— 087. IsCT news - ARDF 2 m transmitter progress. —

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087. IsCT news - ARDF 2 m transmitter progress.

2018-01-28. Patrick.

Fig. 1.    Controller (top) and RF (bottom) PCBs just after testing. The 9V-size battery on the top was powering the controller board and a benchtop power supply was powering thr RF board. The only load on the RF output was the oscilloscope probe.

We've had great progress in the last month. I thought that this weekend we would finally have the first working 2 m transmitter. Maybe not with full functionality, but not a prototype either. A transmitter that would eventualy be used in a real event. Almost. Maybe almost.

We have the first two RF boards built. The third one is almost built. And the next three have arrived from OSH Park. The first three controller boards arrived and I got the first one built yesterday. And I released the magic smoke - oops.

So I started building the next controller board and tested it as I went. Then came fighting with avrdude. In Debian 9, there is some strange behavior in setting fuses on the ATmega328p. I don't have it totally figured out but the board seemed to get flashed OK and appeared to run OK. So I went on to build the connector that fits between the RF and controller boards.

It sort-of worked. The controller seems to have turned the RF board on and off correctly. But the output wasn't amplitude modulated. It's probably the voltages used being different in this test. Or maybe some grounding issues.

It's 17:00 on Sunday. Other duties call. AAAAaaaarrggghhh!

It's been a mad rush to get these ready for the spring season and it's not over yet. We would like to run the first 2 m school event on April-29. That's 11 weeks away. Can we make it? It will be hard to tell until we have a fully functioning transmitter. We're going to keep trying.

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