Kenwood Radio Equipment

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Last updated: 9 May 09

Kenwood was orginally known as Trio Corporation and the first of their radios I recall was the TS500, an HF radio that was replaced by the TS510 and finally the TS520 and TS520S. They also had many different VHF FM and multimode rigs in the 70s and 80s.

Kenwood equipment sells successfully on classifieds sites, on Ebay and other auction sites and in private advertisements. They were later known in Australia as Trio-Kenwood, or simply Kenwood.

My Kenwood at Ebay page lists radios currently for sale at Ebay Australia.

You can also find various Kenwood radios for private sale at vkham.com. Use the advanced search option to list the Kenwood ads. As the Kenwood name was also used for popular kitchen appliances, the name will often produce those same appliances in seaches. Adding radio equipment or amateur radio to the search terms may help.

Kenwood HF radios

From the beginning Kenwood's HF ham radio transceivers, particularly the very popular TS520(s) and TS820(S) series, were renowned for smooth high quality transmit audio. This was achieved by using careful design in the mike amplifier stages, and I think they deliberately kept the carrier oscillators quite close to the filter edge, to produce a slightly greater proportion of low frequency audio components that somehow were recognised by listeners as an indication of good quality. Other manufacturers tuned their equipment for communications quality and despite the undeniable ability of the Collins mechanical filter to produce excellent communications audio, a lot of hams really liked the "sound" of the Kenwood gear.

The TS520 and 820 series were similar in many ways but internally used quite different electronics. The mixing scheme in the 520 series was based on a 5.x MHz filter frequency whereas the 820 (and later 430/440) used an 8.8 Mhz frequency. hence the optional filters for these rigs are not interchangeable. Oddly enough the TS530S released in the 80s did use the same 8.8 Mhz filter frequency so if you had bought the CW filter for your TS520S it could not be taken out and put into your TS530S.

The TS820 and TS820S (the S version had a digital readout) had some features that were unusual in their time. There was RF negative feedback in the final amplifier stage, improving the distortion rating (IMD) of the transmitter by some 5 dB. Sounds like a minor feature but when you feed the output of the transmitter into a high power amplifier which amplifies everything, distortion products included, it makes a difference to the interference created in adjacent channels. So the 820 series had a good reputation for not only having "Kenwood transmit audio" but also having a very clean output signal even when it was strong. The other innovation was the IF shift circuit. This allowed the operator to move the BFO relative to the filter, without changing the received carrier frequency. It was done using a phase locked loop which included the BFO signal and the HF oscillator (that is premixed with the VFO before mixing to or from final frequency). Moving the BFO frequency by say 200 to 500 Hz to get rid of an interfering carrier or some buckshot from a nearby ssb signal, you also moved the HF oscillator frequency by the same amount in the opposite direction, leaving no net change in received frequency. This innovation was included in all their later radios and copied in one form or another by other manufacturers.

Kenwood offered a station monitor SM220 (and a later model the SM221) which was a small oscilloscope together with RF pickups and a two tone oscillator. This unit made it really easy to perform linearity checks on your external linear amplifier, and check for distortion or faults in the driving radio. There was a panoramic adaptor also available, which had to match your radio as there was one version for the 5.x MHz IF (BS5) and another version for the 8.8 MHz IF (BS8).

My Kenwoods

My first Kenwood radios were a separate receiver and transmitter, types R599 and T599. These were great rigs to operate as well as being attractive to a technophile. Unfortunately I let myself sell them - I'd gladly buy them back now! A few years later I bought a TS820S then upgraded to a TS430S. One of the factors in the early 80s was that the older gear did not have the 10, 18 and 24 MHz bands, though Kenwood did offer an upgrade kit to add one or two of those bands to the TS820 and the TS180.

The TS430S was a compact fully solid state multi band HF transceiver, 100w output and an optional FM module to allow it to receive and transmit narrow band FM on the 10m band (well, any band actually, but 10m was the only one where the FM mode was permitted). It also had facilities for an optional CW filter and an optional narrow SSB filter. The standard SSB filter was a ceramic filter which did a good job but didn't have the ultimate rejection of a high quality crystal filter. I used my TS430S thru the 80s including in Brunei as V85DA where I made about 8000 contacts on a casual basis over 2 and a half years.

The Kenwood TS440S was a very popular successor to the 430. With similar frequency and power specs, it had improvements such as better heatsinking of the final stage allowing it to run 100w full output for some time (eg on RTTY). With all previous rigs I had owned, you had to derate the rig to about 40 or 50watts output when using modes like rtty because otherwise the output stage would melt (almost literally). The 440S also had full QSK or break-in mode on CW. This means the rig is switching between receive and transmit, and back again, for every element of a morse character. Very hard on the antenna relay but they did an excellent job and if you have ever used full breakin on CW in a contest, you'd never return to the semi-breakin or vox type system.

Six metre band

In the 80s and 90s I owned a TS600, a 6m only multimode radio. 10 watts output and a hot receiver. I used this radio in Brunei and I worked thousands of Japanese hams on six metres, as well as other Asian countries, Africa, Australia and one unconfirmed contact with Alaska. This rig was heavy by today's standards and had low output. But it never failed. I used a Tokyo Hy Power HL66V to increase output power to about 60 watts, which helped greatly to work dx.

Kenwood next 6m radio was the TS660, which I understand was aimed domestically at a licence class permitted to use the 21, 24, 28 and 50 MHz bands. This radio was internally similar to the HF TS430S with six memory channels, an 8.8 MHz IF and 10 watts output. It was upgraded to the TS670S which had a different set of bands, this time 7, 21, 28 and 50 MHz, again reflecting the band allocations of one of the licence classes in Japan. They called this one the quadbander and it was similar in many ways to the TS440S, with the same 100 memory system, same filter frequencies and a final IF of 455 kHz. Still only 10w so for 6m use, an external amplifier was a popular add-on.

The TS680S was next in the series. It included 10w on 6m in a 100W HFrig which was also marketed in its base format as the TS140S. This radio was very popular in Australia. While an external amplifier was still necessary, this was a multi-purpose radio which appealed to many operators. Six metres gained in popularity over the sunspot peak of 89/90/91 and many signals heard were from TS680s.

Continuing the dual-format radio, Kenwood then released (around 91) the TS450S HF radio with corresponding "HF+6m" version, the TS690S. This time 6m was given 50w output, removing the need for an external amplifier and making this a very desirable radio.

I believe the TS570S was the next "HF+6m" radio, released around 96/97. In this radio the 6m power was 100w.

The inclusion of 6m in HF radios became common in the majority of mid and high range radios produced by the Japanese brands, making the 6m band more accessible and available to more operators than ever before. This can only be good for the band's enthusiasts.

Receivers

Kenwood produced a series of receivers too. The earliest I know of was the 9R59DS (and variants). This was a tube based HF receiver for general shortwave listening and I was not sure when it was produced, I notice rigpix says 68-69. The QR666 was a solid state version of the general coverage receiver and was produced in the early 70s. Like other receivers the QR666 used a bandspread system to give a slower tuning rate and a secondary dial, which was a good system when the operator knew how to use it.

The next Kenwood receiver I took notice of was the R1000, which was produced in the 79-85 period and had a synthesised HF oscillator giving it a 30 position band switch, with 1000 KHz range on each band. In other words, 0 to 30 MHz, with the same tuning rate on all bands. This receiver is a very handy tool for monitoring HF signals, listening to short wave broadcasters and even the local Broadcast band stations when HF is out. It has a clock and you can use it to turn on a recorder at a certain time, record a program from the radio, then turn off.

Kenwood's R2000 is a very attractive upgrade of the R1000, with a front panel speaker, an improved tuning rate and a digital tuning system with band up/down buttons instead of the 30 position switch on the R1000. It also has digital memories reflecting the trend towards building more digital functions in radios during the 80s.

The R5000 was essentially a receiver version of the TS440S transceiver. It has the clock like the other Kenwood receivers but it shares its internal design with the TS440S as far as I can tell, including the optional narrow filters. This makes it a very capable receiver for general or ham use. Some transceivers including the 430 and 440 had provision for using a secondary receiver in addition to or instead of the receiver in the transceiver. The R5000 would have been a very good candidate for that role.

Recent Kenwood models

Transceivers such as the TS850S, TS870S, TS570D/S, TS480S, TS2000 have typified the increasing sophistication of amateur radio equipment using microprocessors to drive the memory system, scanning of memories or between band edges, multiple morse keyer modes, retention of last used frequencies etc, at the same time as adding the 50MHz band to HF radios as an almost standard feature, then adding the 144 MHz and 432 MHz band with a wave of the hand. The TS2000 for example offers all the hf bands and the VHF bands mentioned and can even have the 1296 MHz band added to that.

Some amateurs view these "super rigs" with concern. If something fails, they cannot fix it because they don't have the test equipment and don't really understand much of the equipment's technology anyway. And if it does fail, they have possibly lost all of the bands until the radio is fixed. The answer to those problems is either to keep using multiple radios with specific band ranges, or simply buy more than one "super rig". At least you'd know how to drive the menu system!

 

Written by Andrew Davis VK1DA. October 2006.

Updated 2008 and May 2009.