From: wa2ise@cbnewsb.cb.att.com (robert.f.casey)
Subject: FT23 FT73 & FT211 mod files
Keywords: mods
Organization: AT&T
Date: Sun, 24 Jan 1993 01:06:18 GMT


copied from packet:

 Msg# TSF  Size #Rd  Date  Time From   MsgID        To
33018 BF   5506   0 13-Jan 1158 F1LOU  30537_ON7RC  YAESU@WW ()
 Sb: FT23/73/211 mods


MODS FOR FT23, 73 and 211:
**************************



9600 BPS with Yaesu FT-211RH
----------------------------

RX AUDIO:
---------
On the RX "IF UNIT" (sub board F2869104) connect the screened lead inner to
the TK10420 IC pin 9 with the outerscreen to pin 15. Caution should be taken to
solder these if soldered to the underside of the board.

TX AUDIO:
---------
On the rear of the "MAIN UNIT", a small potentiometer will be seen (peak devia-
-tion adjust.). Unsolder the leg nearest to the rear of the set, and connect
the inner of the screened TX leads to this point, the outer to the earth plane
adjacent to this point. To ensure that the 9600 bauds modem is terminated in
the required impedance, it is essential that a suitable terminating resistor be
placed across the screened lead inner/outer (a 560 ohm resistor); this may
usefully be done at the FT-211RH potentiometer connection.

No further adjustments need to be made to the radio. On the tested modem a
suitable level of 2.5 kHz deviation was achieved with one third rotation clock-
-wise of the modem TX AF level potentiometer.


YAESU FT-23R case disassembly:
------------------------------

1)  Remove the black screws from the top panel of the radio.
2)  Remove the knobs.
3)  Remove the black screws from the rear panel of the radio.
4)  Remove the battery.
5)  Remove the 6 screws on the bottom of the radio, where the battery attaches.
6)  CAREFULLY remove the front panel of the radio.
7)  In the left of the microprocessor and battery are several printed circuit
    jumpers. The jumpers labeled 7, 8 and 9 are for the frequencie mods, like
    explained in the following.
8)  Re-assemble the radio in the reverse order of these steps.  
9)  The Microprocessor will loose all what the memory contains.


YAESU FT211/23/73 band mods:
----------------------------

The uP's in the FT-23/73 and the FT-211 can be set for many frequency and
memory mode combinations. These modes are controled by the jumpers (solder
pads) marked 7,8 and 9 on the "CONTROL UNIT" board of either radio. Here is a
list of what is possible:

      JUMPER         FREQUENCIES
   7    8    9         COVERED

  open open  in     140 to 164 MHZ
  open  in   in     140 to 160 MHZ
   in  open  in     144 to 148 MHZ
   in   in   in     144 to 146 MHZ
  open open open    220 to 550 MHZ
  open  in  open    440 to 450 MHZ
   in  open  in      50 to 300 MHZ
   in   in  open    430 to 440 MHZ

The FT-211 has separate VCO's for transmit and receive and will lock over about
38 MHZ from approx. 130 to 180 MHZ. The FT-23 has only one VCO and the overlap-
-ping lock range (Xmt & Rcv) is about 25 MHZ from approx. 135 to 175 MHZ. Don't
forget, if you adjust the VCO you must realign every electronically tuned stage
in the front-end of the radio. The transmitters can be tuned for somewhat
higher power output above 164 MHz but at a great power loss at 2m.

The non-amateur (commercial) memory mode will cause these functions changes:

 1.When in the MR mode, the channel number will be displayed instead of fre-
 -quency. You can toggle back to the original "amateur" mode display by pres-
 -sing F<up-arrow>. Pressing F<down arrow> bring you back to commercial mode.
 However, when switching from D to MR, the display will always revert to the
 commercial mode.

 2.The function of the Dot<Pri> button will be exactly reversed. That means now
 you can press just one button (Dot) to get into or out of the Primary function
 The Pri funtion (in memory mode) will be indicated by a large "P" on the left
 side of the display.

 3.The only indication of low power operation is in the memory mode. A "C" will
 appear in the upper left corner of the display (where the primary "P" used to
 be). The bargraph will always read 100%.

 4.The band scan is now even more useless. The uP will painfully count from 50
 to 300 MHz.


FT23/73 in packet-radio:
------------------------

If you want to work in packet-radio, open jumper 10 to dissable the battery
save.

73's de Phil, F1LOU @ ON7RC.BT.BEL.EU
======================================================================
Note: I haven't tried or verified this, proceed at your own risk.  And
DO NOT transmit outside of legal bands!  WA2ISE
Newsgroups: rec.radio.info