Radio pot, antenna routing

[Colin Helliwell]

Just wondering what's the accepted practice for putting holes in a plastic radio pot for the servo wires (best to bring them through high in the pot, or towards the base?), and for sealing the apertures after?
Also, for a 2.4GHz radio, is it the norm to route the antenna up through the deck to get good visibility?

[Larry Stiles]

I think a hole in the side wall of the pot, no bigger than necessary, as high up as possible would be best. I usually don't but if you want try to seal the hole. I recommend a loctite product called Fun Tac Mounting Putty, found in most stationary stores.
I have heard it said and I believe it to be true that RF is a BLACK ART. What will work perfectly in one installation could fail completely in another and antenna placement falls in this category. However you can up your odds by using a few guide lines culled from the user guides for the Futaba and Sektrum systems;
The last 30 mm of the antenna wire is the actual antenna. Keep it as straight as possible.
Most receivers will have two antennas, position them at right angles to each other and if possible make one of them vertical.
Most installations are below deck. If this is the route you're going get the antennas up as high as you can IE. fastened to the underside of the deck, not laying loose in the bilge. An RF signal does not like to go through water and utterly refuses to go though salt water.
An above deck installation of one of the antennas will work fine but may present some water proofing challenges. From below deck, run one of the antennas up inside a vertical tube placed well aft, very near the transom.
May the farce be with you.
Larry Stiles

[David L Alston]

Colin,
I am intrigued.. why do you want to put a hole in the pot lid and poke the aerial out.. You do not need to do this. An IOM is glass not carbon there is no problem with range, even with the aerial's coiled up in the pot. .

Just be sensible.. Battery at the bottom, all wiring next and the receiver on the top and the aerial/s on the very top.
Never had a range problem and never will…not with 2.4GHZ. Spectrum, Multiplex or Futaba.

Keep it simple don't look for problems where there are none.

[Colin Helliwell]

Thanks.
I'm a digital/software engineer, but working in the field of RF products - it is indeed a black art! Yep, 2.4gig is readily absorbed by water - that's why we use it to cook with
The questions re. antenna placement was for the polarisation: 90 degree antennae both lying flat would be ok-ish with the Tx antenna also fairly flat. But I figured that having one of the two mounted vertically would always be good (with a vertical Tx antenna) since the 'nulls' are above/below. Noted re. the waterproofing - hence the question - I was thinking feeding it up through a tube in the deck (not through the pot lid). If I can detach the antenna from the Rx then I'd maybe route it to the aft deck as you suggest.

[Larry Stiles]

Colin:
I believe disconnecting either of the antennas from the receiver is impractical. That little grey wire is a very delicate shielded coaxial cable that needs to be treated with respect or IT WILL BITE YOU.
You might think about getting a receiver with at least one long antenna lead. The Spektrum MR200 and MR3000 will fill that bill. I'm sure there are others. As a mater of fact the MR3000 does have antenna leads that can be unplugged but I still would not recommend going that route. They are just too fussy.
I would use an above deck installation only as a last resort. Way too much hassle for so little need. David is right; the hull of the boat is completely invisible to these radio waves.
You can have a vertical antenna and keep it under the deck, forward under the fore deck, where it stays above the water line. Think about it.
Ciao.
Larry

[David L Alston]

Digital software engineer or not .. The antenna on the majority, 90%, of IOM yachts installation are coiled up in the pot. I do not quite have mine coiled up but none the less it is in the pot. Only on my RM is it protruding from the hull because of the carbon hull. The top of pot never below the water line anyway.

The difference between Aircraft installation and IOM is we never sail more than about 150 m from the transmitter unlike aircraft where his distance is a lot greater. Signal strengths at this range are very high.

But if you and your friend want to make something so simple so complicated go on ahead.

Dr David Alston Phd Eng

[Colin Helliwell]

Thanks

[Dave Pickett]

I guess the easy way is to simply run the aerial as best you can then do a range check with the boat at the furthest distance you are likely to use. Most TX's have a range check function that reduces the TX power for test purposes.

It will probably be fine but this check will give you confidence that you shouldnt have radio problems..............