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antenna splitter

mm2347

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Oct 21, 2008
238
oday 222 niagara
I have found mixed info. on using the VHF antenna and a splitter for a VHF and an AM-FM radio? Has anyone any experience that could give some give me some advice?
 
Oct 22, 2014
352
Pearson P303 #221 RockPort Maine
Id like to just say Think about the "WHAT IF". and you'll come up with the right answer. When you share a connection you are creating an issue. Is it my VHF radio or my stereo/AM/FM. The old school thinking is this is my life-line and you don't need anything to prevent me from making an emergency call. Your VHF is your life-line! This is IMO only.
 
May 20, 2016
2,992
Catalina 36 MK1 94 Everett, WA
I hav a Ray 200 splitter works just fine. am/Fm reception is better but poor. Am/fm never interferes with the VHF.
 
Sep 25, 2008
6,315
Alden 50 Sarasota, Florida
The problem with splitters is commonly that they fail eventually, some sooner but inevitably they can and will fail. The problem is exacerbated by the fact it is not apparent when they fail.

Do you really want to trust your ‘lifeline’ to a crap shoot?
 
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Feb 14, 2014
5,710
Hunter 430 Waveland, MS
The problem with splitters is commonly that they fail eventually, some sooner but inevitably they can and will fail. The problem is exacerbated by the fact it is not apparent when they fail.

Do you really want to trust your ‘lifeline’ to a crap shoot?
Not me! :plus::plus:

My Boat came with as similar antennae to this installed.
https://www.westmarine.com/buy/shakespeare--seawatch-3015-15-hdtv-antenna--16355778?recordNum=7
AM/FM and Digital TV.
Mounted about a foot below the masthead.

This only problem is when we are anchored in 1-2 seas, the Digital TV sometime fades in and out.
No biggie, TV off!;)
Jim...

PS: We also have a back up to our non-shared antennae VHF.:)
 
Mar 20, 2016
499
Beneteau 351 WYC Whitby
I have had a Glomex splitter, the vhf , am/fm and AIS for 3 years no problems. I don't think they are prone to crapping out ,however anything in life is possible. I just installed a second bilge pump,just in case. Anyways they can be easily bypassed if it were to happen.I also have the Glomex tv antenna no problems for 3 years ,getting over 50 stations
 
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SG

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Feb 11, 2017
1,670
J/Boat J/160 Annapolis
We had a Shakespeare VHF / AM-FM splitter without any failure for 11 years before we sold her 22 years ago.

We’ve had a splitter which also adds our AIS to the equation for 22 years on our current boat. No failures.

I understand some splitters have issues with the AIS function; but have seen it myself.
 
May 20, 2016
2,992
Catalina 36 MK1 94 Everett, WA
This is the same logic I hear opponents of networking instruments is. One device goes down and your hosed, nothing will work and you’ll die. I’ve had my network go down because of a failed component. It took longer by orders of magnitude to get helm relief than to troubleshoot, remove the problem and get it all working again

Where are the statistics showing splitters fail more often than the VHF? Right they don’t exist because none of the vendors publish failure rates. There is a reason I have 3 hand helds. They don’t have the distance, but my in-reach does, and I can get help from people close enough to render assistance. Go ahead and put an antenna&Zaire aloft, but you’ll need to show me that it is more reliable combo than the splitter. Look at you phone (cell or landline) you are multiplexed with dozens of other callers and never realize it. Same for AIS transmission.
 

LloydB

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Jan 15, 2006
543
Macgregor 22 Silverton
I have a handheld that can be connected to a permanent external antenna when I wish. I can think of no good reason to connect a device that will cut my power by more than half on the transmitter. Even a cheap 2nd antenna is more reliable than a ? splitter. KISS
btw who has a radio that interconnects the am and FM tuners?
 
Sep 25, 2008
6,315
Alden 50 Sarasota, Florida
Putting aside the fact there is no indication of failure to know when they do, you might want to consider insertion loss inherent in all splitters. We all see lots of discussion regarding the best coax to use to minimize loss. It makes no sense to use good quality coax just to negate any advantage by installing a larger loss.

Glomex specs state the insertion loss of their splitters between antenna and VHF is 3 - 4 dB which equates to a 50% loss. Shakespeare splitters even more. Both have insertion loss between
antenna and AIS at 5dB and from antenna and AM FM is 5dB.
 
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Oct 22, 2014
16,119
CAL 35 Cruiser moored EVERETT WA
I bought a Vesper Marine AIS, splitter, and tuned antenna.
Install was simple. Splitter is powered.
On failure it cuts out and passes VHF signal by default. If no signal is getting out it is a 30 second effort to remove the antenna coax connection and attach it directly to back of radio. All is backed up be a VHF hand held which I have attached to my person while sailing.
3 years no issues.
 
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Sep 25, 2008
6,315
Alden 50 Sarasota, Florida
I bought a Vesper Marine AIS, splitter, and tuned antenna.
Install was simple. Splitter is powered.
On failure it cuts out and passes VHF signal by default. If no signal is getting out it is a 30 second effort to remove the antenna coax connection and attach it directly to back of radio. All is backed up be a VHF hand held which I have attached to my person while sailing.
3 years no issues.
I know my repeated warnings are getting annoying but please understand it is a valid concern which motivates me to do this.

The “on failure it cuts out and passes VHF signal” is a misleading claim the manufacturer makes. In reality, they designed the splitter to default to antenna upon power loss, not “failure”.

Ultimately, it’s your boat and your choice.
 
Oct 22, 2014
16,119
CAL 35 Cruiser moored EVERETT WA
Thank you Don.

Help me understand the point failure.

Power loss to the splitter appears to be the prime issue. If water gets to the unit it is toast. But at that point the decks are awash.
A short in the splitter could induce failure. Suspect it might also fuse the internal wiring. It could at that point I suspect block the VHF signal. I would anticipate smoke and burnt smell at the Nav station.

Would that not be a time to remove the coax connection to the splitter and attach the antenna directly to the vhf radio?

An advantage of this configuration is I have one antenna on the mast. There are no ancillary connections to degrade the signal between the radio and antenna. The reported VWSR is <2:1 good.

I understand the concept of singular equipment on boats versus fully integrated systems.

I’d like to more clearly understand your observations. I’m learning new things every day.
 
Sep 25, 2008
6,315
Alden 50 Sarasota, Florida
Thank you Don.

Help me understand the point failure.

Power loss to the splitter appears to be the prime issue. If water gets to the unit it is toast. But at that point the decks are awash.
A short in the splitter could induce failure. Suspect it might also fuse the internal wiring. It could at that point I suspect block the VHF signal. I would anticipate smoke and burnt smell at the Nav station.

Would that not be a time to remove the coax connection to the splitter and attach the antenna directly to the vhf radio?

An advantage of this configuration is I have one antenna on the mast. There are no ancillary connections to degrade the signal between the radio and antenna. The reported VWSR is <2:1 good.

I understand the concept of singular equipment on boats versus fully integrated systems.

I’d like to more clearly understand your observations. I’m learning new things every day.
The typical loss expected from two common manufacturer splitters is depicted in the picture below:

C2787157-01D2-4770-8A81-CE1295B3EAAC.png
Note the loss is minimum observed with a 1:1 SWR for new components still within tolerance, not subject to extended use, vibration, humidity or nearby magnetic fields, all of which can contribute to component failure not readily apparent. Failure doesn’t usually result in “letting the built-in smoke” escape the case.
 
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cjm1

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Jul 10, 2013
40
custom Herreshoff 33 sloop Lake Charlevoix
I have had a Shakespeare unit for over 20 years and no problem at all. On the original question was for use with FM and I suspect they just use the braided ground as the FM ant anyway. AIS may be a different story.
 
Mar 20, 2016
499
Beneteau 351 WYC Whitby
I have the glomex and have vesper AIS ,am/fm radio
and have had no problems whatsoever picking up targets miles away in other harbors ,nor any problems transmitting or receiving radio calls miles away .glomax states their splitter is twice as powerful as competitor
rated at 100 watts and going to there spec's on their site I could find no reference to db loss of 50% . They do have a 15db amp to reduce loss.To each their own ,if they were so bad why would they even make them period. Don't install one then. I'm quite happy.Also it depends on cable ,the cable I'm running has 50% less loss than regular , rg213 ,its like a hose
 
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Sep 25, 2008
6,315
Alden 50 Sarasota, Florida
I have the glomex and have vesper AIS ,am/fm radio
and have had no problems whatsoever picking up targets miles away in other harbors ,nor any problems transmitting or receiving radio calls miles away .glomax states their splitter is twice as powerful as competitor
rated at 100 watts and going to there spec's on their site I could find no reference to db loss of 50% . They do have a 15db amp to reduce loss.To each their own ,if they were so bad why would they even make them period. Don't install one then. I'm quite happy.Also it depends on cable ,the cable I'm running has 50% less loss than regular , rg213 ,its like a hose
Please understand I’m not being critical. I’m only expressing an opinion based on decades of experience.

While Glomex doesn’t publish loss characteristics, please don’t be misled by their advertising a “15dB amp” as that refers to a receiver preamp which is irrelevant for RF radiated transmit power or power getting to the antenna. Receiver preamps amplify noise as well as signal as they can’t discriminate between them. Consequently, they do nothing to improve signal to noise ratio which is the indicator used to determines readability of received signals.
 
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