IC - R71
überarbeitet am 19.10.2010
The Icom R-71 did replace their R-70 in 1986, it came with a direct frequency entry keypad and 32 memories, but sufferes from losing not only memory content but also informations necessary to operate the internal microprocessor, so radio might seem dead after the RAM backup battery failing.
Icom's IC-R71 the successor of the IC-R70 communications receiver,
it is technically very similar, but a microprocessor control and 32 memories as well
as a direct frequency entry keypad have been added. It's dimensions are
28,6 x 11,1 x 27,6 cm and it's weight 7,5 kg. There is an optional external speaker in similar
sign and grey - blue - black colour, the sound quality is much better then the
one with the internal auxiliary speaker.
Many of the IC-R71's controls are quite small and difficult to operate with hefty
The big main tuning knob is spinning easily, use a small screw to adjust it's resistance. The upmost of the four pushbuttons at the left of the main tuning knobs dims the S meter illumination. The other pushbuttons are used for VFO access, scanning and memory modes.
At the right, at the place of the monitor speaker of the predecessor, You find
the numbered keys for direct keypad frequency entry, just type in the correct frequency
followed by ENT to access the desired frequency. Just below, there are another two rotary
controls. The left one is used to select the memory channel to recall a frequency. The concentric knobs of the other
control operate the excellent notch filter (active on the R.F. level) and the
PBT. In contrast to the passband tuning as found in classic Drake receivers, the IF filter passband
can be narrowed up to 500 Hz from either edge of the passband, this will give You the
capability to select the less disturbed sideband of a signal in case of interference
from a carrier on an adjacent frequency. The passband tuning on the original IC-R71 has been improved
over the older set's one with a better quality filter and is active on all reception
modes. In sets produced after March 1989, the PBT feature had to be omitted due to a patent / copyright dispute,
it has been replaced by a so called IF shift function.
The IC-R71 is a very attractive receiver, but it suffers from the RAM failure problem: when the internal
RAM backup battery fails, not only all memories are erased, but the content
with informations to control the radios internal microprocessor is lost also,
so the R-71 can become completely inoperative and has to be sent in to Icom
or has to be equipped with a modified EPROM replacement board to "resusscitate"
the radio again. Because of this precedure is time consuming, quite a few sets are
sold as "not in operational" state on internet online auctions - beware, You
cannot mend this fault just with a bit of contact cleaner somewhere inside
the cabinet. There are possibilities, to replace the receivers RAM by a modification
using a larger memory EPROM, which was available years after the receiver has been designed,
try Willco Electronics for details.
© Martin Bösch 4.7.2010