I plan to reuse my receiver on my new plane. The antenna was ripped in half on the last flight of my previous plane.

Is it ok to splice antenna wire? If not, how do you replace the antenna wire?

Thanks,

Wings

Yes, you can splice the antenna wire, just solder a similar wire to it and cut it the same length as the original, it will be some where near a total of 40 inches (for 72 mHz) Put a piece of heat shrink over it. Make sure you have a good solder joint after twisting the ends of two pieces together. Strip off about 1/2 inch of insulation off each piece.

Pardon my ignorance,

But can you tell me what heat shrink is?

Thanks,

Wings

Heat shrink tubing is a plastic tube of different diameters used to insulate electric wiring. You slip it into where you want to then use your heat gun to apply heat (could use a lighter if you are very careful and dont melt it) and it shrinks tightly over the spliced section.
Personally, I hate splices on my antenna and the only time it broke I just removed it from the receiver and soldered a new antenna wire. If you decide to do that make sure its EXACTLY the same lenght as the original wire.

You could do that or go to your local shop and pay the $5 for a new wire. It may not be common, but the shop where I go has 3-4 wires on the shelf all the time... They are already covered etc... All you have to do is open the rx remove the old one and soldier the new one on.

One thing that I've gotten in the habit of doing is measuring the antenna length of a new Rx and writing it on the Rx for future reference if ever needed. I've been splicing antennas back together for over 20 years...you get good at it if you ever get into R/C combat. For around $10 you can get a nice little soldering iron kit from Radio shack. They also sell shrink wrap and spools of wire for less than a couple bucks that will repair countless antennas. Just take a piece of your old antenna in to match up the size, and make sure you get braided wire, not solid.

Can anybody comment on the length? Smitymax said 40", but I thought it was more like 29.

Any antenna experts out there?

Just measured Futaba and FMA Fortress rcvrs. both are 39 ins.

The length is 39.36996 inches or 1 meter in length.
This is from the PCB to the tip!

Its based on one meter wavelength.

Any length from 39 to 41 inches will work well. Your receivers all are base tuned (coil and condenser used in input circuitry) with the coil usually being a slug tuned item factory set and sealed. You won't be able to test any difference in range if you stay within those limits, i.e. exact length not real critical.

I personally would send in my RX, have them replace the antenna and retune the RX. If you change the length of the antenna or change the resistance, impedence or anything else....it will change the tune. Probably not enough to make a huge bit of difference...but enough that it will be always be a throught in the "back" of your mind in a crash.

But thats just me.....too many things already to go wrong on a good day.

Ok, my mistake. Just thought I'd check.

OK, now I confused.
I thought that is what I said.
If I was wrong, please explain to me why?
Is it because I didn't add that the length of the antennae needs to be the length of one cycle of the RF signal?

So is can be a big problem if I make it too long?

is that 39 to 41 inches standard for all Futaba?

Thanks guys,

[quote]ORIGINAL: Geistware

OK, now I confused.
I thought that is what I said.
If I was wrong, please explain to me why?
Is it because I didn't add that the length of the antennae needs to be the length of one cycle of the RF signal?




[sm=lol.gif] Chill bro, all it means is that you are right, I just added some extra info.

peace

Actually the receiver's antenna is about 1/4 wavelength. A full wavelength at 72 MHz in free space is 300/72 or 4.16 meters. However, I stand behind the others when they say that receiver antenna length is not critical. Close is close enough.

SkyChaser,
aka NK1N (amateur radio operator since 1974)

I noticed all kinds of answers to your question. But what I really noticed was that you stated the antenna was ripped in half in your last plane. Does that mean it was crashed? If it was send it in to be checked, no telling if any other damage has been done internally to the other components. If you do repair it make sure you do a range check on the ground with the tranmitter antenna collapsed and pointed away from the model. If the receiver works adequately past 50' or more you should have no problems. It may be cheaper and safer to just replace the receiver if it was crashed. Think about it ![&:]

Listen to Geistware. He is absolutely correct.

The antenna length should be at a length of 1 meter, or roughly 39 1/3 inches. Over the years, I have had the misfortune at one time or another to cut, break, glue, or burn several receiver antennas. Repair was never a problem.

If you crashed your plane, a very complete radio check is in order prior to using that reciever again in flight. If ANYTHING does not seem right in the range and vibration tests, DO NOT FLY! Send the reciever back to the manufacturer for check out and possible repair. If you have the funds, you can purchase another receiver to use until your original is returned. Hitec's Supreme series of receivers are of ultra high quality and are reasonably priced if you are so inclined.

Silversurfer

My futaba's wire was broken on impact about six inches from the rx case. I was told on another forum to just solder a new piece on and make sure it is 39 inches from the case to the end. It cost somethind like $39 bucks to have a new wire installed if you send it back. That with shipping costs makes no sense to me. For a few bucks more just buy a new one. I'm gonna repair mine and then check it out good with the engine running. We fly at a field of about 50 acres so I have plenty of room to check it without taking off.

Finally, some common sense! [sm=rolleyes.gif]

Actually......

I havn't checked the length yet because I have no plane to put it in at this time. However... the reason I asked is because I believe it just stripped the covering off about 2 inches of the end of the wire. I already did a range check. I walked down the road about a 100 ft or farther with the tx antenna down and pointed to the ground in the opposite direction. My wife stood in the garage and said all servos were moving.

So, hopefully all I will have to do is just cover the end of the wire. I am going to measure it when the time comes to make sure. I agree it would be foolish to put my new plane in danger if I am not sure the receiver is ok. On the same token, it appears to work fine, I had it wrapped in thick foam. Unfortunately I'm not made of money and I think I will take my chances with it. I may regret it, but I feel that if it works fine from 100+ ft antenna down in the ground it should be ok. I will do some additional range checks but at this point I plan to use it on my new plane.

I appreciate all the advice. I know how electric flows and know that splicing is fine, but I know very little about how radio waves propogate through a wire.

I have gathered that as long as I get the length right, it doesn't hurt to splice. That is the info I needed.

Thanks a billion,

Wings

I think the question would be better asked this way. Should you splice the antenna wire? IMHO for 5.00 vs. the cost of getting it wrong; have a new wire put on. The length of the wire is critical with each Rx. I accidentally snapped about an inch off my antenna on one of my models. I called Futaba and here is what they told me. The length effects the range distance and the further away you get the range drops exponentially if the wire length is incorrect. If you get this wrong you could have a real problem. Why take the chance for such an inexpensive part? Add to this the potential for additional interference and IMHO it's just not worth the risk. By the way, how are your soldering skills? I don't think this is the item you want to learn on. If you are like me, and your question leads me to believe you are, then you probably don't understand all that you need to know about transmitters and receivers and how they are tuned one to the other. There are guys responding with much experience with this than you and I. I'm all for learning and you have to try things to learn. If you are going to do this I would have someone with experience in the matter do it the first time. My response is not meant as a challenge to guys I respect and have shared post with over time, but more toward your experience level on this subject. Rx. glitches are a bear that can bite you over the simplest things. Then again they work amazingly well when everything is set up properly, tuned and balanced. IMHO I wouldn't take the chance.

I agree 100% with having the Rx tested if crashed. I have a mule airplane I use to test out Rx. even after having them bench tested by the Mfg. I lost one airplane due to a Rx. problem. Maybe this is why I am so careful when it comes to this subject.

Fortunately I asked the question can you splice the attenna wire because that is the question I wanted answsered.

As I have already stated I doubt I will have to solder anyway. I just wanted to know if it would be ok in the even that I had to. I think all I will have to do is recover the wired where the covered got pulled off.

As I said, I have already ranged tested it, it appears to be ok. I got the answer I was looking for and appreciate your concern.

Wings

If you are going to all the trouble to splice one, it is not any more work to take the bottom off of the receiver and just replace. My LHS has replacement wires for a buck. It is only one solder connection to the pcb board. I have done it several times for myself and my friends, not any big deal really.