About Grant McDuling

I am a retired writer and enjoy amateur radio in my spare time. I operate CW most of the time and run 100% QRP. I have written a book on QRP, it's called QRP, The Zen of Amateur Radio and is available here: http://www.amazon.com/dp/B00T74ID7W. My latest book is called SOTA, Taking Amateur Radio to new Heights. You can check it out here: http://www.amazon.com/gp/product/B019H4LB66?*Version*=1&*entries*=0

Windcamp proves its worth in Samford CP activation

Today I activated Samford Conservation Park VKFF-1639 once more in an attempt to secure four contacts to bring my total to ten. It would also be the first time I would use my new Windcamp LiPo battery.
Setting up my long wire antenna was interesting: I needed a heavy tree branch to act as an end support. The far end was supported by my squid pole.

It’s all about improvisation.

At the start of the activation, my internal Windcamp LiPo was putting out 12V which allowed me to operate at a full 5W. By the time I had made four contacts, I had been operating solidly for an hour and seven minutes. The voltage on the display was now reading 11.8V.

I am more than happy with that.


New battery power for my FT-817

I have long wanted/needed to upgrade my battery power for my Yaesu FT-817. The prompt came when the internal battery died. My choice was the kit put out by Windcamp; a 3000mAh internal LiPo battery and new battery compartment lid for the radio that comes fitted with a PCB and charging circuitry that allows the supplied mains charger to charge the battery while inside the radio.

The parcel arrived from China beautifully packed. The battery and the new replacement lid came packaged in very nice plastic cases, which, together with the instructions and charger, all fitted into a compact cardboard box for shipping.

The contents of the parcel.

After extracting the individual components from their packaging, it was time to think about installing the battery into the radio.

It is a tight fit but the components plugged together as intended. Note the PCB on the underside of the new lid.

When the battery and associated wiring was all nice and snugly fitted, I popped the lid closed and got ready to charge the new LiPo battery.

The new lid in place and ready for charging.

The charger has a double-coloured LED to indicate the state of the charge: red for charging and green for a completed charge. The initial charge takes around 5 hours to accomplish.

According to the supplied documentation, the rated voltage of the battery is 11.1V, with the output voltage range stated as between 9 and 12.6V. The maximum output current is 4A.

Now to test it in the field.

Another Power Distribution Board

I decided it would be nice to have a power distribution board made of wood and sporting Anderson Power Pole connectors on the bench. The PCB and power poles were sourced from SotaBeams in the UK. This is what I came up with.

The connectors have been loaded onto a PCB, a nice piece of dark wood has a dado routered and the back panel is cut to size.

I drilled and cut the back panel to fit the PCB.

Cutting the back panel.

Next, the PCB was pushed into place.

The gaps between the connectors was filled with small off cuts of wood.

Next, I cut a second piece of timber to use as a back panel to the backing board. This will protect the PCB as current will be flowing through the solder joints.

I used a router as a crude milling machine to make a recess on a backing board to cover the PCB from the rear.

Once that had been done it was just a matter of screwing the two backing boards together and dropping the completed assembly into the base. This was also screwed into position. A coat of protective varnish was then applied.

All done.

My new power distribution board ready to be pressed into service.

Working F0-29

Now that I have worked an FM satellite (in my case SO-50) the next challenge was to try a SSB satellite.

The basics would be the same I figured, except I would need to use my Yaesu FT-817. In fact, all I needed to do was to switch rigs and take into account that I would be needing to run to 817 off my 7 a/h SLAB, which I would need to slip into a spare camera bag so I could carry it over one shoulder.

The battery is in a camera bag hanging on my left side, and the FT-817 is slung around my neck (I knew the strap would come in handy some day).

So that I could work the satellite single handed out in the field without the aid of computer software, this is what I did:

  1. Set the rig into split mode
  2. Set VFO A to 145.960. This is the uplink.
  3. Set VFO B to 435.840. This is the down link
  4. Make sure the antenna connection is set to the front connector on the radio
  5. Keep the radio set to VFO B

When I saw the satellite is within range (using Satellite Explorer on my PC), I went outside and pointed the antenna into the rough direction of the satellite’s approach. This was roughly north. Then I put out a call (the radio switches to VFO A automatically when the PTT is activated but returns to VFO B when it is released. Then I immediately began tuning down the band to listen for replies.

Sure enough, I heard Wal VK4CBW, George VK2WEL and Geoff VK2ZAZ. I had a very satisfying QSO with them, but it was challenging having to continually alter the receive frequency by hand during the receive cycle while altering the direction of the antenna to take into account changes to direction as well as height, all at the same time.

Next is to think about improving my operating setup, perhaps with some form of automatic tracking capability.



Working Satellite SO-50

One aspect of amateur radio that I am enjoying lately is working the FM satellite SO-50. To do so I use my Boafeng GT-3TP dual band hand held and an Elk log periodic antenna that I have mounted on a camera tripod.

My basic satellite communications setup.

SO-50 carries several experiments, including a mode J FM amateur repeater experiment operating on 145.850 MHz uplink and 436.795 MHz downlink. The repeater is available to amateurs worldwide as power permits, using a 67.0 Hertz PL tone on the uplink, for on-demand activation. The repeater consists of a miniature VHF receiver with sensitivity of -124dBm, having an IF bandwidth of 15 KHz. The receive antenna is a 1/4 wave vertical mounted in the top corner of the spacecraft. The receive audio is filtered and conditioned then gated in the control electronics prior to feeding it to the 250mW UHF transmitter. The downlink antenna is a 1/4 wave mounted in the bottom corner of the spacecraft and canted at 45 degrees inward.

The Elk was loaned to me by Wal, VK4CBW, an avid satellite fan who lives down the road from me. The antenna is basically a held-held job but I do find it gets a bit heavy after a while, hence the tripod.

Today SO-50 was within range at 4.56pm, so I put out a call and was answered by Roy, VK4ZQ, from Nundah in Queensland. And although Roy isn’t that far from me, the satellite is. The apogee height is 665km, which means at its furthermost distance from the earth, it is 665km away. Not bad for a two-way FM contact.


Building a single stage audio amplifier

I have long wanted to build an audio amp for my regenerative receiver, so designed a simple one-stage affair around a BC547 transistor.

My calculations for the design weren’t as good as I had hoped.

I used what I had in my junk box to build the amp.

All the components in place ready for testing.

I hooked up my Hantek 6022BE oscilloscope and wasn’t impressed withe the output signal; it was cropping off the top of the amplified sine wave.

Input signal is the yellow trace with the green being the amplified signal.

I tried changing the values of the biasing resisters until I finally achieved a better result.

The amplified signal looks much better now.

Now it was time to integrate the amplifier into the receiver and turn on the power.

All ready for the smoke test.

The result was pleasing. It worked. But the sound isn’t exactly room filling. That hopefully will change when I build a second stage just the same as the first and add it to the system.

Another successful project.

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.