Re: BBC2 on UHF38?

In message <R_2dncMOyLBwUAfUnZ2dnUVZ8svinZ2d@xxxxxx>, "marky.mark@xxxxxxxxxxxx" <?@?.?.invalid> writes
jamie_p84@xxxxxxxxxx wrote:

> > I've always thought that in the lead up to switch-off the analogue powers
> > would be reduced.
>
> It certainly was (unofficially) when 405 was going out. Some were hardly
> giving out a whif when finally put to rest.

That's only because they used valves and kept breaking if run at max
capacity.


The high powered 405 transmitters at some sites had already been switched off
and started be removed leading up to the 405 service switch off. Some of the
main sites were running on low powered transmitters, running a few hundred watts
into the main antenna.

My experience of that time is that 10's of kilowatts were replaced by kilowatts, using the Reserve transmitter pair, at one BBC site. At another, a Medium Power one, the output power was not significantly reduced - a dB or so only - as it became increasingly difficult to operate the equipment reliably. I would be very surprised if these 2 sites were unique in operating as they did at this time.

It was not that the valves kept failing (and it was very, very, unusual that one was broken), as I do not recall any real shortage of supply of these, but other, specialised, components. My memory of those times is that some types of valve were, and had been for many years, re-built by the manufacturer after failure. It was often impossible to find replacements for some other components once the existing spares were used.

It was an attempt to force viewers to go UHF 625 lines, but in the present
DSO it isn't possible to reduce the powers by 10dB without causing problems
to the viewer. Many viewers don't have any alternative to the analogue service.

For most viewers, I would have thought that it was the 'attraction' of coloured pictures that was the incentive to change.

--
JohnA
.

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