Dilshan R Jayakody’s Web Log

Recently I got an ICOM IC-R71A receiver from my friend. ICOM IC-R71A is a multi-mode quadruple superheterodyne receiver with the frequency range from 100kHz to 30MHz. When it comes to my workshop it's completely dead but outer casing and front panels are in really good condition. Before troubleshooting the receiver, I download both user manual and service manual from the internet. As like all ICOM products this receiver also comes with very detailed user manual and service manual. Restored ICOM IC-R71A receiver As I observed this receiver consist of many PCBs which including: Mainboard Front boards (altogether 7 boards, which including 1 mainboard known and matrix board and 6 small PCBs) PLL board RF board Logic board and RAM board Power supply board In addition to above boards, there are some previsions in this chassis to install other optional boards such as FM board. After observing the power supply board, I notice a couple of dry joints in the rectifi...

This is a quick post about 100W RF dummy load which we build to use with HF and VHF transmitters and transceivers. This dummy load uses two non-inductive 100Ω 50W thick film power resistors manufactured by Vishay Sfernice and both these resisters are connected in parallel to achieve 50Ω impedance. The final version of 100W RF dummy load. Outer-casing (which also act as a heatsink) of dummy load is constructed using four bonded fin 50mm × 115mm × 20mm heatsinks. During our testing, we got flat 1:1.2 SWR with this dummy load. Internal view of 100W RF dummy load. Above mentioned 100Ω 50W power resistors are obtained through Farnell element14 .