[Synchrodyne]

Interesting! I guess that one should always expect some setmakers to use valves outside of the application ranges recommended by the valve makers. I don’t think frequency changer was amongst the ECL80 applications covered in Philips Book IIIC. I guess that that Pye receiver was Band I only; the ECL80 at Band III frequencies would be something of a stretch.

The early use by Pye of a “high” IF is notable. Evidently back in 1949 a BREMA Special Committee had made the case that an IF in the 34 to 38 MHz range was desirable, but it was then too early to make a general recommendation (Wireless World 1952 April, p.145). The said committee was revived in 1952, and in late 1954 BREMA recommended the 34.65/38.15 MHz numbers (WW 1954 December pp.582,583)

Anyway, the ECL80 would seem to lay claim to having been the first triode-pentode frequency changer used in a production TV receiver. My best guess in the American case is that the 6U8 and 6X8 would have been first used in some 1952 season models, perhaps announced late in 1951.


Cheers,