Lulled by the sexy small size, I succumbed (or, rather, the credit card succumbed) and bought a Kenwood TH-79 dual-band H-T recently. Already owning a TH-78, the comparison comes easy.

SPECS. The TH-79A is a U.S.-spec dual-band transceiver, featuring coverage from 144-148 and 438-450 MHz. Receive coverage is extended on the 2M side from 118 to 174 MHz with AM in the aircraft band; there is no extended UHF coverage without modification. Max power is rated 5W on VHF and 3.5W on UHF with a 12V source; max power with stock 600 mAH nicad pack is 2.5/2.0. There are three power levels for each band - high, low, and extra-low (30mW). There are 80 memory channels, with no evident expansion capability. U.S./Canada version comes with the CTCSS encode/decode option. Going price at a 7/17/94 hamfest was $480.

GENERAL IMPRESSIONS. Tiny, tiny, tiny. Imagine putting a small duckie on the ARRL Repeater Directory - except that the 79 is narrower by about an inch. With the standard battery and not counting the belt clip, the dimensions are roughly 2" wide, 5" tall, and 1" thick. The belt clip adds 3/8" to the thickness; I left it off so it would be pocketable, and, frankly, it fits moderately comfortably in my work slacks' front pockets, which was surprising. It's tiny! (Oh, I said that already.)

The 79's keyboard has larger buttons than it's predecessor (lacks the cover, too) which are much easier to use. Control layout in general is better and even in just a couple of days I appreciated the change. No more ambiguous power switch - it's in the primary band volume knob in a normal OFF/ON/VOL setup. Secondary band volume control is on the "ring" of the freq/channel encoder knob in a coaxial arrangement.

There are no squelch knobs; it a key+knob function for both bands. Squelch control was, well, interesting. There are only six "settings", with usually only the lowest setting opening the squelch under no signal. Reading between the lines in the manual, apparently the squelch circuit is semi-automatic. I expected some limitations, but had no complaints under actual use - it worked well.

With my expected habit of putting it in my pocket, I like the control lock switch - it's *not* an F-key function, but, rather is a slide switch next to the PTT. No more fumbling around to unlock it. Unfortunately, the lock function does not lock PTT - that has to be disabled with the "Tx Stop" menu setting. I found this out the hard way by putting it in my pocket and inadvertently keying-up a repeater.

The 79 has an alphanumeric display capability of two lines of 10 characters, which is used in several ways. First, there is a "guide" facility, which provides online instruction for most operation features with a scrolling display. Then there is a "menu" function, which provides access to the settings which were normally done with obscure F-key commands in the 78. Setting the various functions is very clear this way. There is also a status review mode, where the more important settings are displayed.

Finally, the alphanumeric display can be set for each programmed channel. Seven characters positions are available, and almost the entire extended ANSI character set - that's right: lower case, symbols, and accented characters - can be used. However, alpha display is mutually exclusive with frequency display. Frequency display mode can be selected in case you forgot what was "underneath" your programmed channel ID.

PERFORMANCE. I was impressed, without a doubt. The '79's sensitivity is markedly better than the 78, in both bands and especially in the extended portions of VHF. And, spurious signal (intermod) rejection seemed to be much better as well in the side-by-side tests.

The stock antenna, however, was awful. I bought an ANLI 5" dual-band flexi and it made a huge difference - signals just breaking squelch with the stock duck were full-scale with the ANLI.

Audio is fairly good for something so small. The quality was marginally better than the 78 and tended to distort less at max volume settings. Audio power would be stretched to use it, say, with the car window open going freeway speeds.

Having loaned my wattmeter to a friend, I wasn't able to get transmitter measurements to confirm power ratings. Reports from those on the receiving end have been favorable so far, though.

ADVANTAGES. As mentioned previously, the 79's receiver quality is significantly better than the 78, in both sensitivity and intermod rejection. Battery life - even with the smaller batteries - is supposed to be drastically improved due to a number of design changes, particularly in the transmitter finals. Have not been able to confirm that. And then there's the size.

DISADVANTAGES. There are, unfortunately, a few. One thing that jumped-out very early was that there is no facility to "lock out" a channel from the memory scan. If you select memory scan (hold [MR] for 1 second), you get every channel programmed in the band active for that "side", whether you want it or not. IMO, this was a grave over sight on Kenwood's part. If someone knows how to do this or there is a "hidden" lockout function, please post it, because nothing in the manual even hints at being able to do this.

Another disadvantage, albeit minor, is that there are no clocks or timers. I normally eschew these gimmicks, but "on the road" I've made use of the timer feature in the 78 as an alarm clock. I'll miss it a little.

It has no 800 MHz receive, which the first two generations of TH-78 has. This isn't a hard disadvantage, because the current TH-78 has 800 MHz missing, too. I only mention this for current 78 owners who have pre-4/94 units.

And, so far it seems that there are fewer "hidden" features available, like cross-band repeat. I said "so far". There appears to be no extended F-key function activated by holding down the F key for 1 second; most of those feature selections are covered by the menu display. But there's more exploring to do and we might just bump into something interesting in the next few days - "power on" has significance in one important command (memory channel clear), so it may be important in switching other modes.

MODIFIABILITY. I studied the schematics (supplied) for the usual strap selections for extended range and different markets. Yes, they are there. When the opportunity permits I will cross-reference the mod codes against other Kenwood schematics and determine where the range extensions are. HOWEVER, there is very clear allusion to an 800 MHz receive feature, and checking the component list for the U.S. version codes, it appears that *all* of the 800 MHz components are missing. Kenwood is meeting the "no cellular" requirement purely by eliminating the 800 MHz receive section altogether. So, technically, you would probably be able to mod it for 800 MHz receive, but getting all of the right parts (about 40 or 50 surface mount components) and getting them to work without destroying something borders on improbable.

Overall, I like it, though I'm really hacked by the lack of scan memory lockout - they *REALLY* messed-up by not including it.
  ...mm

P.S. After another day with the TH-79, I'm bumping my head against more limitations.

Another feature lost from the TH-78: special scans. With the TH-78, it was possible to have a variety of special scan conditions. One of my favorites was to load a freq into the "call" channel, and by holding [CALL] for one second it would flip back and forth between two freqs. I used this a lot, and it just isn't there on the 79.

Also, I spent some time trying various power-on key combinations and found absolutely nothing. One thing for sure - if it isn't in the manual, it isn't likely to be discovered accidentally.

The more I "explore" this rig, the more I get the impression that feature selection may be "back to basics". Kenwood might be a little sore after the TS-50 experience with the FCC and may feel the need to make access to "tweaks" a little less obvious.
  ...mm

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