General Inquiry/FAQ thread

[Danub]

Alex i got 2 questions about my new flying environment, power wires and RF propigation.
Found a great new flying site in b-more 15min from home. . . closed down golf course
Near the site are some high powered lines.
my stuff
1.2 gear. . . . . crosshair and SPW
2.4 gear. . . . . helical and CL

Questions

1. Why does 1.2 seem to be effected by proximity to the power lines more than 2.4?

2. 1.2 definitely "pushes" through and around obstacles much more than 2.4. Is this only due to the frequency change or is this due to the difference between the crosshair vs helical? Basically is it worth it to "upgrade" my 2.4 helical to a crosshair??

[IBCrazy]

Powerlines shouldn't affect video at all so long as your ground station isn't directly under them. In the chance that the lines carry a traveling wave (look for a big circular ring called a wavetrap) for communication, it could have some effect, but I wouldn't think it would do much.

1.2 has more punch for 2 reasons: 1. You are using a Crosshair which is the most incredible antenna I ever made and 2. because it has a longer wavelength and therefore a larger Fresnel zone.

-Alex

[Danub]

Time to learn to make RX antennas for me

[daveycan]

Hi ibcrazy, I just bought a 2.4 5 turn helical from someone and there seems to be some damage. The last turn seems to bend back down towards the base. Also, it doesn't seem to follow the previous path when it was painted. Can I bend it back myself?

[IBCrazy]

You sure can! I would recommend it. Tuning happens at the base, not the upper turns, so as long as you get it close, it will work perfectly. That looks like an early model black cannon.

-Alex

[daveycan]

Thanks Alex!

Does that mean it is a collector's item and will be worth it's weight in gold years down the road?

BTW, what frequency are these tuned to? 2450 +- 100?

[IBCrazy]

Center tune is 2450MHz. The band width is +150/-130MHz.

-Alex

[neo__04]

Just a quick question for you Alex. Just received a Cloverleaf/SPW set from readymaderc. Didnt come particularly well packed. I checkit it out on my DIY SWR meter i just finished (thanks again to you).
SWR of the SPW was 1.01 (amazing work alex! ), Cloverleaf was 1.53. Does this indicate the Cloverleaf may have been squashed a bit out of shape in the box? Any way I can tune/bend/fix this to improve the SWR?

Not sure if it matters but im running 1280mhz

Thanks again! Making my helical 5 turn tonight.

[IBCrazy]

That's actually right where it is supposed to be. RMRC has both 1280 and 1258 MHz frequencies, so I make my sets hit right in the middle of those frequencies. Mind you 1.5 SWR is 96% efficient, so the resonance is still excellent and better than most factory antennas. I'm not sure of your testing environment, but humidity and proximity to other objects will also have an effect on SWR. In fact, the skew wheel should have been closer to 1.2

-Alex

[Beauregard]

Hi Alex and other if you want to chime in.. If I turn over the cloverleaf antenna on the tx side will it reverse the polarity? When I use the "right hand rule" from physics class it seems to??

Thanks,

Cedar