Antennae Wire Length - Whats the best length to use?

[tim morris]

[color=#000000]i am trying to figure out if the length of wire from the reciever to the wtc connector, plus the wire from the wtc .


i was trying to calculate the optimal length of this wire and i got]

[robse]

Hi
I'm about to put my

[color=#000000]Hi
I'm about to put my receiver inside the same WTC as the engine etc. as well. I'm planning on cutting the wire from the receiver and replace it with a shielded coax-wire from the reveiver and to the plug, and then put the un-shielded wire I just cut off on the outside of the WTC, and away from the engine etc. This moves the receiving 'antenna' away from the engine and servos, and not least the regulator! (Quite noisy too) Remember to connect the shielding in the coax wire to GND. (GND=ground) To reduce noise, add a pair of small capasitors on your engine poles, 100nF should do, or something like it. Connect the capasitor between the engine's + and -.

U also ask to bundeling]http://www.subcommittee.com/forum/icon_biggrin.gif[/img]

About the length]

[bigdave]

Hi Guys, The best length

Hi Guys, The best length is what was on it when you bought it. It is tuned for that length. It may sound like a dumb statement but you should not alter that length. Just as long as the wire in not coiled up you can just leave it inside of your WTC. I would not suggest running it past your motor if possible. One trick I always use is I run my antenna out the end cap of my WTC inside a length of golden rod. If you are not familiar with golden rod it is used in R/C airplanes to connect servos to the control surfaces. It is blue plastic tubing with yellow tubing that runs inside. I use the yellow tube. I just glue the tube into the end of my WCT and run the antenna out into the tube. Then I seal the end with a drop of RTV. You can bend the tube into any shape you want, and can make it any length you want. I usually make mine about 2FT. I have used this for more years than I care to remember and have had no problems or leaks. I have even used the tube to blow into to add pressure to the inside of the WTC to check for leaks. Give it a try.

[ramius-ii]

Hi Tim]http://www.subcommittee.com/forum/icon_wink.gif
EMI/RFI/E-I E-I

Hi Tim]http://www.subcommittee.com/forum/icon_wink.gif[/img]
EMI/RFI/E-I E-I OH is a bit more tricky and not impossible. If you are running both a power lead and a ground lead to a destination it is typically best to put the wires in an electric drill and twist them together. Twisting will add capacitance as well as provide a bit of shielding. Keeping the receiver battery close to the receiver is also a good practice. Batteries are the best filters. Another technique (in the early stage of construction) is to go to a "single point ground" system. This is where all ground connections go to a single stud.

Bypass capacitors of .01 mfd are very good too. You can not have enough of them. Be sure the cases of all your motors have a nice heavy ground wire well soldered to them.

Voltage regulators like to have a 1 mfd cap on their output along with any other filter caps. It's common practice to put "one of each" that is a 1 mfd, .1 mfd, .01 mfd and .001 mfd! The last, .001 mfd is only necessary if you are working with high frequency stuff like 2.4 GHz.

If all this does not handle the problem, then a ferrite bead or torroid on the receiver power lead!

Best, Ed

[anonymous]

Hello All,

Have a couple of

[color=#000000]Hello All,

Have a couple of quick questions about some of the suggestions in this thread]

[robse]

Hi, Floats_like_a_Rock.

1) Well, I would

Hi, Floats_like_a_Rock.

1) Well, I would leave an inch or so on the circuit board of the receiver, so I wouldn't have to solder on the board it self.
It most likely a multi-layer PCB (Printed Curcuit Board), and the last thing we want is to dammage the board. (Been there, done that.. ) I would also make sure to tie the coax cable to something fixed, so that the mechanical stress from the vibrating cable during sailing does not end up in the small, thin wire from the receiver it self, breaking it with time.

2) Yes, Sir. Connecting the shielding to the ground within the receiver ensures low noise penetration, and equal electrical potential. Not connecting the shielding anywhere almost turns it into an antenna, and connecting it to ground (GND) somewhere else poses the risk that you get "ground-loops". Ground-loops causes interference, and are hard to pin-point. Eg. when building HIFI equiptment you should put *ALL* ground connections at ONE point within the 'box', and not just the nearest screw or bolt point. Remembering this praksis everywhere saves you alot of troubles, regardless what U build.

Hope this answers your Q's? If not, please let me know.

[bob the builder]

Hi Tim]http://www.subcommittee.com/forum/icon_wink.gif

Best, Ed

Hi Tim]http://www.subcommittee.com/forum/icon_wink.gif[/img]

Best, Ed

I have a quick question on a related topic.

I just finished modifying a 16th century galleon model conversion to RC, and (as I was on a strict budget), I utilized the running gear from an old Radio Shack RC car that I had lying around.

The car's antenna says that it's on 27mhz. Somewhere along the way, I misplaced my antenna, and now that I want to run one up one of the masts, I'm not sure of the correct length to use.

The above post's formula makes my antenna length somewhere around 105 inches. Does this formula not apply in this case, or do you use a smaller fraction for the antenna length? I'm sure that the original antenna was only about 14" long (approx).

Any help would be appreciated.



Edited By Bob the Builder on 1064846664