Using a Mobile Antenna as a Temporary Base Antenna

For our July Fourth Safety Watch this year, I used my dual-band mobile antenna on a ground plane mount on a camera tripod. I’d purchased a Nagoya GPK-01 NMO Ground Plane Kit ($28) to test my NMO mobile antenna, because my mag mount seemed flaky.

As I was drifting off to sleep one night, I thought that the 1/4-20 screw on my camera tripod might fit the holes on the ground plane kit. It did, so now I have a robust, free-standing, dual-band antenna for em-comm use.

IMG 4753

The antenna is a Comet SBB-5NMO with 3 dB of gain on 2 m. Not a flamethrower, but a solid antenna when used with a good ground plane.

The radials unscrew from the mount, so the ground plane kit packs up small.

IMG 4750

Our station was up on a hill, so we had great line of sight to the whole valley. We ran a mobile rig (Yaesu FT-8900R) at 50 W from a battery, so we had a great signal. We could also hear the other stations clearly, so our station was net control.

IMG 4748

The only thing I’ll change next time is to use 1/4-20 wingnuts instead of regular nuts. I might paint them orange, too. I was sure that I would drop a nut in the grass and never find it.

And yes, that is a classic Gitzo Reporter aluminum tripod. If needed, I could extend the center column to get the radials above eye level.

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Voile Ski Straps

Better than bungee cords! I purchased a few of these, thinking they might work for strapping my fiberglass radio mast to posts and stuff. They are great. Stretchy, adjustable, and super easy to fasten and unfasten. After I tighten a strap, just releasing the tension almost always catches a hole on the buckle to secure it. Lovely design.

Here is one of the two I used to strap my mast to a railing on top of Mt. Umunhum for a SOTA activation. My shortest straps are red and 15 inches long.

Voile 1

Earlier, I used a longer blue one (20 inches) and two of the red ones, linked, to strap the same mast to a walkway post for ARRL Field Day.

Voile 2

A red strap held the balun to the top of the mast to take stress off the connectors.

Voile 3

I started with this variety pack of three sizes ($16.50 at Amazon), then stuck with the same color scheme for ordering more.

I’ll be taking these on every field radio outing. That means I’ll have swap them back and forth between my emcomm go bag and my SOTA gear. I think I can manage that.

Whip Antenna Support for KX3

A Nite Ize Gear Tie seems to do a decent job of supporting the MFJ-1820T 20 m whip antenna on my Elecraft KX3. I first tried forming it into a bipod, but then got the idea of attaching it to the SideKX endplates. Success!

KX3 gear tie 1

I’m using a Nite Ize Gear Tie 12 inch because I had one. The fatter one didn’t really fit through the handles.

The whole setup is pretty cheap. $25 for the antenna and $6 for two gear ties. It isn’t as efficient as a 20 m dipole, but it is kind of cute.

23cm PC Board Yagi

I wanted a bit more “oomph” from my 1W 1.2 GHz HT, so I purchased a PC board Yagi to get another 6 dB.

I have a Yaesu FT-911 1.2 GHz HT. It is a 1990’s rig gifted me by the wife of a Silent Key at my work. It is a sweet handheld, but with limited power.

WA5VJB makes a variety of PC board antennas. The 1.2 GHz 3-element Yagi is $6, which was hard to resist. He also makes other nice microwave antennas: log-periodics, patch arrays, wheels, vivaldis, etc.

I went to HSC Electronic Supply and picked up a PC mount BNC and a right-angle BNC by navigating this aisle.

23cm yagi 2

I found a short, stiff BNC cable from this bin.

23cm yagi 3

I soldered on the BNC chassis connector and epoxied it to the antenna. The PC board is beat up because I’ve been carrying it around in my backpack for ARRL Field Day. It was pristine when I got it. Nice design, the feedline attaches at the edge of the board, then there is a stripline to the driven element. The reflector element is on the back side of the board. You can just barely see it in this photo. The shield of the coax attaches to a thru-hole pad that goes to the stripline on the other side of the board. That is hidden by the connector in this photo.

23cm yagi 1

And now I have a 1.2 GHz “flamethrower” HT.

23cm yagi 4

I need to find something to stiffen that bit of coax so I don’t have to use my hand to stabilize it. Other that than, pretty sweet.

Speakers for my Elecraft KX3

Want speakers for your rig? No need to wait. For about the cost of a tank of gas, you could be sitting back and enjoying armchair copy.

The internal speaker in my KX3 is good but not great, plus the rig has stereo effects which you can’t hear through the single speaker. The headphone jack provides 100 mW per channel, which is not enough to drive speakers to a reasonable listening level.

This is my under $35 setup for an external audio amp and stereo speakers. Of course it would work for any other rig.

The KX3 has stereo output, so this is a 15 Watt per channel stereo amp that runs off 12 V, plus a pair of simple 3 inch speakers. The amp is mounted on top of one of the speakers with 2 inch wide velcro. The power lead has Anderson PowerPoles, so it plugs into the rest of my station power bus.

IMG 0221

Let’s walk through the parts list. You can choose your own speakers, of course. I was looking for some vintage Radio Shack Optimus Pro-X44AV speakers on eBay, but ran out of time before JOTA last October. I have one of those speakers on my Lowe HF-150 Europa.

The Pyle speakers are compact, inexpensive, and sound fine. I’m sure there are lots of other small speakers that work.

Item Cost
Pyle Home PCB3BK 3-Inch Cube Speakers, Pair 21.38
DROK Audio Amplifier (TDA7297 15W+15W) 8.50
Velcro 2″ by 4″ strips (optional) 2.77
Belkin Rockstar Headphone Splitter (optional) 10.99
Speaker/power wire had it
Anderson PowerPoles had it

The DROK stereo amp varies in price on Amazon, sometimes around $8, sometimes around $11. It is built around a TDA 7297 integrated amplifier. It works with a DC power supply from 6.5 V to 18 V, perfect for ham use. In small quantities, the IC is under $4. Add in the heat sink, board, pot, and connectors, and even $12 is a fair price. It is a pretty cute little amp, really.

A separate volume control for the speakers is handy. I can turn those up or down as I’m in, or not in, the “shack” (our bedroom).

The blue “power on” LED is very bright, so it is normally taped over with some black photo darkroom masking tape. I removed that for these photos.

stereo speakers and audio amp

I also use a headphone splitter so I can leave everything plugged in—my headphones (Yamaha CM500), the amp for the speakers, and the USB audio A/D device (not plugged in for this photo).

Belkin Rockstar Headphone Splitter

Here is the velcro that I used to mount the amp on top of a speaker. I have extra for other stuff that needs stuck down. The next candidate is my MFJ UTC clock. After that, who knows? I have plenty of velcro left.

two inch wide adhesive Velcro

Finally, here is the whole grand setup in the shack. Such as it is.

KX3 station with speakers

SOTA at Philmont

There are thirteen summits inside Philmont Scout Ranch that are listed in the Summits on the Air (SOTA) amateur radio program. There are another three within the Valle Vidal region to the north of the ranch. Only two of these sixteen peaks have been activated by SOTA operators, Baldy Mountain and Shaefers Peak.

SOTA is an award scheme for radio amateurs that encourages portable operation in mountainous areas. I think it is a great match for Scouting, combining the outdoors, technology, and world fellowship. Grab a radio, hike to the top of a mountain, and talk to people.

Here is a map of the Philmont South Country, which has most of the SOTA summits.

Philmont SOTA South

Starting at the north and moving south, these are the SOTA summits. If the summit does not have an official name, SOTA uses the altitude. An unnamed summit that is 8820 feet tall will be “Point 8820”.

Philmont Region Summit Name SOTA Reference Number of Activations
Valle Vidal Little Costilla Peak W5N/CM-001 0
Valle Vidal Ash Mountain South W5N/CM-005 0
Valle Vidal Point 11100 W5N/CM-007 0
North Country Baldy Mountain W5N/CM-002 2
North Country Point 8820 W5N/CM-023 0
South Country Point 8988 W5N/CM-018 0
South Country Phillips Mount W5N/CM-004 0
South Country Bear Mountain W5N/CM-011 0
South Country Schaefers Peak W5N/CM-016 3
South Country Black Mountain W5N/CM-010 0
South Country Garcia Peak W5N/CM-009 0
South Country Point 8881 W5N/CM-021 0
South Country Mesa Urraca W5N/CM-026 0
South Country Train Peak W5N/CM-013 0
South Country Burn Peak W5N/CM-014 0
South Country Lookout Peak W5N/CM-015 0

I used CalTopo.com to make maps with the Philmont boundaries and the SOTA peaks overlaid. CalTopo is a fantastic, free tool for making custom maps. For a modest subscription ($20/year), you can unlock more features. But the free version is still very useful.

The PDF maps are geospatial PDFs, so you can use them with a mapping app like Avenza Maps (free).

  • Map of all of Philmont with SOTA peaks, in PDF, JPEG, and on CalTopo.
  • Map of the Valle Vidal with SOTA peaks, in PDF and JPEG.
  • Map of Philmont North Country with SOTA peaks, in PDF and JPEG.
  • Map of Philmont South Country with SOTA peaks, in PDF and JPEG.

I don’t have a ride this year, but I want to go back to Philmont, with a radio!

Short Podcasts for the Beginning Ham

Since 2011, Onno (VK6FLAB) has been producing weekly podcasts for beginning Australian amateur radio operators. The podcasts are short, from one to three minutes long. I’m no longer a beginner, but I really enjoy the podcasts. They are full of curiosity, advice, and encouragement. They make me want to get on the air.

The first series of podcasts, What use is an F-call? ran from 2011 through June 2015. These were about operating with with the Australian Foundation Licence, the entry-level license there.

The second series, Foundations of Amateur Radio, is still for Foundation Licence holders, but has a name that makes a bit more sense to non-Australian hams.

Each podcast has a text transcription, which helps with handicapped accessibility. Those are available on the website and I can see them in my iOS Podcasts app.

There are a few terms unique to Australia and amateur radio there, so I’ve compiled a short glossary.

  • The ACMA is the government agency that issues amateur radio licenses.
  • An F-call is an Australian call sign with a four-letter suffix starting with “F”, like “VK6FLAB”. All Foundation Licence holders have F-calls.
  • The Foundation Licence is the entry level amateur radio license. Unlike the US Technician license, it allows operating on HF bands (80, 40, 15, and 10) with voice and Morse at 10 Watts. It does not permit data modes, homebuilt transmitters, or automatically controlled transmitters. Other license classes are Standard and Advanced.
  • Holden is the Australian arm of General Motors, so a “Holden vs Ford discussion” is like a Chevy vs Ford discussion.
  • The LCD (Licence Conditions Determination) is the set of rules and regulations for amateur radio operators.
  • The WIA (Wireless Institute of Australia) is the national association for amateur radio, similar to the ARRL in the US.

Whenever I start one of Onno’s podcasts, I listen to three or four. I’ve listened to over eighty so far and I think I’ll be sad when I finish the backlog and have to wait a whole week for the next one.