Long wave and medium wave units confusion

['LIVEWIRE?']

American (or American market) AM radios often had the dial marked 54-60......up to 16. As Graham (Station X) noted, this was simply a short way of stating 540 - 600....up to 1600kHz -in other words the standard MW Band. Regarding Channel Numbers on VHF radios, it used to be the case that German sets had Channel (Kanal) Nos. on their dials.

[dseymo1]

Originally Posted by 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.

I suspect that this has a lot to do with it. I understand that until relatively recently, measurements of radio frequency (wavelengths) were usually made using Lecher lines, so it would seem natural to simply note the corresponding length.

[emeritus]

All the scales on my late father's HMV 1120 (circa 1949 I think) are marked in metres only.

[hannahs radios]

Yes I remember Radio Luxembourg's earth link program after midnight, presented by Tony Prince announcing, THIS IS LUXEMBOURG ON 208 METRES 1440 KHz and 6090 KHz 49.26 metres. Oh and sometimes a mention of 1.3 million watts on 208! Also anyone else remember Radio Moscow was using wavelengths right to the end both for short and medium wave especially in winter when they where on 194 201 214 and 227 metres

[G6Tanuki]

Originally Posted by dseymo1

I understand that until relatively recently, measurements of radio frequency (wavelengths) were usually made using Lecher lines, so it would seem natural to simply note the corresponding length.

Lecher Lines were OK for VHF measurement but getting a 1/4-wavelength setup for Long/Medium Wave would have been a bit unwieldy to say the least.

Frequency-measurement was more-generally done with a "Heterodyne frequency meter" - basically a variable-frequency oscillator whose calibration could be checked against a crystal-oscillator contained within the instrument.

The frequency-to-be-measured was then matched against a couple of harmonics of the variable oscillator [which by way of the xtal oscillator now had reliably calibrated 100KHz points on its dial].

BC221 and "Wavemeter Class D" being the WWII-military implementations.

There were also 'fluorescent crystal' wavemeters: in these a Quartz crystal was precision-ground to the required frequency and then sealed in a glass envelope which also contained a small amount of a suitable gas [neon being the usual one].

When the RF-to-be-measured was coupled to the crystal's electrodes, if it was at the same frequency as the crystal was cut-to, the crystal vibrated and significantly-high voltages appeared across it, enough to ionise the gas and cause a nice orange glow. The brighter the glow the closer your applied-signal's frequency was to the calibration-frequency of the crystal.

[Synchrodyne]

Originally Posted by G6Tanuki

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]

In the US, the MW band was extended upwards to cover 535 to 1705 kHz (previously 535 to 1605 kHz) in 1993. As far as I know, this extension applied only to ITU Region 2, Regions 1 and 3 staying at 525 to 1605 kHz. But I think that there was some use of the extended band outside of Region 2.

That extension was long-anticipated. For example, the Carver TX11a tuner that I bought in 1986 covered the extended band. Very long-range anticipation was shown by the Bush EU24 export model of 1951, whose MW band coverage was 524 to 1750 kHz (marked in kc/s). Actually, I suspect that that was done to provide continuous coverage; SW ran from 1.75 to 30 MHz in five bands.

Originally Posted by G6Tanuki

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

I haven’t seen an explanation, but a reasonable guess is that it was part of the pan-European plan for uniform use of 8 MHz TV channels in Bands IV and V, as agreed at the ITU Stockholm 1961 meeting. Concomitant would be uniform channel numbering that was also clear of the various VHF TV channel numberings schemes then in use. These used numbers up to 13, although the highest number used was lower than that in many countries. Given that there would be an unavoidable gap between the highest VHF channel and the lowest UHF channel for such countries, likely it was thought preferable to make a clean break, and so leave a definite gap and start the UHF sequence at a logical higher number, viz. 21. That also allowed room in case there were any subsequent upward extension of Band III.

Here in NZ we used the European UHF TV channel numbers. But an earlier proposal (extant in 1973) had the UHF channels numbered from 10 upwards, at a time when there were but 9 VHF channels. Two more, NZ10 and NZ11, were added later, so it was just as well that the original UHF numbering scheme was abandoned.

Cheers,

[Junk Box Nick]

Originally Posted by G6Tanuki

In the past I've seen Band-II FM radios with a scale labelled "channel"

IIRC RNI used to announce "FM Channel 44 100MHz" to their Dutch listeners.

[Junk Box Nick]

Just found this - Radio Times schedule for Christmas day 1943.

Details for Home Service in wavelength and frequency for medium wave and 49 metre band can just be made out on this scan.

I guess the 49m transmission was for the benefit of those in the forces that might be close to a receiver - or clandestine listening in Europe*.

*I doubt the latter would have a copy of the Radio Times!

[emeritus]

Interesting that Disney's "Snow White and the Seven Dwarves" is referred to as a "fantasy" rather than a cartoon.