To the original poster:
Your DX-7 will work just fine with a gas installation. Remember to have your transmitter charged overnight. As far as batteries go for the airplane. Here is what I use and there will be other guys who use different setups. But I like to keep my airplanes simple.

1. Hydrimax 5 cell battery pack for your receiver.Use a good quality charger to make sure yourbatteries are peak charged. I do not recommend lipos but that is your choice.

2. I use digital servos (DS-821 or metal gear servos) again your choice.

3. make sure there is no metal to metal contact on your throttle arm. If you do this becomes an antenna and even though we are using 2.4 it still can affect your receiver.

4. Usethe AR 7000 or betterreceiverwith satellite. Make surethe receivers are orientated 90 degrees apart and route them per the directions on the data sheet that comes with the receiver.

5. Ignition battery - ONLY use a 4 cell battery 4.8-6 volts. Any higher can and will damage your ignition system. If you do by chance use a higher voltage battery on your ignition, the engine will still run but the automatic advance portion of the ignition module will not work or work erratically and will cause weird things to happen. So just use a 4 cell battery pack.

6. Run a 3 line fuel tank. one is for the carb, one is for the fill and the other is your vent. The vent line will need to come out of your firewall and point towards the ground. Use a piece of hardwood or a clamp and glue it to the firewall so it will not get into your exhaust. Use tygon fuel tubing. It has a very low melting point and if it gets up against your exhaust is will melt together and cause your engine to go lean and quit running. Bad mojo when on a takeoff run and this happens. Place a piece of copper fuel tubing on the bottom portion of the line.

7. DO NOTcover your spektrum receivers or your ignition system with foam. Use double sided tape to secure the receivers and ignition system to the wood and use a couple of tye wraps to secure them to the structure.

8. Use a volt watch so you can monitor your batteries on your receiver.

9. Invest in a good quality dual switch. 1 is for your receiver the other for your ignition

10. Buy an opto kill switch.

11. Ensure your radio has been set to failsafe prior to flight. (engine to idle and controls neutral) the opto kill switch helps here to.

Here are a couple of pictures of my setup. Hope this helps. If needed I can be reached via e-mail at [email protected]

Enjoy
Glenn Williams