HF transceiver suggestion

Discussion in 'On the Road' started by K7OFG, Mar 26, 2019.

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  1. K7OFG

    K7OFG Ham Member QRZ Page

    I'm looking for an HF transceiver that isn't so dependent on the 13.8 volt input that seems so prevalent in the market today. My go to portable rig at the moment is an icom-7200. I really like this radio and have used it for both maritime mobile and in my RV. My only complaint is if the full 13.8 volts is not available full output power is also not available. So, unless I'm running a generator or am plugged into 110 I can't get full power out.
    Is there an HF transceiver on the market than can operate at a full 100 watts of power at 12 volts or less?
    Thanks for any info.
  2. KJ4VZJ

    KJ4VZJ Ham Member QRZ Page

    Your amperage draw will be more of a factor than your voltage. I have an FT-857 which draws 22 amps when transmitting at 100 watts. I operate it in my truck and have a separate battery when I want to dismount it. When I transmit at 100 watts of power, my voltage reading will fluctuate from 13.7 volts to just below 12 volts at times. As the battery discharges, drops in voltage are more noticeable. I only pull 22 amps when transmitting at 100 watts. If I'm just monitoring, the draw can be around 2 amps which doesn't tax the battery as much and the voltage remains around 12 volts. I can dial down my power below 100 watts (say 10 or 50 watts) when transmitting to increase the life of my battery. So your real issue is with amperage draw and not the voltage. There may be certain types of batteries that provide consistent performance that you seek. R
    W4EAE likes this.
  3. W4EAE

    W4EAE Subscriber QRZ Page

    I would start with a LiFePO battery. You will not get more consistent voltage across the drain cycle with anything else. Lithium Ion is close in that regard, but it has other significant downsides.

    You could install a device between the battery and the radio that maintains 13.8V to the radio. There will be heat losses though.

    But is insisting on 13.8v and exactly 100w even beneficial in the end? It all depends on what your output is dropping to. Doubling power of transmitted signal only improves received signal by 1 S unit. It is possibly a point to be argued, but I would not worry too much about getting 100w vs 85w. (If your transmitter is dropping down to 20w, that is a different discussion; and maybe it is time for a new radio.) I have no idea what antennas you are using, but improving your antenna would reap much, much greater rewards per dollar or hour spent than trying to marginally increase your power.
  4. K7OFG

    K7OFG Ham Member QRZ Page

    Thank you for the responses. I understand the current supplied being the most important and with my set-ups in both the boat and the RV I use multiple batteries in parallel to supply the necessary amperage. It just seems that with my ic-7200, full output power cannot be achieved without the full 13.8 volts being delivered to the radio.
    I know about the step-up systems and have thought about going that way but was just curious if anyone knew of a radio that wasn't so dependent on the 13.8 volt input.
    Thanks for the input.
  5. W5LZ

    W5LZ Ham Member QRZ Page

    I haven't had any low voltage problems in several different vehicles (TS-480sat). Nothing special about the battery/alternator/etc.
  6. W4EAE

    W4EAE Subscriber QRZ Page

    What is your power out when your radio is fed 12v? I genuinely wish to be helpful, I am just concerned that you are chasing number on a meter as opposed to trying to eliminate a problem that has an actual bearing on operations.
  7. WL7PM

    WL7PM Ham Member QRZ Page

    I regularly use (two) IC-7200 radios on battery power... they work just fine.
    Under load, a Lead-Acid battery will quickly drop down in the 12.2 or 12.3 volt range, and bounce back to 12.6 open circuit.
  8. K7OFG

    K7OFG Ham Member QRZ Page

    Thanks again. My ic-7200 works just fine and I really like it. Especially the PBT filters and the USB plug for digital use (Winlink). And also it's rugged construction. It just likes a full 13.8 volts. Yes, it works fine on just normal battery voltage and I have had many good QSO's that way. But if I'm having a QSO with a friend and start up the generator I gain a good S-unit or more by their report. And no, the batteries are not low.
    So, back to my original question, is there any HF transceivers that can operate on battery voltage and put out it's top rated power?
  9. W5LZ

    W5LZ Ham Member QRZ Page

    To the question:

    There are quite a few. But be aware that the advertised power rating for almost all radios is only an approximation. Just too many variations in component values in any factory assembly line. And the it goes to the advertising department and Lord knows what they'll say. If its within 10% of spec figure it's right.
  10. W4EAE

    W4EAE Subscriber QRZ Page

    This would require your transmitted power to be cut in half at least. 13.8v vs 12v should not account for that. I think your gremlins are somewhere else in the power system.

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