Quote:
Originally Posted by G8HQP Dave
Once Radios 2, 3 and 4 were on FM...
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Ahem.
The Light, Third, and Home.
There were several years before nationwide FM became reality, so respectable AM performance was important well into the 1960's. And then, just as it did, Radio 1 was launched. though I suppose the target audience was youngsters with little AM-only portable trannies.
The EABC80 does seem to appear in 90% of AM/FM designs - while having limitations, it does allow the minimum of IF switching as all the diodes can stay permanently connected to their respective transformers.
A separate diode for AM AGC would have been nice - this could have shared the triode/ two diode cathode, though even then an extra pin would have been needed. Was the B10B base (as used for the PFL200) in existence then? This would have accommodated it.
I've always been a bit curious as to the numbering of the EABC80, with regard to the diodes that is. The 'B' indicates a double-diode, so would this have been the two diodes intended for FM (one of which has an isolated cathode), with the 'A' denoting the single, higher-impedance AM diode (sharing the cathode with the triode and one of the FM diodes? Or did Mullard consider the 'A' as being the isolated FM diode, with the 'B' being the two common-cathode diodes, ignoring the fact that they are different?
(I know, I should get out more...)