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New KD1JV ultralight rig for 80/160

There’s been a higher than usual level of activity on the AT-Sprint email list over the last few days as  hints have emerged of a possible new offering of the popular MTR (Mountain Topper Radio) the latest of Steve Weber KD1JV’s radios that define the possibilities of ‘trail friendly’. To get a view of one in action check out this video from G4ISJ shot on a SOTA activation.

PCB of Steve KD1JV’s popular MTR, ‘a very small, very efficient, two band rig’
Steve KD1JV’s popular MTR, ‘a very small, very efficient, two band rig’, is set for another future offering

Steve KD1JV is the designer behind the PFR-3 and a number of other radios offered by Doug Hendricks’ QRP Kits along with the new Tri-bander Transceiver kit. But he also enjoys a passionate following for his high performance but tiny (Altoids tin size) radios in the ATS series where ATS stands for Appalachian Trail Sprint. These radios (especially the ATS-3B and the MTR) are prized by ham hikers and walkers who watch the ounces and milliamps. They are also an example of masterful interface design using small push buttons and minimal LED display. As Steve mentioned recently in a post reflecting his deep field operating experience “Little tiny rigs and knobs don’t work well together”.

During the buzz earlier today about whether he would offer more of the MTR kits (he will), Steve also announced his latest project “An 80/160 dual band rig with direct conversion receiver and a DDS/PLL hybrid VFO using all through hole parts.” (The ATS series made extensive use of microscopic SMD components and lots of the assistance Steve offers via the AT Sprint Yahoo group is concerned with discovering and rectifying makers’ errors assembling these devices.)

His website carries a pretty detailed three-page description of the design thinking behind the new rig which he’s calling the Super Deluxe Direct Conversion Transceiver. Tantalisingly he’s suggested it may be able to work at 500kHz. The new rig also features an “LCD frequency read out, built-in keyer and rotary tuning”.

He’s planning to offer only 50 kits at about US$75 at the end of November. Expect to see them sell out in two minutes! I suspect if he offered 200, they might last an hour or two.

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QRP at Bamarang

Last weekend I had a great time playing radio. Along with half a dozen other families and all our kids we went to spend the Easter weekend at the “mud brick mansion” at Bamarang on the Shoalhaven River, a few km west of Nowra on the south coast of New South Wales. Courtesy of the pod on my car I was able to take quite a few radio bits and pieces along.

We enjoyed perfect autumn weather while it rained back home in Sydney!

I even managed to build the neat little EFHW (End Fed Half Wave) Tuner designed by Stu, KI6J on a shady verandah. The kit had arrived a few days earlier and I made sure I had everything I needed to build it away from my attic/shack/workshop. In fact the weekend became a sort of trial for field day and a great way to identify the essentials. If there’s a lot of gear on hand an awful amount of time can be wasted deciding which bits to use and how.

I was inspired by reports about the EFHW tuner and the appeal of not having to worry about ground radials. What clinched it for me was a photo I saw on one of the (far too many) qrp email groups I try to follow showing a ham on a mountain side beneath his arching squid pole with the little tuner matching the hi-Z of the half-wave antenna to the 50 ohms expectations of the tiny transceiver which was probably an ATS3b.

So that was my mission for the weekend.

The tuner kit went together in a very short time. Before accepting my order Stu, KI6J sent me a powerpoint of the assembly instructions so I was sure I could handle the construction. The fiddliest bit was the tiny binocular ferrite core transformer for the bridge. Fortunately he provided enough wire in the kit for me to botch it the first time round and do it perfectly the second!

After a couple of leisurely hours mostly taken up with drilling holes in a tiny plastic box it was working on the test lash-up. The polyvaricon is delightfully sharp. You tune by dimming the LED – and then switch out the bridge to transmit.

The KI6J EFHW Tuner kit almost complete with the 5k ohms test load in place. The builder provides the enclosure and connectors. (Photo sourced from instructions)
The KI6J EFHW Tuner kit almost complete with the 5k ohms test load in place. The builder provides the enclosure and connectors. (Photo sourced from instructions)

I had a 10m (almost 33 feet) squid pole (aka Jackite or crappie pole) with a tiny pulley from a boating store attached to the top with cable ties. I used the guy ropes from my Buddipole setup to hold the pole up straight. It stayed up all weekend.

The half wavelength formula in feet is 477/freq in MHz, or just on 68 feet (20.7m) for the code end of 40m. The far end of this was held up – via a plastic button insulator – by a fishing line launched up into a tree using a half-filled plastic drink bottle. All too easy! The near end of the antenna simply terminates in a banana plug that connects to the little tuner. I also connected a short 5-6 foot counterpoise, which was essential.

I had a great time playing with the tuner and my new SDR-Cube pumping out a whole watt of RF, as well as the trusty little FT-817.

Now I have a clear idea of what’s required for an effective little kit of gear to take up a hill for relatively speedy SOTA style deployment. And maybe I’ll fill the water bottle for those trips.

If you’re interested in getting hold of one of these nifty little EFHW Tuner kits you should contact Stu KI6J at ki6mwn@yahoo.com. US$27 included shipping across the Pacific Ocean! Fast and very fair!

My blissed-out second operator in the field at Bamarang, near Nowra NSW. He helped me retain my QRP calm.
My blissed-out second operator in the field at Bamarang, near Nowra NSW. He helped me retain my QRP calm.

During a trip into the township to replenish supplies I found a fishing tackle shop with an Easter sale on, and bought a couple of handy Plano tackle boxes and some inexpensive 10m lengths of nylon coated stainless steel ‘leader line’ wire which I’m sure can be used for a handy weatherproof dipole. As long I don’t have to solder the stuff.

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And they’re racing!

Interesting thread on the softrock40 email list about how easy it is these days to get a good sense of how well your station and the ionosphere are performing in an almost ‘hands-free’ way.

Increasingly modes like WSPR and tools like SDR have enabled us to let the radio do its thing and in a short amount of time access detailed logs of our successes – where we were heard. The softrock40ers were using this approach to compare their SDR rigs performance to other sets.

Rob KL7NA joined in the conversation. He pointed to his recent paper on what he calls ‘Robotic radio‘ that he presented to the DCC meeting in Vancouver WA recently.

Your radio is doing what the operator used to do automatically, and as you have been finding out, it is really fun to horse race different software demodulators, receivers and antennas, and radio locations this way.  I am trying to promote it as a way for our youth to get into amateur radio.  They seem to be very enamored by robotics.

Rob’s paper is full of interesting ideas and he lists the building blocks of Robotic radio… hardware, software and networks. He introduces his open source project CW Robot which is still in alpha and explains the thinking behind it.

This looks like a very rewarding place to play and discover – and there’s already a road map.