Who remembers how bad analogue television was?

It always struck me as fine. We were late getting it in Northern Tasmania - the first transmissions that made it were from the 1956 Melbourne Olympic Games, and the only people who bought sets were mad optimists because the signal vary rarely made it across Bass Strait.

I didn't get to see it much until I started my university studies in Melbourne in 1960 when there was a TV in my residential college.

It was a PAL system - pretty much the UK-German system

By 1976 I was working at EMI Central Research (where Alan Dower Blumlein had pretty much invented television in the late 1930s, and my boss had been involved in the legal dispute between RCA and EMI about whose patents had priority - RCA won mainly because the US court didn't want to see that quadrature decoding was was the same thing as sine-cosine decoding). I never owned a home TV - but when I got married in 1979 my wife insisted that we buy one, and it worked fine.

By then I knew exactly what it was doing. At Cambridge Instrument we used standard consumer TV tubes as displays for our scanning electron microscope - we'd buy a couple of hundred out of a commercial batch, and bodge the cabinets to accommodate that batch. The next batch was always a slightly different shape, and the sheet metal shop could always adjust the cabinet to accommodate the new batch.

For a while we generated a 624-line display - a timing PROM had gotten corrupted. One of the other engineers eventually worked out that the timing was wrong and I worked out how the PROM had been intended to be programmed.

TV based visual displays could be remarkably good. Cambridge Instruments offered a photo-monitor which presented a slow 4000 line display - intended to show slow high-resolution scans to be recorded on photographic film for publication. They used very special tubes with the inner surface metalised to provide electrostatic screening. A batch came in where the metal layer didn't look shiny and they almost worked ...

Commercial networks sometimes had operas, then even PBS stopped showing them, then the Bravo cable channel was created for them, then it became the Real Housewives channel.

It was the valve ones from the mid to late 60's that were both seriously expensive and unreliable. So much so that most people at the time rented them since then routine service and repair was included. Enough money was made on the TV rental business to fund a new Cambridge college.

Valve sets ran hot and somehow valves would gradually work themselves out of sockets or just plain and simple fail at switch on. I saw one or two very old all valve sets survive into the 80's that kept the valve filaments warm continuously even when the set was nominally off.

That's how Colossus was run reliably at Bletchley Park. The valve filaments were always on.

I remember those days. When in the 1970s the 1N4000-series rectifier diodes became strong enough and cheap enough, we would bridge the power switch with one such diode such that the filaments stayed warm (not hot) even when the TV was off.

Joe

Television shows used to come from New York.

Now they come from Hollywood.

They did that so that they didn't have to pay PAL license fees. But no-one cared because the picture on their first set sold in the UK, although small screen, was superior to any other set on the market.

The history of Sony colour is interesting. Trinitron came about because this had to be abandoned:

I think they worked with a Texas Instruments facility in the UK where the necessary transistor was produced to make it possible to do the line scan and EHT without valves. R2008B I think. Doesn't seem possible to find any data on it now.

Some sets used the BU105 transistor which was rated for 1500V for line drive and EHT. I once salvaged one from the junk pile at the back of a TV repair shop and was able to get about 10W out of it at about 1MHz.

John

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

That's exactly the problem. I told one station manager that it would be a mistake to go full digital (well, the government made them) and even more of a mistake to give up their VHF channel without a fight. That it would erode viewership in the fringe areas, hence for people with more disposable income, who will migrate to the Internet, resulting in advertising income to drop, which will lead to painful staff cuts.

He didn't believe me. And then pretty much all that happened.

It doesn't make much sense to blast megawatts of RF out into space, for a modest amount of one-way bandwidth.