Solar Roof Panels

[The Other Mike]

Coax and FDM/TDM rather than baseband in the UK, lots of microwave too.

You could get private copper circuits from BT / PO that were essentially copper pairs that worked down to DC but not usually for circuits of more than 10 or 20 miles.

Isolation of telephony / audio circuits (used for signaling) was a major consideration for HV substations before fibre arrived, hence the use of private microwave / UHF networks in the transmission and distribution utilities.

But it is surprising that a continuous 33kV circuit of 500 miles would be strung with a copper pair for comms. Power line carrier kit has been around for many decades that piggybacks an audio / signaling channel or multiple channels on the HV connection.

[The Natural Philosopher]

The issue there was 'within the same exchange area'.

Especially after trunks all became digitally multiplexed over microwave and fibre.

There simply was not a copper link to other exchanges anymore.

I think we are talking 'once upon a time'

[The Other Mike]

Even now there is still plenty of unused / redundant copper in the ground between many cities, it has been viewed as BT's most valuable asset.

Matty F must be ancient then as the UK, mainland Europe and the USA were using Power Line Carrier 50 years ago.

[tony sayer]

In article , The Other Mike scribeth thus

He is talking about the late Sixties in another article and he is also talking about practice in New Zealand where he's from and they aren't backward in any sense. Its prolly more to do with the layout and geography of the country more then anything else.

In fact one of the better comms radio makers are based there, TAIT of Christchurch..

[Matty F]

In 1968 I was asked to make replacement transformers for the NZED communica tion system. I'm sure the whole system has been completely replaced by now. I'm still checking on the details but the system may have existed from the 1920s when the national Grid was established, supplied by hydro-electric p ower stations. Telephones were rather primitive in the 1920s! However, if s omething works reliably, why change it? There were only 12 phones in the sy stem, so I made 12 epoxy toroidal transformers, for a third of the price of the Canadian non-toroidal versions that were insulated with pitch.