Do you need a 40 Amp to transmit 200w on Kenwood TS 480 HX?

Discussion in 'Ham Radio Discussions' started by K7HN, Aug 13, 2019.

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  1. WA4ILH

    WA4ILH Subscriber QRZ Page

    point taken but the TS-480-HX was one of a few that was designed with two power input cables.
    Tom WA4ILH
  2. AA7EJ

    AA7EJ Ham Member QRZ Page

    200 /12 = ~16 X 1.30 = ~ 20

    Watts / Volts = ~ Amperes x power supply inefficiency ( grossly exaggerated) = ~ Amperes
    (~ = approximately )
    You need APPROXIMATELY 20 Amperes DC power supply of continuous output of 20 A.

    Next question to ask - do I need 20A continuous to run SSB or even CW ?

    From the "answers " so far - I would not ask it here. Your dime.
  3. NN4RH

    NN4RH Premium Subscriber QRZ Page

    It didn't occur to you to download and read the manual ?
    WJ4U and WR2E like this.
  4. WA9SVD

    WA9SVD Ham Member QRZ Page

    IF (a big IF!) the power supply can handle at least 40 Amperes continuous, the two power inputs can usually be connected together. The separate inputs are to enable use of two supplies, each providing 20 Amperes (such as 2x Astron RS-35's.) It is usually more economical to use a single, high current (40 Amperes or more) supply than two separate supplies.

    IS 40 Amperes+ necessary? MAYBE, maybe not. IF you ONLY use SSB and/or CW, you may be able to get away with less, BUT... if you EVER run digital, such as RTTY, or several other modes, or FM at full power, you WILL require the full 40 Amperes.
    Downloading and reading the TS-480HX manual is not just recommended, but mandatory, before you make a decision.

    ADDED: (IMHO, of course) I would go with the 100 watt TS-480, not the HX model, and save up your pennies (considering the added co$t of the HX model and an adequate power supply) for a real linear amp. The 3 dB gain achieved by the 200 watt radio is marginal; the standard model apparently has an "autotuner," while the HX model does not. Even a modest 600-800 watt amp will give you much more "bang for the buck" than a mere 200 watt radio can provide, and when you do NOT need the amp with the TS-480 "barefoot," you and other amateurs will be thankful. Only the electric company will lament.:(:D
    Last edited: Aug 17, 2019
  5. WA9SVD

    WA9SVD Ham Member QRZ Page

    That's a bit debatable. The Astrons (as almost all power supplies) are rated by PEAK current, not continuous current supply. Certainly, the AstronRS-50 can provide 50 Amperes on peaks, but will be sorely stressed if asked to provide 50 Amperes on a continuous basis, And would NOT be able to "easily" power much else, much less a mobile V/UHF radio even with a 25 watt output rating; they require (typically) 10-12 Amperes themselves, and WILL require that much at ALL

    What is YOUR definition of a "normal" ham?:confused: And why do you not think he/she wants to communicate via amateur radio?:confused: Your logic fails me.:(:rolleyes:
  6. KQ0J

    KQ0J XML Subscriber QRZ Page

    "1) Antenna
    2) Antenna
    3) Antenna
    4) Antenna
    5) Receiver
    6) Microphone
    7) Headphones
    8) Power Output "

    Why upgrade your antenna when you can hear multitudes of stations already that can not hear you because of your low power?

    If ya can hear them and not work them : More power

    If ya can't hear them: Better antenna

    Getting 6-9 db gain is easier and cheaper with an amplifier than a gain antenna installed properly.

    And of course for many hams the problem with that big gas antenna is:

    1) HOA
    2) Lot restrictions
    3 ) Local regulations
    4 ) XYL
    5 ) Neighbors
  7. K7JEM

    K7JEM Ham Member QRZ Page

    Your calculations are lacking. First, if a radio has 200 watts of output power, the DC input power required to supply that will be much greater. Most HF radios are probably around 50% efficient, from DC input to RF output. So, a 200 watt output radio will need about 400 watts of DC power. If we assume 13v, that is around 31 amps required. IOW, a 20 amp supply just isn't going to cut it. The particular radio may have additional power overhead, or the efficiency may be worse, so that number could go up to 35 amps or greater.
    WA9SVD likes this.
  8. AG6QR

    AG6QR Premium Subscriber QRZ Page

    50 percent efficiency is not a bad rule of thumb, but it's almost always a bit worse than that.

    But one shouldn't rely on rules of thumb when more precise data is available. Early in this thread, I posted a link to the manufacturer's specs. This particular radio requires 13.8V from either a single 41A supply, or a pair of 20.5A supplies. It's a bit unusual in its design for dual power supplies.
    NN4RH likes this.
  9. K0UO

    K0UO Platinum Subscriber Platinum Subscriber QRZ Page

    I have used a RS 35 for years on SSB
  10. WA4ILH

    WA4ILH Subscriber QRZ Page

    With a transmitter that is running 200 watts output?
    Tom WA4ILH

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