Today I wanted check how good the Tenbox 10m AM receiver (part of the intended transceiver) was in real use as opposed to measuring it on a signal generator.
So, I set up my FT817 on 10m AM TX on the lowest power setting, which is around
150mW carrier, and fed this into a makeshift vertical tuned with the T1 ATU. Using my PC, I made a short message "G3XBM testing on 10m AM" that I played in auto-repeat.
I then went for a drive locally with the little super-regen RX in the car being fed from a vertical mag-mount antenna on the car roof. The only antenna I had was an ATX15 base loaded whip for 15m, so I pushed a few sections in to make it resonate on 29MHz.
Results were encouraging. Out in the car my 150mW AM TX beacon message could be copied out to about
2 miles away, although this was limited by QRM from
W2VW (!) and
VE3OWV (!) who were coming through with 59 signals on the RX on 29MHz AM. When they dropped carriers copy was fine. It's fascinating to think my 150mW AM signal was having QRM from 5000km away!
A super-regen is not really suitable for use when 10m is wide open, like it was this afternoon. Nonetheless I was able to copy stateside stations on 10m AM on a short base loaded mag-mount pretty well. For its intended purpose as a local across town natter box, I think the Tenbox is going to be fun. With 6dB more power out (my aim for it) it should be certainly possible to work
G6ALB 3km away in the next village.
The next stage is now to build the TX part and test this.
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