Kenwood TS-680S HF Transceiver
Improvements on the trusty TS-140S.
What Is the 680S?
In brief, Kenwood took the TS-140S, a high performance uncomplicated HF mobile rig, and added to it 6 meters and a receive preamp that is active beginning at 21 MHz. (See review of the 140S) Like the 140S, the 680S has a general coverage receiver, but even the receiver has an added feature—45 to 55 MHz, low VHF coverage.
Since the 140S and 680S are so similar, I don't elaborate on the features here. I list them, though, for those not familiar with the 140S.
The front panel of the TS-680S contains 34 controls, which are dearly labeled, and er-gonometrically well-laid out. Those with thick, blunt fingers, though, should check the rig out before buying, since some of the buttons are small.
Like all modern HF rigs, the 680S is microprocessor-controlled. It has a muiti-Sunc-tion display that gives not only mode, but also frequency, memory channel, mode, rit, vfo (there are two), and frequency to 10 Hz. There are also on-air indicators, as well as a series of LEDs that light up when you activate the memory scroll and allow you to see the contents of the 31 memories, or frequency lock,
Other notable features include memory, VFO, and programmed scanning; a multifunction S-meter; LS8, USB, CW (QSK), AM, and FM modes; split operation; 8.8 kHz range RIT; IF shift to tune out QRM; 20 dB of front-end attenuation to protect your rig from local high-power stations; and speech processing.
The rear panel contains connectors for the antenna and DC power. Two accessory jacks allow computer control and operation, as well as remote control.
The rig is also fairly compact because it has a built-in cooling fan (like the ICOM IC-735) that eliminates the need for a heatsink.
Something Gained, Something Lost
The only 140S standard feature that's nonstandard on the TS-680 is VOX operation.
Since the chassis of the 680 and its predecessor are essentially the same, something had to make way for the pre-amp.
For many hams, it's a more than acceptable trade-off. There are some operators who prefer VOX—and it's an accessory option offered tor the 680. Many, though, are happier with PTT operation. Finding the proper VOX level in many rigs can be very tricky business, especially if the rig isn't thoroughly grounded. Without thorough RF grounding, ambient RF tends to creep up, and into, the microphone, and key up the rig unless you have the VOX set at such a high threshold that a thundering herd of elephants couldn't activate it! So I, like many others, prefer the lack of complication PTT operation offers.
A few years ago, VOX was far more important because it allowed me semi-break-in CW keying. However, the TS-880S features built-in QSK or semi-QSK, obviating that need.
Why the Pre-Amp?
As you move up toward VHF, such rigs tend to generate their own system noise, which is superimposed on any atmospheric noise your rig picks up. This combo can often drown out weak signal stations. A super front end helps, and a pre-amp—a device that amplifies incoming signals just as they arrive to the rig-can make all the difference in the world.
Testing the Specs
Kenwood rates the 680S at 110 watts out, and my testing confirms this. The 680 consistently pumped 80 to 110 watts into a50O resistive load and kept this up for a long time on the HF bands. From 50 to 54 MHz, it puts out only 10 watts, so you may want to think about getting an amp. VSWR protection came on over 1.5:1, which is something thai has been common in other Kenwood gear I have tried.
I found that the pre-amp adds about 1.5 S-units to the receive capability of the rig (roughly 10 dB or so).
Overall, I have surprisingly few nits to pick at in the TS-680S, and those that I do have are easy to live with. For starters, I found that the power slide switch is anything but linear. A small movement produced a radically large increase in output power. Kenwood would be well-advised to swap the power output function with one of the knobs, or combine it with a concentric control knob surrounding one of the other control knobs.
I also found the display a little dim in bright daylight when I used the 680 mobile. Next, at 10 inches by 11 inches by 4 inches, and weighing 13 pounds, it may be a little bulky for smaller cars such as sub-compacts.
Finally, the (two) slide control noise blankers are effective against ignition noise and pulse-type "woodpecker" noise, but after a point they also affect the quality of the signal, causing it to pump and become distorted. All you have to do is remember to keep the adjustmenl below halfway and you'll be okay.
To sum everything up, I found the TS-680S multibander quite a good radio. It measured up to, or exceeds, its specs and is a pleasure to operate. The addition of the six meter module and pre-amp makes it a good value for the few extra hundred dollars the 680S lists for over the 140S.