Montana Owners Club - Keystone Montana 5th Wheel Forum - View Single Post

H. John Kohl · 05-28-2005, 02:20 PM

I purchased the RV7012. My system did not work correctly because of interference from my Ham Radio Transmitter.
The Doran system uses the 430MHZ band. My ham radio was transmitting a beacon on 145 MHZ every minute. This is almost a third sub harmonic of the 430 MHZ freq. My Doran receiver would lock up and have to be reset by disconnecting the power. My ham radio also has a 440 MHZ transmitter and thank goodness I did not transmit on that band or I would have probably blown the Doran receiver.

I noticed the following operating characteristics.
The truck monitors seemed to work fine and always had telemetry on the tires, ever with the radio beacons. This is a good comment for the system
The trailer tires were intermittent - this may be because of the interference. I did turn off the transmitter when installing it and they did work correctly. Every time the system locked up it was one of the trailer tire positions that was effected.

Two of my trailer valve stems would not activate the pressure sending unit because it did not release any air into the unit. I had to improvise by flattening a number four lead shot from a shotgun shell (my brother-in-law loads his own shells). That spacer allowed the valve stem to release air for the unit to monitor pressure.

I did have a valve stem fail on one of the trailer tires. I noticed it in the morning as I was walking around. The system was not in use so I do not know what indications I would have gotten. I am not sure the extra weight of the transmitting units caused the problem but did take them off the rest of the trailer tires. I did not remove the truck units until I was back in NY. Someone told me we should be using metal valve stems when we run 80 psi or higher.

I like the concept and wish it was on a difference frequency.

Because of the Ham interference they did take back the unit and I should see a refund shortly.

Positioning the receiver so it is visible to the driver was a challenge. I used the visor hooks and it stayed in place but was not easy to view during the day. The visor slopped forward so the display was at a 60 degree angle away from me. At night you could see the display well.

Good luck and safe towing.

05-28-2005, 02:20 PM	#2
H. John Kohl Montana Master Join Date: May 2003 Location: New Bern Posts: 4,294 M.O.C. #311	I purchased the RV7012. My system did not work correctly because of interference from my Ham Radio Transmitter. The Doran system uses the 430MHZ band. My ham radio was transmitting a beacon on 145 MHZ every minute. This is almost a third sub harmonic of the 430 MHZ freq. My Doran receiver would lock up and have to be reset by disconnecting the power. My ham radio also has a 440 MHZ transmitter and thank goodness I did not transmit on that band or I would have probably blown the Doran receiver. I noticed the following operating characteristics. The truck monitors seemed to work fine and always had telemetry on the tires, ever with the radio beacons. This is a good comment for the system The trailer tires were intermittent - this may be because of the interference. I did turn off the transmitter when installing it and they did work correctly. Every time the system locked up it was one of the trailer tire positions that was effected. Two of my trailer valve stems would not activate the pressure sending unit because it did not release any air into the unit. I had to improvise by flattening a number four lead shot from a shotgun shell (my brother-in-law loads his own shells). That spacer allowed the valve stem to release air for the unit to monitor pressure. I did have a valve stem fail on one of the trailer tires. I noticed it in the morning as I was walking around. The system was not in use so I do not know what indications I would have gotten. I am not sure the extra weight of the transmitting units caused the problem but did take them off the rest of the trailer tires. I did not remove the truck units until I was back in NY. Someone told me we should be using metal valve stems when we run 80 psi or higher. I like the concept and wish it was on a difference frequency. Because of the Ham interference they did take back the unit and I should see a refund shortly. Positioning the receiver so it is visible to the driver was a challenge. I used the visor hooks and it stayed in place but was not easy to view during the day. The visor slopped forward so the display was at a 60 degree angle away from me. At night you could see the display well. Good luck and safe towing.