Low pass filter or not on 1280 MHz only

[kenkos68]

Is a low pass filter really necessary for 1280? The second harmonic puts it 2560 MHz. Is that still too close to affect Spektrum and Fasst radios? One of my nice parks to fly in also has an AMA field nearby. I don't want to ruffle anymore feathers than I already have with some of them.

Flying with 300mW RMRC mostly.

[aeryck]

Its close enough, and if you use gps/osd, you'll want the filter to prevent gps interference.

[kenkos68]

Thanks, filter it is. Just trying to eliminate any unnecessary equipment.

[aeryck]

Thanks, filter it is. Just trying to eliminate any unnecessary equipment.

Yeah, i hear ya. In my opinion a low pass filter is one piece of equipment that has many more advantages than disadvantages.

[airtruksrus]

Kenkos68, what kind of range are you getting out of your 300Mw video tx? I have an lp filter on mine, don't know if it affects overall range. When my radio locked up i was using the 800 Mw vtx without the filter and no tx amp.

[Crash]

Low pass filter on 1280 doesn't attenuate the signal at 1580 for GPS to do any good. Look at the graph of any of the low pass fiters, the attenuation curve doesnt drop hard until its close to 2.4ish. You need this:

http://aglhobbiesllc.corecommerce.co...ch-Filter.html

Knock out harmonics in GPS band and 2.4

[kenkos68]

Kenkos68, what kind of range are you getting out of your 300Mw video tx? I have an lp filter on mine, don't know if it affects overall range. When my radio locked up i was using the 800 Mw vtx without the filter and no tx amp.

Easily just under 3 miles with omni's. Haven't gone further. Assembling my Eztracker and helix now before I try again. Where I am at 5-6 miles is probably the max I will stay in.

[airtruksrus]

Easily just under 3 miles with omni's. Haven't gone further. Assembling my Eztracker and helix now before I try again. Where I am at 5-6 miles is probably the max I will stay in.

Now i have enough concern about the dynamics of this Vtx, which vendor did you get yours from? Going to bring this up on the Rangevideo forums as well and try to get to the bottom of this, sucks having to turn around after 1.2Km with really weak video. Wondering what the true output of this module really is.

[kenkos68]

I have the ReadyMadeRC version. You should be able to go much farther than 1.2 km's. What about your antennas? My omni's are a turbine and SP that I built, but have tuned using IBCrazy's coupler method. Also where were you flying? I got my distance over a whole area of farmland which was very low noise.

[airtruksrus]

I usually fly at the club site on the Outlying field on whidbey, the touch n go practice strip for the aircraft from the NAS. Tried using a couple custom made cloverleaf rhcp, V antenna (dipole) and ended up cutting down the range to 300 ft or less. The stock antenna is the only one that's had any kind of range so far.