TM721A.15

73's Jim KD3O @ KD3O.MD.USA.NOAM

SB-931

TM-721A Low/No VHF Transmit Power                 4-11-88


Some early model TM-721A transceivers may develop low or no output power on
the VHF band.  This may be caused by coil L6 or L9 on the final unit.  The
coils should be inspected for burn marks on their insulation.  If any flaw
is detected in the insulation, replace the coild with a wider spaced coil.

Required parts:

Coil, 9.5T     L6,L9     Part Number L34-1238-05

1.   Disconnect the power supply and antenna from the transceiver.
2.   Remove the top and bottom covers (12 screws).  Do not damage the
speaker wires when removing the top cover.
3.   Remove the VHF Final unit shield (4 screws) from the top of the TM-
721A.
4.   Unsolder the Final module (Q1), antenna coax, and terminal pin W4 from
the Final board.
5.   Unplug the wires at connectors CN2, CN3, and CN4 on the VHF TX-RX unit
(top side of the transceiver.)
6.   Unplug the wires at connector CN10 on the UHF TX-RX unit (bottom side
of the transceiver.)
7.   Remove the 7 screws from the VHF Final unit.  Remove the Final unit
fromt he transceiver.
8.   Unsolder an remove the coil (L6 or L9).  Install and solder the new
coil.
9.   Assemble the transceiver by reversing steps 1 - 7.


This modification  may be performed under warranty.
Time required for this change is 1 hour or less.

(c) 121589TKC