Surface-mount circuit board NC2030.

Modifications for the IC-3220 VHF/UHF FM Transceiver

The IC-3220 VHF/UHF FM Transceiver

I bought mine used at the Dayton Hamfest in 2007, and its manual was printed in 1990. Definitely not the state of the art, although that sort of thing intrigues me...

There were three variants of the IC-3220. I believe that these are the distinctions:

IC-3220A/E IC-3220H
Power Current Power Current
VHF High 25 W 7.0 A 45 W 10.0 A
Low-2 10 W 4.5 A 10 W 5.0 A
Low-1 1 W 2.5 A 5 W 4.0 A
UHF High 25 W 8.0 A 35 W 10.0 A
Low-2 10 W 5.0 A 10 W 6.0 A
Low-1 1 W 3.0 A 5 W 4.5 A
Icom IC-3220H ham radio multiband transceiver

Extended Receive Coverage

Unfortunately, this requires hardware modification rather than a firmware power-on reset as on some other Icom gear.

[1] Get a service manual

Ask Google something like the following:

icom 3220 "service manual" filetype:pdf

[2] Expanding VHF receive coverage

Expanded VHF receive coverage:
118.000 - 135.995 MHz AM
136.000 - 174.000 MHz FM
The AM demodulation seems to be done by slope detection, and it is not very sensitive. The IC-2SAT handheld (of similar vintage) seems to be more sensitive in the aviation band than either the IC-3220 or the IC-229 mobiles.

To extend VHF receive coverage:
Cut D6 on the Logic board (located at the front of the radio).

[3] Expanding UHF receive coverage

Expanded UHF receive coverage:
400.000 - 479.000 MHz FM
Sensitivity outside the ham FM band of 430-450 MHz is noticeably worse, see the tables below.

To extend UHF receive coverage:
Cut D4 on the Logic board (located at the front of the radio).

[4] Further Notes on extending frequency coverage

Note that the two referenced pages slightly contradict each other, and one contradicts my experience.

This page says that you must cut both D6 and D4 for VHF, and D5 for UHF, and also push and hold [V/MHz], MONI], and [Mic-DN] while turning on the power. I did not have to do that — cutting D6 gave full 118.0-174.0 MHz receive and cutting D4 gave 400.0-479.0 MHz receive, without any button-down power-up.

1SS181 datasheet 1SS190 datasheet

Also, this page says that you can extend transmitter range on VHF to 136.0-174.0 MHz by soldering a bridge between the solder pads next to D9, and on UHF to 400.0-479.0 by installing a 1SS190 diode at D9. The page says that you must install a 1SS181 diode at D9 and solder between lands A and B to extend both VHF and UHF transmit frequencies. I think they're describing the same two changes using nearly identical diodes. Compare the diode datasheets to be certain.

Receive Sensitivity

As measured with an HP 8656B signal generator. Signal levels were set in integer dBm. That means that the microvolt levels are quantized the way you see here.

Frequency Signal level
Decent SNR on AM FM full-quieting Solid copy but noisy Breaks squelch S9 on meter S5 on meter S1 on meter
118-123 MHz 5.0 μV
125 MHz 2.5 μV
130 MHz 1.5 μV
132-135 MHz 1.25 μV
135.995 MHz 0.5 μV
136-162 MHz 0.5 μV 0.25 μV 0.1 μV
162-174 MHz 0.25 μV
400 MHz 5.0 μV 2.0 μV 0.4 μV 15.8 μV 10.0 μV 5.62 μV
410 MHz 5.0 μV 2.0 μV 0.4 μV 22.4 μV 14.1 μV 7.94 μV
420 MHz 5.0 μV 2.0 μV 0.4 μV 31.6 μV 20.0 μV 12.6 μV
430 MHz 5.0 μV 2.0 μV 0.4 μV 56.2 μV 35.5 μV 20.0 μV
440 MHz 0.8 μV 0.3 μV 0.1 μV 6.31 μV 3.98 μV 2.24 μV
450 MHz 0.8 μV 0.3 μV 0.1 μV 3.98 μV 2.82 μV 1.58 μV
460 MHz 5.0 μV 2.0 μV 0.4 μV 70.8 μV 50.1 μV 28.2 μV
470 MHz 5.0 μV 2.0 μV 0.4 μV 70.8 μV 44.7 μV 25.1 μV
479 MHz 5.0 μV 2.0 μV 0.4 μV 56.2 μV 39.8 μV 22.4 μV