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Twin VHF's Bleed Over

Old 05-14-2008, 06:35 AM
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Default Twin VHF's Bleed Over

Got twin VHF's and one is keying over into the other when transmitting. What do I look for first?

Old 05-14-2008, 06:46 AM
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Default RE: Twin VHF's Bleed Over

Ludicrous - 5/14/2008 9:35 AM

Got twin VHF's and one is keying over into the other when transmitting. What do I look for first?
What to you mean by "keying over into the other when transmitting" ?

If one is in the receive mode and you transmit on the other, you will hear your transmission just like another boat would.
Old 05-14-2008, 07:00 AM
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Default Re: Twin VHF's Bleed Over

I'll key on (any channel...not 16) on VHF 1 and it bleeds into the other VHF on channel 16.

Old 05-14-2008, 07:31 AM
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Default Re: Twin VHF's Bleed Over

Is your second VHF just going to 16 when you key the mic on the first vhf, or is what you are transmitting on the first vhf actually being picked up on channel 16 on the second vhf?
Old 05-14-2008, 07:40 AM
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Default Re: Twin VHF's Bleed Over

SeaSwirler23 - 5/14/2008 10:31 AM

Is your second VHF just going to 16 when you key the mic on the first vhf, or is what you are transmitting on the first vhf actually being picked up on channel 16 on the second vhf?
Yes. I'll be on channel 10 x-mitting on VHF 1, and the other vhf on 16 will crackle, snap and pop.
Old 05-14-2008, 08:11 AM
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Default Re: Twin VHF's Bleed Over

They're too close. Try moving the antennas/radios and all wiring as far apart as possible. Also check your grounds - make sure they're perfect.

Ken
Old 05-14-2008, 09:20 AM
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Default RE: Twin VHF's Bleed Over

Are they grounded in the same neg bus?
Old 05-14-2008, 09:41 AM
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Default RE: Twin VHF's Bleed Over

DarthBaiter - 5/14/2008 12:20 PM



Are they grounded in the same neg bus?
I'll check. Not real familiar with the vessel yet. It's needs help in a few departments, but the VHF's are my first priority.
Old 05-14-2008, 09:44 AM
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Default RE: Twin VHF's Bleed Over

Ludicrous - 5/14/2008 9:41 AM
DarthBaiter - 5/14/2008 12:20 PM

Are they grounded in the same neg bus?
I'll check. Not real familiar with the vessel yet. It's needs help in a few departments, but the VHF's are my first priority.
What boat is this? Did you get a new boat already?

I was told, long ago, that VHF should be on it's own neg bus or the neg should be directly wired to the battery.
Old 05-14-2008, 09:49 AM
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Default Re: Twin VHF's Bleed Over

It's the 81' Whaler. I like the VHF's direct to the battery, fused close to the batteries, each vhf on it's own battery. Don't know how this vessel is setup, but I know it isn't right.






Old 05-14-2008, 01:31 PM
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Default Re: Twin VHF's Bleed Over

A VHF radio puts out 25 watts of RF power (when on high power). If the antenna of the transmitting radio is too close to the radio that's in the receive mode, its antenna, or too close to the wiring for that radio, the signal can overpower the second radio's circuits.

Troubleshooting this problem could be difficult and may involve having an experienced pro or ham radio operator track it down.

One thing you can do on your own is to disconnect the antenna from the receiving radio. If this stops the problem, the antenna is too close, you'll have to move it. If it doesn't stop the problem, it could be in the receiver itself or the power or external speaker or GPS interface wiring.
Old 05-14-2008, 10:52 PM
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Default Re: Twin VHF's Bleed Over

Use lower power.
Old 05-15-2008, 02:37 AM
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Default Re: Twin VHF's Bleed Over

Ludicrous,

Please post pics somewhere of your Frontier with the Verados; I'd love to peak at it. Best of luck.
Old 05-15-2008, 09:39 AM
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Default Re: Twin VHF's Bleed Over

Its called bleedover.

George
Old 05-15-2008, 05:59 PM
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Default Re: Twin VHF's Bleed Over

rwidman - 5/14/2008 1:31 PM

A VHF radio puts out 25 watts of RF power (when on high power). If the antenna of the transmitting radio is too close to the radio that's in the receive mode, its antenna, or too close to the wiring for that radio, the signal can overpower the second radio's circuits.

Troubleshooting this problem could be difficult and may involve having an experienced pro or ham radio operator track it down.

One thing you can do on your own is to disconnect the antenna from the receiving radio. If this stops the problem, the antenna is too close, you'll have to move it. If it doesn't stop the problem, it could be in the receiver itself or the power or external speaker or GPS interface wiring.
rwidman has it. I have no experience with trying to run 2 vhfs on the same boat, but 2 ham radios in the truck on the same band (or even in 2 different cars) can cause something similar, especially when running 25 or more watts with a gain antenna.

Here's what I would try:

1) key radio 1 and listen for noise on radio 2. Key radio 2 and listen for noise on radio 1. That may give you clues for later in the diagnosis.

2) remove one antenna. It would be best if you could remove the antenna while leaving the coax still connected to the radio. Key other radio and listen for noise. Repeat for other radio. If this solves the problem then it is likely the antennas are too close

3) remove coax from radio. Key other radio and listen for noise. Repeat for other radio. If this solves the problem then I'm going to bet on a bad coax.

4) If you have them, disconnect external speaker one at a time and test as before. If it's a fix, try shielding the speaker (Aluminum foil will work for the test).

5) If all of this doesn't fix the problem, then check your wiring. You could have bad connections, speaker wires, or coax that is picking up the signal and feeding it back. Sounds like you are going to be investigating the wiring anyway.

6) if none of this fixes the problem then you need to have the offending radio checked out. If you are getting the noise on both radios in test #1, then I would guess that it is a wiring or placement problem and not a radio problem. It would be unlikely for both radios to have the same problem even if they are the same make.
Old 05-16-2008, 08:22 AM
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Default RE: Twin VHF's Bleed Over

I'm super lazy so I would just get some wire and check the neg ground first. I wouldn't even run it, just tape it on to the rasio connectors and out the box to the battery.

If that doesn't do it, then I'd go up and move the antenna around...but that's just my lazy a$$ way of doing things.



My two radios(Icom M-602 and aRay 54)are sitting on top of each other and the antenna(two 8' Digitals)can't be more than 2 feet from each other and the radios. No blreed over. If that info helps at all...

I know it's different for each radio and antenna...

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