Radio Technique
FIG. 1 SHOWS what happens when you build up a Royal servo kit, connect the pigtail for use with an ACE RC system, then forget and plug it into a Cannon receiver. The 4.7 Mid capacitor is reverse-voltaged (same 3-pin Deans Connector, but opposite voltage connections on the pins) so it erupts little droplets of molten metal all over the IC (you see?). Fortunately, the fix, in this case, is easy. You replace the capacitor and check out the servo. If it runs slow, try another capacitor, or one with the next lower value. Electrolytic caps have rather large tolerances (like ± 50%). If the new capacitor won't fit on the PC board, try insulating it with a bit of Mystic tape; then put it on the bottom of the board. There's usually a little extra room in the case that can be recovered by changing the thickness of foam tape, or shifting a few wires.
Radio Technique
NOTICE to RC Airmen: Hot Weather Discharges your Batteries! When you store your batteries in the trunk of your car, then park it in the hot sun for several hours before flying, expect the batteries to be discharged. This warning is particularly directed to working fellows like me, who like to stop off at the field on the way home from the job, in order to get in some flying. We charge the batteries overnight (about 9 hours), store the planes in the car all day long (about 9 hours), then suffer the consequences in the evening. It gets worse when you manage to sneak in a couple of flights at lunch time, and forget to recharge the batteries one night.
Radio Technique
A MESSAGE from Bob Hoeckele, managing editor of Flying Models, alerted me to the fact that 2-part curable polyurethane products contain a dangerous poison in the curing agent. After research, I found that this material, toluene diisocyanate, is listed in Dangerous Properties of Industrial Materials, N. Irving Sax, 4th Edition, Van Nostrand Reinhold Co., NY, on page 1176 as a class 3 material in the following categories: Acute Local Irritant, Acute Systemic Inhalation, Chronic Local Irritant, Chronic Systemic Allergen. Class 3 = Severe Toxicity. Extracting from the hazard analysis, we find the following: Capable of producing severe dermatitis and bronchial spasm . . . particularly irritating to the eyes. Under "Disaster Hazard" we find: . . . When heated to decomposition, it emits highly toxic fumes. Now, the reason I mention this is to make you aware of the fact that Curethane paint, which I described in the September 1978 column, contains this material. You can't buy Curethane because toxicity studies have not been completed, according to Mr. Leonard Ellentuch of Economy Plus, manufacturers of the product. I wish I knew that before I gave it to my son, Tim! That we didn't notice any problems may be due to the fact that Tim worked outdoors with a very small quantity, or it may turn out that the concentration in this product is below some kind of threshold. Time will tell.
Radio Technique
TIM and I did a lot of flying this summer (as usual) but we also spent some time with the RC boat crowd, which was unusual. We found a peculiar situation. Boaters are abnormally congregated on 72.160, 72.320, and 72.960. Boaters generally need only two channels of control; either rudder and sail or rudder and throttle. Futaba makes a couple of dry-battery systems with two or three channels. They are inexpensive and work well, so they are very popular with boaters. One of their features is interchangeable crystals on the five lower frequencies: 72.08 through 72.400. Boaters use this feature to work out their frequency conflicts. We noticed that the NAMBA and AMYA meets that we attended were run by people who scrupulously avoided the use of aircraft frequencies. Not so, in the case of sport sailors, who use any frequency that the hobby dealer has to sell them.
Radio Technique
LAST month I promised to tell you how to go about getting a license to operate on the 6-meter Amateur Radio band. It will take some work, and cost a little money, but there will be some rewards that extend beyond the basic objective. You will learn enough about electronics to make you familiar with the design and operating characteristics of transmitters and receivers. It will be no great trick to extend that knowledge into the ability to repair all of the myriad of electronic devices that fill our lives today. "The Amateur Radio Service is a radio communication service of self-training, intercommunication, and technical investigation carried on by amateur radio operators" (FCC 97.3(a).) "An Amateur Radio Operator is a person interested in radio technique solely with a personal aim, and without pecuniary interest, holding a valid Federal Communications Commission license to operate amateur radio stations" (FCC 97.3(b).)
