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Table 1
ICOM IC-R75, serial number 01206
Manufacturer’s Claimed Specifications
Frequency coverage: 0.03-60 MHz.
Power requirement: 1.1 A, 11.7-15.9 V dc.
(An ac power supply is provided)
Modes of operation: SSB, CW, AM, S-AM, FM, AFSK.
Receiver
SSB/CW sensitivity, bandwidth not specified,
10 dB S/N: 0.1-1.8 MHz, <2.0 µV;
1.8-28 MHz, <0.16 mV; 28-30 MHz,
<0.18 mV; 50-54 MHz, <0.13 µV.
AM sensitivity, 10 dB S/N: 0.1-1.8 MHz, <5.6 µV;
1.8-30 MHz, <1.6 mV; 50-54 MHz, <1 µV.
FM sensitivity, 12 dB SINAD: 28-30 MHz,
<0.22 µV; 50-54 MHz, <1 µV.
Blocking dynamic range: Not specified.
Two-tone, third-order IMD dynamic range: Not specified.
Third-order intercept: Not specified.
Second-order intercept: Not specified.
FM adjacent channel rejection: Not specified.
FM two-tone, third-order IMD dynamic
range: Not specified.
S-meter sensitivity: Not specified.
Squelch sensitivity: SSB, CW, RTTY,
<5.6 µV; FM, <0.32 µV.
Receiver audio output: 2 W at 10% THD into 8 Ω.
IF/audio response: Not specified.
Spurious and image rejection (except IF
rejection on 50 MHz): 70 dB.
Size (hwd): 3.7×9.5×9 inches; weight, 6.6 pounds.
Measured in the ARRL Lab
As specified 1.
2 A. Tested at 13.8 V.
As specified.
Receiver Dynamic Testing
Noise floor (mds), 500 Hz filter:
Preamp off
Preamp one
Preamp two
1.0 MHz
–130 dBm
–137 dBm
–140 dBm
3.5 MHz
–133 dBm
–141 dBm
–143 dBm
14 MHz
–132 dBm
–138 dBm
–142 dBm
50 MHz
–127 dBm
–136 dBm
–140 dBm
10 dB (S+N)/N, 1-kHz tone, 30% modulation:
Preamp off
Preamp one
Preamp two
1.0 MHz
1.7 µV
0.8 µV
0.6 µV
3.8 MHz
1.2 µV
0.6 µV
0.4 µV
53 MHz
2.4 µV
1.0 µV
0.5 µV
For 12 dB SINAD:
Preamp off
Preamp one
Preamp two
29 MHz
0.5 µV
0.2 µV
0.2 µV
52 MHz
1.0 µV
0.4 µV
0.2 µV
Blocking dynamic range, 500 Hz filter:
Preamp off
Preamp one
Preamp two
3.5 MHz
122 dB
120 dB
115 dB
14 MHz
122 dB
120 dB
113 dB
50 MHz
119 dB*
119 dB*
111 dB*
Two-tone, third-order IMD dynamic range, 500 Hz filter:
Preamp off
Preamp one
Preamp two
3.5 MHz
91 dB
89 dB
87 dB
14 MHz
88 dB*
86 dB
87 dB
50 MHz
88 dB*
86 dB*
84 dB*
Preamp off
Preamp one
Preamp two
3.5 MHz
+3.6 dBm
–7.7 dBm
–13 dBm
14 MHz
–0.3 dBm
–9.1 dBm
–17 dBm
50 MHz
+4.9 dBm
–7.1 dBm
–14 dBm
Preamp off, +60 dBm; preamp one, +65 dBm; preamp two, +51 dBm.
20 kHz channel spacing, both preamps on:
29 MHz, 67 dB; 52 MHz, 60 dB.
20 kHz channel spacing, both preamps on: 29 MHz, 67 dB*;
52 MHz, 70 dB*; 10 MHz channel spacing, both preamps on,
52 MHz, 106 dB.
S9 signal at 14.2 MHz: preamp off, 82 µV; preamp one, 31 µV;
preamp two, 9.5 µV; 50 MHz, preamp off, 178 µV;
preamp one, 60 µV; preamp two, 20 µV.
At threshold, both preamps on: SSB, 16 µV; FM,
29 MHz, 0.08 µV; 52 MHz, 0.2 µV.
2.3 W at 10% THD into 8 Ω.
Range at –6dB points, (bandwidth):
CW-N (500 Hz filter): 221-972 Hz (751 Hz);
CW-W: 67-2625 Hz (2558 Hz);
USB-W: 87-2591 Hz (2504 Hz);
LSB-W: 64-2597 Hz (2533 Hz);
AM: 66-2510 Hz (2444 Hz).
First IF rejection, 14 MHz, 81 dB;
image rejection, 14 MHz, 72 dB.
Note: Unless otherwise noted, all dynamic range measurements are taken at the ARRL Lab standard spacing of 20 kHz.
*Measurement was noise-limited at the value indicated.
1Sensitivity reduced below 0.06 MHz.
the supplied—and sizeable—ac adapter.
Fortunately, it’s wired with a plug on the
end of a cord so you don’t have to figure
out where to plug in the hefty cube.
A Capable Receiver
The R75 packs a lot of performance into
its compact frame. Keep in mind that ICOM
was able to concentrate on simply producing a decent-performing receiver here; they
From January 2000 QST © ARRL
didn’t have to worry about what was happening on the transmitter side.
With the R75, you’ve got a receiver that
not only covers a huge chunk of the known
HF spectrum plus the low end of the VHF
(the only thing that would have made it
better would be to have included coverage
comparable to the IC-706, but that’s for the
next version), but also has ample sensitivity over its coverage range. ARRL Lab test-
ing showed the preamp-off sensitivity hovered around –130 dBm—right up there with
the big boys—but it includes two preamp
stages to boost sensitivity by as much as
10 dB. These really can come in handy!
A few words on dynamic range: This is
an aspect of receivers that, while important,
often gets less than a full discussion in the
typical transceiver review. It’s also something that many amateurs are still unfamil-