Jumping Diodes By James Goss      Is it ok to jump the diode that is in line (series) with your charge jack on your radio transmitter? Yes and no, the diode is in there for a reason and the manufacturer thinks that it is best to have it. The purpose of this diode is to provide polarity protection for your radio. Polarity simply means negative or positive on a dc system. Batteries are dc so they have polarity, a negative terminal and a positive terminal. The battery in most of out transmitters is a 9.6-volt pack and is used to operate the radio electronics. Its negative and positive leads are also brought out to a charging port on the side or rear of the radio. This is where you plug up your charger and this is where the confusion comes in.      All radios do not have the same polarity on their charge jacks. Your charger has a female terminal that plugs into the radio that has a male terminal. On Futaba radios the center of the male terminal needs to be positive. On Airtronics radios the center is also positive, but on JR the center is negative. If you have several different radios around like a lot of modelers do, it would be easy to pick up the wrong charger. With the inline diode to block the reverse current flow there would be no damage to your radio. Without the diode in place your radio will be damaged as soon as you plug in the wrong charger. It only takes seconds and it is all over for your radio. You could blow every chip and transistor in the radio. Even if the charge plugs are not the same size, as a lot of the different radios will have various sizes of plugs, you will still make and break contact as you try to plug in the charger and damage will occur.      You may be wondering why anyone would want to jump the polarity diode in the first place. If you have ever tried to cycle your transmitter battery you have found out that your cycler will not discharge the battery, or that it will discharge it. This is one way to check to see if your radio has an in line diode. If the cycler will not discharge the battery, then you do have a diode in line. If it will discharge, then you do not have a diode in line. Jumping the diode will not alter the operation of the radio at all. With Futaba it will not void the warranty, but other makes may, I haven't checked because I only use Futaba. So if you want to cycle your radio without removing the battery and it has an in line diode, the diode must be bypassed. Jumping the diode actually will allow more energy to be placed into the battery while charging because the in line diode drops about .6 volts while the battery is charging, unless the diode is a special low resistance diode. I have about twelve or so radios and most of them had the diode. The first thing I do when I get a new radio is to jump the diode. It only takes about five minutes to solder a jumper wire across the diode and you can then cycle the battery without removing it from the radio. I don't like the idea of unplugging the battery time after time because of developing a faulty connection. Same way with unplugging your transmitter rf module to impound it instead of the whole radio at a fly in.      Anyone that can do basic soldering can place a jumper wire across the polarity diode and experience no problems at all if you use the right equipment. Use a low wattage soldering pencil (iron) around 40 watts or less and some .030 diameter rosin core solder. It will require just a very small amount of solder to be added to the pads on the board to install the small wire, 22 awg will be fine, solid or stranded. Just be sure not to create a solder bridge between two printed conductors. If you do not feel comfortable doing this soldering job get someone in the club to do it for you. There is always someone that can do it and will be glad to do so. Again let me say that if you have a mixture of radios in operation I would not recommend strapping the diode, it will just be a matter of time until you make the mistake of picking up the wrong charger, I know I would.