I did a little more work on converting the web site to the Google, then went and cut the grass. It's been about 2 weeks since I last cut it, as it was raining all last weekend. It took me ages, and required several emptyings of the grass hopper - I usually get away with 2 or maybe 3. Hopefully the hot weather'll keep the grass growth down for a while.
In the evening we went to the airfield and I put a line in from the regulator to the tach. We tested it and it reads accurately up to 5500rpm, so we decided to do some circuits. Well, we were at the runup area when I found that the radio won't transmit. It wasn't busy, so we did a single big circuit, but swapping the headsets over seems to have fixed that (something not quite plugged in? Seems strange, as the intercom was working properly). I'm now wondering if it's interference from the new wire - I'll have to test that out next time.