I got a few questions about my 50 MHz. post last night. Yes I am using the same rubber ducky antenna for both 72 and 50 MHz. operation. I just swap the Futaba modules into my 8UAFS transmitter. This may seem counterintuitive but remember that the stock whip antenna on the TX is the same length for both bands. I also called Smiley Antennas asking for an antenna optimized for 50 MHz and was told to use the same one. Clearly, the TX module has to have a matching network to deal with the non optimum antenna length situation. Flight test results both with power and sailplanes have been totally sastifactory as long as the ground range check was reasonable.
What capacitors would you use at the servos? I am guessing here based on my 30 years as an analog design engineer. I would / will start with 470 pF ceramic cap from signal to ground and a 1.0 uF 10 v. tantalum cap from power to ground ( watch voltage polarity!!) My reasoning is as follows: dipped solid tantalum caps at reasonable temperatures have a good low impedence to RF up into the hundreds of MHz. and you can't get into trouble with too much bypassing on your power line until you use HUGE caps which draw too much current when the power is turned on. The signal line wants to have a low impedence to RF but a high impedence to the 1.5 ms pulse sent for position information so some compromise must be made. Based on the speeds and frequencies involved, I would pick 470 pF ceramic. Both of these suggested caps are quite small and will have to be mounted with care close to the servo (guess less than 5 inches will be OK) I have a new 3 meter on order and this is what I will start off with when I make the wiring harness for it. Regards, Jim MacLean Melbourne, FL ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: http://dl.www.juno.com/get/web/. RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
