From: sseeger
To: "'webmaster
Subject: ICOM T81A Mod

Date: Wed, 23 Jun 1999 10:35:26 -0700



I'm not sure I'm sending this to the right person, but it'd be great to see

it listed in the RADIO MODS section.



I've noticed you don't have any mods for the T81A quad bander from ICOM. I

just wanted to say that after reading the other mods for various radios

I've figured out the receive mod for this one. It seems to be a touch

trickier. The radio must be powered off in VFO mode so that when you turn

it on, it isn't in the memory channels. Hold down SQL and the MULTI button

(you must hold down the button as you would confirming choices in the

radio, ie not in any one diretion but all of them) and then viola, there's

all the receive. Just wanted to share it with everyone. :)



-Steven

KF6WJH





Rob Neff (N7ORY) writes:





Removing the battery pack and two screws at the bottom. Remove the antenna and ring-nut, also remove knob. Lift the circuit out carefully.



Below LCD, right side of pcb, there will be 5 or 6 places for diodes. 1st and 5th diode installed from factory. To the right of small diodes, another set of larger diodes parallel to the row of smaller ones.. The layout looks like this..



[-]

[ ] ( )

[ ] ( )

[ ] ( )

[-]



They are labled (from top to bottom for the small diodes)

d55,d54,d57,d66,d61.. The larger ones are labled (top to bottom) d53,d52,d51..



To open TX, remove the diode from the 5th spot down in the row of small diodes (d61), and also remove the first of the larger diodes (the one at the top, d53). This mod does not require resetting the cpu.



New TX freq limits:

50.000 to 54.000 MHz

136.000 to 173.995 MHz

400.000 to 469.000 MHz

1.2 same



To open TX farther, remove the first smaller diode, d55. This appears to TX on 220. It does open up 5 meters however. It will TX above 54 Mhz. The first mod does NOT open 5 meters.



50.000 to 75.000 MHz

136.000 to 229.000 MHz

400.000 to 599.995 MHz

1.2 same.



From: "Rob Neff" 

SOURCE: The QRZ Windows Ham Radio CDROM