Quick antenna question for the radio buffs....

[grandbanks]

Hi,

 

 

Thanks for the info...

 

The ad I saw where the "i" was missing was here http://www.metzcommunication.com/images/antennasheetforweb.jpg when comparing with a 54" 3dB aerial.. which naturally caught my attention.. Not sure if you have any influence over that advert... I can't comment on the use of dBd by CBers as don't really follow that branch, more the professional and amateur products...

 

However, I would like clarification on how the PL-259 / SO-239 antenna connector can be reliably considered for use as an external connecting system as the ones I have seen are not waterproof or sealed, and I would never use in an external let alone a marine environment...Over time, salty water must creep into both the threads, and between the centre contacts, and very likely into the co-ax braiding. This would be my only criticism of the Metz . It could be overcome with either a change in connector type, suitable external self-amalgamating tape, or perhaps terminating in a length of co-ax that could be brought into a suitable sealed connection box. Perhaps this could be incorporated into the base of the antenna ? However, perhaps the type of PL-259 that the Metz uses/recommends is a sealed item ?

 

My suggestion for the 5/8 was exactly for the reason you confirm, with a bit of vertical component in the beam pattern as well and as you say it is probably easier for the public to grasp.

 

I realise the above points are possibly going to be taken by most people as un-necessarily pedantic, but the work I do demands a zero failure rate and the best practices available, and I would agree that it may be considered financially unviable for most commercial products where a reasoned balance needs to be struck. I apologise if my comments were taken to cast doubts on the product, but were based on past experience of the PL-259 in an external environment - I would not be put off buying one myself, although may make the above mods depending on the application...

 

With regards,

 

Nick

 

Hi,

 

I hadn't noticed that reference; it's a bit odd because Metz in the USA never refer to the gain of their own product but in that case have used it to describe a generic 54" antenna. We do quote gain over here, but always with the "i".

 

The PL259/S0239 connection is used by most of the manufacturers for boat whip antennas of this type. We've been using it since 1977. So, conformity with the industry norm is probably the most compelling reason it has persisted.

We recommend that the joint be covered with a silicone self fusing tape - this is easily removed and leaves no sticky residue - but I have to say that I've seen many applications where no tape has been used and the joint has not been compromised in any way. My own ketch had an un-taped joint for over six years and when we finally took the mast down there was no corrosion or water ingress. I suppose the quality of the plug and socket helps. Still, I would always recommend taping the joint. We also recommend tinned and stranded conductors in the coax cable in order to prevent corrosion and metal fatigue when flexing.

One of the reasons for using the old PL259 on boat applications, they are often use with a barrel connector to make an intermediate join, is that they have great mechanical integrity. Also, they are more easily fitted by the layman than some of the other types.

 

John

[Semitrad]

Hi,

 

I hadn't noticed that reference; it's a bit odd because Metz in the USA never refer to the gain of their own product but in that case have used it to describe a generic 54" antenna. We do quote gain over here, but always with the "i".

 

The PL259/S0239 connection is used by most of the manufacturers for boat whip antennas of this type. We've been using it since 1977. So, conformity with the industry norm is probably the most compelling reason it has persisted.

We recommend that the joint be covered with a silicone self fusing tape - this is easily removed and leaves no sticky residue - but I have to say that I've seen many applications where no tape has been used and the joint has not been compromised in any way. My own ketch had an un-taped joint for over six years and when we finally took the mast down there was no corrosion or water ingress. I suppose the quality of the plug and socket helps. Still, I would always recommend taping the joint. We also recommend tinned and stranded conductors in the coax cable in order to prevent corrosion and metal fatigue when flexing.

One of the reasons for using the old PL259 on boat applications, they are often use with a barrel connector to make an intermediate join, is that they have great mechanical integrity. Also, they are more easily fitted by the layman than some of the other types.

John

 

We used to use PL259 connectors on marine VHF installations without any great problems that I can recall. If exposed to the elements they were filled with silicone grease, the idea being that if they were already full of something, nothing could get in!

[Nickhlx]

We used to use PL259 connectors on marine VHF installations without any great problems that I can recall. If exposed to the elements they were filled with silicone grease, the idea being that if they were already full of something, nothing could get in!

 

I guess there's a certain logic there...

 

Nick