VHF cable connector type advice please

[picardy]

I want to be able to cut a VHF cable below deck and have a connector to allow for the antenna to be removed. The connectors I am researching are a total minefield.

Please can someone send me a link for a male to female connector that is as small as possible - am looking at FME and BNC (assume that' right?) but connector will be in a locker so some moisture in the air is inevitable....

Many thanks

 

[V1701]

PL259 connectors are likely to be the ones that you need, loads of them on ebay. There are videos on Youtube showing how...

 

[179580]

PL259 connectors are likely to be the ones that you need, loads of them on ebay. There are videos on Youtube showing how...

BNC are smaller

 

[st599]

There is no standard for PL259 and SO239 which are 1930s designs.

BNC is more strictly defined and has better impedance matching. Just make sure you get the correct impedance.

 

[harvey38]

There is no standard for PL259 and SO239 which are 1930s designs.

BNC is more strictly defined and has better impedance matching. Just make sure you get the correct impedance.

Impedance matching to coax cable I assume?

Watching with interest as I can't find an antenna with sufficient cable attached!

 

[Skylark]

What size is the coax cable, this may determine the type of plug and socket to use?

How often do you plan to remove the antenna and how much moisture in the locker?

Your choice is likely to be PL259 (large) and BNC (smaller). If you are concerned about moisture, particularly salty, then why not consider making the join permanent but leave an excess for a second/third cutting? Moisture could affect the plug and socket and impair the signal.

 

[picardy]

Hi thanks for the comments - all really helpful. It's RG58 cable.

Locker should be fairly dry but nevertheless in a damp environment as they all are - likely to remove 3 times a year.

 

[st599]

Impedance matching to coax cable I assume?

Watching with interest as I can't find an antenna with sufficient cable attached!

Yes, should be 50 ohm. 75 ohm BNC and the like are used in pro video applications, and have a different sized centre pin which ruins 50 ohm sockets.

 

[Skylark]

Hi thanks for the comments - all really helpful. It's RG58 cable.

Locker should be fairly dry but nevertheless in a damp environment as they all are - likely to remove 3 times a year.

Just one of many from a Google search
BNC Connector Plug for Rg58 Coax 50 Ohm CCTV Ham Scanner Radio for sale online | eBay

Choice of plug and socket is typically either solder and compression or crimp. Both types require tools and a bit of skill but there's lots of YouTube help available.

 

[SlowlyButSurely]

My vhf coax cable is connected using a choc block. Simple and works fine and has been for the last 35 years.

 

[ProDave]

Definitely BNC would be my choice. But make sure you buy 50 ohm type, they are also available as 75 ohm. Get an in line plug and in line socket.

The BNC series have rubber gaskets built in on the mating surfaces and on the cable clamp so should be moisture resistant.

 

[st599]

My vhf coax cable is connected using a choc block. Simple and works fine and has been for the last 35 years.

With a return loss meaning that at least half your power is being reflected back to the transmitter and never making it to the antenna.

 

[jwilson]

Two "no solder" 50 ohm BNC plugs and a 50 ohm BNC barrel coupling. I think I bought from CP Farnell when i had to remove mast and original uncut cable.

 

[picardy]

Excellent thank you everyone

 

[TopBanana]

You can wrap the connection in self amalgamating tape

 

[SlowlyButSurely]

With a return loss meaning that at least half your power is being reflected back to the transmitter and never making it to the antenna.

Is there a way of measuring that because in practical terms there has been no discernible loss of range when transmitting or receiving.

 

[st599]

Is there a way of measuring that because in practical terms there has been no discernible loss of range when transmitting or receiving.

Yes, with a VSWR meter or similar or by measuring the PA temp vs. an impedance matched cable and antenna.

There will be a loss of range, but it will be inverse square law based, not linear.

 

[Skylark]

Yes, with a VSWR meter or similar or by measuring the PA temp vs. an impedance matched cable and antenna.

There will be a loss of range, but it will be inverse square law based, not linear.

Could you measure / compare impedance of the coax using the Smith Chart function on a NanoVNA? I bought one of these instruments recently and would like to better understand the usefulness (or otherwise) of the Smith Chart.

 

[savageseadog]

Do a radio check with the Coastguard to make sure it's OK..............................Noooooo! Please don't. Use a handheld, liase with other boats or Marina.

 

[st599]

Could you measure / compare impedance of the coax using the Smith Chart function on a NanoVNA? I bought one of these instruments recently and would like to better understand the usefulness (or otherwise) of the Smith Chart.

You'd be better off measuring S11 (reflections) and S21 (loss) - but yes you could use it to show the impedance. Antenna Matching with a Vector Network Analyzer