29-10-2018, 11:12 AM
I was expecting this early UK made FM radio receiver to be a poor performer on on FM so it came as a surprise to find that it is excellent on all wavebands. However, it does have an instability problem in the AM frequency changer which is also apparent on FM, the 12AH8 heptode section serves as the first FM 10.7Mc/s IF amplifier. I fitted a metal screen around the hexode section of the 12AH8 valve. This provided a temporary cure but the instability problem still exists.
Valve lne up is: 12AT7 FM RF amplifier and mixer-oscillator. 12AH8 AM mixer-oscillator and first FM IF amplifier. 6BJ6 IF amplifier. EABC80 FM ratio detector, AM detector and AGC. 6BW6 output. 6V4/EZ80 rectifier. All valves are Brimar make.
The set was made in 1955.
Geordie McBoyne.
Valve lne up is: 12AT7 FM RF amplifier and mixer-oscillator. 12AH8 AM mixer-oscillator and first FM IF amplifier. 6BJ6 IF amplifier. EABC80 FM ratio detector, AM detector and AGC. 6BW6 output. 6V4/EZ80 rectifier. All valves are Brimar make.
The set was made in 1955.
Geordie McBoyne.