VHF - AIS antenna splitter ??

Refueler

Refueler

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OK .. this is a thread to ask why ? Not to ask for links to specific units. Hoping that someone can answer ...

I have avoided using a splitter by having a rail mounted AIS antenna separate from my masthead mounted VHF antenna. Range of AIS is course reduced ....
I have looked at Splitters to improve the AIS capability but prices I find high and I feel can be better spent elsewhere.

During searches though - I found various VHF antenna splitters that were basic generic boxes with required electronics inside. I decided to buy and see what I get. Price ? ~27 euros + any customs fee.

14.15￡ 40% OFF|2 Way VHF 136 174MHz Antenna Power Divider Splitter for Radio Repeater Power|Device Cleaners| - AliExpress

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The question is :

I can easily understand that reception can be easily split and served ... but when VHF is keyed and sending 25W out ... is that box going to switch and protect the AIS side ? When AIS is sending out its 3W or 10W depending on your AIS ... is that sufficiently divided ?

I have not installed the unit yet .. basically still limited mobility from spine injury. So I thought I would put the question and see what answers I get.
 
You've bought some unknown Chinese tat. No one can answer your questions unless they bought the same junk and tested it. All that testing is what the major manufacturers do before they sell their products.
So fit it, test it and let us know if it works or kills your radios. ;-)
 
I confess not understanding the logic of wanting a splitter: the AIS uses a difference range of frequencies to the VHF so if you have a correct VHF antenna, it is hardly going to benefit the AIS. An AIS antenna doesn't seem to need great height - I have no mast now and I get 10nm range easily. And the last thing I would want to risk is the performance of the VHF by sharing - another connection in the system. I admit to be prejudiced against splitters.
 
From the product listing, I couldn't tell what function it is meant to provide. At a guess, it is a simple passive receive-only device - like using one antenna for 2 TVs. I would not risk my VHF radio or AIS using it as there is probably no isolation between the two outputs. There is no indication of what transmit power it will handle, so presumably none. The insertion loss is high at 3.4dB, so your AIS transmission will be weaker than using the direct antenna connection you have now.

Fully-specced splitters have defined VHF and AIS connections. This is because the failover mode is for VHF to remain connected and AIS isolated.
 
tillergirl said:
I confess not understanding the logic of wanting a splitter: the AIS uses a difference range of frequencies to the VHF so if you have a correct VHF antenna, it is hardly going to benefit the AIS. An AIS antenna doesn't seem to need great height - I have no mast now and I get 10nm range easily. And the last thing I would want to risk is the performance of the VHF by sharing - another connection in the system. I admit to be prejudiced against splitters.
Click to expand...

The difference in antenna for VHF radio vs AIS is not that great and for practical purposes can be ignored.

I too have been a non splitter person ... but decided to revisit the matter. Of course my rail mounted antenna will give at worst at least more than Line of Sight ... and with a high mounted antenna on another vessel - more than that.

I have sent question to seller .. will be interested to read reply.

As I mentioned - I am still limited mobility after spinal surgery - so I have time to reflect on the unit and its use.

If it does actually work - then even though I can afford the crazy 'marine' price - I am not averse to saving a few quid ! Considering that vast majority of electronics today is 'chinese tat' (using anothers words) .. whether cheap budget or expensive gear.
 
MikeCC said:
From the product listing, I couldn't tell what function it is meant to provide. At a guess, it is a simple passive receive-only device - like using one antenna for 2 TVs. I would not risk my VHF radio or AIS using it as there is probably no isolation between the two outputs. There is no indication of what transmit power it will handle, so presumably none. The insertion loss is high at 3.4dB, so your AIS transmission will be weaker than using the direct antenna connection you have now.

Fully-specced splitters have defined VHF and AIS connections. This is because the failover mode is for VHF to remain connected and AIS isolated.
Click to expand...

The passive I can see may be true as there is no power to it ...

Waiting reply from seller ....
 
tillergirl said:
I confess not understanding the logic of wanting a splitter: the AIS uses a difference range of frequencies to the VHF so if you have a correct VHF antenna, it is hardly going to benefit the AIS. An AIS antenna doesn't seem to need great height - I have no mast now and I get 10nm range easily. And the last thing I would want to risk is the performance of the VHF by sharing - another connection in the system. I admit to be prejudiced against splitters.
Click to expand...
Actually, the frequencies are (about) 162MHz for AIS and 156-162 MHz for VHF (rounded to the nearest MHz). The difference in length of antenna is minimal, and easily covered by the bandwidth of the antenna. So, a VHF antenna will do very well for AIS.
 
It looks like a simple passive splitter, I would not want to send power out and have it overload the input of either vhf or ais, I’ve made similar for ham radio use but for receive only.

for transmit you really need active switching
 
AntarcticPilot said:
Actually, the frequencies are (about) 162MHz for AIS and 156-162 MHz for VHF (rounded to the nearest MHz). The difference in length of antenna is minimal, and easily covered by the bandwidth of the antenna. So, a VHF antenna will do very well for AIS.
Click to expand...
And the separation is so small, that a passive splitter would be very difficult to design.

The original looks more like a 3dB splitter - with unknown separation between the 2 ports. Could test with a NanoVNA before attaching to anything expensive.
 
Refueler said:
I can easily understand that reception can be easily split and served ... but when VHF is keyed and sending 25W out ... is that box going to switch and protect the AIS side ? When AIS is sending out its 3W or 10W depending on your AIS ... is that sufficiently divided ?

I have not installed the unit yet .. basically still limited mobility from spine injury. So I thought I would put the question and see what answers I get.
Click to expand...
It is difficult to answer this as no doubt the manual and labelling is difficult for us folk to read and understandso we are unaware if this is a basic splitter only designed to have transmit from one source as is usual with only the second receiving source protected or if it is the Supa Dupa A1 version which can accept transmissions on both inputs and which would suite you. Personally I would play safe and not use it between a transmitting AIS and a VHF transceiver unless I was absolutely sure of its design as even 5 watts might fry your VHF radio receiver.

The legend on the label suggests it may actually only be suitable for splitting between two receivers so you could easily fry your AIS and your VHF.I wonder if any one here can read the legend.
 
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I can ask my Chinese Office for translation of the characters. Stand by ....

edit : Picture sent to my guys ... so lets see what it says. The only wording is that small label ... nothing else.

My guys replied :

"Microstrip Two way power divider"

So says nothing that we already did not know.
 
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Bilgediver said:
Thanks. I have asked a friend in Singapore but might take overnight.
Click to expand...

My Chinese office in Shanghai already answered ... thanks anyway.

The translation first given me was : "Two way power divider " ... then a second given that added the "Microstrip".

I am considering getting my guys to find a factory that makes them .. but it could be needle in haystack ... and as I know and they also said - Seller is not manufacturer and will know very little tech ...
 
Refueler said:
My Chinese office in Shanghai already answered ... thanks anyway.

The translation first given me was : "Two way power divider " ... then a second given that added the "Microstrip".

I am considering getting my guys to find a factory that makes them .. but it could be needle in haystack ... and as I know and they also said - Seller is not manufacturer and will know very little tech ...
Click to expand...
They are being more polite than I would be about Ali E. ;) ;) ;) That does suggest it may only be receive divide only . Beware.
 
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