Review: Micron Mini FM Receiver Kit
After you've built your model, nothing quite beats the satisfaction of building your own radio. However, with good radios so readily available, most of the kit manufacturers in the UK have gone by the wayside.
One exception is Micron, who have been making R/C kits for many years. Following good reports in the ISA list, I decided to build their Mini Competition 7-channel receiver. This is one of a range of four receiver kits on offer.
The receiver supports both 35 and 40 MHz operation without modification and uses Futaba single-conversion crystals.
Above: kit of parts
A jiffy bag containing all the bits arrived four days from date of order. In the bag:
- Electronic components
- Two PCBs
- Plastic case
- Detailed drawing
The receiver uses two boards. The RF board uses an MC3371P chip mounted on a carrier. The decoder uses a 4017.
The trickier bits - connector block, chip carrier and one surface mount component - are pre-soldered at the factory.
A beautifully clear drawing is supplied, and some tuning notes. Assembly was a pleasure but there are a few points worth noting:
- A fine tip (2.5mm approx) is required on the soldering iron.
- The sole transistor must be mounted on the PCB flat side up - it states this on the drawing but it's easy to assume otherwise.
- Slight trimming of one PCB was required for an easy fit in the case. This was easily done using a Permagrit block.
- An RF choke has to be assembled from a ferrite bead and enamelled copper wire. The enamel must be scraped off the ends with a knife.
- The channels are arranged non-sequentially 4-5-1-2-6-7/B-3.
- The connector block is not polarised. Reverse insertion is not fatal on many units, but with the Mini it's also possible to stagger the connections since there is no shroud. This problem is probably due to the case design not being changed since the phasing out of SLM sockets.
Above: RF board on left, decoder at right. Connector block is pre-soldered.
I slid the boards into the case, plugged in the Xtal, servo and battery, and hey presto the unit burst into life!
The single coil needs to be tuned according to the notes - it's a one man job and it takes only a few minutes without the need for a meter. The boards can then be fitted into the case. A Micron sticker shows the channel numbers.
A cheap and cheerful receiver which is fun to build, but you must have good soldering skills as the component density is quite high. The only real niggle is the lack of a proper shroud for the connector block.
I have now flight tested it in my Enigma, using a Multiplex 3030 Tx - and it works a treat.
Nigel Wrigley writes:
"I have built and flown with the Micron mini and found no problems using JR Tx and crystal. Ian Harrison who did the web site for the Rivington Soaring Association also flies with Micron receivers with no problems.
I did however slip up in swapping two resistors - I think they were the 4K7 and 470K, yellow purple orange and yellow purple red. Easy mistake to make. I have done other electronic kits and thought this one would be a doddle, but that mistake took me a couple of evenings to find and was overlooked three or four times!"
|Op Voltage||4.8 - 6 V|
|Channels||7 (one shared with battery)|
|Xtals||Futaba (single conversion)|
|Size||43 x 30 x 24 mm|
|Price||£21.50 as of 06/99|
|info AT micronradiocontrol.co.uk|
Castle Howard Road
|Fax||0870 055 4578|