Weak VHF

[frelin]

I heard somewhere that the VHF unit can be damaged if you use it without any antenna plugged in, true/false?

I've been thinking about changing the standing rigging. I think it is original, 1978. I know I'm supposed to change it, but; a lot of people that had a close look to it says that it's seems fine. That includes the surveyor who said he normally tells anybody to change if it's older than 10 yrs, but ours looked good....

In Guatemala it not very easy to change the standing rigging. But I'll probably go down to Panama this spring. May be somebody here has any experience with riggers ad prices down there?
(I guess I should start a new thread soon....)

[Sailndive345]

Well, you wouldn't want to try to transmit w/o an antenna - for testing purposes, we use a dummy load (sink) - This is for ham/ssb radios - imagine it would apply to a VHF radio as well.....

Sailndive

[s/v Jedi]

The modern radio's all use a final stage power module that has automatic protection but like with any kind of protection you should try not to need it. Older radios (but how old?) don't have that and can be damaged by a big antenna mismatch.

About the standing rigging: if it's from 1978 you sure must replace it. You should also not use that surveyor anymore because he should have told you that the likely problems are in spots you can't see like inside the swage fittings. It's 32 years old!!

There is some rigging guy here in Colon, Panama but if it would be for me, I would replace it myself. Measure your stays & shrouds and order them in the USA with one swage end-fitting (upper end) attached, a couple of inches extra length and a Norseman or Sta-lock fitting for the other (lower) end. Ship that to Panama and replace one by one. Take an old one off, pin it stretched out on the ground, new one next to it, cut to exact size and put the Norseman fitting on. Easy and fun job to do. The extra cost for the Norseman fittings and shipping is easily compensated because it's all much better priced in the US.

cheers,
Nick.

[fairbank56]

Originally Posted by s/v Jedi

The modern radio's all use a final stage power module that has automatic protection but like with any kind of protection you should try not to need it. Older radios (but how old?) don't have that and can be damaged by a big antenna mismatch.

The power module itself does not provide any protection from a mismatch. There is circuitry between the power module output and the antenna jack that develop voltages based on forward/reflected power which is used to control the power output of the power module. This generally cuts the power down to around 10 watts on high power with no antenna. You'd have to go back 25-30 years to find quality radio's without this protection. On a sailboat, this doesn't much matter anyway as the losses in such a long cable run with no antenna are so high there probably won't be enough reflected power to even activate the protection. Iv'e seen an SWR meter indicate less than 2:1 when in fact, the coax was cut in half by a halyard at the top of the mast. Aging capacitors can increase your odds of a failure but I know of many old Icom M100's, M120's and even a few M80's still going strong.

And here's a good story. One of the brand new MKII training sailboats at the Naval Academy did their VHF operations all year without complaint with nothing but the 8 turns of the coil in their Metz antenna. Seems the installer's cranked down on the antenna rod clamp nut so hard that they turned the whole rod fixture which sheared the internal screw that connects the coil to the antenna rod fixture. The whip wasn't even connected.

Eric

[frelin]

Originally Posted by s/v Jedi

About the standing rigging: if it's from 1978 you sure must replace it. You should also not use that surveyor anymore because he should have told you that the likely problems are in spots you can't see like inside the swage fittings. It's 32 years old!!

There is some rigging guy here in Colon, Panama but if it would be for me, I would replace it myself. Measure your stays & shrouds and order them in the USA with one swage end-fitting (upper end) attached, a couple of inches extra length and a Norseman or Sta-lock fitting for the other (lower) end. Ship that to Panama and replace one by one. Take an old one off, pin it stretched out on the ground, new one next to it, cut to exact size and put the Norseman fitting on. Easy and fun job to do. The extra cost for the Norseman fittings and shipping is easily compensated because it's all much better priced in the US.

cheers,
Nick.

Do you think the rigging guy in colon is reliable, any conntact info?

And if you order it from US, do you know any good rigger there that I could trust. Also, I hear it could mean troubles to get at package into Panama, custom fees etc...

[s/v Jedi]

Panama is one of the best places to ship stuff to. Sail your boat into Shelter Bay Marina (will cost you) and check with Marine Warehouse if they can order the rigging for you. Delivered right here at your boat and no customs trouble at all.

I have used a rigger in FL but found them a bit too arrogant for my taste. Marine Warehouse will probably have a better contact. Email miami[at]marinewarehouse.net and tell them I sent you. I always ask for stuff that they normally don't sell and they always get it to me anyway. They have a local rep here in Panama who takes care of everything.

cheers,
Nick.

[colo.sail]

Still building. Will have a hollow wood mast soon, why not just put the antenna inside the mast? I know, changing it later will be nearly impossible, but that's a long time from now (I would hope!)

Just curious

[senormechanico]

Originally Posted by Sailndive345

If the in-mast wires are so aged, it is likely that your standing rigging is quite tired as well... If you unstep the mast, it may be a good opportunity to replace whatever else needs replacing for your piece of mind

Sailndive

While you're at it, as long as the rigging is aged and needs replacing, why not the hull as well? And while you're at that, get the new boat dealer to install all the wiring.
Eees Seemple, no??

[hellosailor]

" why not just put the antenna inside the mast? "
Because wood, wet or dry, absorbs and blocks radio signals. Wet wood especially. If you want to hide the antenna inside the mast, mast the mast of radiotransparent fiberglass.