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[kiwimodeller]

Greetings from down under. I have been using a Spektrum DX5e to control my boats for some time now and am very happy with it. Following a tip on Mayhem I have just purchased an Orange receiver from Hobby King for the next project for the great price of 3pounds. I managed to get it bound to the Tx (although the Spektrum bind plug worked better than the Orange one) and everything seems to be working fine but I am surprised about the very short (about 20mm) length of the Orange aerial whuich is much shorter than the Spektrum one and I am worried about the range it will have. There is am extra small plug in the side of the Rx and I remember seeing something on Mayhem about an auxillary aerial setup for these receivers. Do we need the extra aerial in boats? Thanks, Ian.

[malcolmfrary]

The active bit of the aerial is the 1.25" or so at the end - the rest is a convenient bit of co-ax to connect that to the radio.  If the Orange one is about half that, the length is probably tuned for a different harmonic. 
Fitting a longer lead, unless absolutely vital because of being unable to otherwise mount the radio with the end bit of the aerial above the waterline, would probably be counter productive.  At the frequency used, signal loss in the co-ax is considerable, the longer the cable, the more loss, and the shorter the range.  Add to that that the tuned length is very critical, much more than with old fashioned gear.  Lose a couple of millimetres off a 27MHz aerial, its very unlikely anybody will notice.  A couple of millimetres off 40 is a big percentage.

[Stormbringer]

the length of ariel even differs between types of spektrum rx's  , some 6ch rx have 2 about 1" long others have a short and a long arial ie 1" and up to 6 "or so , just mount your rx as high up in the hull as possible so that arial is above waterline or higher , 2.4ghz doesnt penetrate water

[kiwimodeller]

My Spektrum receivers (AR500 five channel) have two aerials, both fairly short but one shorter than the other. This time I am using the Orange reciever that Hobby King sell as an alternative to the genuine Spektrum part. I tried the boat today and the radio gear seemed to work fine even with the very short aerial supplied (less than 1") but I did not have the cabin fitted and I did not let the boat get very far from the shore. I am sure I have read a post about the auxillary aerials that can be fitted to these receivers but I cannot find the post again. Cheers, Ian.

[Netleyned]

I operate orange rx's in my yachts with the rx velcroed under the deck
and they are still in range when I can hardly see them.
You should have no trouble.

Ned

[CF-FZG]

the length of ariel even differs between types of spektrum rx's  , some 6ch rx have 2 about 1" long others have a short and a long arial ie 1" and up to 6 "or so ,

Don't remake the mistake a lot of us made when Spektrum first came out

The antenna length is the same across the range, and the reason that the length differs is because it's only the tip, (about 20mm long), that's the 'active' part of the coax, the rest is the shielded part of the coax and is only to 'extend' the overall length.


Mark.

[spearfish99]

Hi Kiwimodeller,

  While I haven't seen extension aerials for Spektrum sets, they are certainly available for Futaba  2.4G Rx's.  Prestwich Models in the UK advertise these. You have to open the RX case and unplug the current aerials and plug in the new.

  They appear to be considerably longer and should make leading out of the hull easier, while claiming not to affect range.  Like you, I have bought an Orange RX for my Futaba FASST set, and the aerials are really short on that.

[Netleyned]

The orange 6 ch rx has a socket for a satelitte rx which is not necessary unless you are flying allowing two ways of aerial orientation.
The 6 ch has a 3 cm aerial.
I use them as I said in ya chts just above watef level and in tugs and springers and have no problems with range.

Ned

[Netleyned]

Just to put things in perspective, 3cm at 2.4 GHz is a quarter wave aerial.
A quarter wave at 27MHz is 2 1/2 Metres.
A boat with a 27 MHz aerial of around 33 in is a twelfth wavelength so the 2.4 aerial is about three times as efficient.

Ned