Made a Wire Rack

[Mike Watterson]

I don't think anywhere in Southern Hemisphere had LW. Also furthest south in the Northern Hemisphere was likely Algeria, or North Africa. No use as you get closer to equator. Even MW gives way to Tropical Bands closer to Equator.

Tropical Bands include the 60, 90 and 120 metrebands on shortwave. The International Telecommunication Union (ITU) allocated these bands for domestic broadcasts in principle to countries located in the Tropical Zone between the Tropic of Cancer on 23 degrees north and the Tropic of Capricorn on 23 degrees south.

In Asia LW was maybe only in former USSR regions and maybe Mongolia as those are northern.
Much LW & MW (and many SW) has closed due to theory it's replaced by FM, DAB, Digital Radio on Terrestrial, Satellite and cable, and also streaming. However really it's an accounting decision, not technical.

Issues:
FM coverage is poorer.
DAB coverage is poorer still and power hungry on receivers. Quality could be good but often more distorted due to greedy accountants not paying for extra muxes or bitrate.
Digital Radio via TV, cable, Satellite or streaming isn't usually portable. Vulnerable infrastructure and needs mains power except for DAB, but DAB battery consumption is high.
Streaming uses a fragile infrastructure and can be worst for energy use. Best used for niche stations.

Satellite is vulnerable to solar flares (and also DAB, DTT etc due to using gps derived timing instead of standalone), jamming and acts of war.

SW, MW and LW are complementary to the other technologies and best in disaster scenarios such as war, storms, earthquakes and once in 100 year severe solar activity (overdue). Also gives best battery life. Even a battery valve set powered off Alkaline AA for HT and Alkaline D for LT will out perform many DAB sets on running time!

Norway has entirely switched to DAB. Some countries have entirely ended AM (Ireland, Switzerland, Norway). Other countries have either abandoned plans for DAB or turned it off. It suits national rather than local stations. UK says smaller local stations will never leave FM. Ireland only briefly had SW for the public in 1948 despite the diaspora and International interest in Ireland and being one of the early MW broadcasters. LW ended last month. DAB 2 years ago. The salary of top presenters is far more than x10 running cost of LW was. Iceland closed a LW site last month.

[Radio Fixer]

Just type into Goggle: “australian vintage radio” and it will bring up several leads to societies and groups with meetings in major Australian cities. I had a quick browse of Etsy, an auction site, and most of the early radios were from the USA. A friend down in NZ, said when he started collecting, as a young man, he called it Atwater Kent land as there were so many to be had.

In an article by him (https://nzvrs.com/peter-lankshear-articles/) one of those on the Early Days, he repeats what I said about distances ‘down under’ being similar to those in the USA and multi valve sets sold and would perform better than the sets made in Britain and Europe. Here, in our country, the distance between transmitters and receivers was short and 4 or valve sets the norm (don’t forget the valve Tax). Even Europe was behind the USA in receiver design and as an example Philips didn’t make a Superhet until about 1934/35 .

The Zenith, we are talking about here, is from 1936 and is before the triode hexode was commonly in use. It was probably invented around this time but even in radios worked on by me, from 1939, isnt seen.

Even Philips British sets in my collection from that year dont have it. I am aware of a German version of one of mine, the D58 1938/9, that used used an ECH11 triode hexode. This valve type was, it has been said, cleared up many problems. As you have noted it isolated the aerial from the oscillator better.

Yes! Adding a tuned RF stage in front of a multi grid ‘mixer’ would do the same and I think on the sets that I have worked on improves sensitivity on MW and LW bands (I was too late into the hobby for there to be much to explore on SW). I read somewhere of gain up to X10 but maybe this is unlikely. It would be easy to be impressed by the presence of big multi valve sets to imagine sensitivity that isn’t really as much as thought and I have no means of measuring and comparing.

A read I shall do again, when I have the time, is the chapter on Frequency Changers (Page 88 on) in the book “70 Years of Radio Tubes and Valves” by John W. Stokes. This whole book could be downloaded on line at the time I wrote an article on restoring the Zenith.

Gary

[Mike Watterson]

This has some comment on Tropical Bands and an issue I'd not thought of for AM stations (MW really) in relation to abolishing the clock changing (introduced mostly by UK & Germany in 1917) if USA goes to year round DST.
https://swling.com/blog/tag/tropical-band/