AM outdoor aerial - feed into different rooms?

If you follow the signal path, you will note that the choke is there for the very reason you mention

Oops, in my mind I thought is was in series to stop to much SW BC getting in, indeed you are right.

Never in doubt, often wrong!

[Radio Wrangler]

I have a few 2N3866 TO5 bipolars which were developed for this sort of use kicking around in case anyone wants to try that circuit.

David

[AC/HL]

Originally Posted by merlinmaxwell

The transmitter survived.

Hopefully the idiot didn't

[Synchrodyne]

Given that marine and professional/commercial LF/MF/HF aerial distribution systems have already been mentioned in this thread, it is worth recording that there is also a BBC Monograph on the subject, namely #53, 1964 July, “Aerial Distribution Systems for Receiving Stations in the L.F, M.F. and H.F bands”. It is available at: http://downloads.bbc.co.uk/rd/pubs/a...nograph_53.pdf.

From the vintage era, a different approach to antistatic aerials was adopted by BICC, per the attached Wireless World (WW) advertisement. In place of the customary vertical rod, it used a wire dipole, transformer coupled to a coaxial feeder (rather than screened twin), with a step-up transformer at the lower end to match the typically high aerial input impedances of domestic receivers. The coaxial feeder would I think have been amenable to splitting using passive or active splitters or multicouplers. The basic assembly would be reasonably replicable today, using say the Wellbrook UMB-130 as an impedance transforming balun to couple the dipole to the coaxial cable, and then another UMB-130 at the receiver end to provide an impedance step-up, although that would not be needed for receivers with low impedance coaxial aerial inputs. A horizontal dipole could be better than a vertical rod for HF reception, although the latter would be better for MF ground wave reception.

I have also attached an item about AM aerial performance and classification from WW 1949. It would appear that high-mounted vertical rods produce quite a bit of signal, so that one may see why the makers of conventional antistatic systems using such rods suggested that a couple of so receivers could be connected to one aerial by simply paralleling them from the balanced twin feeders. Presumably this was in connection with domestic receivers used for programme content listening, and not for DX’ing of weak distant stations.

Cheers,

[G8HQP Dave]

Originally Posted by Synchrodyne

It would appear that high-mounted vertical rods produce quite a bit of signal

At MW and LW it is usually the total height which matters, as the 'feeder' forms part of the antenna. The rod is merely the end part of the antenna, and functions partly as an extension and partly as a capacitive hat. If people ran a wire up to the rod, but forgot to add the rod, then they would get nearly as much signal. Of course, the rod makers did not want people to know this! In some cases the rod makers, like some modern antenna suppliers, did not understand this either.

[Synchrodyne]

I suppose in favour of the rod aerial was that its was a simple way of getting the top of the aerial around 5 metres or so higher than would easily be done with a wire, and also in the clear above the roofline. Also, for antistatic systems that used a phantom circuit via the screened twin feeder to provide a noise-free earth path from the aerial side of the transformer, the rod was the only active signal collector, in which case the higher and longer the better.

Aerial maker knowledge and understanding probably varied, and in some cases the expertise may have been more on the fabrication side than with he theory. Nevertheless, the section on broadcast aerials in “Radio and Television Engineers’ Reference Book”, 3rd edition, 1960 appears to better than most treatments of the subject, and it was written by an Aerialite staffer. See p.21-2ff of that book, and the same in the 4th edition, 1963.

Cheers,

[emeritus]

Just found this "three sets on one aerial" distribution system in my 1936 Bulgin catalogue. It seems that Bulgin's ordinary screened wire was suitable for the feeder.