YAESU FT-690

           YAESU MICRO-PHONE NUMBER MH-15 C8.

MOD.: HOW TO PREVENT THE TOUCH-TONE PAD FROM 
AUTOMATICALLY KEYING UP YOUR RIG.
RIGS INVOLVED: THIS MIC. COMES WITH THE YAESU FT 290 MK 
II (2 METER RIG), THE FT 690 MK II (6 METER RIG), OR THE FT 490 
MK II (UHF RIG),  AND POSSIBLY OTHERS.
1) TAKE THE THREE (3) BACK SCREWS OFF.
2) TAKE THE TWO (2) SCREWS OFF THE CIRCUIT BOARD TO FREE 
IT FROM THE CASE.
3) FIND THE RED WIRE GOING TO THE MICRO-SWITCH, IE, THE 
PTT LINE.
4) FOLLOW THAT RED WIRE TO THE CIRCUIT BOARD.  AT THAT 
PLACE ON THE CIRCUIT BOARD ANOTHER RED WIRE WILL JOIN THE FIRST 
ONE.
5) UN-SOLDER BOTH RED WIRES FROM THE CIRCUIT BOARD AND 
CLEAN UP THE SOLDER MESS, OTHERWISE HUM WILL OCCUR.
6) SOLDER THE TWO RED WIRES TOGETHER AND COVER WITH TAPE 
OR SHRINK TUBING.
7) PUT THE CIRCUIT BOARD IN PLACE AND SCREW IT DOWN.
8) PUT THE "LOCK" SLIDE SWITCH BACK IN PLACE.
9) PUT THE REST OF THE CASE ON.
10) PUT THE OUTSIDE SCREWS IN.
11) YOU ARE NOW READY TO TRY IT OUT, SO GO AHEAD AND RE-
ATTACH IT TO YOUR RIG!
12) ALL SHOULD WORK:
PTT WORKS AND RELEASES,MIC PASSES AUDIO,
TOUCH TONES WORK WHEN PTT BUTTON HELD,
TOUCH-TONE RED "LED" STILL LIGHTS UP WHEN TOUCH-TONE 
PAD KEYS ARE DEPRESSED, EVEN IF PTT BUTTON IS NOT HELD DOWN,NO HUM NOTICED.


THE SAME GOES FOR ALL 3:FT-290R/FT-690R/FT-790R
From: DL8SET @ DB0RBS.#BW.DEU.EU  (Manne)
           Extending the tuning range of the Yaesu FT690mkII.
           --------------------------------------------------
Although the ft 690mkII covers 50-54 it can be 'stretched' to cover any six
megs  between  44-54Mhz.  A  very useful mod for listening to early warning
video signals on 48.25+-, 49.25+- and 49.75+-.
Firstly  replace  the  crystal on the 55Mhz vcxo (part X4002) on the pll/pa
unit with a new one of the following spec.
        Frequency - 27.34925Mhz, fundemental cut.
 load capacitance - 28pf
series resistance - low (15-20ohm)
           Holder - HC-18/T/3P, middle pin to case.
To  modify the PLL divider and display, first switch off the memory back-up
battery  and then install a 1N4148 diode, soldering the cathode to pin 5 of
P2501 and the anode to pin 6 of P2502 of the CPU unit.
Turning the rig back on, the VFO's will display 5.000.0 (this is 45.000.0).
The  mark "HIGH" will be displayed above 0.000.0 (50Mhz). Now adjust TC4001
on  the  VCO unit for the desired range. Next adjust T3018 and T3021 on the
transmit  path  as  well  as T3001 to T3005 on the recieve path for optimum
flatness and sensitivity over the chosen frequency range.
In  case  the range 48 - 54 is required, there is no need for the above VCO
and  RF circuit adjustments. Please note that the performance will decrease
approaching the lower 44Mhz limit.
For  accurate  frequency  display,  adjust T4001 on 0.000.0 against a known
50Mhz signal and VR4004 for 25Hz frequency difference between 9.998.475 and
9.998.500  using  the  25Hz step mode. The step when moving from 9.998.4 to
9.998.5 is the most critical as it represents the maximum possible error of
the display reading.
Modification  as  supplied  by SV1DH and printed in Six News, Issue 41. All
modification done at owners risk.
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