Category Archives: Mobile

Field Reports, FT8, Guest Posts, Mobile, News, QRP

Field Report: Dave ventures into the fog to play FT8 POTA!

October 26, 2023 Thomas Witherspoon 5 Comments

Many thanks to Dave (K1SWL) who shares the following field report:

October 6th POTA activation

by Dave (K1SWL)

I’m pretty much a died-in-the-wool CW guy. I’m not averse to dabbling in other modes, though. Friday, October 6, 2023, was such an occasion. I’d noted that there’d been little recent Digital activity in one of our area’s Parks. As if it needs more familiarity, it looms over I-91 only three miles from the Connecticut river. As a result, it’s been activated more than 75 times.

This was Mount Ascutney State Park in VT, and at 3144′, features a paved road to the summit. Off I went!

Finding a parking space at the summit lot wasn’t an issue. The top of the mountain was socked in above 2500 feet. Visibility was 30 to 50 feet, and sightseers were inexplicably scarce.

I normally use a 20M end-fed antenna and homebrew pneumatic launcher. The stunted trees at that elevation made that less practical. I used instead Hustler resonators for 10M and 20M atop the truck cab on a mag mount. I usually consider that setup a compromise, but at 2000 feet above average terrain (HAAT), it didn’t matter.

The operating position inside the truck is quite comfortable. A melamine-clad slab serves as the operating surface. (see above) The chain at the far end was a design ‘iteration’. I’d originally just supported that end on the passenger-side arm rest. I’d operated from the driver’s side, and one day got out, went around and absent-mindedly opened the passenger door. The whole station headed for the ground. I caught the rig but the Vibroplex Iambic paddles were a loss. A fabulous excuse for a Begali- and a hard protective case! When I’m operating from the truck, an IC-706MKIIg and 15-AH Bioenno battery does the honors. If gear needs to be carried any distance, the KX3 makes more sense. The station itself takes two minutes at most to set up.

So how’d it work out? A closeup of the WSJT-X screen (seee above) illustrates it. (The device is an MS Surface.) I was getting as many as 3 replies to my CQs at a time. I wound up ‘interleaving’ three contacts at a time. It got confusing! I need to look into ‘Fox/Hounds’ operation to speed things up for the future.

All in all- a great success. A total of 62 FT8 contacts in a little over 2 hours. 16 of these were on 10M at the start and the balance on 20M. The attached QSO Map (att. 4) shows the contact distribution- mainly eastern US with a few Europeans for good measure. Will I do it again? You bet!

73- K1SWL

Accessories, Guest Posts, How To, Mobile, News

Scott builds a mobile desk for HF park-roving

April 19, 2023 Thomas Witherspoon 8 Comments

Many thanks to Scott (KK4Z) who shares the following post from his blog KK4Z.com:

Necessity is the mother of invention

by Scott (KK4Z)

Plato’s Republic he said that *our need will be the real creator* or the proverb as we know it today *necessity is the mother of invention*. Recently, my friend Thomas K4SWL acquired a Yaesu FT-891. During his YouTube video, he expounded on how much fun he had with it. It did indeed look like fun. During this time I was pondering about doing more day activations instead of overnights. With the cost of everything still climbing, the need to conserve becomes apparent. I thought an FT-891 might really be a great radio for these day activations. Then reality set in.

I already have a number of projects I am working on and misc things like maybe having to replace my old 33′ push-up pole, it was not in the stars nor was there a twinkle in my wife’s eye when I mentioned it. In reality, the IC-7300 is a great radio and does everything I need to do especially in the field. I don’t need another radio, I have three 100 watt radios and three QRP radios. I still wanted an easy setup for these one-day activations. I want to drive to a park, set up in a few minutes, operate, tear-down in a couple of minutes, and head for home or another park. I also wanted to make my day activations park ranger friendly. To me, that means trying to be inconspicuous.

I have two projects planned. The first is a desk for my truck. I am making a desk to sit over the center console and front passenger seat big enough to hold my IC-7300, a laptop and a CW paddle. My plan is to secure the desk to the truck and the radio to the desk. I also wanted to make this as cheaply as possible. I used stuff I had on the property such as a half sheet of plywood and some construction lumber. The only things I had to buy were some screws and eye-bolts, about 14 dollars worth.

The plywood was cut to 24 x 38.5 inches. The length covers the center console and front seat while still allowing me to get to the heat/AC controls. I gave the corners a generous radius and I broke the edges with a router. On the underside, I used a 2 x 12 to make a spacer for the center console where the cup holder is and a leg for the other side over the passenger seat. The spacer is glued and screwed to the desktop but the leg is not attached. This is to make it easier to store. I made a socket for the leg using 2 x 2’s. It’s probably easier to look at a picture than me to try to explain. I added eye rings to the rear of the desk and use a bungee cord to secure the desk to the passenger seat. The only other thing I did, sprayed the top with polyurethane. Note. I am not a carpenter or cabinet maker. I use rough hand tools to get the job done and I am often making do with what’s on hand or what’s the cheapest way to do it.

Continue reading Scott builds a mobile desk for HF park-roving →

Antennas, Articles, How To, Mobile, News

Dave sorts out vehicle-mounted antenna SWR issues

December 3, 2022 Thomas Witherspoon 9 Comments

Many thanks to Dave (K1SWL) who writes:

Comments on vehicle-mounted antennas

by Dave Benson (K1SWL)

As with Rand’s recent post about his effective vehicle setup, I and others also use a small operating table inside the vehicle. I’ve tried a number of approaches to antennas. Without elaborating on those schemes, I’ll note that winter is now closing in here in NH. As a result, I’m now operating exclusively from my truck. My interest is now in minimizing setup and tear-down times. Barry (WD4MSM)

also commented about the improvement in vehicle-mounted antennas with an added ground. I’d like to quantify that.

I’d recently ordered a number of Hustler Mobile antenna components. They’re used as a stationary-portable setup using that company’s high-quality mag-mount. As I first evaluated the antenna, I was disappointed to find the minimum SWRs to be on the high side.

These results were related to the ‘floating’ coax shield, which serves as a counterpoise with the mag-mount setup. Worse yet, these results were inconsistent. Touching the coax connector shell at the antenna analyzer caused the SWR to jump up, as did just changing the way I held the analyzer. Bad juju! It means RF inside the vehicle, with the potential for RF-‘hot’ symptoms at the rig.. Adding a 1:1 balun inline eliminated the stray RF at the rig, but didn’t do much for the SWR. It’s also just one more gadget to bring along.

A better fix was a custom bracket that bolted to the truck frame. I first confirmed that there was low-resistance continuity between a target location and the vehicle’s cigarette lighter shell. This was something of a ‘comedy of errors’. I had a sheet-metal angle bracket on hand and went to work enlarging a hole in it. This had the usual outcome: a drill bit grabbed the workpiece and spun it. The bracket itself was buckled beyond redemption and my finger’s now healing well. A length of 1-1/2 inch aluminum angle bracket was just the ticket. Note that the mounting hole needs to be offset from the coax fitting mount. This avoids an interference between the mounting bolt and coax connector shell. Ask me how I know. The bracket assembly uses a specialty coax fitting from DX Engineering. It’s their part number DXE-UHF-FDFB.

This bracket is bolted down on one of the corners of the Tacoma’s passenger seat assemblies. It’s the closest location to the antenna I found without drilling holes and cutting the coax. For this vehicle, it’s a 10mm bolt and was paint-coated for appearance reasons. I replaced it with a stainless-steel bolt from a hardware store. It’s important to include a split-lockwasher between the bolt and the bracket. This’ll keep the conductivity to the frame good over time. The bracket is deburred and its corners rounded to preclude injury to passengers.

In any event, it’s out of the way of the seat’s legroom space. A 3-foot coax cable assembly brings the coax nicely up behind the rig atop the operating surface.

So- how’d it work? It’s like the difference between night and day! The broad SWR curves vanished – replaced by typical characteristics for monoband antennas. The sensitivity to handling the coax has vanished. (A representative curve at right.) The curves are narrower, and that’s actually a good sign- it means that unwanted resistances have been reduced.

With this fix in place, here are the SWR minima:

Frequency SWR

14060 1.04:1

21060 1.05:1

28060 1.16:1

I took advantage of the CQ Worldwide CW Contest this past weekend. I was able to work 101 stations on 10M, 15M and 20M with this setup. That was from a State Park 5 minutes away. The attraction was a large and sunny parking lot, and solar gain was such that I needed to leave the truck door open several times. This area is kept plowed out in winter, and I may try for the POTA ‘kilo’ award from there at the 1000-contact benchmark.

We’ll see…. 73, K1SWL

Guest Posts, Hams, How To, Mobile, News, QRP

Rand’s “Shotgun!” Mobile QRP Station

November 22, 2022 Thomas Witherspoon 15 Comments

Many thanks to Rand (W7UDT) who shares the following guest post:

‘Shotgun!’ My Mobile QRP Station…

by Rand (W7UDT)

I’ll confess, at our overly stylish home, sadly, I don’t have a shack… my XYL has “concerns.” So, in an attempt to keep my operating license and man card active, I happily practice portable QRP field operations at my QTH and afield.

This time of year however, with winter bearing down on us, I choose to deploy via my ‘Shotgun!’ mobile QRP station. Simply, a quarter inch sheet of birch plywood, cut and finished nicely to fit suspended from the grab bar and headrest of my Jeep Wrangler’s passenger seat. Ergo, ‘Shotgun!’