Repeater question

Discussion in 'VHF/UHF - 50Mhz and Beyond' started by W7CJD, Apr 29, 2019.

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  1. W7CJD

    W7CJD Ham Member QRZ Page

    My "elmer" and his partner had a 1.2 GHz repeater, and used a 2-meter frequency to make changes.

    It seems a repeater group uses the reasonably nearby 2-meter repeater RX/TX for their sending changes to the repeater. For example, they link up other repeaters, add an announcement of the net, and whatever.

    I am having a problem:

    When this activity signals "busy" my transceiver overheats to the extent it had burnt my furniture, twice now. Okay, I am setting the alarm on my phone to turn ON my transceiver now, leaving it OFF until it is time for the net.

    Have I correctly accessed what is happening?

    Is it their using digital access to their 2-meter repeater on the repeater public frequency?
  2. AG6QR

    AG6QR Premium Subscriber QRZ Page

    After the burning incident, I'd suggest you leave your radio unplugged at all times unless the control operator is present at the control point and monitoring the operation (including temperature) of the radio.

    If your transceiver overheats to the extent that it burns furniture, you've got a problem with your transceiver which is your responsibility to fix. That sort of problem can't be caused by someone else's transmissions.

    A transceiver should run very cool when it's in receive mode, regardless of what it's receiving or what someone else is transmitting on a repeater frequency or otherwise. It's normal for a transceiver to warm up when it's transmitting, and continuous high-power transmissions may make some amateur transceivers fold back and eventually shut down. None should burn furniture, though.
  3. W7CJD

    W7CJD Ham Member QRZ Page

    I am present, and it runs cool all day.

    I have sat next to it, with my hand on it sitting on edge for maximum air around it.

    It was sitting directly on acacia wood furniture.

    Max power: 45 Watts

    Transmit: the worst SWR on 2/440 measured is 1.5

    I have a Diamond X50A collinear.

    I am not transmitting.

    I check-in on the net, and it doesn't get hot.

    I run it off a 10 Amp Radio Shack power supply, the power cable has fuses inline.

    The only time it makes excess heat is at those specific times I described.
    Last edited: Apr 29, 2019
  4. W7CJD

    W7CJD Ham Member QRZ Page

    I have this on the Radio Shack 10 Amp regulated power supply, so it isn't a power surge in this 1930's small rental house.

    The only other problem I can think of is the ground isn't good.

    ..but that wouldn't happen coincidentally at the same time.

    The 2/440 meter transceiver is an ICOM IC-2710.
  5. KD4UPL

    KD4UPL Ham Member QRZ Page

    I'm not totally sure I understand your original question but I agree with AG6QR, there's nothing anyone else's radio activities should be able to do that would cause your radio to overheat. Is any of your radio equipment being used by these repeaters or are you just listening to them. If you are just receiving a repeater output then you have some kind of radio problem.
    I will add that a 10 amp supply seems rather marginal for a 2m rig running at 45 watts. Have you checked you're radio's current draw when transmitting?
    As for the "power sure" in the house, a 10 amp 12v supply is only about 150 watts. That is hardly a big load for even the oldest of electrical wiring.
  6. W7CJD

    W7CJD Ham Member QRZ Page

    I don't have anything more than a UHF/VHF meter for SWR/Watts.

    The 12 VDC 10 Amp power supply should be "ample" for 45 Watts.

    The collinear was a repair, and a "gift" antenna.

    I do not have the SWR/Watt Meter inline.

    The 1940's house has 2-wire wiring, and only one 20-amp 3-wire outlet I requested located near the service outside the house.

    It is a rental after all.

    I have it on to monitor, as it is my understanding that is an obligation for 2/440 repeaters I can hear at my location.
    Last edited: Apr 29, 2019
  7. AG6QR

    AG6QR Premium Subscriber QRZ Page

    I agree with KD4UPL, it might be adequate but might not. I'd call it marginal, not ample.

    A transmitter's PA is typically about 50 percent efficient, more or less. So 45 watts out would require about 90 watts in. At 12V, that's 7.5 amps.

    True, 7.5 amps is lower than the supply's rating of 10 amps. So it ought to work, right? But the ratings on many supplies are peak or intermittent ratings. If you'll ever be transmitting for longer than a minute or two, you should find out what the supply's continuous duty rating is, and use that as a guide. The continuous duty rating of a supply with 10 amps written on the front nameplate might well be below 7.5 amps.

    I'm doing some guesswork here. If it were my gear, I'd take out a multimeter and measure the actual current draw while transmitting at full power, and compare that to the continuous duty rating of the supply, as listed by the manufacturer.

    But wait: I just looked at the manual of the Icom 2710 you said you have, and Icom claims a current draw of 12.0 amps when transmitting at max power. A ten amp supply is inadequate, even without getting into the difference between peak and continuous ratings.

    Be that as it may, a 10 amp supply should easily handle the radio when only receiving.
  8. W7CJD

    W7CJD Ham Member QRZ Page

    I transmit only the check-in.

    It gets hot, only at the time specified.

    I see 42-Watts out on the SWR/Watt Meter.

    There is nothing on the plate on the front or underside or any place else about continuous duty.

    I see the ICOM IC-2710 Specifications.

    10-watts Mid power is 6.5 Amps, however I cannot get into the repeater on Mid power.
    Last edited: Apr 29, 2019
  9. W7CJD

    W7CJD Ham Member QRZ Page

    I guess I am looking for a regulated power supply that will support 12 Amps High power transmit ICOM IC-2710 to more reliably get into the repeater.

    Meanwhile, the overheating when Busy while the repeater group is switching over repeaters and adding announcements for the net is still a mystery.
  10. W7CJD

    W7CJD Ham Member QRZ Page

    I read source over voltage can cause the power supply to fold back.

    I have had over voltage be a problem at this house.

    This is how I got the new service box on the outside of the house and one 3-wire 20-Amp outlet.

    The local electrical service offered a power conditioner to customers, for a price, but said the the one offered was insufficient.

    I would need a much more expensive power conditioner.

    This is why I have not used my rather expensive HF transceivers at this location.

    I may be better off operating 2/440 meter mobile and HF off my RV 4-solar panels.

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