From: aviator
Subject: Re:Needed:Kenwood TH-26A and TH-46A Mods

Date: 3 Oct 91 12:50:26 GMT

Organization: Flight Transportation Associates, Cambridge, MA

Lines:177

Nntp-Posting-Host: e40-008-10.mit.edu



What follows below is the most extensive description of TH-27A mods

that I have ever seen.  Sorry about the ALL CAPS, it came that way.

I've performed the "snip-the-green-wire" mod on mine in order to be

able to use it for the Civil Air Patrol.  Works great.  ...Joakim



---- Cut here ----



The following info on the TH27A was posted before, just after Christmas,

and is reposted due to recent queries.  Please respond directly to the

author, Tom, at Internet:N5OFF
  Packet:N5OFF


I HAVE BEEN DOING SOME EXPERIMENTING WITH MY TH-27A, AND HAVE

FOUND IT TO BE AN EXCELLENT AIRCRAFT RECEIVER AS WELL AS A FINE

TWO METER TRANSCEIVER.  IT WILL ALSO DO FULL 136-174 MHZ TX/RX,

BUT I HAVE NOT YET FOUND A MOD CONFIGURATION THAT WILL ALLOW

FULL TX/RX AND AIRCRAFT RECEIVE AT THE SAME TIME (EXCEPT THE

ASIAN CONFIG, TH-F27, WHICH I WILL DESCRIBE BELOW).



WHEN MODIFIED FOR FULL 136-174 TX/RX IN ANY OF THE WESTERN CONFIGS

THE AIRCRAFT AM IS DEFEATED (SEE CHART BELOW).  IN THE ASIAN CONFIG,

THE RIG BECOMES A VERSATILE WIDE BAND RECEIVER 118-174, 200-400 (DISPLAY

ONLY) AND WILL TX 136-174.  THE PROBLEM WITH THIS CONFIG IS THAT SOME

OF THE KEY POSITIONS BECOME RELOCATED (SEE CROSS REFERENCE).

THE KEY DIFFERENCES ARE OBVIOUS IF YOU COMPARE A JAPANESE

KENWOOD BROCHURE WITH A YANKEE ONE.



SO, CAN ANYONE OUT THERE SHED SOME LIGHT ON HOW TO GET FULL

136-174 TX/RX AND PRESERVE THE RELATIVELY HIGH QUALITY

AIRCRAFT RECEIVE PRESENT IN THE WESTERN STANDARD CONFIGURATION?

I HAVE INCLUDED BELOW MY SUMMARY OF THE POSSIBLE RESISTOR

COMBINATIONS, ALONG WITH A PARTIAL RESULTS LIST.(DID I MISS

A RESISTOR SOMEWHERE?)





  R334      R335      R337     W301         REMARKS

    O        -         O        O          K,P US STOCK CONFIG

    O        O         O        O          E     144-146 TX/RX  NO AIRCRAFT

    O        O         O        -          E2    136-174 TX/RX  NO AIRCRAFT

    -        -         O        O          M     144-148 TX/RX NO AIRCRAFT

    -        -         O        -          M2    136-174 TX/RX NO AIRCRAFT

    O        O         -        O          X     144-148 TX/RX

    O        -         O        -          US MARS 118-174 RX 142-152 TX

    O        -         -        -          US MARS+ 136-174 TX/RX NO AIRCRAFT

    -        -         -        O          ASIAN STOCK

    -        O         O        -          ASIAN MOD 118-174,200-400 RX,

                                                     136-174 TX

    O        O         -        -                136-174 TX/RX NO AIRCRAFT

    O        -         -        O          NOT TRIED

    -        O         -        O          NOT TRIED

    -        O         O        O          NOT TRIED

    -        -         -        -          ASIAN RECEIVE MOD 118-174 RX,

                                           200-400 RX, 144-148 TX

    -        0         -        -          COMMERCIAL 136-174 TX/RX, 5.7 MHZ

                                           OFFSET, 150 DEFAULT





"O" MEANS RESISTOR OR JUMPER IN PLACE

"-"  MEANS OPEN

THE FIRST SIX CONFIGS ARE SHOWN ON THE KENWOOD SCHEMATIC

W301 IS OUR OLD FRIEND, THE GREEN WIRE.



TH-27A TO TH-F27 (ASIAN VERSION) KEY RELOCATIONS



       TH-27A KEY      =      TH-F27 KEY



      TONE/TONE SEL         CALL/C-SCAN

       CALL/C SCAN            BELL/STEP

       3 TALT                 3 TONE

       SHIFT/REV              REV/SHIFT

       MHZ/STEP               MHZ (NO F FUNCTION)







I HAVE SETTLED ON  THE ASIAN MOD FOR MY TH-27A, AND FIND THAT

THE BUTTON  DIFFERENCES ARE EASY TO LIVE WITH.  ALL FUNCTIONS ON THE

RIG SEEM TO WORK IN THE ASIAN CONFIG EXCEPT I DON'T THINK THE

AUTO-DIALER WILL DIAL A * OR #.  NO BIG DEAL FOR ME. IT WILL MANUALLY

SEND A # OR * THOUGH.



AS STATED EARLIER, THE COVERAGE OF THE RIG IN THE ASIAN  CONFIG IS



        118-136 AM RX (WITH A REAL AM DETECTOR)

        136-174 FM TX/RX

        200-400 RX



I DON'T THINK THE 200-400 WORKS AT ALL BECAUSE I'VE COMPARED IT

TO STRONG LOCAL SIGNALS ON A SCANNER AND HEARD NOTHING ON THE

TH-27A.  SEE THE SENSITIVITY MEASUREMENTS BELOW.



OTHER BUTTON DIFFERENCES NOT MENTIONED EARLIER ARE:



                        TH-27A                     TH-F27

           F1SEC,3      TONE ALT SOUND             TONE SELECT

            F MHZ       STEP                       BAND SWITCH 118/145/340

          

OTHER NOTES:



AUTOPATCH WORKS WELL



CTCSS TONES SENT OK, DTMF AND CTCSS SQUELCH WORKS



BAND SCANNING, ETC WORKS OK



PROCESSORR RESET DEFAULTS TO 145.000 INSTEAD OF 144.000



TX/RX NO PROBLEM ON VHF FM



RX AIRCRAFT, GREAT! AS GOOD AS A BEARCAT 100/200, BETTER THAN

ICOM 2SAT. THE TH-27A HAS A "REAL" AM DETECTOR/AGC (SEE SCHEMATIC).



WISH LIST, FOR SOMEONE ON THE NET TO FIGURE OUT THE MOD TO GIVE

136-174 TX AND PRESERVE THE AIRCRAFT RECEIVE IN ONE OF THE STANDARD

US OR WESTERN CONFIGURATIONS. IS IT NECESSARY TO GO TO THE ASIAN

CONFIGURATION TO HAVE YOUR CAKE AND EAT IT TOO?



SENSITIVITY MEASUREMENTS 

TH-27A   12/18/90 

USING AN IFR MOD 1000S SERVICE MONITOR 

REFERENCE IS 1 LED SEGMENT LIT   

1000 HZ TONE 

 

FREQ.SIGNAL 

MHZMICROVOLTS 

 

1181.7AM

1201.5 

1220.9 

1240.9 

1260.9 

1280.9 

1300.8 

1320.8 

1340.8 

1360.8 

1360.5FM

1380.4 

1400.4 

1420.3 

1440.3 

1460.3 

1480.4 

1500.4 

1520.4 

1540.4 

1560.5 

1580.5 

1600.5 

1620.6 

1640.8 

1660.8 

1680.8 

1701.0 

1721.3 

1741.5 

200-400NO RX 

 

INSERT USUAL WARNING/DISCLAIMER HERE.



DE TOM N5OFF
                      







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-- James Dugal,N5KNX Internet:jpd
Associate Director Ham packet:n5knx
Computing Center US Mail:PO Box 42770  Lafayette, LA  70504

University of Southwestern LA.Tel. 318-231-6417U.S.A.







--

Joakim Karlsson            | aviator
Flying Fanatic in Training | FAA:P-ASEL  CAP:Freedo