Newsgroups: rec.ham-radio Subject: Don't junk that old Bearcat BC-300 scanner x DON'T JUNK THAT OLD BEARCAT BC-300 by Bob Parnass, AJ9S Although the Bearcat BC-300 scanner is no longer available, it occupies a fond place in my collection. I exercise little self control when I see a used BC-300 for sale cheap, and have adopted two broken units. They make fine radios after repair. The BC-300 was the forerunner of today's 760XLT. It was a 50 channel feature laden scanner, introduced around 1979, back when Bearcat was part of Electra. Retail sales of the BC-300 continued until 1987, when it was discontinued by Uniden. Although Electra offered the pricey BC-350 as a step above the BC-300, firmware bugs and a batch of bad power transformers doomed the 350, and the 300 remained the jewel of Bearcat line. It's easy to see why the BC-300 model was offered for several years. It boasted premium features like a clock, a carrier operated solid state relay for tape recorder activation, a transmission counter, and a Service Search of 11 ROM banks of preprogrammed channels. For memory, the BC-300 used EAROM (electronically alterable read only memory), so backup batteries were not necessary. The Dog House, a radio shop in Fairfax, Virginia, at one time offered the DH 1000, a 1,000 channel adapter for the BC- 300! Unfortunately for federal band listeners, the BC- 300 lacked coverage of the 138-144 and 406-420 MHz bands. While outwardly impressive, internal construction was typical of Electra hand wiring in that era -- a bit messy. BC-300 schematics show at least 100 components changed between earliest and later units. The scanner went through many circuit design changes, but rather than changing the printed circuit board, new components were tack soldered on the foil side in different positions. Electra stamped all of its scanners with a manufacturing date code on the rear of the cabinet. The code is comprised of a single character (C = Cumberland, Indiana, P = Puerto Rico), followed by four digits denoting year and week the radio was built. For example, "P2284" denotes the radio was made in the Puerto Rico factory during the 22nd week of 1984. Switching power supply failure was common in early units due to insufficient capacitance. Electra responded by increasing the value of capacitor C98 from 22 ufd/16 v to 47 ufd/25 v, but I recommend 47 ufd/35 v. If your display is getting abnormally dim, C98 is probably the culprit, as it was in five Bearcat scanners I fixed. Squelch preset potentiometer R81, mounted on the radio circuit board, was misadjusted in new units, requiring readjustment after the components aged. In one radio, I replaced Q9, a small signal PNP transis- tor. Its failure caused the BC-300 to become deaf on all but the UHF band. Failure of squelch gate transistor Q15 caused the squelch to remain open at all times. Cold solder joints, especially on the wires and ribbon cable connecting the radio board to the logic board, have been responsible for other failures. I have seen serious IC failures in three BC-300s built around 1984. These include CPU chip IC201, memory chip IC202, and IC203, not in stock at your your local Radio Shack. The BC-300 circuitry, especially on the radio board, is very similar to the circuitry in the the BC-220, BC- 20/20, BC210XL, and BC-350, so some of the previous remarks may be applicable to these models as well. I can neither furnish schematics nor repair your radio. If you come across a broken BC-300, obtain a schematic from Uniden and spend some time troubleshooting. If you give up, your BC-300 can be fixed by Electronic Repair Centers in Franklin Park, Illinois, (312)455-5105. I'm told they do good work. The BC-300 is a classic scanner and worthy of your efforts. -- Bob Parnass AJ9S, AT&T Bell Laboratories