On the bench:

2011-May-17 - Starting the Ginko Transceiver

I have started to build a new Radio. Ideally this is going to be a whole transceiver that can operate on multiple bands. For now it is just a phasing receiver and uses my HP Signal Generator as the VFO. My first challenge was to design and build a quadrature splitter for the 14MHz VFO. I used a design from EMRFD. Initially I was confused and configured it for exactly 180 degrees of split between the I and Q signals. I realized my mistake when I could not null out the opposite sideband. Of course it should be 90 degrees between the I and Q signals. It was tricker to measure 90 degrees on the oscilloscope, but I managed it.

My issues were not over though. The splitter used a toroid and two capacitors. When I connected the splitter to the mixers, it was no longer well behaved and the phase delay was different. I found that I needed to use the "all band splitter" design from EMRFD which has a low pass filter in the I/Q outputs. Then it was well behaved once connected to the mixers. After that the lower sideband was easy to null out. This time I used 10 turn potentiometers for the phase and amplitude adjustments. I learned from the the Gateway 40!

I have built the front end, down converter to audio and the phasing circuits. I also built part of the audio amplifier and the first audio filter, shown in the picture above. Enough circuitary for a test on the air. I received some CW signals on 20m to confirm that it was working. I even managed to tune in an SSB station using the signal generator, but it was tough. That was very satisfying. It confirmed that I was receiving Upper Side Band!

Next I need to design the VFO. It will probably be at about 5-7MHz and then mixed with a crystal oscillator. I also plan to run the receiver as an IF and then use converters for each of the bands. That seems to be a much better approach than using different local oscillators for each band. It means that the phase and amplitude can be set once for the IF frequency. Otherwise it needs to be tweaked for each LO.

But should I be working DX...

Progress on the new radio is slow however because I'm really enjoying working DX. I worked Mali today! TZ6TR. My first African station. That felt really good. The amplifier is working superbly. That means I have worked 42 countries. All on 40 meters. A QSL card arrived today from Latvia, bringing me to 20 entities confirmed.

Chasing the rest of the paper is turning out to be hard. So far I have sent 2 QSL cards to Venezuela, for example, with no response. The first I sent in February, the most recent in April. I guess I should wait a bit longer before sending another, though I have at least 2 other YY5 stations in the log.

Some stations have only been worked in a contest, such as 9A - Croatia. Perhaps its understandable if that takes longer, or even if they do not QSL all of the contacts that they make. If I work another 9A outside of a contest, then I will QSL it too.

Interestingly, as I look back in the log, some of the stations that have not replied were problem QSOs. The CO - Cuba station that I sent a QSL to was very difficult to understand. I wrote in the log that I had to ask for his name twice. Perhaps he did not get my callsign down straight or I did not get his call right. It would be nice to at least get a reply back saying "not in log".

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