VHF Solderless connectors

[santavey]

Coax cable is terminated at the antenna (Vtronix) end by a small hollow metal bullet that that makes contact with the outer braid.
The inner is cut flush with the top of the bullet such that none of the inner protrudes or can make contact with either the antenna proper, the bullet or braid.
The whole assembly is then pushed into the base of the antenna.
Question: if the inner doesn’t make contact with the antenna proper how on earth does it work?

 

[ProDave]

There must be a pin, or something similar inside the antenna that does make contact with the inner when you push the assembly in. So make sure you push it in nice and square. Check VERY carefully that none of the strands of the braid are over the end of the cable, or you will probably get a short.

Check the SWR once installed. If it's poor, that connection is the first place I would look.

 

[santavey]

Your right. There is a minute pin only seen with a magnifying glass, at least with my eyes, that makes the connection.
Not very impressed, seems a bit hit and miss.
Anyone know of an antenna thats already assembled with 50ft of cable?

 

[Poignard]

I have a Glomex vhf aerial and the masthead connector is very easy to assemble (no soldering needed). A short length of the inner core is exposed and folded back along the dielectric. That makes contact with the aerial. I have taken mine off every winter for years and not had a problem remaking the connection.

 

[Bilgediver]

Your right. There is a minute pin only seen with a magnifying glass, at least with my eyes, that makes the connection.
Not very impressed, seems a bit hit and miss.
Anyone know of an antenna thats already assembled with 50ft of cable?

Providing the coax is correctly prepared and the centre conductor is multi strand it wors fine as the pin forces its way down between the strands.

Mind you if the coax is corroded due to water penetration then the connection might not be good. This is quite a good system for a connection that sometimes is dealt with from a Bosuns Chair swinging 30 ft above the deck.

There is no need to break this connection when the mast is taken down as most brackets are slotted and so allow the antenna to be taken off and turned end for end and put back on the mast facing the wrong way for storage with out disconnecting the feeder.

 

[Playtime]

Coax cable is terminated at the antenna (Vtronix) end by a small hollow metal bullet that that makes contact with the outer braid.

If it's a standard VTronix whip like the one I fitted a few weeks ago, there is a simple DC resistance test that can be used to check for a good connection. If you measure across the pins of the PL259 plug on the end of the coax at the radio, you should get a reading of 10K Ohms. It would be worth checking the installation instructions (if you've still got them) to see if this applies to yours.

If you get zero or short circuit then it indicates a problem (or that you have a different type of antenna ).

 

[davidpbo]

If you measure across the pins of the PL259 plug on the end of the coax at the radio, you should get a reading of 10K Ohms. It would be worth checking the installation instructions (if you've still got them) to see if this applies to yours.

If you get zero or short circuit then it indicates a problem (or that you have a different type of antenna ).

I am open to correction but I seem to remember when messing with my aerial which may be a Vitonix that I had a very low resistance of 1 Ohm between core and screen of the cable. Further investigation showed that this was intended and caused by a coil in the base of the aerial with a centre tap, can't remember exactly how things were connected but both the screen and the core of the cable were connected to the coil, one to the bottom and the other either to the centre tap or other end. The long and short of it was that the D.C. meter saw it as a short with maybe 1 Ohm but it was high impedance at radio frequencies.

I too remember wondering how the cable was connected until I saw the pin.

 

[dutyhog]

That's a huge coincidence - this afternoon I was struggling to discover why my brand new Vtronix whip was only working intermittently (not yet on the mast). I unscrewed the black plastic thing that pushes in the coax to the aerial, and the "bullet" stayed behind. Fortunately it is threaded, and an M6 screw pulled it out. I could see the sharp pin inside, withdrew the plastic bits, put the coax neatly back in to the bullet, and pushed the coax plus bullet in as far as possible by hand, then screwed it all together hand tight.

The 10kohm test is fine for continuity, but not for RF performance (which should be 50 ohms) which needs a SWR check, as suggested above.

 

[pteron]

Push fit? On a boat? In seawater?

Doesn't seem right to me.

Solder it.

 

[planteater]

Push fit? On a boat? In seawater?

Doesn't seem right to me.

I've had two of these of the years and they work fine, in my experience. If you can manage a good push fit at the masthead and another at the radio with no connectors in between you will get excellent VHF performance.

 

[Bilgediver]

Push fit? On a boat? In seawater?

Doesn't seem right to me.

Solder it.

Push fit is wrong.....you are supposed to have enough excess braid through the bullet to bend back over the bullet nose and this clamps the coax in place. The inner core I believe is left about 7 mm proud with a flush end.

Certainly not intended to just push fit!!!!!!

Soldering is not possible due to design.

 

[PetiteFleur]

I've just removed a Glomex aerial from my mast and that had a similar system - the copper wires were all corroded when dismantled. I fitted a new aerial which had a PL259 connector on it - so easy to have a cable with a soldered end fitting.

 

[VicMallows]

I am open to correction but I seem to remember when messing with my aerial which may be a Vitonix that I had a very low resistance of 1 Ohm between core and screen of the cable. Further investigation showed that this was intended and caused by a coil in the base of the aerial with a centre tap, can't remember exactly how things were connected but both the screen and the core of the cable were connected to the coil, one to the bottom and the other either to the centre tap or other end. The long and short of it was that the D.C. meter saw it as a short with maybe 1 Ohm but it was high impedance at radio frequencies.

I too remember wondering how the cable was connected until I saw the pin.

Older Vitronix antennas indeed appeared as a very low resistance due to the coil. Current ones show as 10k, presumably to make it much easier to identify an unwanted short somewhere in the cable/connectors.

Vic

 

[ithet]

I fitted one of these last year and wondered if it was possible to fit a connector as the thread seemed right, just a matter of whether the centre would reach the pin?

 

[pteron]

Push fit is wrong.....you are supposed to have enough excess braid through the bullet to bend back over the bullet nose and this clamps the coax in place. The inner core I believe is left about 7 mm proud with a flush end.

Certainly not intended to just push fit!!!!!!

Soldering is not possible due to design.

Fair enough, but you need a gas tight connection to prevent corrosion getting into the joint. I personally would replace it with a soldered connection.

Get an Iroda pro 120 and the jobs a good'un.

 

[earlybird]

Fair enough, but you need a gas tight connection to prevent corrosion getting into the joint.

The OP's Vtronix would have 2 O-rings and a screwed ferrule which, with a smear of silicone grease, should make it fairly vapour-tight and also mechanically strong.
My experience of Vtronix has been good.

 

[john_morris_uk]

The OP's Vtronix would have 2 O-rings and a screwed ferrule which, with a smear of silicone grease, should make it fairly vapour-tight and also mechanically strong.
My experience of Vtronix has been good.

I agree - I always put grease on mine and have never had any trouble with the connection.

There is no double entendre intended in this post for those of you with less than pure minds...