104mhz to 108mhz ?

The good stuff on the wireless and in the shops
Post Reply
Clive
625 lines
Posts: 279
Joined: Sat Dec 08, 2012 6:53 pm
Location: Stockholm

104mhz to 108mhz ?

Post by Clive »

I have done a bit of googling on this but not yet found a clear answer, I am wondering if anyone on here has a clearer answer.

I have a number of old valve and transistor radios from the 50's up until the late 60's which have the VHF band ending at 104mhz. Every radio I have which was produced since around 1970 extends the band upto the current day 108mhz frequency.

Does anyone know when, or what caused the VHF band to be extended to it's current 108mhz limit ? In the UK the launch of the Independant radio stations occupied this band, but this extension of the VHF band seems to have been a Europe wide initiative which I can't pin down to a specific event.

Any ideas ???

David Ballard
405 lines
Posts: 35
Joined: Sat Dec 08, 2012 8:40 pm

Re: 104mhz to 108mhz ?

Post by David Ballard »

The change in Europe came about as a result of a decision by the World Administrative Radio Conference in 1979, although the actual change took a while to implement. In the UK, the VHF band for broadcast radio only went up to 97.6MHz with police mobile radio using the band above that, although Radio Scotland did have some transmitters in the band up to 100MHz. The band changed to 88 - 108MHz in about 1984 but the work required to move the police radios to new frequencies obviously took some time, so the remainder of the band was made available in stages with the final range 105 - 108MHz only becoming free for broadcast use in about 1995.

Clive
625 lines
Posts: 279
Joined: Sat Dec 08, 2012 6:53 pm
Location: Stockholm

Re: 104mhz to 108mhz ?

Post by Clive »

Really ? Thanks, that is much later than I thought.

As I mentioned, most radios covered the 105-108 band from the early 70's onwards, so there must have been prior knowledge of the changes beforehand in the radio industry. But with so long a time to the lead-up of the official changes,then I guess this answers my questions on why there was no public out-cry over why their radios could not receive stations in the new range.

I do remember listening to police broadcasts in the upper range and also the audio from Band I tv broadcasts. I guess this is why older, national broadcasters, such as the BBC, occupy the lower frequencies with lots of room to spare and the upper frequencies are jam-packed with the independents.

TonyCurrie
625 lines
Posts: 147
Joined: Sun Mar 17, 2013 6:19 am

Re: 104mhz to 108mhz ?

Post by TonyCurrie »

The VHF Radio Band dates back to 1945 when the USA adopted frequencies between 88 and 108 for radio, having previously used part of Band I. As VHF/FM radio developed, manufacturers tended to produce sets which could tune the whole of the band, irrespective of its use, in order to be able to market the sets globally.

In fact, although band II begins at 87.5MHz, that's also part of the US TV Channel 6 and so there are very few (in fact only two) US stations using frequencies in that part of the band. Japan and OIRT countries have different FM bands, but with the switch to Digital TV, there is a suggestion that the USA might extend the band from 76MHz which would tally with the lower end of Japanese use of the band.

Early VHF receivers manufactured in the UK and intended only for the UK market tuned 88 - 100; some later sets went as far as 104.

Of course the initial allocations were only to the BBC; with National transmitters in the sub-band 88 - 95 (with some exceptions, notably the Third Programme from Wenvoe and the allocations to Les Platons) and BBC Local Radio in the band 94 - 98. ILR stations began in the same sub-band, but a reorganisation later (when the frequencies above 100 were finally cleared by mobile users) moved many commercial stations to the 100 - 108 sub-band. Radio 1 was given its own space (97.7 - 99.7), as was Classic FM (99.9 - 101.9), and in Scotland, Wales and Northern Ireland, Radio 4 can be found in some areas in the 103.5 - 104.9 band.

Nigel Stapley
625 lines
Posts: 186
Joined: Sat Dec 08, 2012 9:32 pm

Re: 104mhz to 108mhz ?

Post by Nigel Stapley »

After the band was expanded beyond 97~98 for broadcast use, I missed listening in to North Wales's finest as they chased drunk drivers up and down the A55 on a Friday night.

Transdiffusion - From A Distance

Clive
625 lines
Posts: 279
Joined: Sat Dec 08, 2012 6:53 pm
Location: Stockholm

Re: 104mhz to 108mhz ?

Post by Clive »

I also miss listening to BBC Wales TV sound which was in the same VHF frequency range, this was around 1984.

David Ballard
405 lines
Posts: 35
Joined: Sat Dec 08, 2012 8:40 pm

Re: 104mhz to 108mhz ?

Post by David Ballard »

Clive wrote:I also miss listening to BBC Wales TV sound which was in the same VHF frequency range, this was around 1984.
VHF tv was never in the same band as VHF radio before or after the changes. VHF TV used bands I (41-68 MHz) and III (174-216 MHz), with radio in between in band II. VHF tv also used AM for the sound modulation rather than FM.

Clive
625 lines
Posts: 279
Joined: Sat Dec 08, 2012 6:53 pm
Location: Stockholm

Re: 104mhz to 108mhz ?

Post by Clive »

So how come I could hear TV audio around 100mhz ?? You are totally correct in what you say but I am now wondering how I got TV audio in the upper bands. ??

Or perhaps the aeroplane bands....

Brian F
D-MAC
Posts: 522
Joined: Mon Dec 10, 2012 4:09 pm

Re: 104mhz to 108mhz ?

Post by Brian F »

I'm sure I could at some time receive TV sound on VHF, but only on one radio (Russian manufactured), I was wondering if it was due to some fault in the local oscillator giving a harmonic that tuned into the FM audio of a UHF transmission. I live fairly close to the Crystal Palace tower.

User avatar
Scary
625 lines
Posts: 271
Joined: Mon Dec 10, 2012 1:30 pm

Re: 104mhz to 108mhz ?

Post by Scary »

I remember being able to hear BBC TV audio in the FM radio band too, around the middle where the police radio used to be and Radio 1 is now. I remember the first time I heard it it was a snooker match commentary so I was pretty sure it wasn't a radio service

Nigel Stapley
625 lines
Posts: 186
Joined: Sat Dec 08, 2012 9:32 pm

Re: 104mhz to 108mhz ?

Post by Nigel Stapley »

I can confirm that TV sound could be picked up in the FM broadcast band. I used to have an off-air recording of an episode of the TV series of Hello Cheeky which I'd picked up somewhere around 90MHz. Could it have been some leakage or emanation from the TV downstairs (I was in my bedroom)? It couldn't have been a transmitter, as the nearest one at that time was about twenty miles away.

deltavega
405 lines
Posts: 50
Joined: Fri Jan 18, 2013 2:56 am

Re: 104mhz to 108mhz ?

Post by deltavega »

I concur.
In the late 70's / early 80's I was able to pick up Anglia tv audio on my dads FM receiver . I assumed it was from the 405 transmission which I thought was in the same VHF band as FM radio.

User avatar
penfold
625 lines
Posts: 132
Joined: Sun Dec 09, 2012 7:19 am

Re: 104mhz to 108mhz ?

Post by penfold »

And we used to listen to TV audio on the CCF's backpack radios.......mid 1970's this would be....

Post Reply