Review Of The Kenwood Tr Handheld

I can t remember when I have been as favorably impressed with a new piece of ham radio equipment as I have been with my new Kenwood TR-2400 This new microprocessor-controlled, hand-held. 2-meter FM rig has many advanced operating features that make it compare favorably with many larger mobile and base station rigs that I have used-

The TR-2400 covers the entire 2-meter band, with some additional coverage at each end of the band tor MARS operation. Synthesized 5 kHz channels are selected by pushing the calculator-style keypad switches on the front of the rig. and both receive and transmit frequencies are displayed on a large liquiti-crys-tal digital readout display above the keypad on the front panel. The liquid-crystal display is on whenever the -ig is on. it is very easy to read and is not washed out by bright sunlight. A frontpanel switch turns on a lamp to illuminate the display for night viewing.

For repeater operation, a iop-mounted rotary switch selects the transmitter offset: +600 KHz. -600 kHz simplex or a fourth position that allows for operation with any non-standard repeater split by offsetting the transmitter to a frequency stored in memory.

Speaking of memory, this little rig has ten programmable memories' This may seem like a bit of overkill at hrst, but if you are Jike me, you will soon find that you are using them all' It is very handy to be able to return to a frequency instantly by simply punching up the appropriate memory channel.

Memory programming is easy; Simply push the M key followed by a number key (0 to 9) ana the displayed frequency is entered into the memory channel corresponding with the num-be1 key that was pushed

Frequencies are recal led from memory in a similar manner, by pushing the ' MR' (memory recall) key followed by the desired memory number key All frequencies stored in memory are held in storage even if the TR-2400 power switch is turned off. The memory circuitry used draws only 700 microamps from the rig s battery, so a freshly-charged battery will hold Ihe memories contents for over four v;eeks without a battery recharge.

The TR-2400 also Offers very convenient scanning features. You can scan the memory channels by simply pushing the "MS" key, and the rig will scan through the ten memories, always starting with memory number one. The memories are scanned at a rate of approximately one channel per second, which allows enough time to read the frequencies displayed as channels are sampled. A top-panel-mounted h'busy/openHh switch selects one of two memory scanning modes. In the " busy' position, therig willstop scanning on the first occupied memory channel. Scanning will resume when that signal goes oil the air. 1i the "open1 switch position, the scanning will stop on the first memory channel that is not occupied Scanning can be instantly stopped at any time by simply pushing ihe "stop" key.

The TR-2400 also provides a manual or "band scan function. Two of the keys on the keypad control this feature, M the ,kup" key is pressed once, the frequency will lricrease by 5 kHz. and if this key is held down, ihe rig wtll scan rapidly up the band.

Similarly, pushing the "down" key once will cause the frequency to decrease by 5 kHz, and holding this key down will cause ihe rig to scan rapidly down the band. Using these two keys allows you to "June up and down the band to search for the presence of signals. The scan rate for this 'unction is very fast .. about 30 kHz per second. You can scan through the entire 4 MHz of the 2-meter band in less than a minute.

The TR-2400 has two lllock" switches on the front panel One is used to disable the push-to-laik switch, the other is used to disable the keypad switches. These two functions come in very ¡handy if you are carrying the rig in your pocket and don't wani to be surprised by an unwanted transmission or frequency changed The squelch and on-offJvolume controls are top mounted, a convenience that allows adjustment of these controls without removing the transceiver from your pocket

The liquid-crystal readout, in addilion to displaying the receive and transmit frequencies, also shows I he memory channel number in *ise and has four smati triangle shaped indicators that are activated to indicate. (1) The rig is in the transmit mode. 12) the frequency displayed has been recalled from memory, (3) the lamp switch ison, and (4)the batteries need charging.

In addition lo ihe frequency and memory control functions, the keypad also functions as a fult 16-key touchtone pad when in the transmit mode. There is also a switch provided to enable an internal subaudible tone encoder or PL Kenwood does not provide or make available a tone encoder module, but they are available from a number of sources or can be home-brewed A momentary action push-to-revefse switch can be used to reverse the transmit and receive frequencies instantly to listen on the input of a repeater. This :eature is very handy to use? for checking to determine if you are within simplex range of a station being heard or worked v>a a repeater

Input/outpul jacks include an external speaker/earphone output jack, external microphone and push-to-talk inputs, charger Input, and a standard BNC connector for the antenna connection, which makes the antenna changing easy for mobile;por-

Kenwood 2400

TR-2400 handheld from Ken wood tattle change-over. This transceiver has separate speaker and microphone elements, and, like the built-in microphone, the remote microphone input is designed to accept a condenser microphone. A low-impedance dynamic microphone can also be used if a 1 microfarad nonpolarized capacitor is added in series with the microphone "hot" lead to block dc,

The battery pack in Ihe TR-2400 is a 9.6-volL 500-mAh nicad unit constructed from eight size AA mead batteries

The ac charger that is supplied with the TR-2400 is a constant curreni charger. The TR-2400 must be turned off to accept a charge from this char ger and a full charge takes 15 hours. Optional quick-chargers are available as accessory items

Like most hand held rigs, battery life is on the short side, but If you listen much more than you transmit, you will get surprisingly long operation from a charge, Using a laboratory-grade digital multimeter, I measured baltery current drain as follows:

Spectrum's TTCiOO

squelched [or scanning*—27.2 mA, squelch open, audio at minimum—37.6 mA; receiver at "normal audio level- 40.0 mA; very loud audio volume level— 50 lo 100 mA; transmitting -525 mA. display lamp on —25.0 mA additional.

The above current drain conditions would correspond to bat-1 ery charge life conditions as foilows continuous squelched — TB 4 hours; continuous receiving—12.5 hours: continuous transmitting—0.95 hours

A realistic example ot combined operating !>me would be hour transmitting, 3 hours receiving and scanning

I ve found the TR 2400 to be a very smooth working little machine! Not only is it a great little portable rig, but I ve lound its many convenient features make it a very good performer for mobile operation as well! Using a magnetic-mount 5/8-wave vhip antenna on the roof of my car. have no trouble at ail hitting my favorite repeaters with the TR-2400's i1i Watts output . . and the TR-2400 is small enough that I even have room for it in my compact car.

Audio quality is excellent, both on transmit and on receive, and when used with a larger external speaker. Ihe receiver sounds as good in my base station as any 2-meter rig I've used. Receiver sensitivity is excellent much better than I would have expected from such a small package.

A radfo this small with all its sophisticated features could have been described by a science fiction writer twenty years ago. Today, its merely taken for granted as a product of our expanding technology. My overall impression ot the TR-2400 is that it is a lerrific rig

_ +almost the ultimate in a hand-held. But I'm an old nit-picker" who can find faults with anything, and t have three minor nits to pick with the TR-2400:

1. Thelowbattery indicator, in my opinion, does not give sufficient "early warning ' ot a low battery condition. When the low battery indicator comes on, you have to say your 73 s fast , . . because there is only about one minute of transmit time remain^ ing!

2 There is a slight delay of about a naif second after the push-to-taik switch is pressed before the rig actually starts transmitting. This fact must be constantly kept in mind or the first part of a transmission can be clipped out!

3. When using the earphone supplied with the TR-2400, there is a very loud and annoying click that occurs on squelch break I've found that adding a 200* to 6000hm resistor in series with the earphone reduces the earphone s sensitivity sufficiently to allow a higher volume control setting to be used. This effec-hveiy reduces the click sound to a tolerable level I would suggest using a 1/8-Watt resistor and installing it in the earphone itself, rather than at the earphone |ack inside the rig. as this method will still allow for driving an external speaker from the earphone jack when desired.

The TR-2400 price class is under $400 and it comes complete with ntcad battery pack, charger earphone wrist strap, and rubber flex antenna. Optional accessories include a leather holster carrying case, a spare baitery pack, a service manual, and quick chargers for both ac and 12-voll dc thai will iully charge a dead battery m an houi and a half.

In conclusion the TR-2400 es a superb portable transceiver \ can only think of one thing ehat \\ is lacking; a signal strength indicator (I think a bar graph type indicator incorporated In the liquid crystal display would be great for the S-meter func-lion!) Not only is this new rig a top performer, but it is also one of the best looking rigs I 've seen. I've found lhat carrying a portable hand-held of this type will attract a lot of attention from non-hams It's a great way to start up a conversation and in troduce someone to amateur ra dio Trio Kenwood Communica hons inc 11J1 West Walnut Compton CA 90220.

John Rehak N6HI

Garden Grove CA

SPECTRUM'S TTC100 TOUCHTONE™ DECODER/CONTROL BOARD

The TTC Touch-Tone™ Decoder/Control Board is designed to remotely switch a control function in a repeater or other radio system by means of a 3-digit touchtone control code The board can be used for various on/olf applications, including transmitter on/off, autopatch on/off, PL on/off, high/low power, and audio on; off, for selective calling using individual codes, etc. The audio tone input to this board can be from the repeater's receiver, an auxiliary receiver, a land line link or any other audio source.

The TTC 100 employs a digital anti-falsing design which prevents false triggering of the control function by stray noise, voice, or other tones. Also, the correct tones must be entered in the correci sequence or the cir cuit will not trigger.

The output switching circuitry can be jumper wired to produce a 5-V TTL level trigger pulse, or latch on or off. Two transistor switches are provided to trigger external circuitry, e,g,, relays, external logic, etc. These tran sistor switches can sink as much as 100 mA each. The 3-digit code can be changed in the fiefd with a minimum of effort by changing jumper wires and retuning the decoders. Five phase-iocked-loop tone decoders are provided on the boa^d for good flexibility tn tone seiec* tion. Multi tufn cermet tnmpots are used for ease of "setability" and maximum stability. Low-current-draw CMOS logic is used {TTL compatible}.

Spectrum Communications, 1055 W. Germantown Pfc., Nor-nstown PA 19*01. i215)-631-1710. Reader Service number 68

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