Nearly 2W out with it running from 24V. Pretty sure I didn't try this back in the 80s.
Yes, that's a Home Office logo on my power meter's 19" panel. It was from a decommissioned emergency services radio site, sold at, I seem to recall, the McMichael rally when it was still held in Burnham at the community centre.
I'm sure my original had a sniff of bias, which often increases the gain. I might try that, but not tonight.
Actually it’s doing a bit more than 1W but not much. (bottom scale divided by ten for my 10B element)
I built my first FM transmitter in the late 1980s using bits that I had lying around, with no real knowledge of RF but a tenacious approach to trial and error. I had a 2N3866 driving a BD139 to get around 1W. BD139s are audio devices and I have a drawer full of them so I thought I would verify that this really works. It does. It’s very stable owing to the meagre 3dB or so of gain. DC efficiency is an excellent 85% for the amplifier in isolation and you have to ignore the fact that the driver is using more current!
If you liked Brass Eye then these deep dives are interesting, here's the music one.
https://www.youtube.com/watch?v=vfnyOaifpBY
Brass Eye Music References #vinylcommunity #vc
A sub-aquatic plunge into the extensive musical references in Brass Eye by the series director - Michael Cumming #vinylcommunity #vc
718 clone works better now. Two of the three bands of compression in action. PWM chops the signal up to control the amplitude.
The audio processor that I made emits a horrible amount of RF noise. It seems to be caused by the discrete comparators, I've built a single comparator on a breadboard and confirmed that it rings badly at around 12MHz, particularly when only partially activated by a very short or small excursion beyond its threshold. Adding 1000pF on the base of the "waggling" side seems to stop it without unduly loading the signal.
@North you made me make a graph
There are lots of French FM stations on my radio this morning.
Paul