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

Fixing the DC power jack on my Yaesu FT-817

The Yeasu FT-817 would have to be one of the most revered and iconic QRP radios of all time. But this doesn’t mean it doesn’t have its faults.

Take the DC input jack, for instance.

This is a crazy design that is prone to failure, especially if the radio is used as intended: out in hostile environments. The input jack on the DC power chord features a flimsy right-angled input plug that is prone to become problematical due to its unprotected mounting situation at the rear of the rig. What happens, and this happened to mine, is that the 1.5mm annulus of plastic at the end of the plug snaps off and becomes stuck around the input shaft inside the jack. And as long as you continue using the damaged plug all remains well and the radio continues to work. But come the time when you decide to use a different power chord, this is when you run into trouble.

In my case this happened when I ordered an FT817 PowerPole Adapter from Sotabeams (https://www.sotabeams.co.uk/ft817-818-powerpole-adapter/). The thing secured nicely to the back of the radio but I couldn’t start the radio. No power was getting through. So I emailed Sotabeams and Richard replied, explaining that my problem was in all probability the failure of the plug as described above.

It was time to take action and fix the situation.

I started by removing the cover of the radio, unclipping the speaker cable and examining the DC jack. I could see the offending ring with the aid of my trusty Mini Maglite. I decided to take a more drastic approach, and instead of trying to remove the little black ring, I decided to remove the plug and, in its place, solder in a new power cable that is terminated in PowerPole connecters which are housed in the Sotabeams housing.

FT817_5

The DC input jack is top right.

I then removed five retaining screws from the PCB and the ribbon cable, securing it safely out of the way with sticky tape. I decided not to chance my luck by removing the larger ribbon cable: it wasn’t in the way in any case. The two thick cables were twisted out of their housings okay and pushed out of the way.

Then came the tricky task of unsoldering and removing the DC input jack. I tried to unsolder the connections but found this didn’t work. And I didn’t want to risk overheating the board or damaging some of the minute surface mount components that are absolutely everywhere. So I reached for my side cutters and cut the jack off.

FT817_6

Removing the input socket.

Once the main heatsink strapping was cut loose I prized the thing up and used my soldering iron to assist in loosening the remaining terminals.

FT817_1

The solder tabs weren’t in too bad a way so I left them as they were.

With my DMM I determined which terminal was the ground and which the positive. Then I prepared a short length of red and black power chord, connected a pair of PowerPoles and swapped this arrangement with that which came with the Sotabeams adapter. I then fed this chord through the hole in the radio’s chassis and screwed into plase the Sotabeams adapter. All that I needed to do now, before assembling the radio’s enclosure, was to solder the positive and negative leads of the chord to the respecrive tabs on the PCB.

FT817_2

Not the prettiest soldering job I have ever done!

I then screwed the five chassis screws into position again, connected up the two cables and ribbon cable, and sat back to admire my work.

FT817_4

Everything in place and ready for the speaker wire to be connected and the top of the enclosure to be screwed into place.

I then connected my SLA battery to the back of the radio and pressed the power button. It fired up beautifully!

 

FT817_3

The PowerPole adapter offers a safe and secure solution to help overcome the FT-817s vulnerability.

VK5JST Antenna Analyser: completing the build and testing.

The time had come to do the first smoke test of the analyser. I powered up my DMM and checked that the voltage regulators were putting out 8 volts and 5 volts respectively. I obtained 7.94 and 4.93 volts. Phew, all good so far.

Next I checked the signal generator section: I was to expect between 1.10 and 1.25 volts at Test Point 1. No problems there.

The centre pin of IC1 showed 1.534 volts which was just about spot on. And as the oscillator and following amplifiers are dc coupled, this reference voltage has to be correct for everything to work correctly. Now I had a problem: the collector voltage of TR3 was only 0.742 volts.

After much head scratching and tracing through the schematic, I decided to send Jim, the designer, a shout for help. Quick as a flash he responded saying that this is typical of an open circuit switch. So I pulled to offending item from the board and checked it with my DMM. All appeared fine. Jim wasn’t convinced and recommended I make my way to Jaycar to pick up a replacement. This I did, only to find the same result when I checked TR3 once more.

I sent Jim some high resolution photos of the PCB for him to run his beady eye over before resorting to packaging up the board and posting it to him for a more detailed analysis. He picked up that one of the solder connections on the variable capacitor looked a bit dodgy. So I sorted out the offending wire and tried again.

Success! I was back in business.

Next, I had to connect a good quality 50 ohm dummy load directly to the N connector of the analyser. Not having one that would connect to an N connector, I borrowed one from Wallace, VK4CBW, and proceeded to adjust the three 20K linear trimpots as described.

All other tests were well within the specified tolerances, so I was happy.

Final bench test with the dummy load connected.

I decided to check the SWR of a 6m dipole that I build last year using theory only for dimensions. And I know the antenna worked reasonably well because I used it in a VHF/UHF Field Day contest and won my category.

Connecting the analyser directly to the antenna produced a pleasing SWR reading.

 

 

VK5JST Antenna Analyser build: Populating the PCB

Once the enclosure had been sorted, it was time to start up the soldering station and melt solder. First I soldered the connector printed circuit board to the mainboard. The important thing here was to make sure the boards were 90 degrees to each other. Next I began mounting all the small components, making sure to double check each resister and capacitor; the resisters are small and the coloured bands not easy to read. The N connector was bolted into place and a short piece of wire soldered to its centre pin.

I always use a fume extractor when soldering.

The tuning switch was mounted on the component side of the PCB and then the inductors were inserted and soldered into place, making sure not to use too much heat or soldering them all into place in one go as this would damage the switch.

A wire was soldered from the switch’s common terminal to the PCB.

The next job was to solder all 16 wires from the PCB to the LCD.

This took time and patience.

Everything in place and ready to be fitted into the enclosure.

All that was left to do was to complete wiring up the various switches and battery compartment. Then, once the eight AA cells were in place, it would be time to run some initial tests.

Looking good and ready for testing.

Building the VK5JST Antenna Analyser

I have long needed a good antenna analyser so that I can tune my existing antennas and build better new ones. Trouble is, they can be very expensive.
All that has changed, now that there is a new kit on the market.
The new analyser covers the HF bands as well as 6m – perfect for my SOTA and WWFF needs.
I ordered mine from their website, http://www.vk5jst.com, and it arrived well packed.

The quality of kit is excellent and came well packaged.

The instructions call for the mechanical build to be tackled first; attending to the enclosure by drilling all the necessary holes and cutting out the hole for the LCD. Suggestions are provided, which I found very useful.

The main PCB is used as a template for positioning and drilling the mounting holes into the lid of the enclosure.

Cutting out the hole for the LCD screen is probably the most tricky part; I used a coping saw and although it took time, I was able to achieve a very satisfying result.

Getting the measurements right was important.

Once I had finished with the drilling and sawing, I cleaned up the mess and took a rest. The result was more than acceptable, I think.

The completed front panel.

The final job to be tackled was to cut the opening for the N-connector and tuning capacitor knob. The instructions suggested using the course wheel of a bench grinder. My initial feeling was that this would be rather ‘drastic’, but it turned out to be a piece of cake.

The bench grinder sliced through the plastic like a knife through butter.

All that was left for me to do was to complete the job using a fine file.

First Australian SOTA and VKFF DMR contact?

After weeks of poor weather in Queensland, Saturday 10th November dawned bright, sunny and hot. This would be the perfect day to head for the hills and make a DMR contact, in simplex, on Talk Group 99 in Time Slot 1.

At first, my plan was to climb to the summit of Mt Beerwah (VK4/SE-057) but on reading a few blogs about the climb and what it entailed, I decided that discretion would certainly be the better part of valour on my part as I am not as young as I’d like to be. Much of the way up is undertaken on all fours, so the bloggers said; I didn’t want to chance becoming a helicopter Medivac casualty. Moving about on all fours isn’t advisable especially if you have gear that includes a rather long and unwieldy ‘squid pole’ to contend with.

So I set my sights a little further up the Sunshine Coast and settled on Mt Coolum (VK4/SE-114). And to make things even better, it falls within the Mt Coolum National Park (VKFF-0344).

My gear for this activation was my Elecraft KX1 (with six internal AA cells) and 24 ft long wire antenna with two counter-poises of 16ft and 32ft respectively. For seating arrangements I took along my Helinox Chair One.

Mt Coolum is the second largest solid rock mountain in Australia; the largest is Uluru (previously known as Ayers Rock) in the Northern Territory. This fact alone made it fitting that I should climb it as I had visited Uluru in July.

The way up to the summit is very steep but the path is excellent, consisting of suitably arranged rocks that act as steps. It is a very popular outdoor venue with the locals and as a result the way up and down is very busy.

20181110_103949

The was a constant stream of people making their way to the summit.

As soon as I arrived at the top I put out a call to Greg, VK4MHC, on DMR simplex with my CS750 hand held radio. He replied and sounded as if he were a few feet away, so strong and clear was the audio. And considering he happened to be at a local resort some 2km away, the quality of the signal was nothing less than astounding.

The simplex calling frequency in Australia is 439.200 MHz.

This I believe is the first time DMR has been used as a mode for SOTA and WWFF in Australia. (Our local VKFF representative in VK4 later told me after I had submitted my log that he was unable to process the DMR QSO as the system wouldn’t accept a Digital Voice call even though it’s listed as an accepted mode. He has progressed the issue further up the line, something that tells me it hasn’t been encountered before.)

We then proceeded to talk on 2m and 70cm FM; I used my Yaesu FT-70D and he used his Yaesu FT-818.

I then looked for a suitable spot out of the way of curious onlookers to set up my HF station. That spot turned out to be right in the middle of a thicket of sharp bushes that I cleared just enough for the chair.

20181110_081312

Keeping out of the sun was the name of the game.

Once my gear was in place, I settled down into my chair and uploaded a spot to SOTA Spotter. Who said the bands were dead? Here’s the list of the stations I worked using only 2W.

VK4JAZ 09/11/2018 22:39 VK4/SE-114 433MHz DV VK4MHC. (First DMR call in VK?)
VK4JAZ 09/11/2018 22:43 VK4/SE-114 144MHz FM VK4MHC
VK4JAZ 09/11/2018 22:44 VK4/SE-114 433MHz FM VK4MHC
VK4JAZ 09/11/2018 23:26 VK4/SE-114 14MHz CW VK7CW
VK4JAZ 09/11/2018 23:30 VK4/SE-114 14MHz CW VK1MCW
VK4JAZ 09/11/2018 23:35 VK4/SE-114 14MHz CW VK3CAT/P
VK4JAZ 09/11/2018 23:37 VK4/SE-114 14MHz CW VK3ARH
VK4JAZ 09/11/2018 23:40 VK4/SE-114 14MHz CW VK3IL/P
VK4JAZ 09/11/2018 23:43 VK4/SE-114 14MHz CW ZL3GA
VK4JAZ 09/11/2018 23:53 VK4/SE-114 7MHz CW VK2IO/P

In addition, VK3CAT, VK3ARH and VK3IL were also summit activations.

20181110_094433

At leas the view was good amongst the prickly shrubs.

 

 

 

 

 

 

Testing the miniHFPA2 with the Elecraft KX1

I received a query from a reader yesterday regarding tuning up an antenna using the internal ATU in his Elecraft KX2 if it were connected up to the miniHFPA2 amplifier. The reason he wanted to know about this was because he was considering ordering one for use with his Elecraft KX2.

He wanted to know if it is it possible to run an antenna such as a doublet, by tuning the antenna using the KX2’s internal tuner with the amp in bypass mode, then switching the toggle switch on the amp to put it inline. He said that it appeared to him that this procedure would not work because the amp, once in line, would probably change the SWR of the antenna.

I decided to conduct a test to find out if this would in fact be the case. This is what I found:

I carried out the test in two parts:
Firstly, with the KX1 (powered by a 12V supply voltage) connected to a PWR/SWR meter and 50 Ohm dummy load.

On keying down, the PWR/SWR meter read the following: output 3.5W with SWR of 1.0:1

A straight through test with the signal going to the dummy load.Secondly, connected up the miniHFPA2 directly to the KX1, and the Pwr/SWR meter and dummy load.
With the Amp in bypass mode, the reading was 3W output and 1.0:1 SWR.

The only difference now is that the amp has been connected up but left in bypass mode.

With the Amp switched on and placed inline, the reading was 18W output with SWR 1.0:1.

With the amp in action, the SWR remained 1.0:1

Note: the lower than expected power output with the amp inline was due to the fact that the amp is set up for an input of 5W. My KX1 can only supply it with 3W, so the final output of the amp will be lower too. With 5W in, as is the case when connected up to my Yaesu FT-817, it outputs 30W.

First C4FM SOTA contacts in Queensland

Going through the Activator Roll of Honour results for QLD recently, I noticed that there were no results for Digital Voice. Checking the state of play for the other states, I saw that the Australian Capital Territory and Victoria had one each.

It was time to put that right, so on Saturday 23rd June, I headed out for Mt Cotton (VK4/SE-115) with nothing more than my Yaesu FT-70DR hand held radio.

I had activated this summit more than a year previously, so if I logged at least four qso’s, it would count as another activation and my tally would increase by one point.

The climb up to the summit was uneventful and I headed to a clearing that featured a rather tatty picnic table and a good view.

I set the radio’s frequency to 147.400, the calling frequency for digital modes, and the mode to DN (Normal Digital Mode).

I had pre-arranged with Wal, VK4CBW, to listen out for me on simplex. His was the first contact I made. The distance between us was 26.33 Km (16.456 miles) and his Yaesu FT-2DR connected to a beam antenna sounded excellent. I ran a few quick tests too, to see what difference it would make to the signal if I placed my radio flat on the ground while he spoke. It made absolutely none!

Trying to get more height when calling CQ.

I am well used to using FM simplex on summits and noticed immediately that with C4FM there was no background hiss at all. The audio was as perfect as can be, very similar to that of a mobile phone.

I then had a long qso with George, VK4HGT, followed by Phil, VK4MOT and Bob VK4YA. All contacts were remarkable in that the audio was perfect. I think C4FM is far superior to FM analogue and it’s a mode I’ll be using more often in future.