17-04-2012, 12:26 AM
Agreed.. for TR1 it would be better to take a lead from a 30's trf set, use a cap and variable resistor on the RF groundy end of the reaction winding and set the stage bias sensibly with a fixed audio takeoff point from the RF "hot" end before the bias resistor. I would be tempted to add an RF wideband common base simple transistor "buffer" rather than pre-amp stage, just to cool down the "grid" loading. Maybe 6 more components.. 1000% improvement.
Nice to see a proper blast from the past. The white plastic box and trailing bits takes me right back.
In my teens I used to build all kinds of weird things using the ubiquitous EF80.. from "duplex" trf sets to audio amplifiers. I generally found Gilbert Davey's designs worked pretty much out of the box and were not too critical on using the exact bits and bobs. My record DX on a thing with home wound coils and a random ex-tv EF184 was hearing the Olympics on the Pacific regional broadcast of the Australian World Service, and some rock music broadcast from Tokyo (frequency??.. your guess is as good as mine, only info in English was the station id and "from Tokyo, live" ) was a regular.
Nice to see a proper blast from the past. The white plastic box and trailing bits takes me right back.
In my teens I used to build all kinds of weird things using the ubiquitous EF80.. from "duplex" trf sets to audio amplifiers. I generally found Gilbert Davey's designs worked pretty much out of the box and were not too critical on using the exact bits and bobs. My record DX on a thing with home wound coils and a random ex-tv EF184 was hearing the Olympics on the Pacific regional broadcast of the Australian World Service, and some rock music broadcast from Tokyo (frequency??.. your guess is as good as mine, only info in English was the station id and "from Tokyo, live" ) was a regular.
