copied from the Internet:
From: brian@towers.uucp (Brian Murrey)
Newsgroups: rec.radio.amateur.misc
Subject: FT470 Xtended UHF receive Mods
Summary: This text file explains how to extend the rcv of the FT470 to 500Mhz

This mod is from Darrel Sego (KM9S) and it will allow your 470 to receive up 
to 500 Mhz without affecting the xmit of the unit on 440.

Mod follows:

YAESU FT-470 UHF RECEIVE MOD.

This modification will make the popular Yaesu FT-470 dual band ht
receive above 450 mhz.  Basically, this procedure stores the upper
limit into the U memory.  To use it tune to the U memory channel press
the (MR) hey to go to the MR mode then tune down to the desired
frequency.  Once the correct frequency obtained, you can place it in
any memory but remember to keep the U memory channel active with the
highest frequency you would want, (I keep mine at 470 mhz).

Here are the steps in proper order.

1.  Program the frequency of 450.00 mhz simplex.

2.  Press the FUNCTION and then the RPT button for the offset.

3.  Enter the code 0000 into the keypad.

4.  Shut the transceiver off and turn back on.

5.  Press the RPT key twice for a + (plus) offset.

6.  Press the REV button one time.

7.  The radio should now display 1450 mhz.(The radio will not operate
at these frequencies.  My service monitor shows that above 500 mhz
the rx is very weak.)

8.  To get to the proper frequency to store in the U memory channel
press F and then hold the down arrow key to drop in frequency one
mhz at a time.  Stop for now at 500 mhz.

9.  To store this frequency in memory press the F key and hold until
you hear two beeps.  At this time rotate the dial knob until the
channel U is displayed.  Press the F key again, you should hear a
beep.  this indicates that this upper channel is stored in the U
memory channel.

10.  To use the higher frequencies you have to go to the U channel and
press the MR button, this puts you in the MT (memory tune) mode.
from there you can scan down or use the dial knob to go to a lower
frequency.

11.  ANY selected frequency can be stored in a memory channel.

12.  That's it!

NOTE.  Some radios will not let you go up in frequency only down.  If
you try to go up the rig will default back into the original ham band.
for some reason mine will let me go up or down.
GOOD LUCK
Darrell Sego KM9S
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: Brian Murrey - KB9BVN
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Note: I haven't tried or verified this, proceed at your own risk  WA2ISE
/EX