Need Input / Advice for Owners with Copper in their Keel for Older SSB Radios

Discussion in 'Boat Design' started by SuenosAzules, Feb 20, 2012.

  1. viking north
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    viking north VINLAND

    Good point BertKu -- Receiver sensitivity, S to N (signal to noise) ratios, Antenna gains, all have improved greatly from the time she was built. Still a strange way to go about it -confounds me why they did not use copper mesh . However the Op is still caught between a rock and a hard place in complying to the request of the customer, that being he wants to re install the de laminated coppersheet. If he does and it delaminates again he faces a possible free re work or law suit.(profits plus lost) If he doesn't the customer can refuse to pay thus another lawsuit to get his money.(profits plus lost) My choice would be the re work using copper mesh. It has little to no chance of ever delaminating--It acts as a solid copper sheet to the radio frequencies involved. Basically I agree that with modern gear less of the sheet should allow tuning the SWR (standing wave ratio) to very close if not a 1 to 1 ratio. Thus as Michael suggest remove the delaminated copper and seal the remainder should be ok--However convincing the customer and attaining a good SWR after is both a task and choice the OP as a businessman has to endure. No doubt costs will play a role here.

    A yacht is not defined by the vessel but by the care and love of her owner
     
  2. mydauphin
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    mydauphin Senior Member

    This is a little of the topic, but since all the radio experts are here... Would a metal vessel of any kind require a grounding plate?
     
  3. viking north
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    viking north VINLAND

    Mydauphin --I assume you mean ground plane as you referred to Radio .The metal in the vessel itself acts as an excellent ground plane for the antennas. The last motorsailer i built was in aluminium and the local wood and fiberlass boat owners were always envious of my signal levels. Then again I tweaked it by having oversize low loss coax with no joins from the radio to the mast top antenna. Every join reduces your transmitted and received signal by 3db. This reduces you power by half. Also every coax connection is the greatest cause of problems. I tune my antenna (SWR) after the boat is launched and sitting at anchor with the help of a mast monkey.( a light weight skinny kid) :) The biggest source of trouble is the coax to antenna connection at the top of the mast, being so exposed to the envioriment. Be sure you create a drip loop(U shape the coax where it is fastened to the bottom of the antenna so the moisture flows down and drips away from the connection. I then coat the entire connection plus an inch or so of the coax with 3M5200 or some other marine sealant. Don't use silicone it has a tendancy to release over time.---

    A yacht is not defined by the vessel but by the care and love of her owner--
     
  4. mydauphin
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    mydauphin Senior Member

    Thanks, Viking. What cabling do you recommend?
     
  5. Milehog
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    Milehog Clever Quip

    And be sure to remember to use dielectric grease on any connections. I've had good luck with self vulcanizing rubber tape over said connections on land based applications.
     
  6. michael pierzga
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    michael pierzga Senior Member

    Im on a metal boat...the ground plane is a short copper cable, to a knife switch, grounded to an aluminum frame. The connection, earth to the aluminium frame is a ss stud glass tower to eliminate corrosion between copper and aluminum. The knife switches on antenna and earth cables are to guard the equipment against lightning strike. Seem to work fine. Good reception , 15400 BBC AFRICA SERVICE is playing now. Some religious conflict in Nigeria. Transmit range seems fine at sea...In harbour Im shielded by mountains and city background junk and a Navtex transmitter station so things are noisy
     
  7. viking north
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    viking north VINLAND

    Mydauphin--Listed in order of worst to best Rg58(short runs only) Rg8, RG8u, Rg213 (all rated for long runs but with the rg213 being the best but hardest to install connectors) I use RG8u. I will also expand a little here on antenna selection. VHF antennas come in various DB gain ratings. The antenna does not amplify the power from the transeiver(VHF set). it simply achieves gain by shaping the radiated signal thru manupilating the built in wiring of the directors/reflectors. Visualize the radiated signal (electromagnetic energy) coming off the antenna in the shape of an ever expanding donut shape travelling out into space at approx the speed of light. A 3DB gain antenna's radiation pattern is in the shape of a fat donut, so it has good communication close in and reasonably far out. A 9db.gain antenna has a radiation pattern shaped as if you walked on the do nut. You can visualize it will flatten and expand outward. Resulting in, the 9DB antenna has the capability to communicate with a stronger signal at distance but with a disadvantage. If placed higher up like on the mast top it will have weak signals close in as it has a thin vertical aspect and the signal will travel high above the water at close range missing those antennas at lower elevation. The recommendation is --for mast top mounted antenna use one with a 3 DB rating. For lower mounted antenna use a 9 DB rated. Here's how I look at it --If your sailing area is mostly crowded coastal work use a mast top 3db. If it is mostly offshore coastal i would use a 9db. with a handheld for any close in communications.--
     
    Last edited: Feb 23, 2012
  8. viking north
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    viking north VINLAND

    Michael--is that setup for your SSB or VHF or both. Suspect it is for your SSB as at VHF frequencies that setup would possibly mess up the coax. impediance creating standing waves and a poor SWR reading( loss of power to the antenna). There's an old trick we used in HAM work years ago. We ran a conductor to the coax center wire and placed an automotive spark plug as an automatic by pass switch to ground in case of a strike.Don't know if that would be fast enough acting today to save solid state circuits. Those old tubes could take one hell of alot of punishment. Many times we'd overdrive them (red Plates) getting the power out knowing we were dramatically shortening their lives.However we always had a few spares next to the set for a quick ex-change. :D (Off to the shop) cheers --Geo.
     
  9. bntii
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    bntii Senior Member

    The electronics guy mentioned this to me some time back:
    http://www.kiss-ssb.com/about.html

    I haven't used it but he installs it for his clients and has had no problems.
    A far cry simpler than the copper sheathing installation above eh?
     
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  10. viking north
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    viking north VINLAND

    Very interesting --an electronic ground plane(counterpoise). I will definately have a closer look at this system for myself. I'm always leary of markrting claims so would like to see comparative test results with an identical set up one using copper mesh and this one. I pay little attention to the "no Problems" claim as most customers would not know the difference unless it was a drastic one. I.E. if it was 75% as effictive as a traditional copper sheeting /mesh very few would be aware. Then again 75% as effective would satisfy 90% of the communications out there. The tuner itself will compensate for alot of mis matching - the real test would be comparing the radiated power across the band when comparing the two set ups. Being a radio nut that squezzes for max. out with a given in, it would be an interesting comparison. All in all it appears to be a good set up.
     
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  11. CDK
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    CDK retired engineer

    No, that doesn't work nowadays. Long before the spark has bridged the gap, the front end semiconductors are fused or evaporated.
    To protect modern equipment without signal loss, there are glass encapsulated spark gaps with the electrodes only microns apart (Siemens/Matsushita ).
    Same principle, tailored to the lower voltages used with solid state circuits.
     
  12. BertKu
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    BertKu Senior Member

    Agreed, provided the input circuit of the semiconductors can handle up to 1000 Volt. The rise time from a lightning arrestor (glass encapsulated spark gaps) is in the region of a few KiloVolt per micro-seconds and the lightning bolt is faster. By the time the arrestor has shortened, the voltage is already up to 1000 Volt. I don't know what today’s progress is on TAZ's (transients Zener Diodes) with respect to the power dissipation. I would consider a 2 stage protection. TAZ at the front end of the electronic equipment and an arrestor at the aerial part, a few meters away just to have a few micro Henry before the bolt hits the TAZ.
    bert
     
  13. FAST FRED
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    FAST FRED Senior Member

    When the repair is attempted just be sure they use epoxy , as polly resin does not bond very well to old glass , no matter how well ground down.

    FF
     
  14. mydauphin
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    mydauphin Senior Member

    Interesting guys, never had a SSB. But definitely getting one of these days. I want to run the wires to get started. Then one day when I run across a good used radio, I can start. So keep going giving advice.
     

  15. viking north
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    viking north VINLAND

    Man my electronics is getting rusty--I'm an old military Comm/radar tech upgraded to CET on civy street but haven't used this stuff in 20yrs. Hope it's like riding a bike, this year I am getting back into HAM after some 40yrs. absent. From the responses i observe there's ample opportunity to re-learn and if my brain can handle it surpass old theory. Expect a scattered enquirey-- boat related of course :)
    Bntii-did a little more thinking on that electronic groundplane/counterpoise unit.I suspect it is some combination of freq. cut radii and what is referred to in transmission line theory as tuning stubs. Be interesting to see a schematic of it but have a feeling they are guarding that design for fear of copy-- not that i blame them one dam iota in todays commercial world.
    Wonder how the OP is doing on his repair--??? Any chance for a few photos old boy. :D --Geo.
     
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