Effect of line voltage on tube radio

Discussion in '"Boat Anchor" & Classic Equipment' started by VR2WAR, May 4, 2012.

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  1. VR2WAR

    VR2WAR QRZ Member QRZ Page

    I live in Hong Kong where the line voltage is 220V 50Hz while in US it is 120V 60Hz. The converters or transformers that normally available here are 220V to 110V type. Therefore the closest I can get is 110V 50Hz to supply to US made tube radio (such as Collins'). Do you think these radio will run less efficient or even misaligned on 110V 50Hz?

  2. K9STH

    K9STH Ham Member QRZ Page

    If you look closely at tube type radios you will see that they operate fine on 110 volts. Certain manufacturers, such as Collins Radio Company, actually rated a lot of the equipment for between 105 VAC and 135 VAC with either 117 VAC or 120 VAC as being "nominal". Line frequencies between 50 Hz and 60 Hz are definitely within the specifications.

    As for the Collins S-Line: A lot of the equipment, especially the later models, have dual power transformer primaries which allow for either 120 VAC or 240 VAC operation. Of course, the equipment works fine on 110 VAC or 220 VAC.

    A number of the older tube type receivers have various "taps" on the power transformer primary which provide for voltages as low as 100 VAC and up to at least 140 VAC (depending on the individual transformer). A few receivers actually have a knob on top of the power transformer which selects the appropriate tap.

    Glen, K9STH
  3. KE3WD

    KE3WD Ham Member QRZ Page

    Your Collins should run just fine on 110VAC/50Hz.

  4. KM1H

    KM1H Subscriber QRZ Page

    Since 120-125VAC is common in the US many old radios run excessively hot transformers and many of us use bucking transformers to reduce the input to 110-115V. Almost all of mine, including transmitters, run at those lower voltages.

    There will be no reduction in sensitivity, about the only difference will be a little less wide open audio.

  5. KB3PXR

    KB3PXR Ham Member QRZ Page

    You won't have any problem with 110 volts at 50 Cycles Per Seconds (50Hz). Most equipment back then was made for either 50 or 60 cycle operation as some parts of the country used different frequencies, Southern California I think used 50 cycles for the longest time. The voltage is of no concern as that is also within tolerance and in some older houses back then that had old 120 volt 30 Amp service usually had voltages down toward 105 at nights when everybody in the neighborhood was watching television.
  6. KH2G

    KH2G Ham Member QRZ Page

    Thing only thing the frequency difference may cause is a slight increase in heating of the transformer core but doubtful you'll notice.
  7. WA7KKP

    WA7KKP Ham Member QRZ Page

    As long as the line voltage is 110-120vac you shouldn't have problems. The rub here is the line frequency . . . many power transformers in the US are NOT rated for use at 50 Hz, and tend to overheat. Why? Transformers need a minimum reactance at the power line frequency. If the transformer is clearly marked as 50/60 Hz, then you're okay. If not . . . you may be asking for trouble.

    Gary WA7KKP
  8. K9STH

    K9STH Ham Member QRZ Page

    If a Collins radio, then no problems. All transformers used by Collins Radio Company were spec'd for 50 Hz to 60 Hz.

    Glen, K9STH
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