Modifications for the IC-3220 VHF/UHF FM Transceiver

I bought it 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 — US & Asia (Japan) model — includes CTCSS/PL subaudible tone encoder and DTMF tones with the HM-56 microphone
IC-3220E — European model — includes 1750 Hz tone call, has slightly different default receive coverage
IC-3220E — Seems to be like the IC-3220A with higher transmit power:

		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

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 IC2-SAT 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).

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
Frequency	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