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Problem Solved: RFI Problem

Question:

– Hide quoted text — Show quoted text -Many thanks to all who responded to my request for help with my RFI problem. Every one of you were directly responsible for the solution. You all said I needed to provide more info and in compiling all the conditions under which the RFI occurred, I discovered the source of the problem.  I discovered that the isolator relay was staying closed, keeping the coach and chassis batteries connected at all times, thereby putting engine noise (EMI/RFI) onto the coach battery lines to which the radio is connected.  The cause of this is a defective Bi-Directional Isolator Relay Delay Diesel (Yes, that is the real name as stamped on the device)Part No. 00-00366-000, made by Intellitec.  This device, as near as I can logically assume, controls when the isolator relay is activated.  It apparently senses coach battery voltage, when the ignition switch is on, when the gen set is on and when you activate the Aux Start switch on the instrument panel.  I found that when ever the engine was running normally, the isolator relay was closed and  coach and chassis batteries were connected together and IT HAS BEEN THIS WAY SINCE THE COACH WAS NEW! I have disconnected the Aux Start switch input to to the Intellitec device and the EMI/RFI problem is history.  As the Aux Start switch also provides 12v directly to the isolator relay, the relay can be activated by the Aux Start switch.  At the present, I have the Aux Start switch sense wire dis-connected.  Anyone have any idea why the Intellitec device is installed in the system? Can any harm be done by leaving the wire dis-connected. For general info, during my trouble-shooting, I measured the AC hum on the coach  12v line at well under 100mv with a digital voltmeter. (BTW Will, I know the difference between a power converter and a power inverter.) Thank you all. Gee Bee

Hi Glenn,         This relay senses the voltage of both the starting and coach batteries. When either one is above 13.3 volts, it assumes that battery is being charged, and closes the relay to charge both sets. This is so it will charge the chassis battery when you are plugged in to shore power.         The generator lead "locks out" the relay, so that you will not have a conflict between the generator and the converter/charger (or inverter) trying to charge the battery at the same time. The ignition switch input locks out the relay when the voltage drops below 12 volts to charge the chassis batteries faster.         The other thing that it does is to reduce the coil voltage to the solenoid to about 4 volts after engaging to prolong the life of the solenoid coil. This may be the source of your problem- if they use a pulse width scheme to reduce that voltage , and the wire to the aux start swich is acting as an antenna (just a guess).         You might try calling Intellitec at 800-251-2408, they are a division of the Brunswick Corporation (the defense contractor), and they should be able to help you with your rf problem (maybe something as simple as a choke, or ferrite beads or something- I bet the hams on the group would know better than I).         Hope this helps. — Chris Bryant Bryant R.V.

Response:

It appears I was over optimistic as the problem is not solved as yet.   If there are some hams out there ( or anyone else)  who have some ideas about what I should do please let me hear from you.

The problem is not well enough defined to solve it by correspondence, in my opinion. Here is what I suggest: contact a Ham who lives close enough to actually look at the problem with you "hands on".  Any legitimate Ham with a higher class of license should know enough about the nature of interference to help you quickly.  But it is a shot in the dark from a distant keyboard!  If you don’t know any local Hams, the FCC database on the web will allow you to get the name, address and license class of Hams in your town or zip code.  Most (not all) are likely to be friendly and helpful – and if they do not personally feel competent to help they will be likely to name someone who is.  (We have a guy in our club who is an RFI consultant for the FAA). Will KD3XR

Response:

EMI/RFI problem is history.  As

It appears I was over optimistic as the problem is not solved as yet.  At least I know where the problem is.  Many thanks to Bryant for your info and I will contact Brunswick.   If there are some hams out there ( or anyone else)  who have some ideas about what I should do please let me hear from you. Windbreaker is certainly correct in that I am dealing with Black Magic and Voodoo. GeeBee

Response:

Many thanks to all who responded to my request for help with my RFI problem. Every one of you were directly responsible for the solution. You all said I needed to provide more info and in compiling all the conditions under which the RFI occurred, I discovered the source of the problem.  I discovered that the isolator relay was staying closed, keeping the coach and chassis batteries connected at all times, thereby putting engine noise (EMI/RFI) onto the coach battery lines to which the radio is connected.  The cause of this is a defective Bi-Directional Isolator Relay Delay Diesel (Yes, that is the real name as stamped on the device)Part No. 00-00366-000, made by Intellitec.  This device, as near as I can logically assume, controls when the isolator relay is activated.  It apparently senses coach battery voltage, when the ignition switch is on, when the gen set is on and when you activate the Aux Start switch on the instrument panel.  I found that when ever the engine was running normally, the isolator relay was closed and  coach and chassis batteries were connected together and IT HAS BEEN THIS WAY SINCE THE COACH WAS NEW! I have disconnected the Aux Start switch input to to the Intellitec device and the EMI/RFI problem is history.  As the Aux Start switch also provides 12v directly to the isolator relay, the relay can be activated by the Aux Start switch.  At the present, I have the Aux Start switch sense wire dis-connected.  Anyone have any idea why the Intellitec device is installed in the system? Can any harm be done by leaving the wire dis-connected. For general info, during my trouble-shooting, I measured the AC hum on the coach  12v line at well under 100mv with a digital voltmeter. (BTW Will, I know the difference between a power converter and a power inverter.) Thank you all. Gee Bee

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