myths
 

I have 3 myths that I am unsure of... 1) is it ok to pass the antenna over the servos or will that cause any interferance. 2) do strong earth magnets cause interferance when within 1/2' of the servos, reciever, and antenna? Lastly why Can you use 2 st. fuel in a 4 st. engine, why do they create 2 types of fuel if one works on both engines?

thanks for clearing these questions up, dave trimmer

RE: myths
 

I've done it and haven't encountered problems. I do try to route the antenna away from the other wires if possible.
Several people are using rare earth magnets to hold down boat hatches. In many cases, these are quite close to the radio box. They haven't had radio problems.
Yes, you can use 2 stroke fuel in a 4 cycle engine. Why do they create different types of fuel? In a word, marketing. ;) It seems some people want to buy a special product instead of the same old stuff.

RE: myths
 

Like Piper says...All three myths are just that ..myths.....

RE: myths
 

myths=rumors=legends=lies.

1. antenna slack in the fuse,as long as you pass a radio check you should be fine.

2. magnets can cause problems with electronic devices,but are you sticking one on your reciever,I don't think so.refer to answer#1.

at least for me, I use fuel that has 10%nitro in my 2st and 4st engines, as long as your fuel has at least 18% oil then you can run it in just about any engine with the exception that certain 4st engines like YS run best on 20% nitro 20%oil min.

RE: myths
 

I would add a caveat to the fuel. Some 2st fuels are fine for some 4sts. But there are engines both 2 and 4 stroke with particular requirements.

EG Cox 010, Moki 210, STs [the big ones], MVVS 49s, Laser 4sts.

RE: myths
 

I will address question 1. Antenna routing is normally done for convenience, and at times can be problematic.

Consider that 'signal' wires should be routed in a different route than 'power' wires. But considering servo's have all three in parallel to each other, well, that sort of blows holes in that theory.. except the antenna. Consider the antenna as a separate wire altogether and try to keep it away from other components. Non necessarily because of inteference, but to get the best efficiency out of the antenna. It should be routed in one length, with as few bends as possible, and routed the entire length of the antenna without folding back and so on..

The antenna for 72 MHz is about 1.04 meters, or about 39 inches long. That is a quarter wavelength, by the way, for those of you that understand such techie stuff. Optimal length means that it is getting the best signal from the transmitter so the antenna should be strung out as straight as possible (note.. as possible... I know that there are times when this is not exactly possible). This will give you the best signal strength received and thus the best range and response.

I usually try to get my antennas out of the fuselage as much as possible. I've even routed it out the bottom right behind the servo tray, then run it along the bottom of the fuselage and held in place with a narrow strip of covering material that runs the length of the fuselage, keeping the antenna straight and all the way back. If the antenna is longer, then secure it in place and let it dangle. It won't hurt anything.. but NEVER cut it.

DS.

RE: myths
 

With 4 strokes it is better to run an engine with synthetic oil because castor build up and foul the valves and cause a bad seal around the valve seats. Castor is good on a 2 stroke because it uses ports instead of valves

RE: myths
 

It is pretty common for "4 stroke fuel" to contain at least 10% nitro and at least 20% oil. This varies from brand to brand though. The ingredients are the same, the difference is the percentages of the ingredients.

RE: myths
 

the reason that you can run the signal wire near the power wires for a servo is that the signal is much stronger in the servo leads then an antenna wire where the signal is very weak and it is amplified inside the reciever. the servo signal is a powered signal and is less suceptible to being influenced by the power wires

RE: myths
 

Most of the time you won't get a problem if the antenna is routed close to other gear. However, there are several ways this can cause interference.

The servo signal wire could create noise in the antenna if they are close enough or wrapped around each other. This works like an inductive tap. But since the power involved in the servo lead signal wire is fairly low, I suspect you have to work to get this one to show up. Except at extreme range.

More seriously, you could get noise coming from the servo motor or pot. Servo motors are (mostly) basic brushed motors, and as they age, the brushes can start arcing. Even new motor do generate some RF energy, and worn ones can generate more. The pot is less of an issue, but a worn pot can cause the motor to jitter back and forth, which makes more noise from the motor, and maybe some arcing in the pot.

So, keep the antenna as far away from servos and other stuff as you can, don't sweat the servo wires as much as you do servos (and obviously things like ignition wiring in gassers).