14-06-2017, 08:23 AM
Also from Hi-Fi News 1959 June is this correspondence about the JTV:
This indicates that it could cause mutual interference to nearby TV receivers, perhaps more so when they were fed from the same aerial system.
The use of the standard FM receiver IF of 10.7 MHz was a factor, but it was nevertheless otherwise a logical choice. I suspect that the JTV2, with its grounded grid triode input stage, had a higher backward leakage of oscillator and IF harmonics than did the JTV, with its cascode input stage.
At least in the valve era, in TV receivers with double conversion sound channels, 10.7 MHz as a second IF was avoided in order to minimize interference problems. For example, Murphy chose 6.31 MHz for its TV-FM receivers, as recorded in Wireless World (WW) 1958 October page 477. And early Belgian four-system TV receivers with split sound had second Ifs of 7.0 or 11.8 MHz (WW 1956 November page 559ff). In the solid-state era though, where presumably better screening was easier to provide, a second sound IF of 10.7 MHz was found in some TV sound tuners and “component” TV tuners.
Cheers,
Steve
This indicates that it could cause mutual interference to nearby TV receivers, perhaps more so when they were fed from the same aerial system.
The use of the standard FM receiver IF of 10.7 MHz was a factor, but it was nevertheless otherwise a logical choice. I suspect that the JTV2, with its grounded grid triode input stage, had a higher backward leakage of oscillator and IF harmonics than did the JTV, with its cascode input stage.
At least in the valve era, in TV receivers with double conversion sound channels, 10.7 MHz as a second IF was avoided in order to minimize interference problems. For example, Murphy chose 6.31 MHz for its TV-FM receivers, as recorded in Wireless World (WW) 1958 October page 477. And early Belgian four-system TV receivers with split sound had second Ifs of 7.0 or 11.8 MHz (WW 1956 November page 559ff). In the solid-state era though, where presumably better screening was easier to provide, a second sound IF of 10.7 MHz was found in some TV sound tuners and “component” TV tuners.
Cheers,
Steve
