smee204

Hi
ive got a jabo 2 electric helicopter. I have been flying with the antenna just dangling below the helicopter however today the antenna some how got wrapped round the main shaft and snaped in several places.

Where can i buy a new one? Can you get better solid antennas?

Im located in the UK so need 35mhz.

Cheers

Ozydego

GWS sells a micro antenna and there are several others on the market. These have you cut the original antenna to less than 6 inches and solder the replacement on. The first thing I would do is measure the length of the old antenna, I think most are around 36-39 inches in the US, If its the same, then the 35mhz are the same as the 72mhz. Then its just a matter of installing the new one. Basically all they are is the antenna wrapped around a tube.

smee204

ive been told the 72mhz are not compatable with 35mhz is there anywhere which sells 35mhz ones or can i make my own? Could i just replace the antenna with any old wire as long as i make it the same lenght? If i can where is the best place to mount the antenna?

Thanks

Ozydego

yeah u can just replace the wire, wire is wire, the key is the length, the channel uses a specific amount of wire to give the maximum distance without glitches, and that is why the new wire needs to match the old one... do u still have the pieces that got sheered off? If so, put them end to end with the part still attached and find out the total length, and then u can then match it. I use servo wire for my replacement antennas because it is small and flexible. I have seen guys wrap the antenna around a carbon fiber tube, then mount it, or run it back and forth thru straws attached to the tail boom.. The best place to mount it is as far away from interference sources like servos and motors, hence don't wrap it around the tail boomdown to the tail motor, and don't wrap it around the main chassis. I have seen some that mount it around the landing gear... check one of your local hobby shops, and even if they don't carry helicopter parts, most will sell micro antennas, optimized for your 35 mhz reciever...

smee204

think i will just replace the wire. Looking in the manual it says the antenna is 800m (yes 800m!!!) long and on the website 0.96m long. however mine was about 0.5m and i was getting a very small range on it. Which length do you think i should go for, and where shall i run the antenna so it doesent get caught in the blades again?

Thanks for the help

Ozydego

They may have meant 800m range, the .96m length could be right, Try wrapping it around a wood dowel or a short piece of carbon fiber rod, (I am thinking light in this case) make the wraps right next to each other, but be careful not to overlap the wraps. Then secure it to the tail boom about half way back. The micro-z antenna I showed a picture earlier uses the same concept except they take the insulation off the wire. I found the picture of the guy who did it, caseyjholmes, he put a rubber cap on the end and secured it with zip ties, here's a pic

Pops Racer

My Feedback: (1)

Whenever the antenna crosses over itself (like around the skids) range will be reduced. Carbon Fiber has the same effect and you should avoid contact as such.

A simple but effective method is to attach a cut down R/C car antenna tube (or similar) to the skids and coil around.

smee204

does the thickness of the wire matter as ive tried all these things and the range is not very good. How much range should i be getting with a jabo 2?

Pops Racer

My Feedback: (1)

With a decent radio system you should easily have enough range to fly futher than you can judge the Helis orientation.

Most of the RTF supplied radios are mediocre at best, but in the learning phase you are never more than a few feet away so range should not be a problem even then.

Look for a possible loose crystal in the TX and RX (seem this before). Sometimes one of the pin sockets is sloppy which can be corrected with a small screwdriver. A hard crash into an inmoveable object can damage receivers/crystals.

24-22 gauge stranded wire is commonly used for RX antennas.

smee204

where would i find this crystal as all i can see is a cirucit board with some chips on as its an all in one board, also anywhere i can get some spare antenna wire or a new antenna for 35mhz in the UK?

tnd2000

Warp the antenna on anything will shorten the range. For best reception, the antenna needs to be straight and the correct length.

If you really want to know the optimum length of 35MHz antenna, from what I recall of high school physics (you should google to confirm this, I'm pretty old)
wavelength = 3e8 / 35e6
antenna length = 1/2 wavelength = 4.28m

Oh yea the antenna on your tx probably isn't the correct length neither, so just estimate the length of old antenna, find a similar length wire and use it.

Ozydego

a half is 4.28m, but from what I have heard, most only use a quarter wave so 2.14m, which is still huge... what about 1/8 1.07m? remember, 1 meter is about 3 feet so a 12 foot antenna? 3 foot is still fairly long but manageable. The manufacturer must use a custom length, so finding out the original length is best. But the 1/2 wave is the proven method used to get the radio distance so its confusing.

tnd2000

The antenna on my radio is longer then on my micro heli. Honestly, there is no way anyone can remote control a micro heli 1/4 mile away. If you are going to fly the micro within 50ft of yourself, you can get away with much much shorter antenna length. Look at your FM radio. For some stations, I get excellent reception no matter what length of the antenna, others, I must extend it all the way. For the range we're talking about, 1/2 of the optimal length hardly matters.

smee204

thanks for the help i will have a go when i get some wire.