What are you using? How has it performed?

[Dusty]

Well, not flown FPV with my turnigy 9x yet, but I generally fly LOS untill my bixler is just a barely visible speck in the sky (high altitude HD footage). so I'd say a couple hundred metres easy with no control issues. I wont be pushing the boundaries of my 9x until i have a RTH/RTL system installed in the bixler, which should be here in Feb in the form of APM 2.0

[Ian]

I fly 35 mhz, Futaba on PCM, ive had over 8km and regularilly fly 2 or 3 km without issues all on standard gear except for receiver arial lengthened as per Coyote instruction! Futaba PCM is far more resistant to interference.

[londonguy]

I fly 35 mhz, Futaba on PCM, ive had over 8km and regularilly fly 2 or 3 km without issues all on standard gear except for receiver arial lengthened as per Coyote instruction! Futaba PCM is far more resistant to interference.

Have you got a link to extended receiver range?

[Ian]

One mod thats very popular with FPV flying is extending the length of the receiver antenna. A rx antenna is not a tuned antenna but the length can have a great effect on its performance.

This is done to extend the range of the reception. Its very effective. But its not as easy as doubling the length, it should be though but when the units are mass produced they are not cut accuratly in the first place.

Most rx antennas are supplied with around 1 meter long antenna length, this is practical and very useable. This length is called a 1/8 wavelength antenna. Its 1/8 the size of the 35mhz wavelength.

If you double this then you get a 1/4 wavelength antenna, more usefull and still fairly practical.

If you use a 1/2 wave antenna your getting pretty good performance but your antenna is getting very long at this stage, over 4 meters in length. Most stop at this point. When using a 1/4 wave antenna be carefull not to be standing on the wire when launching. Or it will end up being a shorter no wave length in particular antenna and bad for flying lol

Below are the lengths for each frequency

Channel        Frequency    1/4 wave            1/2 wave

channel 55    34.950        214.59cm            429.18cm
channel 56    34.960        214.53cm            429.06cm
channel 57    34.970        214.47cm            428.94cm
channel 58    34.980        214.40cm            428.82cm
channel 59    34.990        214.35cm            428.69cm
channel 60    35.000        214.28cm            428.57cm
channel 61    35.010        214.22cm            428.45cm
channel 62    35.020        214.16cm            428.33cm
channel 63    35.030        214.10cm            428.20cm
channel 64    35.040        214.04cm            428.08cm
channel 65    35.050        213.98cm            427.96cm
channel 66    35.060        213.92cm            427.84cm
channel 67    35.070        213.86cm            427.71cm
channel 68    35.080        213.79cm            427.59cm
channel 69    35.090        213.74cm            427.47cm
channel 70    35.100        213.67cm            427.35cm
channel 71    35.110        213.61cm            427.23cm
channel 72    35.120        213.55cm            427.11cm
channel 73    35.130        213.49cm            426.98cm
channel 74    35.140        213.43cm            426.86cm
channel 75    35.150        213.37cm            426.74cm
channel 76    35.160        213.31cm            426.62cm
channel 77    35.170        213.25cm            426.50cm
channel 78    35.180        213.19cm            426.38cm
channel 79    35.190        213.13cm            426.26cm
channel 80    35.200        213.07cm            426.14cm
channel 81    35.210        213.01cm            426.01cm
channel 82    35.220        212.95cm            425.89cm
channel 83    35.230        212.89cm            425.77cm
channel 84    35.240        212.83cm            425.65cm
channel 85    35.250        212.76cm            425.53cm
channel 86    35.260        212.70cm            425.41cm
channel 87    35.270        212.64cm            425.29cm
channel 88    35.280        212.58cm            425.17cm
channel 89    35.290        212.52cm            425.05cm
channel 90    35.300        212.46cm            424.93cm 

As you can see there is only 2.13cm between the start and the end of the channels we use if making a 1/4 wavelength antenna. Because you can or have to swap crystals at meets then cutting to 212.46cm will cover all the wavelengths available.

Because of the nature of Uk flying a 1/2 wavelength antenna is a bit over kill for the ranges we fly. But the info it there, choose to use at your own discretion. 

So making your antenna 211.40cm would be ideal for general use. Or 422.80cm for a 1/2 wavelength. If you want to tune it to the channel you most use the data is there for you.

[londonguy]

Thanks Ian very informative!

What sort of wire should I use to extend the antenna? And should I solder onto the existing or replace the whole lot with a new wire?

[Ian]

I used servo wire and soldered on to the existing aerial

[londonguy]

Cheers Ian