Model airplane news: Guide to micro R/C receivers

Model Airplane News, Nov 1999 by Aberle, Bob

IF YOU HAVEN'T already heard, some R/C modelers are coming indoors to beat the heat, wind, snow and freezing conditions and enjoy the thrills of a new hobby: indoor, micro R/C flying. Others are staying close to home to enjoy a few quick, after dinner flights at local parking lots and athletic fields, and sometimes, even in their own backyards. The key ingredient that makes all this possible is the new breed of micro R/C components now on the market. Surprisingly, much of this equipment has been developed by individuals and small companies, so finding and choosing the right product for the job may prove difficult because many of these folks can afford little or no advertising.

To help modelers who are interested in the new generation of very small aircraft, we gathered samples of all the micro-size R/C receivers we could locate, surveyed the individual features of each and then photographed them so we could present our readers with this product guide. In future issues, we plan to look similarly at microservos, micro-electric-motor speed controllers, tiny electric motors, and last, the kits and ready-built models that will ultimately use these micro-components.

For the purpose of this survey, we defined a micro R/C receiver as one weighing 1/2 ounce or less, although, as you will see, we took certain liberties with that figure. Individual write-ups and photos will provide the details of each micro receiver, along with a list of the names, addresses, phone and fax numbers, email addresses and websites for all the manufacturers, distributors and suppliers.

Please keep in mind that many of these tiny receivers are not what we would call "full-performance" types. In other words, some may not be capable of operating in a narrowband environment with adjacent channels only 20KHz away from one another. Some of these tiny receivers may also have somewhat limited radio ranges. These will work best when operated with similar equipment, i.e., gear designed for micro aircraft that fly indoors, in backyards, at local parking lots and schoolyards, etc. You probably would not want to operate some of this equipment-those receivers that are not narrowband-at busy flying fields where all 50 R/C aircraft channels are regularly used.

Another word of caution involves flying in an indoor facility, such as an auditorium or gymnasium. If you fly during daylight hours, your signals generated indoors might interfere with the signals of fliers outdoors, if there are flying fields nearby. Be very careful of that prospect; to be on the safe side, fly after dark.

Also note that all R/C receivers-in fact, any RF generating device-must be certified to comply with certain FCC regulations to be certain it won't interfere with other electronic devices. Before you buy your new micro R/C receiver, it is best to ask the product's manufacturer or distributor whether a compliance form for it is on file with the FCC. In this survey, we have made an effort to include only receivers that are FCC-compliant. As tiny as these receivers are, they must still be certified.

Common sense will tell you that limited production-in some cases, hand-made units-and tiny size can lead to some large price tags; see our comparison chart to get a sense of the varying prices of the receivers now available.

After reading all about these micro R/C receivers, you may wish to keep up with the constantly improving technology. To do so, we suggest you subscribe to the Slow Flyers listserve, a free, email-based service to modelers offered by Model Airplane News. We've included instructions on how to quickly join this fine network of dedicated micro R/C pilots.

Now, on with the report!

FMA Direct

"Tetra"

One of the "heavier" units in this group, it weighs in at 0.5 ounce (14g) and measures 2 1/8 x 3/4 x 1/2 inch. This is a 6-channel function, single-conversion, full narrowband, performance-capable receiver that is available on all 72MHz R/C channels and on the 50MHz (6m) R/C channels, FM as well as AM. A series of five dipswitches allows the modeler to select transmitters manufactured by Futaba, Hitec, Airtronics, Ace and JR, along with the correct FM deviation (high or low side). The connector block is conventional; this means that it's able to accept most popular servo connectors, including the new "Z type" from Airtronics. It is not marked on the case, so the polarity must be carefully noted. The signal pin is closest to the label side of the receiver, followed by the positive battery pin and then the negative pin. Excellent range and selectivity make this receiver suitable for any active R/C flying field. Primarily suitable for schoolyard or park-type outdoor fliers, it may also be used for indoor, slow-flying R/C models.

Hitec RCD "Micro 555"

This is the only receiver in the survey group that employs dual-conversion circuitry (two IF frequencies using two separate crystals). Expect full, narrowband performance and excellent radio range. It operates on FM and is available on all 72Mhz RPC channels, but not on 6 meters. It has a 5-channel control capability. Weight with its case is 0.78 ounce (22g); with the case removed, the weight drops to 0.64 ounce (18g-just slightly heavier than our guideline for inclusion in this survey). We included this receiver because it is known to be an excellent performer, and it is the smallest unit that still uses dual-conversion circuitry Without its case, the Micro 555 measures 1 1/2x1x1/2 inch. It is intended for Hitec servo connectors.