SSB Antenna

[john_morris_uk]

You do get about a bit, don't you? RF engineer, Royal Marine padre, teacher... what next?

Mind you, our chaplain at school had had a varied life as well. Kicked out of the Royal Navy for more drunken fighting than is usually tolerated, seaman on container ships, found God while at sea, Army padre, then boarding-school chaplain and the TA. Probably makes for a better pastoral understanding I reckon.

Pete

Guilty as charged. I was very keen on ham radio when I was a teenager and on leaving school I got a job as a Scientific Officer at the Royal Radar Establishment, Malvern. After two years I realised I needed a degree to really advance myself and the rest is history…

 

[SimonJ]

Why not have a 'rope antenna' which is more efficient, no issues joining to ss backstay, uses non wound copper, not twisted ss of backstay? No insulators in backstay or inefficient joints or problems with lead in cables. Cheap simple and the best! Make your own or google and a fellow will sell one (not me, I hasten to add!) With my simple low powered ham radio rig I invariably have the best signal ( even when powered right down) as I can tell you from daily experience in the Caribbean - even today! A SS backstay with all the complications plus it beingo a second choice material is invariably a poor compromise. Imop for too long it is suggested that you have to use a backstay - this is a myth!
Good luck with whatever you do!

 

[William_H]

Why not have a 'rope antenna' which is more efficient, no issues joining to ss backstay, uses non wound copper, not twisted ss of backstay? No insulators in backstay or inefficient joints or problems with lead in cables. Cheap simple and the best! Make your own or google and a fellow will sell one (not me, I hasten to add!) With my simple low powered ham radio rig I invariably have the best signal ( even when powered right down) as I can tell you from daily experience in the Caribbean - even today! A SS backstay with all the complications plus it beingo a second choice material is invariably a poor compromise. Imop for too long it is suggested that you have to use a backstay - this is a myth!
Good luck with whatever you do!

Well I looked through the promotionm on the "rope antenna" IMHO it is a lot of hype over nothing. There is no way it can give a gain over a backstay or any other type of antenna. It is just a piece of wire hidden inside a rope. Yes that is fine however the rope will inevitably be mounted near and parallel to other rigging and mast. The advantage of the backstay is that it is the most remote from the mast and other stays. I would not imagine that the insulators used for fitting in the backstay should be quite adequate in terms of flash over distance. I certainly don't think that back stay insulators are likely to fail as suggested.
The only conceivable problem with stainless steel backstay is dc resistance. However for typical 6 or 8mm wire this must be well below .2 ohm. This will be insignificant in what is a 50 ohm impedance min and mostly more, antenna. Am I completely wrong? Other wise I think someone has gone into snake oil salesman mode in describing the rope antenna. ie it is OK but nothing special.
I would always go for a stern mounted whip antenna simply for its usefullness if dismasted. I note Oz ocean racing requirements are to carry a whip either as a main or standby HF antenna. olewill

 

[HunterWanderer]

Guilty as charged. I was very keen on ham radio when I was a teenager and on leaving school I got a job as a Scientific Officer at the Royal Radar Establishment, Malvern. After two years I realised I needed a degree to really advance myself and the rest is history…

Are you sure that this is sufficient to not fall into the trap of " a little knowledge ..." ?

 

[oldvarnish]

To connect the ATU to the backstay I was advised that the single core high voltage cable used by installers of neon signs did the trick.

i blagged a metre or so from a neon installer and it did the trick nicely.

 

[john_morris_uk]

Are you sure that this is sufficient to not fall into the trap of " a little knowledge ..." ?

True, but it was an area I specialised in, and I still wouldn't make any claims about being a world authority! However I think there was a fairly unanimous conclusion from various people who had worked in the field and who commented that Hunterwanderer had not understood the problem properly.

 

[MM5AHO]

Re "rope" antenna:
I once tried a hoised antenna alongside the installed backstay. Hoisted a copper wire vertically up the mast and held it away from the mast at the lower end. This became very similar to the backstay, only copper rather than stainless, and no built-in insulators, joints etc. Used a seperate ATU (manual type)
There was no discernable difference in signal reports either way, on any band tried (frequencies ranging from 1.8MHz to 28 MHz.)

 

[AHoy2]

Interesting thread for me, since changing boat to one with gaff rig I no longer have the option of using the backstay. Currently considering a stern mounted whip, however, a home made rope aerial strung to the bowsprit or hoisted alongside the (wood) mast on the topsail halyard seems a good and/or option. Any "feedback" welcome (re use on amateur bands).

AHoy2
M0HOC

 

[HunterWanderer]

True, but it was an area I specialised in, and I still wouldn't make any claims about being a world authority! However I think there was a fairly unanimous conclusion from various people who had worked in the field and who commented that Hunterwanderer had not understood the problem properly.

I dont claim to be a world authority either but I am qualified to RSGB Advanced level.

I agree that for the best RF performance the ATU should be mounted next to the backstay connected with a short jumper lead above the insulator. In practice though its usually better to mount the ATU below deck or in a locker to prevent water ingress and physical damage.

With the ATU mounted below I believe its better to connect the two with coax with the shield earthed at one end as . This will achieve a better EMC and ERP losses reduced. This section should probably be as short as possible.

Its probably not much of an issue though as both ways will work and I certainly know that using coax feeder to the backstay works very well. Just because people use one method does not make it the right way and the other way wrong. Unless you know better.

 

[ytd]

Many years since I have had a marine ssb but I remember waiting out a bass strait gale in refuge cove and having a succession of other yachts skippers coming over to use our ssb to make phone calls via Melbourne. They all had backstay antennas. We had a 4m loaded whip because we had running backstays. The trawlers also stuck there had whips and could contact their bases. I've always suspected backstays aren't as good at transmitting as is commonly thought. As I recall the phone freqs we used were 2Mz. Maybe backstays were better at higher freqs.

 

[William_H]

Interesting thread for me, since changing boat to one with gaff rig I no longer have the option of using the backstay. Currently considering a stern mounted whip, however, a home made rope aerial strung to the bowsprit or hoisted alongside the (wood) mast on the topsail halyard seems a good and/or option. Any "feedback" welcome (re use on amateur bands).

AHoy2
M0HOC

I would suggest you go for a whip antenna on the stern. A rope antenna on the bow sprit would result in a lot of wire from tuner to the bottom of the bow sprit.
A wire up the mast may work provided there was no other wiring in the mast although inevitably the antenna willo sit inside a frame of stay wires each soaking up power.
Actual perceived performance of HF antnenae is verry subjective. The conditions vary so much and slight improvements are hard to detect. I can't imagine why ytd found that whip was better than backstay. Theoretically a backstay shuld be better than a whip. However as I said a whip might still be standing in a dismast situation so is far better from that point of view. olewill

 

[john_morris_uk]

I dont claim to be a world authority either but I am qualified to RSGB Advanced level.

I agree that for the best RF performance the ATU should be mounted next to the backstay connected with a short jumper lead above the insulator. In practice though its usually better to mount the ATU below deck or in a locker to prevent water ingress and physical damage.

With the ATU mounted below I believe its better to connect the two with coax with the shield earthed at one end as . This will achieve a better EMC and ERP losses reduced. This section should probably be as short as possible.

Its probably not much of an issue though as both ways will work and I certainly know that using coax feeder to the backstay works very well. Just because people use one method does not make it the right way and the other way wrong. Unless you know better.

I humbly suggest that all the co-ax does is add capacitance to the output of the ATU. It doesn't act as an effective 'screen' in those circumstances. Depending on the frequency and the length of the co-ax used there will be induced RF currents in the sleeve and it will almost certainly still radiate. What is confusing to many is that the ATU and antenna will probably work (and it might work just as effectively) but its not working in the way you intend or want and the extra capacitance on the output of the ATU might not be helping at all. You are correct when you say that the connection from ATU to backstay should be as short as possible.

What call sign? I don't often use my licence now, but I have held my Class A G4BXS (under the old scheme) for 35 years (and VP8CQZ when I was in the Falklands/Antarctica) After two years at college and in an RF lab at the Royal Radar Establishment I went to university to read electronic engineering. Transmission lines and transmission theory was one of my areas of interest. Its a long time ago but this is fairly basic stuff. Two years into my four year degree I realised that my vocation was elsewhere. The rest is history as they say.