MX-6800 Pico Universal Receiver

Model Airplane News, Oct 2000 by Aberle, Bob

Maxx Products Intl. (MPI) recently introduced a new micro RC FM receiver, the MX-6800 Pico Universal unit. The receiver comes in a small, orange plastic case that's 1 1/4X1/2X1/2 inches, and a rather large crystal projects an additional 5/16 inch above the case. It weighs in

at 7 grams (0.246 ounce) with the case and 5.5 grams (0.193 ounce) without the case-about 1/4 ounce or slightly less. The receiver antenna is only 22 inches long and is a relatively fine gauge, like no. 26 wire.

The MX-6800 is a single-conversion, narrow-band FM receiver that has what is called "auto shift select." In other words, the circuit receives a signal from your RC transmitter, determines if it is high or low deviation (like Futaba or Hitec on one side and Airtronics or JR on the other) and sets itself automatically so that when you order the MX-6800, you don't have to specify which transmitter you plan to use. At the time of these tests, the MX-6800 was being offered on 72MHz on all even RC channels with the exception of channels 12, 14 and 36, and MPI expects to have most of the odd channel numbers by the time this article is published.

The MX-6800 also has a fail-safe feature that will lock on the last frame received if the signal is interfered with or lost. In practice, I did find that the controls tended to go hard over when the signal was lost. You might experiment with this and make your own observations before your first flight. Keep in mind that the range is very good, so for most applications you won't expect to see the fail-safe kick in.

Operating voltage is claimed to be from 3 to 7 volts. For some very lightweight applications, it may be possible to operate on only 3 Ni-Cd cells. The connector block will accept Futaba, Hitec, JR and Airtronics Z connectors. The center pin is battery positive, and a decal on the side of the receiver case indicates the proper polarity. Keep in mind that this is a 4-channel receiver but has only four connector ports, so when you use all four channel functions, you must use a Y-harness to connect the fourth servo.

Range is stated in the specifications as 1,000 feet. In my tests, I used a Hitec Prism-7 transmitter with a Spectra synthesized radiofrequency module so that I could simply dial up the correct channel. With only one transmitter antenna section extended, the MX-6800 had a range of about 150 feet. With the antenna fully extended, the receiver operated at 720 feet before the fail-safe started to kick in. At 750 feet, I could no longer see the model clearly. This is excellent range, and remember: it was accomplished with just a 22-inchlong antenna!

This micro receiver also proved to be very selective. Using several transmitters, I tried to "hit" the MX-6800 on both adjacent channels (just 20kHz away). In each case, there was no interaction whatsoever. So this micro receiver could be flown successfully and safely at an RC flying field.

If you use the MX-6800, two microservos and a micro electronic speed control with BEC, the total radio airborne weight could easily be less than 1 ounce, which would enable you to operate three control functions (rudder or aileron, elevator and motor control). For a glow plane or a glider, you need only substitute a small battery pack of 50 to 100mAh capacity for the speed controller. Best of all, the MX-6800 costs only $59, including the crystal. Very impressive! -Bob Aberle

Maxx Products Intl., 815 Oakwood Rd., Unit D, Lake Zurich, IL 60047; (800) 416-6299; (847) 438-2233; fax (847) 438-2828.