Icom IC-820D extend rx/tx frequency

hello , is anyone familiar with icom ic-820D?
according to manual this radio work vhf 144 to 146 mhz and uhf 430 to 440 mhz,
is it possible to modify working frequency vhf 137 to 174 mhz ?
many thanks for your attention

How comfy are you with pulling it apart and removing diodes? Icom have been doing this kind of inhibit system on many of their own brand, own factory radios for years now - certainly back to the late 70’s/early 80s with portables like the IC-2E - there are diodes that need to be removed, or if not surface mount, just have their leads cut. I found this instruction sheet. ICOM IC-820H

     This modification is to open the IC-820H for extended receive
(and transmit) operation.  This is a two (four) step modification
which will open the IC-820H to the following frequencies:

VHF Band    136 - 174 MHz
UHF Band    420 - 460 MHz

These frequencies are not guaranteed for accuracy or sensitivity.

1.  Remove Diode D25 on logic board for VHF RX Expansion.
2.  Remove Diode D26 on logic board for UHF RX Expansion.

3.  Remove Diode D27 on logic board for VHF TX Expansion. *
4.  Remove Diode D28 on logic board for UHF TX Expansion. *

* RX modification must be done before the TX modification will work. *

hai Paulears, many thanks for your attention and info, i already done this before but it isn’t working. its may be work on 820H series only.
because for 820D series no diode d25…d28 was install on display board.
ic-820D and ic-820H have different cpu chipset
may be some things else to do for modification.
its hard to find schematic diagram of ic-820/M/D on the web