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.

Springbrook National Park dissapointing

Sunday 21st May 2015 was to be a good opportunity to work some Park to Park contacts as the VK5 mob had organised a mass activation to coincide with the WIA AGM. So I decided to activate Springbrook summit VK4/SE-011 and Springbrook National Park VKFF-0463.

The only problem was that Cyclone Debbie had washed away all bridges leading up to Springbrook. The only access road was a back road through the Numinbah Valley. So my wife and I set off nice and early on the 1 hour 40 minute run, but missed the crucial turn and ended up going the normal way up, via the Gold Coast. By the time I realised my mistake it was too late; we were committed.

Just as we drove into the Springbrook National Park, we encountered a road block. Those manning it told us what I suspected. If we wanted to reach the summit we’d have to retrace our route back and go the back route – an additional 40 minutes they told us. So we decided to set up the station along the banks of the river just inside the boundary of the park.

My shack for the activation. Nice cover at least.

My rig for the day was the Yaesu FT-817 with an LDG Z-100 Plus ATU, 7a/h gelcell and an endfed antenna supported by a squid pole. My paddle was the Pico Paddle from Palm Radio in Germany.

This was the first time I used my new Sherpa pack. Fabulous.

All went well and I heard loads of traffic on 40m, all working the various VK5 parks. It was the first time I had been working against pile-ups! Fortunately I was able to tail gate a few contacts and worked two parks: Gerard VK2IO in VKFF-1278 and Rob VK2AAC/2 in VKFF-0004. That was the end of my SSB contacts as my 5W was no match for the 100W stations I was competing with. So it was out with the Pico Paddle and within a few minutes I worked Mike VK2CCW and Ian VK2BJT. CW is really great as it allows you to make contacts despite being low power.

I wasn’t able to activate the summit for SOTA; that will be another time now as I have unfinished business. But we did get to log four contacts towards WWFF and saw first hand the damage a cyclone can cause.

DSC01800

These are some of the trees that were up-rooted during the cyclone.

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.

Samford Conservation Park VKFF-1639

Easter Saturday was the day I decided to activate Samford Conservation Park, VKFF-1639, which is situated around 40km from my QTH. This time I had insect repellent in my go-bag and I’m glad I did.

I set up my equipment on a park bench that was at the far end of Iron Bark Gully, a picnic area in the park. As usual, I had my FT-817, LDG Z100 Pro ATU and endfed antenna held up at the far end by a 7m squid pole.

All set up and ready for calls.

I could hear lots of SOTA action but even though I had self-spotted, I was getting nothing. So I decided to pounce on a SOTA QSO. The first one I came across was VK2HRX operating fromVK2/NW-019, which also happened to be a National Park, VKFF-0111, so when he completed working a chaser, I pounced. He replied and I was up and running. And with a park-to-park QSO at that. Then I heard my old mate John, VK4TJ working him so I tail-gated that QSO and worked him too. Two in the bag, but that’s as far as I got.

I think my position in the gully was not the best, so I decided to pack it in and head off for a restaurant for lunch. Also, using only 5W could have been the problem. Mean time, Scott VK4CZ posted on Facebook that he would like to visit my operating position as he lived nearby. But I had already hit the road. Along the way I stopped to admire the view from McAvee’s Lookout in Mount Nebo, which is situated in the D’Aguilar National Park VKFF-0129. As luck would have it, he called me on 146.500 FM (simplex calling frequency) so I was able to add that to my log, and from a different park.

So I was happy with the way the day turned out. But there is unfinished business. I will return.