IC-765 Overview

The IC-765 has been ICOM’s flagship HF-radio for many years. Even today (2006) it represents excellent value for money as it has one of the best receivers ever made. The IC-765 has 4 IF stages (69MHz, 9MHz, 455kHz, 9MHz), built-in power supply (PS-35) and automatic antenna tuner (AT-150), and it comes with 500Hz CW filters (mounted from the factory. Optional 250Hz CW filters (FL101 and FL53A) are available, too, as is the optional FL102 6kHz AM filter.

Many of the classic radios from 1980-1990 suffer from being dependent on a built-in battery. They store the operating system / firmware in RAM that needs continous battery power. If the battery power is lost, the operating system of the transceiver is lost too and the radio is dead, and you can not count on support from the manufacturer (radio too old). Several workarounds and replacement procedures have been developed, nevertheless it is a delicate and risky operation.

Fortunately, the IC-765 does not have this problem because it uses EPROM for storing the firmware. RAM is only used to store dynamic data, like the band stacking registers and the memory channels. Thus, if you backup battery dies, you will only loose dynamic data and the IC-765 will still work properly.

On the negative side one can mention the cheap and not too good filters and the lack of passband tuning. There is, however, a mod for the latter, see here.

The receiver of the IC-765 sounds quite good, in particular when combined with the SP20 speaker. You can try to listen to it on in the video attached below.

Author: Alexandru Csete

Embedded software engineer in the satcom industry during the day. Radio amateur and SDR hacker during the night.