Dilshan R Jayakody’s Web Log

This post is about beat frequency oscillator (BFO) module which is used to receive SSB and CW signals from the ordinary shortwave receiver. The original circuit which is related to this post is obtained through the internet and we modify it to get more precise output with commonly available electronic components. ( Unfortunately at the time of writing this original link is no longer accessible due to a dead link. ) This module consists of two general purpose NPN transistors and we select 2SC828 because of its availability in the local marketplace. For the crystal, we use commonly available 455 kHz ceramic resonator. Assembled 455 kHz BFO module. This BFO unit is easy to construct and may not need any test instrument for calibration. To receive the SSB signals, power this unit with regulated 5V or 6V DC power source and place BFO module near to the shortwave radio receiver. To get good results to place output wire of BFO near to the IF amplifier section of the target receiver....

I got Trio ( now Kenwood ) JR-310 and TX-310 SSB receiver and transmitter pair recently. When it comes to me both receiver and transmitter are in very bad shape and most of the PCBs and chassis are covered with dust and some of the components are very badly damaged. After examining both the chassis I decided to repair both units because of its vintage value (and also I like to try some tube base SSB receiver and transmitter pair). Trio JR-310 is AM, SSB and CW mode HF receiver. This receiver has 3.5, 7, 14, 21, 25 and 50MHz operating bands and sensitivity is around 1µV. This receiver consists with 6 vacuum tubes, 5 transistors and 19 diodes. JR-310 which I restored is working with 110V and total power consumption is around 70W. Bottom view of restored JR-310 receiver TX-310 is 20W SSB transmitter and designed to match with JR-310 receiver. It is capable of LSB, USB, AM and CW transmissions in HF bands. This unit consists with 10 vacuum tubes, 5 transistors and 9 diodes. Like ...