FL2100B.1

YAESU FL2100B 12 METER MODIFICATION
by Bill Walton KJ6EO

If you do not mind losing 10 meters on your FL2100B, this quick mod
should have you up and running on 12 meters with near full power
output.

Place the FL2100B on its side with the LOADING control nearest the
surface that the amp is setting on.  Make sure that the amp has been
UNPLUGED and that the PLATE VOLTAGE has dissipated before you proceed.
Remove the screws that hold the bottom cover on and remove the bottom
cover of the amp.

Set the BANDSWITCH to : 10
Set the PLATE CONTROL to : 9
Set the LOADING CONTROL to: Fully counter-clockwise

Disconnect the 850 volt red wire that leads from the transformer to the
DIODE BOARD (located right behind the TRANS - OPERATE switch. Install a
SWR bridge between the EXCITER and the FL2100B.  Tune your HF rig to
24.950.  Turn the FL2100B on and place the amp in the OPERATE MODE.
Excite the the AMP with an AM signal, enough so that you can calibrate
(set) your SWR meter.  Place your SWR meter in the REV position and
read the SWR.  While in the TX mode, tune L206 (located near the
GROUNDING WINGNUT just inside of the amp chasis) untill you achive your
lowest SWR reading.  You have just completed the retuning proceedure of
the 10 meter ANTENNA INPUT COIL.

If you would like to operate both 10 meters and 12 meters,  you may
want to tune L206 on a frequency between your operating fre-quencys on
10 and 12.

Re-solder the 850 volt red wire (with the AMP off and un-pluged). Re-
assemble the AMP and enjoy INCREASED POWER OUTPUT on 12 METERS.

Send questions, comments, or other to: KJ6EO @ KJ6EO