Older radios

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Getting started in contesting does not have to be a high-dollar proposition. You can start out with whatever you have, but if and when you decide you need more performance, there are a number of older radios that are available at very reasonable prices and provide excellent performance under contesting conditions.




Kenwood TS-850S

The Kenwood TS-850S transceiver started shipping in 1989 and was discontinued in 1996 when it was replaced by the TS-870. It was the first "Field Day in a box" transceiver: powered by 12v, with a built-in antenna tuner and CW keyer, and optional built-in digital voice recorder. The 850 covered 160 - 10 meters, including the WARC bands and had all the usual modern transceiver features. An outboard digital signal processor (DSP-100) was available but never really seemed to improve performance enough to be worth the expense.

For many years the TS 850 boasted the best receiver specs of any mainstream commercial transceiver, making it a favorite of contesters. It was reviewed by NJ2L in the July 1991 QST here.The usual Kenwood and International Radio filters were available for narrowing the bandpass and in 2009 Inrad here began shipping a roofing filter modification for the 850 that consists of a 6-pole, 4 to 5 kHz wide filter followed by a high dynamic range feedback amplifier. The amplifier provides enough gain to override the filter insertion loss. Inrad claims the IMD dynamic range is improved 5 to 15 dB for some signal spacings and the blocking dynamic range will be improved up to 10 dB for close in signals.

One unusual feature of the TS-850 is that it has an 8-MHz IF output before the roofing filter, intended for use with Kenwood's station monitor, the SM-220. The SM220 suffered from drift and low sensitivity, but with the BP8 panadaptor it can be used to view received signals as well as transmitted signal waveforms. Out of the box the 850 didn't have an acceptable output for viewing the received signal but with a modification here, see mod 5 and appropriate software can be used to support CW Skimmer or other software to provide a broad "band-scope" view of the band in use.

The 850 has some annoying quirks. The RIT/XIT control is a potentiometer, so there is no easy way to reset to zero offset, and there is no center detent at the zero offset position. The only way to change filters is to cycle through both IF settings with multiple button pushes. Using a separate receive antenna required modification. There were a number of common failure modes for early versions - N6TR has a great repair page here. Hams are a resourceful bunch and many modifications to correct some of the quirks are available hereand here.

The 850 is still widely in use and in 2009 most accessories and contest software programs still support it.

TS-930S and TS-930SAT

Kenwood TS-930S

The TS-930 is 4 generations ago for Kenwood, and was last manufactured in the late 1980s, yet it remains one of the best contest-grade radios ever built, particularly for CW.

The TS-930SAT version includes a built-in automatic antenna tuner. The basic TS-930S model does not include an antenna tuner.

Models built for the domestic market in Japan have slightly different transformers to accommodate Japan's 100 VAC electric grid. These transformers include a second tap that may be used on the North American 120 VAC grid without trouble.

Like any older radio, it behooves you to look out for problems in buying one - in particular, be very skeptical about units with serial numbers before 3080001. A number of quality control problems were corrected in the second production run of these radios, beginning with this serial number, and quite a few relatively minor design improvements were incorporated as well. Unless you are confident that the lower-serial-number radio you are considering has been gone through by a professional, you should pass.

The typical TS-930 found on the used market may have optional filters, either by Kenwood or by International Radio [1]. For CW, cascaded 500-Hz Kenwood or 400-Hz Inrad crystal filters in the second and third IFs are a very good choice, because they are narrow enough for S&P operation in almost all circumstances and yet broad enough for effective running.

One add-in that is almost a necessity in today's contest environment is the PIEXX TS-930 replacement microprocessor board [2]; some used radios already have this board installed. It replaces the stock board, enabling you to get rid of the backup power batteries it used before they leak and ruin the original. But most importantly, it provides for computer control of the radio by contest (or any other) logging software that supports Kenwood radios.

A little known attribute of the TS-930 is that it allows for use of an external receiving antenna through one of the DIN jacks on the rear panel.

A good compendium of service bulletins and other modifications for the TS-930 is found at [3]. This excellent site also offers similar information on many other transceivers as well.

TS-940S and TS-940SAT

Kenwood TS-840S

For some reason, the TS-940 does not seem to have as good a reputation as its predecessor, but it does offer one important advantage - it has built-in provision for computer control. The catch is that in stock form it requires both installation of a couple of hard-to-find chips inside the radio and a level converter outside, before it can be used with a standard serial port. Again, refer to PIEXX[4], which offers a single board for installation inside the radio which accomplishes both functions.

Another TS-940 feature that will be of interest to some is that it has a jack offering second IF output before the roofing filter, provided by a separate mixer and original intended for Kenwood's SM-220 panadaptor and station monitor. This jack can be used in conjunction with a simple, low-cost Software Defined Radio (SDR) and software such as CW Skimmer or Rocky[5] to provide a panadaptor display and wide-band multi-stream CW decoding.

The TS-940SAT version includes a built-in automatic antenna tuner. The basic TS-940S model does not include an antenna tuner.

TS-950S, TS-950SD, and TS-950SDX

Kenwood TS-950S

Kenwood TS-950SDX

The TS-950 series was the final competitive entry into the field of high-end, "flagship" radios made by Kenwood. The TS-950S was the first version to be released, followed shortly by the TS-950SDX model in 1992. The original "S" model was offered with options such as a high stability TCXO and a digital processing unit (making it an TS-950SD model) that were incorporated as standard features in the "SDX" version. The TS-950SDX included many design improvements and added more features to the original version.

The TS-950 series are all-band HF transceivers (160-10 meters) with 150 Watts output power. The self contained 120 VAC power supply makes this package heavy compared to modern radios, weighting in at 23 kg (50.6 lbs).

Kenwood offered a separate SM-230 station monitor designed to match the style of the TS-950. This is a 10-MHz CRT based oscilloscope which includes X & Y inputs, a two-tone audio generator, as well as an integrated panoramic bandscope. The SP-950 was a matching speaker cabinet with A/B input and several audio filter selections.

The basic transceivers include unpopulated filter positions for both 8.83 MHz and 455 KHz IF sections as well as a separate filter for the sub-receiver. This allows an operator to populate 250, 270, 500, and 1800 Hz filters into the various IF chains.

An optional DRU-2 Digital Recording Unit provides basic audio DVK capabilities with 3 memories. This feature is controlled using an external "puck" which integrates several other buttons for operating frequency storage & retrieval, as well as split operation.

The TS-950 series are computer controllable when connecting to a PC via an IF-232C level converter. Modern CAT cable interfaces duplicate the function of this Kenwood accessory and can be used instead of the Kenwood device. Unlike the TS-940S, the internal chipset is already installed in all TS-950 series radios.

The early TS-950S transceivers exhibited an audio "thumping" problem when the radio was being polled by contesting programs like CT or NA. This issue was quickly identified and resolved with a physical EPROM replacement (update) from Kenwood.

The TS-950 series operate in LSB/USB, CW, AM, FM, and FSK modes with AM power output limited to 40 Watts. RTTY is generated by using the FSK input jack on the back panel. The receiver audio output is 1.5 Watts across 8 ohms. Main and sub-receiver audio can be split into left/right channels, blended audio (80/20), or mono audio by a menu selection.

It is possible to run two instances of RTTY decoders when the audio is set to "separate" and the left & right audio output channels are connected to the stereo input of a computer sound card. In addition, there are RCA jacks on the back labeled "Phone Patch in/out." These connections can be used for generating AFSK, PSK, SSTV, and other "audio based" digital signals.

The transceivers are "digital design" where both the frequency display and metering functions are displayed on a linear scale or LED display. The metering functions can be set for "peak hold", an apparent carry-over from Kenwood's audio equipment designs. The metering includes display of Watts Power Output, final transistor Amperage, VSWR, and ALC scales.

The menu system includes over 50 settings to customize the radio to your operating style. And because the radio is computer controlled, resourceful owners have "hacked" the system and found many undocumented features that might be useful to you.

Probably the most common enhancement is the "cut diode D-17" change to enable all-band transmit. Another useful feature allows the sub-receiver to be used on bands different than VFO-A and VFO-B. This is a power on feature where you hold down buttons SUB, M/S, and RX/SUB while turning on the power. (Thanks Hanno, DG8JZ)

The Kenwood TS-950 series transceivers are approaching their 20 year anniversary but still provide a lot of bang-for-the-buck when they are found on the used market.



We can reasonably debate whether the FT-1000MP deserves to be called an "older radio", but since it is now 3 generations out of production, and because the 1000mp is still often used as a standard of comparison, it makes sense to discuss it here.

The Universal radio website talks about several of the benefits of this old friend, one being its effective implementation of Digital Signal Processing (DSP)for noise reduction and audio shaping. Another is the highly flexible filter switching scheme, which many operators prefer over the menu-driven scheme in its younger brother, the Mark 5.

Fact is the Ft-1000 MP brought several features that have been utilized by other manufactures one being the ease of identification of which VFO is active for rcv and xmt

Many Contest stations still use the FT-1000MP for good balance between price and performance.

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