Long wave and medium wave units confusion

[stevehertz]

Having not really thought about it much, I recently noticed that vintage radio dials use metres instead of KHz. Why was this done? Was it universal? When did sets start to use frequency (KHz)?

[paulsherwin]

The convention in the UK (and I think France) was to use wavelength for MW and LW and frequency for SW, but with SW 'metre bands' marked in addition. The US and the rest of Europe used frequency for all bands.

This convention only ended during the 70s with the arrival of lots of receivers designed for the global (primarily US) market. Many of the early ILR stations launched with names based on their wavelength in metres ('Radio 210' in Reading for example) and the BBC always referred to Radio 1 as being on 275/285 metres until it left MW. Radio 2 was always '1500 metres long wave' until its transmitters were taken over by R4.

[stevehertz]

Thanks Paul.

[Dave Moll]

Beyond radio waves (i.e. from infra red onwards) though, it seems that frequencies are never used for the electromagnetic spectrum - it is either wavelengths in small fractions of a metre or (at the upper end) energies in large multiples of an electron volt (eV).

[Junk Box Nick]

Some vintage sets are marked in kc/s, Mc/s, (Kilocycles, Megacycles) etc., usually for the short wave bands, even though the particular broadcast band would be marked in metres, 49 metre band, 31 metre band, etc. Military and professional receivers used frequency which, of course, is far more accurate for tuning. The change from kc/s, Mc/s to kHz and MHz arrived in the (early?) 1970s. However, much later, when I was still active on the amateur bands we would often refer to "tuning a few 'kay-cees'" up or down

For European broadcasters on the medium and long waves wavelengths in metres was the norm from the outset and some, in the 'heyday' of wavelengths, would announce a wavelength to tenths of a metre, i.e. 388.1m, for accuracy. However, the average broadcast receiver dial being fairly inaccurate, the wavelength gave a rough idea of where to tune on the dial and then your ears did the rest.

Radio Caroline always liked to use a 9 at the end of its announced wavelength as a rhyme. Initially announcing 199 it was actually transmitting on 197m. Both the North and South stations announced 259, yet South was on 1187kHz (253m) and Caroline North on 1169 kHz (257m). In the mid 1970s it announced 319m when actually on 315m.

By the 1970s many stations were announcing frequency and wavelength. The use of wavelength fell away in the 1980s for reasons Paul described above. There was also a Europe-wide realignment of frequencies in 1978 which saw many stations move frequency and wavelengths became even more inaccurate.

A few years ago I was listening to local radio station out of my area on medium wave. They were discussing 'steam radio' so I thought it fun to email in to tell them they were loud and clear on so-and-so metres on my vintage set. I should have known better. It was an invitation to take the Michael out of an idiot anorak.

[turretslug]

Were there ever dyspeptic letters to the Times or Telegraph complaining about wavelengths being quoted in metres, rather than yards?

Beyond radio waves (i.e. from infra red onwards) though, it seems that frequencies are never used for the electromagnetic spectrum

Probably because of the way they are generated, radio and oscillator made of bits, above that it is stuff with inherent size.

[stevehertz]

Originally Posted by Junk Box Nick

Some vintage sets are marked in kc/s, Mc/s, (Kilocycles, Megacycles) etc., usually for the short wave bands, even though the particular broadcast band would be marked in metres, 49 metre band, 31 metre band, etc. Military and professional receivers used frequency which, of course, is far more accurate for tuning. The change from kc/s, Mc/s to kHz and MHz arrived in the (early?) 1970s. However, much later, when I was still active on the amateur bands we would often refer to "tuning a few 'kay-cees'" up or down

For European broadcasters on the medium and long waves wavelengths in metres was the norm from the outset and some, in the 'heyday' of wavelengths, would announce a wavelength to tenths of a metre, i.e. 388.1m, for accuracy. However, the average broadcast receiver dial being fairly inaccurate, the wavelength gave a rough idea of where to tune on the dial and then your ears did the rest.

Radio Caroline always liked to use a 9 at the end of its announced wavelength as a rhyme. Initially announcing 199 it was actually transmitting on 197m. Both the North and South stations announced 259, yet South was on 1187kHz (253m) and Caroline North on 1169 kHz (257m). In the mid 1970s it announced 319m when actually on 315m.

By the 1970s many stations were announcing frequency and wavelength. The use of wavelength fell away in the 1980s for reasons Paul described above. There was also a Europe-wide realignment of frequencies in 1978 which saw many stations move frequency and wavelengths became even more inaccurate.

A few years ago I was listening to local radio station out of my area on medium wave. They were discussing 'steam radio' so I thought it fun to email in to tell them they were loud and clear on so-and-so metres on my vintage set. I should have known better. It was an invitation to take the Michael out of an idiot anorak.

Thanks Nick, interesting.

[hannahs radios]

I think it was the pirate station Laser 558 that promoted the BBC to change from metres to KHz. Laser always announced 558 KHz, whilst radio one was still announcing 275/285 (and 202) metres, then announced frequency and wavelength then frequency only and of course Radio Luxembourg were always The Great 208, referring of course to 208 metres.

[russell_w_b]

Originally Posted by Junk Box Nick

Some vintage sets are marked in kc/s, Mc/s, (Kilocycles, Megacycles) etc., usually for the short wave bands, even though the particular broadcast band would be marked in metres, 49 metre band, 31 metre band, etc.

HF broadcasts were announced in 'metre-bands' as different frequencies were used for the broadcast depending on time of day, time of year and time of sunspot-cycle.

[PeterRoberts]

Do you remember when the BBC converted from metres to kHz? They gave away labels you could stick on your radio to do the conversion for you, and small diamond-shaped stickers you could put on your dial to help you remember where to tune to.

[paulsherwin]

The stickers were actually issued when the national stations all swapped frequencies, but it's true that the BBC were moving from using metres to kHz at around the same time.

[Paul_RK]

Pegasus, a small manufacturer from Leeds, for some reason produced radios with frequency-only calibration long before it was general: I have one from about 1936. Not sure if that would have contributed much to their early demise, but it certainly won't have made their sets any easier to sell.

Paul

[jamesperrett]

As a youngster I thought I knew all about the wavelengths covered by LW, MW and SW. Then I saw a radio in a shop with a band labelled AM and going from 54 up to 160. What was this mysterious AM waveband? It took me a while to work it out.

[Station X]

540 kHz to 1600 kHz?

[Andrew2]

Originally Posted by jamesperrett

As a youngster I thought I knew all about the wavelengths covered by LW, MW and SW. Then I saw a radio in a shop with a band labelled AM and going from 54 up to 160. What was this mysterious AM waveband? It took me a while to work it out.

Indeed. I was a young teen in the 60's when the shops began flogging imported Japanese pocket radios. To someone accustomed to seeing calibration in 'Metres', I wondered what these strange numbers were. not that it mattered much, we just tuned until we heard Radio Caroline.

[Phil G4SPZ]

It's very interesting to speculate why 'wavelength' was the standard term for so long. I've tried to find out why, but haven't as yet seen a plausible explanation. Perhaps it dates back as far as Lodge's invention of syntony (selective tuning) before the turn of the last century. It was no easier to measure wavelength as it was to measure frequency back then.

However, my theory is that the operating frequency of early spark transmitters was determined by the tuning of the aerial; the aerial wire would have had one or more natural resonant frequencies, depending largely on its length, which could easily be measured. Later, as aerial loading and tuning became more understood, the importance of actual aerial length declined, but by then the term 'wavelength' was in general usage and simply stuck.

I suspect that the metre as the unit of measurement (as opposed to the foot or yard) stems from Marconi's patent for tuning and he would have been used to metric units in his native Italy. I understand that Marconi's patent was based largely on Lodge's own patent.

[llama]

A short-wave exception - I can remember the likes of Keith Fordyce announcing Luxembourg on 49.26 metres short-wave.
Graham

[AndiiT]

Originally Posted by PeterRoberts

Do you remember when the BBC converted from metres to kHz? They gave away labels you could stick on your radio to do the conversion for you, and small diamond-shaped stickers you could put on your dial to help you remember where to tune to.

I can remember these stickers, I think they were around in the late 70's just as I entered the working world (although they may have been prior to that)

Not wanting to take things too off topic, I once encountered a customer who claimed to be some kind of lecturer at our local technical college who insisted that Frequency was sound and Wavelength was light.......

Andrew

[G6Tanuki]

I think announcing wavelengths on Band-II would have been a bit tricky.

"This is Ambridge FM broadcasting between 3-metres-seventeen-and-a-half-centimetres and 3-metres-forty-seven-centimetres".

In the past I've seen Band-II FM radios with a scale labelled "channel" - the US definition of these,

https://en.wikipedia.org/wiki/List_o..._North_America

didn't match what I recall, which went up to something like 80. It would have made sense to me to use 'channel numbers' for FM broadcasts to make things easier when interchanging radios between US/Europe/Japan markets.

[Side-thought: why were the old analog UHF TV channels numbered "21" to "68" ??]

There was also an extension of the medium-wave broadcast band sometime in the late-1970s: old medium-wave radios went down to 194 Metres; later 'extended' ones went down to 1700KHz [where you could easily hear one end of the then-popular analog cordless domestic-phones, which was embarrassing if the user happened to be the local doctor's surgery discussing medical complaints]