24-06-2017, 06:17 AM
Possibly the major difficulty with providing full or nearly full vision bandwidth for the French 819-line system would have been the resultant loss of IF gain, probably requiring another amplification stage. Switching might not have been so difficult. With a wideband IF strip, the lower limit for French 819 would have been defined by the sound trap at 27.75 MHz. Then the 33.4 MHz sound trap (and 31.9 MHz adjacent channel vision trap) would have been switched in for the Belgian 819 and both 625 line systems, narrowing the IF strip input bandwidth, but not changing its basic nature.
Some general information on Belgian four-system receivers was provided in a Wireless World 1956 November article, see page 559 ff. (Available at: http://www.americanradiohistory.com/Wire...gazine.htm.)
And some Philips receiver circuits for study are available at: https://frank.pocnet.net/instruments/Phi..._docs.html. (Only some of the receivers on that list are of the Belgian four-system type.)
Cheers,
Steve
Some general information on Belgian four-system receivers was provided in a Wireless World 1956 November article, see page 559 ff. (Available at: http://www.americanradiohistory.com/Wire...gazine.htm.)
And some Philips receiver circuits for study are available at: https://frank.pocnet.net/instruments/Phi..._docs.html. (Only some of the receivers on that list are of the Belgian four-system type.)
Cheers,
Steve
