From: flloyd@L1-A.West.Sun.COM (Fred Lloyd [Phoenix SE])
Newsgroups: rec.radio.amateur.misc
Subject: Kenwood TM732A Review
Date: 12 Aug 92 20:59:41 GMT
Organization: Sun Microsystems, Phoenix, AZ
NNTP-Posting-Host: l1-a.west.sun.com


Since there have been a few requests, I have updated the article
and am reposting it at this time.

-fred


First Impressions: The Kenwood TM-732A          April 20, 1992

Fred Lloyd, AA7BQ


The TM-732A is Kenwood's newest entry into the fiercely
competitive dual band mobile market.  It is designed to replace
the TM-731 dual bander, which in its own right was an extremely
solid performer.

The TM-732A (or 732 for short) is closely related to Kenwood's
other late model radios like the TM-x41 series.  I have personal
experience with the TM-241 and the TM-741 and find that there is
a good deal in common between them and the 732.  On the other
hand, the 732 does hit the ground running with a few new
features which make it stand out from even its higher priced
brother the 741.


Physical Description

The 732 is the same basic form factor as the TM-2/4/541 series
mono band radios which goes to say that it is an very small
package for a full featured dual-bander.  The package is a bit
longer, however due to the small fan mounted on the rear
heatsink.  The manufacturers seem to be opting for the fan
instead of the heat sink these days, and my only guess is that
its ultimately cheaper to produce them that way.  Nevertheless,
the 732 is _considerably_ smaller than the 731 that it
replaces.

Like the TM-741, the unit features a removable control head.  The
control head's release latch on the 732 is nicely recessed on the
left side of the radio making it a bit more secure  and less
likely to be inadvertently actuated.  The latch clip also seems a
lot more positive on the 732.  Also, the inside of the base unit
is covered by an integral black plastic panel which keeps the
base unit's electronics covered when you remove the control head
(unlike the 741 which leaves its guts exposed).

The shape of the control head is somewhat different in that it
is not exactly rectangular in that there is a cutout of about
1.5cm^2 where the microphone plugs in to the panel behind it.
The microphone receptacle, an 8 conductor RJ-45 type, is the
same as that used on the 741 and looks to be an emerging (ham
radio) standard, perhaps borrowed from the cellular telephone
industry.  The receptacle is a part of the base unit, not the
control head, and so when the control head is removed it is
rectangular except for the cutout mentioned above.  (I have
found that it is the same connector as that used in 10-base-T
ethernet networks :-)

The control head displays both bands simultaneously with the
first two digits of megahertz being a bit smaller than the
others.  The clear front bezel was thoughtfully designed to be
recessed a bit, so as to prevent scratches.  Finally, there is
a nice littel lip on both the top and the bottom of the case that
protects the bezel.

The controls have the typical legends borrowed from the 241 and
the 741 series.  It is disappointing to note that the key
legends are not illuminated for nighttime use.

There are two speaker jacks on the rear, one for each band with
one that can output both bands.  The antenna connectors are
typical Kenwood pigtail style with no built-in duplexer.  The
same mounting hardware and bracket is used as with the TM-241.

A look under the covers reveals an impressive dual-hollowed die
cast aluminum case which looks like it could withstand an air
drop.  The The upper hollow contains the VHF transceiver with
the UHF in the lower portion.  The speaker is a nice size (about
2") and sits in the upper (VHF) portion of the case.  The base
unit includes a third circuit board which is attached to the
front and is a "mother board" of sorts which contains the base
unit MPU and interface connectors.  The only other circuit board
is the one found in the remote control head unit.

The overall integration of the unit is impressive.  My first
thought at seeing the inside was that it seemed nearly empty.
That's because the surface mounted components are so small and
the integration so high that there are only a few visible
building blocks present.  There are, for example, no wires
inside this box.  Well, to be accurate, there are the two wires
which feed the speaker.  That's it.  The rest of the connections
are all made via printed circuit paths.  There is one short,
small, green wire in the control head, which when clipped
enables extended receive capabilities (see below).

There are a couple of small adjustable pots inside, and these
are the smallest that I've ever seen.  They, like everything
else, are surface mount types.  I would guess their size to be
on the order of 3mm square!  If I were to try and adjust them,
I'd probably use the eraser end of a pencil.  These pots adjust
the high and low power output settings as well as the max
deviation.

The unit comes DTMF ready, which means that a DTMF decoder board
is included.  This gives it remote control ability, DTMF squelch
and paging, and a 10 number autodialer.  The only internal option
offered is the TSU-7 CTCSS (PL decode) board ($50 US).


Operating Features

Kenwood has done a fairly good job at maintaining a consistent
user interface between their models.  Being familiar with the
241 and 741, I found it pretty intuitive to operate.  Not
intuitive enough, however, to venture out of the house without
taking the operators manual along since they sadly omitted a
quick reference card (like the gave out with the 741).  Unless
otherwise noted, the 732 generally has the same basic feature
set as the TM-241 plus several extras.

The following is an unordered list of outstanding bits of trivia
regarding the 732's features:

1. Dual In-Band Receive:  Competitive pressures (e.g. Icom's
2410) has now made this a standard.  You can set the display to
receive any combination of: VHF/UHF, VHF/VHF or UHF/UHF.  This
capability is quite well engineered and makes it possible to
transmit as well as receive on either band's second display.  It
is not possible (understandably) to have a full duplex QSO on an
in-band setup.  In other words, when you set the radio to
monitor two UHF or two VHF frequencies, one of these frequencies
is muted when you transmit on the other.  This is not so when
the selection is VHF/UHF, where the receiving band is not muted
during transmit.

Looking at the schematic, the dual in-band receive is well
implemented with each of the transceiver boards having two
receiver front end units (RF amp and mixers), one for each
band.  There are some unsymmetrical aspects to the dual in-band
receive.  First, the UHF receiver does not have an AM mode which
means that you cannot monitor AM aircraft spectrum at 118-136
MHz with the UHF receiver.  Similarly, you cannot monitor 800
MHz with the VHF receiver.  Each of these modes AM aircraft and
800 MHz, are unique to the VHF and UHF receivers respectively.

A nice touch is that even though the second receiver is utilized
on the other band, the transmitter is automatically switched
back to the proper band which allows you to transmit on either
of the two frequencies while using the dual in-band mode.  In
this way, it really feels like you have two radios on the same 
band.

2. Smart Mute:  The MUTE function is now intelligent in that it
mutes the non-PTT band only when necessary.  This means that the
audio muting (actually, 20Db of audio attenuation) is switched
into the auxiliary band only when something is being received on
the primary band.  Previous Kenwood rigs muted the auxiliary
band at all times when the MUTE function was active.

3. More programmable microphone function keys:  Previous
Kenwoods allowed you to program the PF microphone key only.
With the 732, you may program any of the top 4 function keys
(CALL, VFO, MR and PF), even for example, with such multi-key
sequences as [F][VFO].

4. New Display Lighting:  The display is the now-standard black
letters on a light background.  Like the 741, it has 4 light
levels, plus OFF (no light) which is nice.  Also, there's
a special feature which when enabled makes the display jump up
to the next brighter display level whenever a button or key is
pressed, returning to the dim level after 5 seconds of
inactivity.  When used with the OFF level it gives you a display
which is completely dark at night and comes on only when you
need it.  There is, however, a small green LED off of the
display which remains lit at all times to show which band is in
use.

5. Memory:  As advertised the radio comes with 25 full-function,
odd-offset capable memories per band for a total of 50
memories.  What's nice however, is that you can have up to 64
memories if you are willing to forgo the odd-offset capability
to varying degrees.  For example, if you can live with only 5
odd-offsets then you'll get 30 memories per band.  If you don't
need any odd-offsets then you get 32 memories per band.  In
addition, you can apportion the 64 available slots between the
two bands in whatever ratio that you desire (in 5 channel
increments).  In other words, you can configure for 50 UHF
memories and 14 VHF memories if you like.

6. Cross Band Repeat:  This is the first Kenwood radio to come
from the factory with CBR enabled and documented - no mods
necessary.  Works in the usual way and has a built-in adjustable
time out timer.  The turnaround hang time is also adjustable.

7. Full remote control from microphone:  There is a special mode
in which nearly all functions are controllable via the keys on
the microphone.  Even volume and squelch are controllable.  The
key sequences are difficult (although no more than others) do
memorize.  Where's my cheat sheet !?!?

8. Remote base operation:  The radio is remote controllable via
another transceiver using DTMF tones.  The key sequences are not
the same as those used for the "microphone remote control" as
mentioned above.  Nonetheless, it is possible to change
frequency, PL, Repeater ON/OFF, memory channels, etc. from
remote.  Determining your current frequency from remote base is
only indirectly possible, and then only if you've got a perfect
pitch ear.  You can command the radio to "speak" its frequency
in which it will emit one of ten documented unique tones for
each digit in the frequency display.  ICOM solved this in the
2410 by including a Voice Synthesizer option which will really
"speak" the current frequency.  There is no way to determine any
other operating parameter via remote control.  You must set what
you want.

9. Channelized Operation:  Using this mode, frequencies are no
longer displayed and the VFO is deactivated.  Only memory
channels are available for use and the display shows CH-01,
CH-02, etc.  An unusual feature in my opinion.  It would allow
the radio to become an instant business-band unit if it only
had the type acceptance.  

10. New Squelch Features:  The unit essentially has 3 squelch
modes (not counting CTCSS or DTMF).  There is the normal noise
activated squelch and two new squelch modes - S-meter squelch
and Microprocessor squelch.  S-meter squelch works on signal
strength instead of noise level and when it is used you preset a
desired S level on your S-meter using the squelch knob.  Only
signals which are stronger than your setting will break
squelch.  The other new mode, Microprocessor squelch, is
basically a full automatic squelch which disables the squelch
knobs entirely leaving the internal CPU to do the work.

11. Dual band simultaneous scanning: Not particularly new but a
nice feature anyway.  You may continue to scan on one band while
you're talking on the other.  The ability to do dual in-band
scanning has not been tested but should be possible.

12. Extended Receive Modes:  Cutting the now famous green wire
in the control head will unlock the UHF receiver which comes
factory limited to 438.005-449.995.  After the mod (which
requires no radio disassembly) the UHF receiver will cover from
410-570 MHz.  Also, an 800 MHz mode is available by pressing and
holding the MHZ front panel key.  To enable 800 MHz receive, a
capacitor must be installed under the UHF receiver.  (See the
separate article on TM732 MODS for the full info).

13. Memory Cloning:  Take two 732's and you can exchange their
memory contents either by wire or _over_the_air_ using DTMF tones!
This capability is documented in the TM732.MOD file.


Subjective Impressions

Being a TM-741 owner, there were a couple of things that I
missed on the 732.  First, there's no real-time clock, no sleep
timer, no programmable ON time/ OFF time feature.  There is an
APO (automatic power off) with a preset time of 2:59:00 of
inactivity until power down.

Another complaint is the slow scanning speed.  The unit will scan
VFO or memory at no more than about 5 channels/frequencies per
second per band.  I consider this to be terribly slow in today's
age.  The slowness is probably due to the fact that the remote
contains all of the scanning logic and because the data path
between the head and the base is over a 2 wire serial data stream.

Another perennial complaint is that the radio does not cover
the entire UHF frequency band of 420-450 Mhz.  As shipped,
the unit will only operate over the range from  438 to 450,
(transmit or receive) which I find objectionable.  In the US,
we hams _are_authorized_ to transmit anywhere between 420 and
450 MHz!

The manual is of typical quality and fairly complete although
not well indexed.  There are so many functions that a cheat
sheet is needed but as mentioned, was sadly not included.  In
typical fashion I note that the Japanese have never been able to
adequately and clearly explain how DTMF Squelch and Paging
works.  They've tried diagrams and jinglish explanations but in
the end you still end up reading the instructions over and over
before you fully understand them.  I'd love to see a plain
English discussion of how the DTMF features are intended to work
and how they really work in practice.  Follow that with a step
by step example and we'd probably have something that could be
more popular.

One of my reasons for buying the radio was to use the remote
mounted head option.  The option, the PG-4K kit, is advertised
as a 13 foot extension.  What you don't find out until you buy
it, however, is that only the display cable is 13 feet long and
the microphone cable is only half that!  To me this meant that
although the display cable would let me trunk mount the base,
there was no way I could get by with a 6 foot microphone cable.
The solution: buy the PG-4M(?) which is the longer model for
another $30!  Needless to say, I'm not a happy camper!  Are you
listening Kenwood????  (Yes, they have been listening, and
I understand that they have changed this -fred)

On a positive note about the remote cabling, at least with the
732 it is possible to roll your own.  The 4 conductor head to
chassis connector cable could be easily spliced and extended, and 
an ordinary RJ-45 extension cable could be used for the
microphone.  For many folks, however, it's probably easier
to just buy the short ($47) or the long ($78) cable kit.

The extension cable issue aside however, it still looks like it
will be a very good radio.  As always, after spending a big wad
of cash I'm automatically inclined to say that I like the
radio.  This is no exception, the TM-732 does a fine job at
heading off the competition at a good price-performance point.
The price is the same as the older TM-731 which was around $650
retail (real price, not the bogus MSRP).

To conclude, I think Kenwood has come up with a fine replacement
for the 731, and has put a lot of thought put into the design of
the 732.

See you on the air...

-fred,  AA7BQ

-- 
| Fred Lloyd  AA7BQ,  Systems Engineer          Fred.Lloyd@west.sun.com |
| Sun Microsystems Computer Corporation                   ...sun!flloyd |
| Phoenix, AZ    (If it's a fact, I believe it!)         (602) 275-4242 |
Newsgroups: rec.radio.amateur.misc,rec.radio.shortwave