Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[JimW]

Thanks C-3PO, You’ve answered my thoughts exactly, I had thought the RX might have had a plug but seeing that the (sealed) case has to be opened I won’t bother because I see no direct advantage - EXCEPT for keeping its aerial vertical and above water.




Jim

[colh107]

Yep, absolutely. Extended physically for mounting, not range.
Looks like still a standard "half-wave dipole" - the core of the coax protruding ~6cm out of the braiding. There is often nothing more to it than that!
If your tx has the 5" stubby type of plastic antenna - that's all that's inside the plastic.

Do be careful unclipping those little uFl connectors - you need to pop it off vertically upwards. Avoid any levering action, else you could rip the socket off the circuit board....

[JimW]

Interestingly most of my parts have just arrived including the Gas Valve from Regner, also arrived is my RX aerials - 15 Cm long with 35mm tails, ….. erm! What to do with them about 20! ? They have solder terminals at lower ends but would they give more benefit than the original aerial?


Jim

[colh107]

35mm sounds quite long? Can you post a pic?


As C-3PO says, what alternative you can easily use depends on how your current aerial is attached on the receiver. A uFl connector is ok to swap, but if you've currently got a soldered one then I would probably advise "don't mess with it" unless you really think you need to. Perhaps just change the whole receiver?! I you have to solder it, and you accidentally short out the two parts of the aerial then you'll have a range of maybe about a foot.....


A dipole aerial out of coax doesn't have to be the ~6cm - it does need to be a multiple/fraction of 2.4GHz wavelength (12.5cm) though. The radio waves 'travel up and down' at a particular frequency and have to be able to bounce back down the wire and not crash into the next wave. ("Resonance")
Quite complex in detail and I'm not a real RF expert, but just think about it in terms of waves bouncing off a sea wall - sometimes the peaks and troughs meet at the same point and cancel each other out. Roughly the same principle with radio - if they collide and cancel each other out then the signal is going to be weak. Best for radio is that the peaks meet in sync, then the signal is stronger.

[colh107]

FWIW, one of my RC yachts (abs hull) uses a Spektrum AR410. No aerial wire, its built into the receiver circuit board. I've had no range problems at up to around 250 or more metres. I have positioned it to not be too close to the servos and battery as much as I can , no interfering 'lumps of stuff' too close, but it seems to work just fine.
Radio stuff is a black art..... ! :)

[JimG]

I've just checked some of the receivers I have from 4 different manufacturers. None of them have same length of exposed part of the aerial. 2 of them Hitec and Flysky have an added section before the exposed section, this is supposed to improve the signal strength to the receiver. Futaba just has a plain end while some of my FrSky receivers have a length of PC board as the aerial, this has the tracks folded to give the equivalent of 4 times the normal length. I don't think that the actual length is that critical with our modern radios as the electronics can compensate and in boats the actual range is much more than you will ever need. I can remember way back to the old RCME 27MHz FM kits where one of the selling points was that the receiver length could be altered as it was no longer part of a tuned circuit, this being done by the electronics.
Jim

[JimW]

Colth107, JimG,

With my previous boats used at the Norwich Model Yacht club I never had any trouble using 2.4 or the previous 35mhz systems but my book on Radio Control in Boats says that steam and Radio are not the best mix…which kind of puts one ‘on guard’ so to speak.


Jim

[JimW]

When I used-to build model aircraft mainly using Futaba sets I always separated the rx aerials to 90 deg using chopped  off cotton bud tubes secured to the acft frame, and mostly ditto with my boats, in my latest Windermere launch I’m placing said COTTON BUD TUBE vertically in Rx so as to (hopefully) assure signal receipt simply because I don’t want to risk damage to the craft that could be caused through a lost signal.


Jim

[JimG]

Colth107, JimG,

With my previous boats used at the Norwich Model Yacht club I never had any trouble using 2.4 or the previous 35mhz systems but my book on Radio Control in Boats says that steam and Radio are not the best mix…which kind of puts one ‘on guard’ so to speak.


Jim

I think the main problem with steam and radio is the damp atmosphere and heat involved with steam engines. Keeping the receiver separated in its own compartment should cure this. The main importance with 2.4 GHz equipment is to keep the aerials clear of the boiler and engine as they will block the signal, less of a problem though as the transmitter aerial is above the boat at the ranges we sail at. Many years ago I ran a steam tug on 27 MHz with no problems with the receiver and servos in a closed compartment in the stern with the longer aerial kepr out of the engine room.
Jim