19-08-2019, 05:33 AM
There was an interesting commentary on screened vs. unscreened TV aerial feeders in Wireless World 1955 August.
An example was given in which a change to screened twin feeder effected a major reduction in interference pickup as compared with the previously used coaxial feeder.
On the face of it, it was quite convincing. However, I wonder whether the problem was not so much the original use of coaxial feeder, but the lack of a balun at the aerial end, which omission appears to have been customary UK practice.
Not using a balun to connect a balanced aerial to an unbalanced (coaxial) feeder was a recipe for allowing interference picked up by the coaxial screen to find its way to the coaxial inner and thence to the receiver. That was explained in the W.T. Cocking Wireless World 1950 December article mentioned earlier in this thread, and attached here.
WW 195012 Aerial Feeders.pdf (Size: 857.95 KB / Downloads: 3)
Cheers,
Steve
An example was given in which a change to screened twin feeder effected a major reduction in interference pickup as compared with the previously used coaxial feeder.
On the face of it, it was quite convincing. However, I wonder whether the problem was not so much the original use of coaxial feeder, but the lack of a balun at the aerial end, which omission appears to have been customary UK practice.
Not using a balun to connect a balanced aerial to an unbalanced (coaxial) feeder was a recipe for allowing interference picked up by the coaxial screen to find its way to the coaxial inner and thence to the receiver. That was explained in the W.T. Cocking Wireless World 1950 December article mentioned earlier in this thread, and attached here.
WW 195012 Aerial Feeders.pdf (Size: 857.95 KB / Downloads: 3)
Cheers,
Steve
