I gave this some thought myself earlier this year - I did a lot of playing with H2 filled balloon carrying payloads as a kid. I have the flying wing with vidcam xmtr already - plus a brushless motor and bats to help if it gets too far downwind. Although I think I'll try it sans motor for a test flight. So far, my max range test with the vidcam xmtr and R/C gear has been about 3500' of which 2600' vertical was the highest altitude reached. If the servo rcvr antenna gets oriented pointing at or away from the gnd xmtr, and the gnd xmtr antenna is pointing at the plane - at that range the vidcam xmtr will start interfering with the servo rcvr. You can quickly tell this as the camera starts to jerk (on the panning/tilting servos) and so does the plane! Otherwise I'm ok. The vidcam xmtr will go easily 15-20K' with the yagi rcvr antenna and the abt 1W output power it's running rite now. So to go to 100K u need maybe 25w (square function) - not difficult to do with a little linear amp. U cud use a higher gain yagi, but then u'll need to keep the antenna roughly pointed at the plane - either manually (not that hard to do), or automatically. The gnd xmtr needs a boost too - again probably 25w wud be a better number, but here more power is not going to interfere with your plane (maybe somebody else's plane!), and will improve the signal/noise felt at your plane. A beam on the R/C xmtr wud help tremendously, but the size gets to be a problem if u stay on the same freqs. The 72 Mhz band is roughly 6 times bigger than the 440 - so the elements are like 6' instead of a managable 1'. But the bigger problem is interference on the plane. But it ought to still be doable using all the precautions I've had suggested to me, plus the one's I use: What I do: 1) cover all the cabling (including servos), rcvr, and bats, with Al foil. This makes a shield against the vidcam xmtr signal. 2) Put the vidcam xmtr and camera on the OTHER side of this foil (ie on top of the wing). 3) Run the servo rcvr antenna out one wing, run the cable for the vidcam xmtr antenna(s) out the other wing. Mounted in my case 2 antennas with a splitter. One is taped on the leading edge (horizontal) and the other up the coroplast winglet (at right angles to the other antenna). This way I get a signal no matter what orientation the plane (BUT u also have to use a non-directional rcvr antenna - the yagi works great but it is highly polarized for one orientation). Other suggestions: 1) Put a bandpass or lowpass filter between the antenna and the servo rcvr. (I plan to try this next - built the module - just need to try it) 2) Put the rcvr in a metal box, and run all leads in/out thru high freq bypass feedthru caps. This is a pain to do - so I've been saving it for last! Anyone know where I can buy a reliable lightweight servo triggered (like on the gear servo slot) balloon release mechanism? FYI - I'm not interested in setting any records - I'm more interested in trying it from the aspect of taking high altitude pix/vids, and collecting meteorological data. -- Tom Rust Nanochip Inc Box 13249 Oakland, CA 94661 (510) 339-6263 (510) 339-9636 FAX http://www.nanochip.com RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
