Hi all, in my own vehicle I just installed a Kenwood KDC-MP202 stereo which is 4 channels just your regular run of the mill radio/CD player. Works great but my problem is when I transmit with a 100 watt low band radio (on 52 MC) for more than a few seconds the radio locks up on "protect" which according to the manual means it thinks that one or more speaker wires are shorted out. Then the radio must be hard reset which wipes out most all settings.
Thus far I have tried putting a snap on ferrite choke on each speaker pair in common mode configuration but no difference in behavior. I have not tried transmitting with any other band either.
I would appreciate any suggestions on this problem.
Birken
Low Band Transmit Trips Stereo Speaker Protection
Moderator: Queue Moderator
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Birken Vogt
- Posts: 262
- Joined: Thu Nov 10, 2005 7:53 pm
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Birken Vogt
- Posts: 262
- Joined: Thu Nov 10, 2005 7:53 pm
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Birken Vogt
- Posts: 262
- Joined: Thu Nov 10, 2005 7:53 pm
How is the coax run? My bet is that, at some point, it parallels something automotive, which is dumping RF into the stereo.
I had a similar problem with an XM install... ran the cable parallel to some Spectra control cables. System worked great - when the radios were powered down. Fire them up, XM would die.
I had a similar problem with an XM install... ran the cable parallel to some Spectra control cables. System worked great - when the radios were powered down. Fire them up, XM would die.
You might be forced into installing some RF bypass caps
inside the radio itself. Put these on all the speaker wires
with the other side of the caps going to ground. Something
on the order of .01 in value should do the trick.
Had a pickup a number of years ago that had all sorts of
issues when you keyed the low band transmitter. The
speedometer would jump to 60 plus MPH while parked.
Fuel guage would go to empty and other strange things.
After adding the bypass caps to the instrument pannel, I
got desparate. Had to add a couple of shorting bars
across the rear window. It was acting like a tuned duct
to the transmitter signal. The soultion was to add 2
aluminum straps from top to bottom of the window in
two places. Attached them with a couple of sheet metal
screws both top and bottom.
Jim
inside the radio itself. Put these on all the speaker wires
with the other side of the caps going to ground. Something
on the order of .01 in value should do the trick.
Had a pickup a number of years ago that had all sorts of
issues when you keyed the low band transmitter. The
speedometer would jump to 60 plus MPH while parked.
Fuel guage would go to empty and other strange things.
After adding the bypass caps to the instrument pannel, I
got desparate. Had to add a couple of shorting bars
across the rear window. It was acting like a tuned duct
to the transmitter signal. The soultion was to add 2
aluminum straps from top to bottom of the window in
two places. Attached them with a couple of sheet metal
screws both top and bottom.
Jim
Another thought.
Hello all:
First, if you can beg-borrow-or steal an NMO to UHF adapter, screw it onto the antenna mount and hook up a dummy load. Then key the radio. If you still kill the tunes radio then you've got cable leakage (crappy shield), or a poor ground at the antenna mount, or at the antenna cable plug, etc., or even RF coming back over the battery leads of the transmitter (not too great a chance, but hey).
For antenna cable leakage, consider Times Microwave's LMR195. it's a very low loss very low leakage replacement for 58U. It will work into the same connectors as 58.
BTW, where are you taking power for the transmitter from? Most of the higher power radios demand a direct battery connection which should also reduce the possibility of it being RF on the DC wiring.
Otherwise, if you don't get into the tunes radio, then it's radiated energy and it may wind up being a bugger to deal with, might have to consider using shielded twisted pair for the speaker leads, especially any of the longer runs. Oh, only ground that shield at the tunes radio end... don't need to be creating any ground loops, they can make things worse than what you started with.
Stan
First, if you can beg-borrow-or steal an NMO to UHF adapter, screw it onto the antenna mount and hook up a dummy load. Then key the radio. If you still kill the tunes radio then you've got cable leakage (crappy shield), or a poor ground at the antenna mount, or at the antenna cable plug, etc., or even RF coming back over the battery leads of the transmitter (not too great a chance, but hey).
For antenna cable leakage, consider Times Microwave's LMR195. it's a very low loss very low leakage replacement for 58U. It will work into the same connectors as 58.
BTW, where are you taking power for the transmitter from? Most of the higher power radios demand a direct battery connection which should also reduce the possibility of it being RF on the DC wiring.
Otherwise, if you don't get into the tunes radio, then it's radiated energy and it may wind up being a bugger to deal with, might have to consider using shielded twisted pair for the speaker leads, especially any of the longer runs. Oh, only ground that shield at the tunes radio end... don't need to be creating any ground loops, they can make things worse than what you started with.
Stan
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Birken Vogt
- Posts: 262
- Joined: Thu Nov 10, 2005 7:53 pm
For some reason the problem fixed itself. Originally it would happen all the time. Now it does not happen at all. I hope the RF burned up the stereo's protection circuit or something 
I can't remember for sure but I believe the antenna mount is an Antenex one with the RG-8X cable. We quit using those a long time ago and went to the foil shielded GR-58 style which are better anyway and don't have to stock two part numbers any more. We used to use the regular RG-58 Antenex ones for low and high band and the 8X for 220+ and cell phones. I had the 8X run already done even though it was overkill for low band obviously.
Birken
I can't remember for sure but I believe the antenna mount is an Antenex one with the RG-8X cable. We quit using those a long time ago and went to the foil shielded GR-58 style which are better anyway and don't have to stock two part numbers any more. We used to use the regular RG-58 Antenex ones for low and high band and the 8X for 220+ and cell phones. I had the 8X run already done even though it was overkill for low band obviously.
Birken
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High_order1
- Posts: 210
- Joined: Sun Oct 13, 2002 10:39 am
hmmmm
.... I might be showing my age here, but anybody remember how lowband would shut down a Dodge K car.... lol
Glad your problem resolved itself!
-Shawn
Glad your problem resolved itself!
-Shawn