A-B electrical interference

[John Visser]

I am experiencing a lot of electrical noise in my VHF radio that is correlated with the A-B Cold Machine running. How can I surpress the electrical noise coming form the A-B so it doesn't interfere with my electronics?Thanks,jv

 

[Gary Buttrey]

go direct

Wire your ColdMachine directly to the batteries via a 10 amp breaker. Wiring to the battery selector switch should also eliminate VHF RFI.You can drop a temporary line to see if it works. Be sure to use wire of the correct guage for the length of run. Refer to your ColdMachine owners manual.

 

[John Visser]

More

Thanks for reply Gary. First, I don't have an owner's manual (see other note). But, I do understand the importance of the correct gauge wire. Mine looks like 10 gauge, and the run is from the panel (in a C-36) to the port side below the port cockpit locker; I guess about a 40' roundtrip, maximum. This should give me a less than 3% drop at 5 Amps. I don't understand the logic about wiring directly to the battery through a 10 Amp breaker. Mine is wired through a 15 A breaker on a Blue Sea Systems panel, the red on the breaker and the black on the neg. bus. The plus bus is wired to the battery selector switch with 4 gauge wire, and the neg bus to the ship's battery neg. bus through 4 gauge wire. Is there come kind of filter recommended to keep the conducted noise off the bus? How about radiated?It the Cold Machine FCC/CSA approved?Thanks,jv

 

[Bill Ogilvie]

Common Mode Filter

I'm a very new sailboat owner but do know a little about solid state coolers and radios. This is all theoretical, but it may help- Solid state (Peltier junction) coolers operate with the best efficiency when they have a steady DC voltage. To get the right temp. regulation a switching regulator can be used to convert the 14 VDC battery voltage to whatever DC voltage is needed - typically 9 - 20 VDC. A switching regulator chops up the DC and throws a lot of noise back on the DC line. Radios are very susceptible to this noise. When the cooler is switched on the radio's squelch will open and a loud hiss is heard. The solution is to place a common mode filter inside the cooler where the power enters. This is 2 sets of windings over a ferrite core. If you know someone with a Ham licence or have an EE friend, they can help you. I don't know if marine suppliers carry this kind of thing. Usually they are custom made.