey, so I opted for a Yaesu FT-7900R. Basically, no fancy APRS stuff, but I’m less enamored of that as time goes on.

The 7900R is the basic “workhorse” dual band, 50W on 2M and 40W on 70cm. One thing I liked about it though was the fact that it came with the transceiver/head separation kit, which was good as I didn’t really know how I wanted to mount it, as my truck has a full complement of electronics and no room for other devices. I didn’t want to drill any holes, but I wanted a nice looking install. A tall order!

So where to put things and how to run the wires?

The transceiver is tucked up under the crew cab back seat, behind the driver’s seat. It’s about the size of a small paperback book, and just sits on the carpet out of the way. I had to pick up some extra 12 guage DC power wire (12′) since the battery in the Silverado is on the passenger side. I ran the power wire via a technique I found googling, going thru the fender, not the firewall, and then thru a small rubber grommet near the emergency brake to get into the cab. I reinforced the fender passage with copious electrical tape. Then pop up the plastic trim along the cab edge to run the cables. I soldered and taped my extension to the supplied power cable, running to the transceiver, and in the opposite direction, the head separation cable toward the dash. For the head (like a small cell phone), I got a clamp mount that sits nicely on the corner of the dash on the left of the driver. Left enough cable there to easily move it around, and unplug and put out of the way when needed.

So what about an antenna? I decided on a Larsen thru-the-glass mount on the cab window behind the driver, after reading about successes there. I was concerned about its efficacy but it seems to work great! Dropped the RG58 down behind the seat.

I ran the speaker extension cable from the transceiver to coil it under the driver’s seat, where I could, if desired, plug into the infotainment system. However, the built in speaker is actually pretty effective.

Have programmed repeaters into the radio and done some tests, reports indicate good audio, and I’m happy with the way it all looks. So far so good, and no holes in the truck ūüėČ

The only issue? Somewhere under the hood of the truck is an small socket wrench adapter that “got dropped” during the process…

HF Ham!

I’ve neglected my blog for the past couple of months, with no posting since January. ¬†We had a great time on our cruise to the eastern Caribbean in February, so my excuse it that I was having so much fun I had no time for blogging ūüėČ .

However, I did want¬†to chronicle my success with moving to the world of 6M and HF Ham radio. I posted here in January that I’d upgraded my antennae for my 2M/70CM radio, and I’ve been doing a lot of communication on the 2M band, including becoming a regular participating member of the Possum Trot Net, Possum number 3571! I wanted to add the capability¬†to use high frequency (long distance) bands to communicate to more and different communities. ¬†I added a Yaesu FT-450D radio with a 7-band Buckmaster OCF dipole antennae to my “shack.” I plugged it in Monday of last week and tried to communicate with the local 10M net, but did not have any success in transmitting though I could hear the net traffic. Don’t know if there was just a pileup, or something with local conditions. I reached out to a local Ham to give me some assistance and coaching. KM4MDR came over today and spent a couple hours with me, validating the SWR of my antenna with his MFJ analyzer (it did very well on the supported bands, ranging from 1.2 to 1.8), and showing me a few tuning tricks. I’m very appreciative of John’s help! We participated in the 40M 7.772 Ragchew¬†and talked to Net Control in Maryland, and talked to the 20M 14.300 Mobile Maritime Net (you don’t have to be a boat to participate!) Net Control near Houston TX. ¬†Signal reports were good. So, great success, and now I can operate with the confidence that I can hear and be heard.

More Ham fun

I wanted to be able to reliably reach the local VHF/UHF repeaters, so I bought a 2 meter 1/2 wave antenna to mount outside the house and hook up to my handheld radio. It came over the weekend, and I installed it this afternoon. The antenna itself is a set of wires of specific lengths and impedances that you mount in 5 feet of PVC pipe. I hooked it up with a large diameter low loss cable, and used an adapter to connect to the SMA plug on my handheld. Works like a champ! I’m now able to reliably key repeaters 15 miles away with the 5 watt handheld. ¬†I talked to a fellow Ham this evening via the repeater (W4AGC 2M¬†on TV Hill in Durham), and he said I had excellent sound quality with no distortion. Also, was able to successfully test out an IRLP connection via the W4AGC 70cm repeater to my “beach” repeater in Newport, though my new Ham friend from Harker’s Island, KM4NRZ, didn’t answer. Also did a test of an IRLP reflector node, and heard my voice come back. Cool!

APRS antenna update

As I wrote here previously, I’ve been exploring the¬†APRS (Automatic Packet Reporting System) Ham Radio system. I noted that while I had the Kenwood TH-D72 radio configured correctly, it was not reliably getting its packets to the nearest digipeater to be ingested into the APRS/APRS-IS world. I suspected it was an antenna issue, as I was using the “rubber duck” that came with the radio. I replaced that with a Diamond¬†SRH77CA and that’s made a huge difference. I’ve used it to have a “chat” with another local APRS user several miles away, though via the digipeaters, it’s possible to have a digital chat with an APRS user much further away (depending on mutual routing settings). Additionally, I noted that when the radio was inside a vehicle, it was unlikely to successfully send a packet unless the digipeater was just a couple miles away. So, I also got a Diamond¬†MR73S, a small magnetic-mount external antenna with an SMA connector. With that on top of my truck, the APRS “smart beaconing” works perfectly, sending status packets¬†with information that reliably shows position and turns. Interesting stuff.

APRS radio

I’ve been experimenting with APRS (Automatic Packet Reporting System) on HAM Radio. Interesting stuff! Essentially, it is a system that provides situational awareness and context for radio-enabled devices by capturing “beacons” from devices such as mobile radios, fixed point radios, weather stations, satellites, antennas, and creating a data stream that’s used to create a geo-enabled map of devices in real time…an organic “Internet of Things” (IoT) joined in the radio spectrum. As Bob Bruninga, the father of APRS says:

“Since the primary objective is consistent exchange of information between everyone, APRS established standard formats not only for the transmission of POSITION, STATUS, MESSAGES, and QUERIES, it also establishes guidelines for display so that users of different systems will still see the same consistent information displayed in a consistent manner (independent of the particular display or maping system in use)”

There are gateways to the traditional Internet for email, but the value of APRS is in the dynamic resource map it populates to RF contacts in the local area (and through data added to the APRS-IS, the Internet system, and thus generally available), and its ability to send messages between participants. It’s a peer-to-peer network that can grow organically with the addition of “digipeaters” to relay traffic, but still provides station to station information. As the APRS Wikipedia article states, “Anyone may place any object or information on his or her map, and it is distributed to all maps of all users in the local RF network or monitoring the area via the Internet.”

It does depend on access to a digipeater, and one thing I’ve found in a couple days of testing is that my HT 5w Kenwood TH-D72 transmits to the nearest repeater from Emerald Isle with sketchy regularity. It’s 10 air miles, and the standard antenna on the TH-D72 is reliably receives APRS packets from KD4KTO-4, but seems to get them there irregularly. Next week, I’ll be back in the Chapel Hill area, and it will be interesting to see how things fare there. I’ve ordered a better antenna for the radio as well, and that should help considerably with transmit range.