Mount Evelyn DX Report: RETRO RECEIVER REVIEW # 21

RETRO RECEIVER REVIEW #21

(You can click on all photos in this article for a close-up view)

KENWOOD R-5000

Performance and Innovation

by ROB WAGNER VK3BVW

This extended blog post first appeared as a feature article in the February 2024 issue of The Spectrum Monitor magazine. Further details on this excellent publication are available at www.thespectrummonitor.com

I have always wanted to own a Kenwood R-5000 receiver. Perhaps I was dazzled by the mystique that appeared to surround this rig. Somehow, it had always been on top of my bucket list of pre-loved rigs that I wanted sitting on the desk of the radio shack.

Finally, one showed up at a local Sunday morning Hamfest, and I happened to have just enough dollars in my pocket to make a purchase. It appeared to have lived a hard life. The case looked knocked around and was pretty dirty inside and out. So, while I would have liked to have owned a unit in better condition, the price was right, and I decided to take it on as a little project. A few years back, I made several YouTube videos showing some early cleanup and modifications to this unit (search Rob Wagner VK3BVW). So, let’s look closer at the story behind the legendary R-5000.

A Little History

Kenwood has long been considered a manufacturer of fine amateur transceivers and shortwave receivers. The company was founded as Kasuga Musen Denki Shokai Ltd in December 1946 in Nagano, Japan. Its trademark name was “Trio”. By 1955, the company opened a plant in Tokyo for large-scale production of consumer audio, amateur radio gear and electronic test equipment. In April 1957, it released a commercially viable FM receiver to the Radio Shack Corporation of America. In January 1960, the company changed its name to Trio Electronics, Inc.

During the early 1960s, Trio produced some early receivers of mediocre quality. But in the period between 1968 and 1974, the company struck success with the 9R-59D, 9R-59DE and 9R-59DS communications receivers. These were 8 or 9-valve AM/SSB/CW general coverage units, single conversion, featuring calibrated electrical bandspread dials, a mechanical filter and a product detector. Sensitivity and selectivity were quite good for its day. The receiver was especially popular here in Australia, with many SWLs having one of these sitting on the desk of their radio shack!

In the mid-70s, the name Trio-Kenwood was established in California for the purpose of marketing ham radio gear. It was around this time that the quality of their communications receivers made a step up with models like the [Kenwood QR-666]https://medxr.blogspot.com/2016/04/retro-receiver-6-kenwood-qr-666.html (see Retro Review) and the R-300. By 1986, the company dropped the Trio part of the name and traded as the Kenwood Corporation.

During the 1980s, the company hit its straps with a series of receivers for the shortwave listener, pushing the boundaries of technical innovation and high-quality performance. Releases included the R-600 (1982-1985), the R-1000 (1979-1985), the R-2000 (1983-1992), and culminating with the feature-laden power performer of the bunch, the R-5000 (1987-1996).

Also during the 70s and 80s, Kenwood established itself as one of the “big three” manufacturers of solidly designed, high quality and reliable amateur radio equipment (the other two being Yaesu and, a little later, Icom). The company expanded its amateur transceivers to include general coverage receiver capabilities. Sadly, with the end of the R-5000, dedicated general coverage desktop shortwave receivers were dropped from the production line.

The Kenwood R-5000 Service Manual is still available online.

R-5000 Variations

On the used market, variations exist in the spectrum coverage of R-5000 receivers. In the US, Europe and the UK, the frequency range runs from 100 kHz to 30 MHz, the Australian version is 2 to 30 MHz, and the West German version covers 150 kHz to 26.2 MHz. The optional VC-20 VHF converter extends into the 108-174 MHz FM band, and the West German version offers access to the 2-meter amateur band of 144-146 MHz. Modes are AM, SSB, CW and FSK, plus the optional FM board. The circuit is a double conversion superheterodyne for all bands except for triple conversion on FM. The first IF is 58.1125 MHz, and the second IF is 8.83 MHz.

The R-5000 uses four phase-locked loops in its circuitry, providing solid frequency stability. An additional PLL is brought into use for the optional VHF converter. In addition, excellent dynamic range is achieved by using low-noise FETs in the mixer circuitry.

With its relatively compact design (for 1987!) and solid-state technology, the radio packs many features into its 279 x 107 x 307 mm case and weighs in at 5.6 kg (12.3 lbs). On the front panel, there are choices a-plenty for happy button pushers:

Mode/Key numeric keypad provides the dual functions of direct frequency entry plus separate keys for LSB, USB, CW, AM, FM and FSK (Frequency Shift Keying) and the selection of Antenna 1 and 2.
Six status indicator lights above the tuning knob for Frequency Lock, Notch, Antennas 1 & 2, Memory Scroll, and Busy (for squelch).
Fluorescent display tubes provide frequency readout, memory channel, time, VFO A/B and the size of frequency STEP (1 kHz or 100 Hz in AM, 100 Hz or 10 Hz in SSB/CW/FSK).
Five-position selectivity switch for Auto, Narrow, M1, M2 and Wide
Dual Squelch and Notch control
Dual Noise Blanker and IF Shift controls
Dual RF and AF gain controls
RF Attenuator switch to add 10, 20 or 30 dB of attenuation to avoid distortion from very strong signals
AGC (Automatic Gain Control) switch with a choice of SLOW or FAST settings
Notch filter switch, which in CW mode acts as an APF (Audio Peak Filter)
Noise Blanker NB 1 for short-duration pulse noise from automobile ignition systems and NB 2 for long-duration pulse noise for the “Russian woodpecker” Over-the-horizon (OTH) radar - a relic of the late Cold War period between 1976 and 1989.
1 MHz Up/Down key
HF/VHF key
Separate headphone and recording jacks
Dual clocks (useful for local and UTC or other time zones) and timer function switches
Dimmer switch to display two levels of display/S-meter lamp brightness
Voice switch for the optional VS-1 Voice Synthesizer Unit
A set of six program keys (lower left of front panel) for transferring frequencies in and out of memory, clearing memories, scanning memories, and an enter key for direct frequency input from the numeric keypad.

R-5000 back panel.

On the back of the rig are:

Ant 1 - SO239 socket for 50-ohm coax plugs
Ant 2 - 500-ohm terminal for high impedance antennas (e.g. long wire)
50-ohm terminal for low impedance antenna and a ground terminal
AC power connector and voltage switch (for non-USA models)
DC power connector (for the optional DC kit)
Remote connector socket for use with separate transmitters or other external devices such as a tape recorder
6-pin DIN connector for the optional IF-232C computer interface unit
VHF antenna connector for the optional VC-20 VHF converter unit
External speaker jack

Memory and Scanning Operations

The R-5000 boasts 100 memory channels that, for its day, was quite a feature. These channels can be subdivided into ten user-defined groupings, allowing scanning for continuous monitoring. Memory inputting, memory recall, clearing memory channels, scrolling memory channels and scanning memories can be easily achieved with some practice. Stored information includes the frequency, the mode and the antenna number (1 or 2). Memory scanning and programming are possible, and the R-5000 microprocessor remembers the scan parameters you have specified for future use. Variable scan speeds and memory channel lockouts can also be user-defined.

When the receiver was marketed, Kenwood offered optional extras that, of course, are no longer available. However, occasionally it is possible to pick up several of these items in the used market. They include:

VC-20 VHF Converter Kit
DCK-2 DC Operation Kit
VS-1 Voice Synthesizer Unit
MB-430 Mobile Mount
IF-232C Interface for interconnection with an RS-232C computer terminal
IC-10 Interface IC Kit internally installed in the R-5000 to allow control of certain receiver functions by computer through the IC-232C interface
YK-88C 500 Hz CW filter
YK-88CN 270 Hz CW filter
YK-88SN 1.8 kHz SSB Narrow Filter
YK-88A-1 6 kHz AM Filter (with a tighter bandwidth to reduce interference and improve selectivity)

Lab Tests

As mentioned earlier, in the Trio/Kenwood range of receivers, the R-5000 was the pinnacle of innovative design and all-round solid performance. The sensitivity of the stock radio was (and still is) impressive. The February 1988 issue of QST magazine quoted figures from tests done in the ARRL Lab that were, in some cases, significantly better than specifications:

Sensitivity:

AM 1.8-30 MHz - < 2 μV (Lab Test: 0.39 μV at 3.5 MHz and 0.29 μV at 14 MHz)

SSB/CW 1.8-30 MHz - < 0.25 μV (Lab Test: < 0.19 μV at 3.5 MHz and < 0.15 μV at 14 MHz)

First IF Rejection:

1.8-30 MHz - > 80 dB (Lab Test: > 91 dB at 14 MHZ)

Notch Filter Attenuation:

> 25 dB from 500 - 2600 Hz (Lab Test: > 35 dB at 750 Hz)

Other features include a tunable notch filter, passband offset controls, and frequency readout down to 0.01 kHz increments. And, if time is invested in learning all the features offered in the memory and scanning modes, then this vintage radio can really shine.

However, while it worked OK, the stock AM bandwidth filter supplied with the off-the-shelf receiver was a mediocre choice. Investing in the better quality 6 kHz YK-88A-1 AM filter really improved both selectivity and audio. In my rig modification, I chose a slightly different route by installing a 4 kHz AM filter for more serious DXing activities. Even with the tighter filter, it was pleasing to find that the audio quality remained very good for general listening purposes.

The cascade (series) design of the IF filter connection used in the R-5000 (conceptual diagram from the R-5000 service manual).

The layout of the IF filters in this unit is interesting. Filtering is done at 8.83 MHz, and the filters are arranged in series or cascade instead of the more familiar parallel filter design. Filters with passbands wider than the desired receiving bandwidth all pass the signal without attenuating it. The passband width is determined by the narrowest filter used. This results in greater attenuation of interfering signals beyond the selected filter passband.

With the top cover off, we see the power supply and filters.

Signs of Old Age

Like humans, as the decades pass, all receivers in our Retro Review series exhibit signs of old age and component failure. The Kenwood R-5000 is no exception! Push button controls become unreliable. Capacitors leak, bulge and change their characteristics compared to original specifications. And the fluorescent display in a few rigs has been known to fail (replacements are scarce). All the sorts of things that will plague any radio with some significant age on it!

Fortunately, except for several small modules that use surface-mount components, most of the R-5000’s components are through-hole mounted on single or double-sided circuit boards. Access to most boards can be easily achieved after negotiating numerous screws. Servicing is not too much of a pain except for the components and boards behind the front panel.

However, there are two well-known defects with the R-5000; both concern frequency keypad input. The first is the dreaded row of “dots” that appear instead of numbers on the display screen. The second is the “key bounce” issue, where you press a number key, and multiple numbers of that key appear on the screen.

Several suggestions for fixing these issues involve either removing and cleaning the keypad contacts (while being careful not to damage the membrane that surrounds the keys), inserting additional capacitors across the keypad matrix switches, or cleaning out the potting compound on one of the PLL boards (this compound can become conductive with age). None of these fixes is trivial! They require significant experience with repairs, are labour-intensive, and are not for the faint-hearted!

With the bottom cover off, the PLL board (top of photo) and the RF board are shown.

The R-5000 and the TS-440

The circuit design in the R-5000 is almost the same as in the TS440 transceiver, which was released a year or so earlier. So, it is understandable that some believe the receiver performance is identical in the two rigs. However, a few differences between them make the R-5000 a better all-round receiver for the shortwave listener.

The manufacturer’s claimed spec sheets for both rigs show that while SSB/CW/FSK sensitivity is the same, the AM specs are slightly better for the R-5000 (2.5 μV versus 2 μV). And, as mentioned earlier, the ARRL Lab tests found that the AM specs were even better than Kenwood’s claimed numbers. This explains why some users have observed that the reception of AM signals on the shortwave broadcast bands appeared superior to that of the 440.

As the R-5000 doesn’t have a transmitter in its case, room can be found for additional features that don’t come with the TS-440. These include the dual clocks/timer, an additional antenna terminal for high-impedance antennas, front panel selection buttons between the two antennas, a 10 Hz display (although the 440 can also go to 10 Hz by digging inside the rig and cutting a wire), and the ability to improve AM selectivity by allowing filter replacement with the superior YK-88A-1 mentioned earlier (not possible on the 440).

Add in switchable attenuation at 10, 20 and 30 dB (the 440 has only 20 dB), a fixed-level Record Out jack (on the 440, this is where the mic jack resides), two noise blankers (although the woodpecker blanker is redundant these days!), and an optional VHF converter. Overall, a keen SWL would be better served seeking out an R-5000 in top condition on the used market rather than a TS-440.

Performance Appraisal

The R-5000 was always considered a great performer in its day. Fast-forward to 2023, and providing you can pick up a well-cared-for unit that is correctly aligned, you’ll find that sensitivity is still excellent, while selectivity is good—and even better if the improved 6 kHz filter (mentioned earlier) is installed.

In the presence of high noise levels, judicious use of the RF gain control can significantly improve signal readability. Considering its age, receiver stability is usually excellent in this model. So, suppose you tune into a weak signal with deep fading characteristics. In that case, you can successfully switch to Exalted Carrier Single Sideband (ECSS) and significantly improve the reception quality of that signal. This is a great tool when reception conditions are challenging.

Other plusses include good audio quality from the top-mounted speaker, superior image rejection and dynamic range, and excellent reception in SSB and CW modes (a reflection of the relationship with its sibling TS-440 ham transceiver).

On the negative side, due to poor internal thermal design, the R-5000 radiates significant heat when powered by the AC mains. This heat exposure may tell on some ageing components. The odd layout of the numeric keypad with rows of 1-5 and 6-0 requires extra thinking power until you get used to it. The notch filter, noise blankers and IF shift controls are only moderately effective, especially by today’s standards. Note that the IF shift does not operate in AM mode. And the dots/key bounce issues mentioned earlier are a common intermittent fault in some R-5000s of this age.

Kenwood’s full-page advertisement as it appeared in the February 1988 issue of Popular Communications magazine.

Lots of Mods

Copies of the R-5000 user manual and service manual are readily available on the web. In addition, the Internet provides a wealth of information on modifications that radio hobbyists have done to their R-5000 receivers. Some are easy, while others are more fiddly, requiring some prior workshop experience. Here’s a list of some worthwhile mods to try:

Add a plug and cables to the DC points near the power supply (reduces heat significantly)
Plug-in or wire-in filters are still available for the rig from the International Radio company at http://www.inrad.net/home.php
Depending on the version of the receiver you have, it is possible to increase the sensitivity of the AM broadcast band.
Adjustments and extended functions can be made to the rig’s scanning feature. They all involve opening up the covers and accessing the internals of the rig. Not hard to do.
When pressing the mode buttons, the volume of the beep sound can be increased or decreased to silent by turning VR8 on the IF board.
Some folk have installed a small fan to improve internal air circulation.
You can’t turn the AGC off - your choice is slow or fast. It’s never really bothered me. However, you can mod this with the installation of a switch.
The dots/key bounce issues can be fixed, for which you will find multiple solutions being offered on the web. A tough one to correct and requires test equipment, experience with electronic repairs and lots of patience.
Although the audio quality is already good, it can be improved even further by replacing the ageing 4-inch speaker.

The front cover of the four-page Kenwood brochure for the R-5000.

That Fiddly Internal Battery

Changing the internal rechargeable lithium battery (for memory backup and to keep the clocks accurate) involves removing the top and bottom covers, gaining access to the back of the front panel and unscrewing the shield attached to that panel. Then, you need to unsolder the old battery, solder in the new battery, and reassemble the unit. It’s a tedious process (Kenwood could have made it easier!). Some enthusiasts have solved this issue by placing the battery pack in a more accessible location and running two wires back to the connection point. I’ll be sure to do this the next time I have to replace the battery! In addition, finding a compatible replacement battery can be tricky. Ensure you use a rechargeable battery (a Panasonic VL2020 will work) and NOT a standard non-rechargeable button battery.

Final Comments

By now, you have probably guessed that I love my beaten-up old R-5000! It has proven to be a superb old shortwave receiver for general listening and serious DXing purposes. These rigs can still be readily found on the used market, although some sellers are guilty of marking them up at silly, over-inflated prices. However, if you can pick up one in excellent condition at a reasonable price, go for it! A good one is well worth preserving, providing many hours of listening enjoyment.

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Missed the other Retro Reviews? Check them all out by clicking below:

Retro Receiver Review # 1 - The DANSK RX4000

Retro Receiver Review # 2 - The HITACHI KH-3800W

Retro Receiver Review # 3 - The SCHAUB LORENZ ITT TOURING T104A RECEIVER

Retro Receiver Review # 4 - The RACAL RA6790/GM

Retro Receiver Review # 5 - The REALISTIC (RADIO SHACK) DX160

Retro Receiver Review # 6 - The KENWOOD QR 666

Retro Receiver Review # 7 - The RODHE & SCHWARZ EK890

Retro Receiver Review # 8 - The YAESU FR101S

Retro Receiver Review # 9 - The SELENA VEGA B206

Retro Receiver Review # 10 - The DRAKE SPR-4

Retro Receiver Review # 11 - The NATIONAL RF-5000

Retro Receiver Review # 12 - The YAESU FRG-100

Retro Receiver Review # 13 - The MARC NR-82 F1

Retro Receiver Review # 14 - The MURPHY B40

Retro Receiver Review # 15 - The STROMBERG CARLSON AWP-8

Retro Receiver Review # 16 - The YAESU FRG-7

Retro Receiver Review # 17 - The ALLIED/REALISTIC SX-190

Retro Receiver Review # 18 - The PANASONIC RF4800/4900 (DR-48/49)

Retro Receiver Review # 19 - The ZENITH TRANSOCEANIC B600

Retro Receiver Review # 20 - The SONY ICF-5900W

Retro Receiver Review # 21 - The KENWOOD R-5000