Service manual
KB2LJJ Radio Mods Database and Manuals
TX-RX Unit (X57-4360-00) Foil Side View
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R R R R542
5 5 5
4 4 4 R543
7 6 4
R545
(IC403 on component side) R
5
4
8 _______
-| |-
-| |-
-| |-
-| IC402 |-
-| |-
-| |-
-|_______|-
Caution:
This modification requires advanced surface mount soldering equipment that is rated for CMOS circuits. It also requires familiarity with
advanced surface mount soldering techniques. If you do not have the proper equipment or knowledge do not attempt this modification yourself.
Seek qualified assistance from your closest Kenwood Service Center (Long Beach, CA, or Virginia Beach, VA).
The Service Manual specifies a test for the PL. The technician is simply required to verify that any one PL tone is between 500 and 1500 Hz
deviation. This is quite a wide tolerance range! The "standard" PL tone deviation should be 750 Hz. Twice that strong might be too strong and
become audible. There are no trim-pots on the PL deviation, so I'm guessing that the deviation is pretty constant from radio to radio.
The dirty PL is definitely found on early models, but we have had many reports that the PL problem has been fixed in newer versions of the
radio. If you purchased your radio after September 15, 1994, (or your serial number is greater than 55000000) it's a good chance that you may
not have the PL problem.
The other problem concerns the DTMF Confirmation Tones. This feature is off by default (I wonder why :), while it seems pretty useful. To
turn it on, press [PTT] + [Down] on the microphone while powering the radio on. This will generate short DTMF confirmation tones whenever
you send DTMF over the air from the keypad. Unfortunately, it mangles the beginning of the outgoing DTMF tone! This is serious enough that
most local repeaters can't detect the tone, or count it as two tones.
Get a receiver and listen to what you are sending out when the Confirmation tones are enabled. It sounds to me like they may be mixing the
confirmation tone in with the real tone and getting some destructive interference. Just a guess, though.
I called a Kenwood technician (Ricardo) and worked with him on the phone to reproduce the problem there. So, as of today, this is a Known
Problem, and they are looking into a fix. :-)
I am really curious to know what they would say if other folks called up and complained about this problem. Would they deny hearing about it,
or would it really be a Known Problem? Might give some insight into the PL-noise denial thing anyway. :-)
Personally, I'm much more concerned about the noisy PL than the DTMF confirmation tones, since I can just shut those off and pretend that
feature doesn't exist. If enough people call about the PL problem, maybe they will come out with a real fix and offer it under warranty to all the
radios out there (since they're all pretty new). My guess is that it will involve a free TSU-8 tone decode module, but don't hold your breath. :-)
External DTMF Remote Control
The following procedure places the 733 in External DTMF Remote Control.
Note that this mode is different than DTMF Remote Mode. This mode concerns the control of the 733 with an HT, and not the microphone.
● Press Band Select and select the UHF band.
● Pick a UHF control frequency.
● Turn on the UHF DTSS function and select a tone sequence. (p. 89)
● Turn the UHF DTSS function back off.
● Press Band Select to move to the VHF band.
● Press [CONT SEL] to move control back to the UHF band.
● Turn OFF the radio, press and hold [CONT SEL] while turning the radio back on, then release [CONT SEL]. The S-meter scale and
the DT indicators for the UHF band will begin flashing. The LOCK indicator will turn ON, and most front-panel keys (except PWR)
will be disabled.
http://www.kb2ljj.com/data/kenwood/TM-733.htm (8 di 9)30/08/2009 18.42.07