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Old Feb 13, 2012, 04:54 PM
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United States, AZ, Tucson
Joined Mar 2008
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Help needed on purchase of FPV TX/RX setup with my Spektrum DX8. Which MHZ to use

Hello,

I already have my 900mhz FPV system less the TX that was lost when my plane crashed a few years ago.

Getting back in to FPV with a Quad and looking for some assistance.

I read somewhere that they said do not use a video TX/RX lower than your radio frequency. Since I have a DX8 on 2.4 does that mean I shouldn't use 900mhz ?

And, what's the difference between 900, 1.2, 5.8.

I'm not looking for long range, I just want a clear picture so I think I'm ok with 500mw.

Can anyone suggest if I should just buy another 900mhz TX or buy a TX/RX on a different other than 900mhz
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Old Feb 13, 2012, 05:37 PM
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United Kingdom, England, Gt Lon
Joined Nov 2007
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Quote:
Originally Posted by jasper7821 View Post
Hello,

I already have my 900mhz FPV system less the TX that was lost when my plane crashed a few years ago.

Getting back in to FPV with a Quad and looking for some assistance.

I read somewhere that they said do not use a video TX/RX lower than your radio frequency. Since I have a DX8 on 2.4 does that mean I shouldn't use 900mhz ?

And, what's the difference between 900, 1.2, 5.8.

I'm not looking for long range, I just want a clear picture so I think I'm ok with 500mw.

Can anyone suggest if I should just buy another 900mhz TX or buy a TX/RX on a different other than 900mhz
You should be posting this in the FPV section not multirotor section, but I'll answere this anyway.

One of TBS philosophies mention that you shouldent fly an rc link with a higher frequency than your video link. The idea behind this is so that your rc link should have longer range than your video so when your start to loose your video signal you can still control your multicopter!

Not everyone follows this rule strictly but if your doing long range FPV you should follow it. If your going to be flying with your DX8 which is 2.4ghz 10mw then there really is no point getting such a high power mw for your vtx. Most quadcopter flyers use 100-300mw vtx's but I would say even this is way too much if your using a DX8.

If you end up using 900mhz you will need to get a low pass filter.

The difference between 900, 1.2, 2.4, 5.8 is that these are just frequencies. The lower the frequency the better the penetration BUT the less bandwidth (affects video quality). Also certain frequencies cannot be used in certain countries. 900mhz is used for mobile communications in many countries and in places like the US where you can use 900mhz most FPV'ers dont because of the interferance some flyers get because of mobile communications near that frequency.

At the end of the day people choose different frequencies based on what they intend to do and where you fly and sometimes based on what you fly. What factors are more important to you?

I personally use 1280mhz. I prefer it over 5.8ghz which I used to use because I like the fact that there will not be any interance from company buildings because its for HAM users only. This is important for me because I live in london. Also it has much better pentration. 5.8ghz provides a better picture but its not noticeable in my opinion and its a LOS (line of sight) frequency meaning there must be NOTHING between your video rx and your vtx.
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Last edited by malcr001; Feb 13, 2012 at 05:45 PM.
Old Feb 13, 2012, 06:10 PM
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Sorry about that.
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