Modifications to my power distribution board

My latest activation (Springbrook National Park) had one positive side affect: I modified my SOTABeams PowerPole PP-4 Way power distribution board enclosure. My original one didn’t provide sufficient protection for the four power pole plugs when in my back pack. Do I sourced a better plastic container, one that came with a removable shelf that fitted halfway down in the enclosure and a lid to enclose the plugs.

I installed the power pole plugs into position on the removable shelf.

When in use, the lid of the enclosure is in the open position.

The shelf fits nice and snugly in the enclosure.

When ready for transportation or storage, the lid clips on in position and the plugs are well protected. There is room for storage underneath the shelf: I might carry spare AA cells there.

A nice functional solution.

Building SOTABeams’ PowerPole PP-4 Way power distribution board

One of the challenges I was having while operating portable was making sure that my power polarity was correct. Fiddling around on a mountain peak with red and black connectors on a 7a/h gel cell is fraught with danger. And when I have two or more components to connect, well …

The answer I found on the SotaBeams web site (http://www.sotabeams.co.uk/).

I placed an order for their PowerPole PP-4 Way power distribution board.

A week or so later, a padded envelope arrived in my mail box.

The contents of the envelope.

Construction was easy as the kit is very simple. All that was needed was a soldering iron and some solder.

 

The power poles ready for soldering.

I ordered the kit only (without the enclosure), so I headed to the local supermarket and bought a cheap plastic sealable container that would do just fine. All I had to do was to cut out a piece wide enough from the lid for the connectors to stick through.

The PCB sits under the lid with the connectors sticking through. I secured it into place with four nuts and bolts.

The power supply connects to one set of power poles and the radio, atu and other items connect to the others. Simple.

Works like a charm. Will make a difference in a park or on a summit.

Building a mounting board for hand-held radios

Aside

I have long wanted to build something to mount my hand-held radios on instead of having them balancing on my workbench shelf, where they are easily knocked over. I have seen others keeping them mounted in their chargers, but after consulting with the amateur radio community decided this wasn’t such a good idea.

So it was back to my workshop to construct a simple bracket-like mounting board out of wood that I happened to have among my store of timber. I found I had a nice piece of pine as well as a sheet of 6.4mm ply wood that would do just fine. So it was out with my router, to which I inserted a 6.4mm bit to cut a dado. The ply would fit nicely into this, after glue had been applied, of course.

Once that was done I applied some oak refinishing oil, which added a nice touch to the finished product.

 

There is more than enough room for four radios.

All my radios have the belt clips installed, which is handy as they can now clip nicely and securely to the board.

Activating Mt Cotton VK4/SE-115

This was one summit I have wanted to activate for quite some time, partly due its proximity and partly due to the excellent Sirromet Winery nearby. So when Sunday 30 April dawned with beautiful clear skies, I knew it was time. My wife decided this would also make an excellent day out.

The drive to the base of the summit took about 40 minutes. We parked at the bottom in a designated car park and headed for the gate that heralded the beginning of the path up.

This is the beginning of the path up to the summit.

Fortunately the path up is sealed, which made walking up easier, even though it was rather steep at times.

It took us 22 minutes to walk up to the summit.

Once at the top it was simply a matter of seeking out the best operating position. This was important as there are a couple of communication towers there and I didn’t want interference.

The going was tough at times.

I found a suitable spot among a pile of rocks, so I erected the long wire antenna on my squid pole, and connected it up to my Elecraft KX1. It tuned up beautifully on 20m and 40m. For power I use six internal AA 1.5v batteries that give me between 1 and 2 watts output to play with.

It was quite comfortable, really.

I put out my first call on 20m and within seconds was answered by VK3CAT in Victoria. Not bad for 2 watts. I then switched to 40m (only 1 watt) and worked VK2NP, VK2BJT and VK4TJ.

I find the Pico Paddle a wonderful device to use with the KX1. It is magnetically held in place on the tin plate on my home brewed QSO board.

That was sufficient for the activation to count, so it was time to pack up and head off down and to lunch at Sirromet.

Reverse Polarity Protection

As the Yaesu FT-817 doesn’t have any reverse polarity protection or an in-line fuse, I decided to build myself one seeing I do a lot of portable work on summits or in parks.
Diodes work fine but they do incur quite high losses in eventual output power, so with only 5W max available, this isn’t desirable.
The answer lies with the P channel MOSFET (FQP27PO6)
A quick search on line turned up this schematic.

Only one component!

This is quite a simple affair: when the battery is connected up correctly, the MOSFET is turned on allowing current to flow. When connected up incorrectly, it turns off.

It works thus: when the gate to source voltage is around -4V or less, it turns on. So if the battery is a 12V gel cell (as in my case), the voltage through the MOSFET  = 12V – 1V loss (due to the parasitic body diode) which equals 11V with respect to ground.The voltage at the gate is 0V as it is connected to ground. This means that Vgs = 0V – 11V = -11V. This is less than -4V so it turns on.

If the battery is connected up incorrectly, then we have Vgs = 0V –11V = 11V. so the devise turns off.

I mounted the MOSFET on a piece of vero board and used an ice cream stick as strain relief. I also included an in-line quick blow 5A fuse in the positive line.

All the components before final assembly.

Once the heat shrink had been slipped over the component, I heated it up with a hairdryer to achieve a nice, tight finish.

While I was at it I built another one for my Elecraft KX1.

Now it was time to test it.

 

All working as expected with the battery connected up correctly.

Now to switch polarity.

No voltage with reversed polarity.

SOTA Activation of Mt Tamborine, VK4/SE-059

Mt Tamborine is an iconic Aussie tourist destination situated in the Gold Coast hinterland. The summit is right in the middle of a suburb but fortunately there is a good lookout in the Tamborine National Park very nearby.

This activation was a good chance for me to try out my new Pico Paddle with my Elecraft KX1.

I had ordered a Pico plate as well; this is a thin plated piece of metal with self-adhesive tabs on the back. The idea is for this to stick onto whatever surface you want to mount the paddle on. I decided to mount mine on my newly made QSO board.

After erecting my squid pole to secure the end of a 24 foot long wire to, I ran out the two counterpoises and connected up the rig.

Installing the long wire antenna.

Installing the long wire antenna.

Then I began calling on 20m.

This was my first attempt at using my new QSO board, with the Pico Paddle mounted in place.

This was my first attempt at using my new QSO board, with the Pico Paddle mounted in place.

It wasn’t long before I realised the Pico plate was simply not up to the job; the paddle began moving around. The magnets were just not strong enough, even though my sending was gentle. I would need to fix this.

Anyway, the bands were in bad shape and I only managed three contacts all morning. Those were with ZL1BYQ and VK7CW on 20m, and VK4EKA on 40m. I also tried SSB with my Yaesu FT-817 on both bands but to no avail.

Back home I began modifying my QSO board.

The Pico Paddle with the Pico plate in place on the board.

The Pico Paddle with the Pico plate in place on the board.

A quick email to Palm Radio in Germany brought the suggestion that I should try using a metal plate instead of the Pico plate, so I raided my workshop and cut a piece of plate to fit. This was then hot glued into place.

The Pico Paddle now attaches itself really firmly to my board, thanks to the metal plate.

The Pico Paddle now attaches itself really firmly to my board, thanks to the metal plate.

Now to head back to Mt Tamborine some day to give it a go. Perhaps then I will manage four contacts and score the two points that are on offer.

A clipboard for SOTA

One of the challenges I have had to contend with while operating in hostile environments up on a distant summit has been logistical or organisational in nature. You know, trying to deal with various pieces of equipment, pen and notebook, wires, seating arrangements etc, all while trying to decipher morse code, taking notes and ensuring that everything works as intended.

This takes more than one set of hands to do properly.

While sitting on my chair up on The Knobby recently (VK4/SE-097) it occurred to me that the time had come to construct a simple clip board upon which I could mount my Elecraft KX1, my log sheets and anything else I might need. So I headed back down once the activation was completed and rushed straight to my workshop, where I selected some suitable pieces of timber for the job.

This is what I came up with:

sota-clipboard