FT-817 Escort for portable work

I came across mention of the FT-817 Escort on You Tube recently and decided it looked like just the thing I needed. So I ordered one from Portable Zero (http://www.portablezero.com/). It arrived, together with a Sherpa Pack that I also fancied, in about a week.

 

The contents of the package, with a good set of instructions.

Installing the side rails and fold-out stand was easy enough, with no dramas at all. And the completed job looked real cool.

I ordered mine in military green; it also is available in black.

The stand eliminates one of my dislikes of the Yaesu FT-817: it’s hard to read the display when out in the field or even in the shack due to the lack of a tilt stand. The escort also offers protection for the knobs, which are easy to damage or move while in the field.

The stand tilts the rig up nicely. It folds away easily too for transportation.

I have enjoyed using the rig now in the shack and look forward to taking it on an activation.

The radio is use in the shack.

Softrock RXTX v6.3: TX Mixer

The next stage in the project was to construct the TX Mixer stage. The job of this stage is to provide the modulation of the Dividers’ output signals by the four I and Q signals from the Op Amps. The result is a double sideband RF waveform that will be coupled into the PA stage.

This stage centres around U3: FST3253 which is a SOIC-16 Dual 4:1 Mux/Demux Bus Switch. There were also four resisters, a capacitor and two connector sockets that completed the build.

When that was done it was time to test if all was as it should be.

This was when I hit a snag.

First, I had to jumper the hairpin bend of R26 (which hadn’t yet been installed) to ground and then jumper pins two, three and four of socket J1.

R26 needed to be jumpered to ground.

R26 needed to be jumpered to ground.

Current readings were fine, and so were the initial voltage readings. But when it came to measuring the voltage on pins 7 and 9 of U3, instead of getting around 2v I was reading 0.01v.

I tried again but this time noticed that when I turned on my power supply (12V DC) the current surged to around 2A before settling down to more normal levels. I cut the power and began scratching my head.

All the solder joints looked fine as did the components, which were all in the right places. That’s when I decided to take a break and sleep on it.

After the dust had settled, I decided to consult the schematic. I started by tracing the 5V power route, through U4 and into U3. I could see its path to ground was through pins 1 and 15, then on to the as yet uninstalled R26 to ground via C43. So that’s why I needed to insert a jumper.

I then connected up my DMM and swung the switch to the continuity setting. Probing the jumper connection I had inserted into R26 produced nothing. So I probed R26’s other hole and bingo. I had jumpered the wrong whole!

My mistake was immediately apparent.

I had presumed the jumper needed to be in the whole marked with a white circle around it (to indicate that’s where the body of the resister fits). The instructions called for jumpering the hairpin of R26, which I suddenly realised was not the hole indicated by the circle, but the other one.

Resoldering the jumper took only a few seconds, but the satisfaction I received from a full set of good readings lasted quite a lot longer.

This little exercise highlighted to me the importance of being able to read a schematic diagram.

 

Softrock RXTX v6.3: Building the TX Op Amps

This stage has a fairly high component count, so patience was the order of the day. I decided to take it nice and slowly so as to enjoy the process. It would also make sure I didn’t make any mistakes.

The stage consists of four unitary gain op-amps, arranged in pairs. The left channel’s input resolves to two signals: 0° and 180°. The right channel’s input resolves to two signals: 90° and 270°.

Each of the 14 resisters was checked with my DMM to ensure I had the correct ones for insertion into the PCB; it’s easy to mistake brown for red in the colour coding on the tiny resisters.

The Op Amps themselves (IC SOIC-8 dual Op-Amps) were also tiny beasts each with eight pins that required careful soldering so as to ensure no solder bridges or spashover on any of the adjacent empty holes. For this task I used a very handy suction tool that Wallace, VK4CBW, gave me some time ago.

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Positioning U1 on the underside of the board with the suction tool.

Once all the components had been soldered into place and I was certain there were no cold solder joints or solder bridges, it was time to conduct the usual current and voltage tests according to the instructions.

Thankfully my patience paid off with all reading being as expected.

Next is to tackle the TX mixer.

Softrock RXTX Dividers – Stage 3

The dividers stage takes the local oscillator’s signal and divides it by four, producing two output signals that are said to be ‘in quadrature’. This means they are out of phase with each other by 90 degrees.

The trickiest part of this stage’s construction was soldering in U9, a 74AC74 SOIC-14 SMT that has fourteen small pins (or legs). And even though I took great care soldering them onto their respective pads using flux and a very fine soldering iron, when it came time to test if all was okay, the readings I obtained suggested otherwise. So it was out with my more powerful iron (with a larger tip) and with care, the re-soldering exercise produced near perfect readings on my DMM.

Next on the agenda was something I had been waiting for with anticipation: the frequency output test.

To accomplish this I would need my Hantek 6022BE USB DSO, and both probes.

This is what I observed.

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As can be seen, the two signals are 90 degrees out of phase.

Next to do is to build the RX Op Amp.

Softrock RXTX v6.3 – First Smoke test

It’s always a little daunting but it’s also the part I like best – doing the smoke tests. Testing the power supply was really all about ensuring that the SMT caps had been soldered in correctly and that there were no solder bridges.

First I tested current draw with a 1K resister added to the positive probe of my DMM to restrict the current in case of a bridge. I applied 12V power and took readings.

3.0mA so all was in order.

Next I checked the power at the 12V, 5V and 3.3V rails: all fine there.

Now it was time to build the local oscillator.

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Once all the components were in place, it was time for the next smoke test.

Once more I needed to check current draw but this time I did this with a 100 Ohm resister instead of a 1K Ohm one. The readings I obtained were excellent. I was now safe to test without the protection of the resister and again got great readings, all of which were under 80mA.

Next up was a frequency test. I set the dip switch on the PCB to 7.046 MHz and applied 12V. I then tuned my FT-817 to 28.184 MHz (four times the local oscillator frequency of 7.046 MHz) and set the rig to CW mode. After attaching a length of coax in the 817’s antenna socket and draped it close to the Softrock, I heard a good, solid tone.

Excellent. Another smoke test passed.

 

Building a Software Defined Radio

I have decided to melt solder once more and build another QRP radio. This time it’s a Softrock RXTX v 6.3 that Wal, VK4CBW gave me. He said his eyesight doesn’t allow him to tackle such projects anymore.

The kit is fairly complex as one would imagine and although this particular model is now no longer in production, there is still detailed build information on the internet.

The first stage of the build involves constructing the power supply section. This contains many surface mount components, which are tricky to install due to their small size. First to do was to install the board mounting hardware that consisted of nuts, bolts and spacers. Then it was a matter of those pesky little capacitors: eight 0.01 uF caps and eighteen 0.01 uF caps.

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The SMT caps all soldered into place.

Next came U5, the tiny 3.3v regulator. At first I couldn’t find this item it was so small. But after about 20 minutes of searching, I noticed it tucked away in a fold of the anti-static bag the ICs came in. Phew.

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That’s U5 nestled in among the SMT caps. Notice the liberal amount of flux I used just to help the parts ‘stick’ in place prior to soldering.

I am taking this project nice and slowly so will post regular updates as I go along.

SOTA Activation of Mt Mundoonen

Saturday 13 February 2016 dawned hot, with clear skies; a great day to head for the hills and activate another summit.

Tony, VK1VIC , collected me from outside my apartment in Canberra at 9am sharp. It was only a 35 minute drive into New South Wales and up Mt Mundoonen (VK2/ST-053). This time I was going to rely on my Elecraft KX1 at 1W and my Buddistick vertical antenna. Tony would be using his new Elecraft KX3 (the big brother to the KX1) and a trap dipole antenna supported by a squid pole.

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Tony VK1VIC at his operating position

Tony is still getting used to using CW and loved the chance of working some true “gentlemen” who gave him lots of encouragement. He has also recently acquired a Palm Paddle, which is an excellent piece of gear.

Mt Mundoonen (5)

Boy, was it hot up on this summit!

My operating position was far enough away from Tony so as to minimise interference as we would both be operating on the 40m band. The only nice and flat piece of ground I could find happened to be very close to a huge wire dipole that I believe is used for aircraft business.

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I wish I had one like this at my QTH!

All in all, we had a very successful day. I added nine contacts to my log, including two Summit-to-Summit contacts with Andrew, VK1AD, who activated VK2/SW-034 and VK2/SW-027.