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Splitting VHF two ways

Old 09-01-2017, 05:40 AM
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Default Splitting VHF two ways

Hello
I had just bought a boat and it came with two old VHFs and two antennas. I have bought a new VHF just so I feel better and know that I can trust this one, Although I wasnt sure if I needed another VHF antenna or if I can run two VHFs off of one antenna by splitting the cable. Is this possible? Has anyone ever tried it or do I need to buy a new antenna?

Thanks
Old 09-01-2017, 06:17 AM
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For true redundancy, you need two antennas.
Old 09-01-2017, 06:44 AM
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Sharing the same antenna between two transceivers on the same band, where they could be on the same freq. is essentially unfeasable.
Put in a small, metal antenna for the 2nd.
Old 09-01-2017, 06:49 AM
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manual:

https://www.westmarine.com/buy/shake...AaAku_EALw_wcB

automatic:

https://www.westmarine.com/buy/shake...kaAvzaEALw_wcB
Old 09-01-2017, 07:51 AM
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It is certainly possible to do, but not usually advisable. You'll have less problems and more options if you have two antennas for the two radios.
Old 09-01-2017, 09:01 AM
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Originally Posted by tommy099431 View Post
Hello
I had just bought a boat and it came with two old VHFs and two antennas.
I have bought a new VHF just so I feel better and know that I can trust this one,

My guess is, he will put the new "good" VHF - #3 - on one antenna

and wants to know if he can use a splitter for old VHF #1 and 2.

Which of course he can.
Old 09-01-2017, 09:46 AM
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Originally Posted by Fwpratt View Post
My guess is, he will put the new "good" VHF - #3 - on one antenna

and wants to know if he can use a splitter for old VHF #1 and 2.

Which of course he can.
And it's still not advisable.

Would like the OP to clarify. I was thinking he was replacing one of the radios, but you might be right that he is just adding a third. Why would you do that? I'd suggest donating the old radio to another boater who doesn't have one and they can deal with whether it works or not. Having an old radio is better than no radio.

The new radio will also come with the "emergency button" function and should be wired into a GPS unless it's got one built in.
Old 09-01-2017, 10:42 AM
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switches. What happens if both radios key up? is it a race for the antenna, and the odd man is into an open load?
Old 09-01-2017, 10:51 AM
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2 antennas look cool
Old 09-01-2017, 01:44 PM
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Originally Posted by diver dave View Post
switches. What happens if both radios key up? is it a race for the antenna, and the odd man is into an open load?
You do not want to key the mic using the manual switch. The automatic one's switch gets triggered when you key the mic, so no worries there. There is still the potential for signal loss when running any splitter.

Personally, two radios is great, i don't care to have 3. The value of the 3rd is significantly less than the second. if you want a 3rd use a handheld.
Old 09-01-2017, 01:55 PM
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Originally Posted by tommy099431 View Post
... can [I] run two VHFs off of one antenna by splitting the cable.
No--it is not possible to operate two transmitters into one antenna "by splitting the cable," as that really has no meaning to anyone who is familiar with radio transmitters and transmission lines.

Originally Posted by tommy099431 View Post
...Has anyone ever tried it...
Perhaps someone has "tried it" by "splitting the cable"--whatever that means--but I would not make a decision to try it based on it having been tried before.

To feed two transmitters into one antenna is mostly impossible, unless there are extraordinary circumstances that force this to happen and there are also extraordinary money and engineering resources available to make it happen.

Originally Posted by tommy099431 View Post
...do I need to buy a [third] antenna [to use with the third radio]?
Each radio transmitter will need to have its own transmitting antenna if you intend to be able to simultaneously use all three transmitters. Exactly how you'd need to be able to transmit simultaneously on three transmitters in the VHF Marine Band from a small recreational boat seems rather hard to fathom.
Old 09-02-2017, 05:26 PM
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I have three VHFs and only two Antennas, I wanna put the new VHF on one antenna and put the other two on one antenna. But it doesnt seem like its possible so ill just buy a new antenna and have Three VHFs and Three Antennas
Old 09-03-2017, 01:54 AM
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Originally Posted by diver dave View Post
switches. What happens if both radios key up? is it a race for the antenna, and the odd man is into an open load?
I'd suspect those splitters have the other radio hooked to a dummy load.
Old 09-03-2017, 04:18 AM
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Originally Posted by hannahranga View Post
I'd suspect those splitters have the other radio hooked to a dummy load.
the manual version is simply a switch - nothing more.
Using it requires an understanding of that - and some situational awareness.
Old 09-03-2017, 04:24 AM
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Cannot comprehend why you need 3 radios, nor why you would buy new before determining viability of the "old" radios. Remove the worst one.
Old 09-03-2017, 07:11 AM
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Even if i had 3 vhf's i wouldn't have all 3 active. One power surge or lightning would take them all out. Saying that, there are lots of pleasure boats with 2 even 3 helm positions plus even a nav station. I rented a trawler once with no vhf on the bridge. That was bad.
Old 09-03-2017, 10:20 AM
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Originally Posted by tommy099431 View Post
Hello
I had just bought a boat and it came with two old VHFs and two antennas. I have bought a new VHF just so I feel better and know that I can trust this one, Although I wasnt sure if I needed another VHF antenna or if I can run two VHFs off of one antenna by splitting the cable. Is this possible? Has anyone ever tried it or do I need to buy a new antenna?

Thanks
You use a switch. Shakespeare makes one, there are others as well:
https://www.amazon.com/Shakespeare-A.../dp/B000GFWWMS

Note only one radio will be in use at a time.

If you are trying to achieve with two active radios into one antenna is not practical as far as I can tell with off the shelf components.

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