The Refrigerator and Your SSB/Ham Radio

By Carolyn Shearlock © 2013 • all rights reserved

Don't lose a refrigerator full of food by forgetting to turn it back on when you're through with the radio!

Do you have a SSB or Ham radio on your boat?

Do you have to turn the refrigerator off when listening to the radio or sending email so that the compressor and fan don’t cause interference?* (Experts say you shouldn’t have to . . . but many of us do, regardless of how we try to remedy the problem. See Dave Skolnick’s comments below.)

Have you even forgotten to turn the refrigerator back on when you’re finished with the radio?

Uh-huh.  We did.  More than once.  Discovered it when we went to get cold drinks out and they weren’t as cold as usual.

We never lost food, although we came close once.  But we know of two boats that lost almost everything in their refrigerator and freezer because of this.

That’s a lot of money wasted, plus they had to head off to reprovision instead of enjoying the beautiful anchorage.  And you know that disasters like this happen when you’ve just stocked up, not when the refrigerator is bare.

A few days ago, I wrote about using an indoor/outdoor thermometer to monitor the refrigerator.  After I wrote that, it dawned on me that seeing a rising refrigerator temp would also highlight the possibility that you’d forgotten to turn the refrigerator back on.  See the temp up a bit and know to check the breaker and make sure it’s on — not really showing a problem with the refrigerator itself, but more an operator error . . . I hate those!

The down side is that yes, it requires that someone periodically check the thermometer. But if you put the display somewhere very obvious, you’ll check it many times a day without even realizing you’re doing it.

Another option that I’ve heard of is to wire a relay into the radio circuit, which turns the refrigerator/freezer off when the radio circuit is on, and then turns the refrigerator back on when the radio circuit is switched off.  It’s a bit of a PITA to do, particularly to get it working right, but it works . . . providing that you do turn the radio circuit off when you’re through with it.  (Somewhere, I’ve seen a wiring diagram for this, but I cannot find it online . . . nor can Google.)

Got any other “solutions” to remembering to turn the refrig back on?  Please leave a note!

*For those who are preparing to cruise and haven’t encountered this problem, you usually have to turn off anything with an electric motor to use the SSB or Ham radio (but not for the VHF).  Fans, refrigerator/freezer, generator, any inverters and also flourescent lights — there may be other things as well.

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  1. Joie de Vivre says:

    Yup, we’ve forgotten on more than one occasion. Fortunately one of us spotted it before it was a problem. We try to hang something on the radio on/off switch as a reminder to turn the fridge and wind generator back on when we are done with the radio.

  2. Paul Schrodee says:

    There are many kitchen timers that come with an oven-proof temp probe that cost less than $30. The brand that I have used for ten years now is “Taylor”. I use mine every time I make yogurt, both to monitor the scald temp and when I put it in the oven to “work” and monitor its temp there.
    There is an alarm feature that can be set when a given temp is achieved(180 for scalding milk). It only works on a rising temp scale so you cant use it to let you know when temps are falling. You could;however, set this it 45 degrees and it would let you know that your fridge is getting warmer.
    It is important for items on a boat to serve many purposes and this timer falls right in there.
    I use this timer for timing my perking coffee in the morning and reminding me to check on the yogurt after 4 hours and when grilling.
    BTW, I leave my timer on continuously and only change the two AAA batteries twice a year. I use rechargeables anyways, but the power usage is almost nothing.

  3. Paul Schroder says:
  4. Carolyn,

    There is no excuse for having to turn off the refrigerator. There are well known mechanisms (mostly a couple of capacitors and some ferrite beads – all very inexpensive) to reduce interference from compressors. Easy peasey.

    The interference sources that are more problematic are ventilating fans and DC-DC converters used for power supplies for laptops. Even those can be managed. Inverters and battery chargers and gasoline engines (like Honda EU2000i’s) are also sources of interference. Frankly I haven’t bothered with my own fans, Everything else aboard can run without discernible impact on the HF noise floor.

    There are good reasons for refrigerator and freezer temperature monitoring. Dealing with noise on HF is not one of them.

    Let me know if I can help with resources.

    sail fast and eat well, dave
    Dave Skolnick S/V Auspicious

  5. Thanks for this as we just got an SSB and have yet to hook it up 🙂

  6. Ahhhh…that explains the interferance! Thanks Boat Galley!!!

  7. Hi Carolyn,
    I have a red plastic clothespin that I leave by the nav station. When I turn the reefer breaker off, I clip the clothespin to the toggle. It’s an easy and effective reminder.

  8. This article sounds just like us. We have had all of these but it is realy only our wind generator which puts interference on the radio so we have a switch for that. But another interesting thing happened when we were sailing and used the ssb, the auto helm let go and we veered off course rather violently. This happened twice before we connected this phenomenon to the ssb so we had someone on standby when we were on the radio after that. Apparently when the volts drop when transmitting there is not enough in the system to power the autohelm and it turns off. Now we know we can deal with it…start the engine or have someone manually steer.

  9. Dan Thomas says:

    Now that you have the Gemini Catamaran, it has a propane refridge. You won’t have that problem any longer.

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