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Why no shortwave band on radios?

Arran Cameron
I have lost count of the number of transistor (and IC) radios and Hi-Fis that have passed through my hands over the years. Some were high build quality but others were complete junk. What is common between them are that relatively few models have the facility to receive shortwave broadcasts. They only have LW, MW, and VHF bands.


Notable examples from the heyday of the transistor radio with a shortwave band include the Hacker Super Sovereign RP75, GEC G820, and Grundig Yacht Boy, but these were all top of the range models. Commercially available models of radios with a shortwave band at an affordable price to the average person were limited although there was the option of constructing one yourself or modifying an existing LW / MW radio.


What is the reason why so few transistor radios and Hi-Fi tuners had a shortwave band?
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    mapj1:

    There is an unfortunate problem, that means that AM radio generally, not just shortwave, is in decline, namely it is not a protected service (unlike VHF/FM broadcast), so the levels of incidental interference/ man made noise  from switching supplies and radiation from ADSL/VDSL are very high in all but the most rural areas.

    So the listener experience is not that good, so the broadcasters do not invest, so there are no killer programs, and little demand for radios to receive them. The digital mode for HF, DRM has not really taken off for the same reason. . .


     




     

    Thanks Mike. Not long ago I attended a Group Meeting and the speaker was reviewing the development of radio broadcasting. I spoke to him and suggested that Digital Radio Mondiale might be a logical way to re-engineer the AM radio bands, now falling behind and dwindling with this dated technology. This would combine the advantages of LW/MW/SW i.e. good propagation over distance and uneven terrain with the advantage of digital broadcasting, i.e. good immunity to interference.


    His reply that there was at present little commercial interest in investing in those bands; most of the interest was in UHF. This is very much in line with your thoughts.

    . . .And good quality SW reception requires more careful receiver design, both as tuning needs to be multi-octave, an a choice of IF frequency that is OK at MW may lead to spurious responses and lack of selectivity at the 20-30MHz end, and as the dynamic range of adjacent signals can be very high. It is not uncommon to want to extract a signal of a few hundred nanovolts RMS from under the skirts of an adjacent unwanted one at tens of millivolts RMS that may be 10-20kHz offset. For these reasons the common (=cheap) solution on a MW/LW set of  single tuned circuit prior to an unbalanced 1 transistor self oscillating mixer is not likely to be adequate, so attempts to extend an existing LW/MW design cheaply are usually a disaster.

     



    Yes an interesting point. Briefly, few manufacturers see any commercial advantage in developing extra-sophisticated designs for a system for which there seems to be little demand.
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  • 0

    mapj1:

    There is an unfortunate problem, that means that AM radio generally, not just shortwave, is in decline, namely it is not a protected service (unlike VHF/FM broadcast), so the levels of incidental interference/ man made noise  from switching supplies and radiation from ADSL/VDSL are very high in all but the most rural areas.

    So the listener experience is not that good, so the broadcasters do not invest, so there are no killer programs, and little demand for radios to receive them. The digital mode for HF, DRM has not really taken off for the same reason. . .


     




     

    Thanks Mike. Not long ago I attended a Group Meeting and the speaker was reviewing the development of radio broadcasting. I spoke to him and suggested that Digital Radio Mondiale might be a logical way to re-engineer the AM radio bands, now falling behind and dwindling with this dated technology. This would combine the advantages of LW/MW/SW i.e. good propagation over distance and uneven terrain with the advantage of digital broadcasting, i.e. good immunity to interference.


    His reply that there was at present little commercial interest in investing in those bands; most of the interest was in UHF. This is very much in line with your thoughts.

    . . .And good quality SW reception requires more careful receiver design, both as tuning needs to be multi-octave, an a choice of IF frequency that is OK at MW may lead to spurious responses and lack of selectivity at the 20-30MHz end, and as the dynamic range of adjacent signals can be very high. It is not uncommon to want to extract a signal of a few hundred nanovolts RMS from under the skirts of an adjacent unwanted one at tens of millivolts RMS that may be 10-20kHz offset. For these reasons the common (=cheap) solution on a MW/LW set of  single tuned circuit prior to an unbalanced 1 transistor self oscillating mixer is not likely to be adequate, so attempts to extend an existing LW/MW design cheaply are usually a disaster.

     



    Yes an interesting point. Briefly, few manufacturers see any commercial advantage in developing extra-sophisticated designs for a system for which there seems to be little demand.
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