Receiver Review: Kenwood R-5000

R-5000

Year Introduced/Discontinued: 1987/1998
Power: Mains, 12 v supply optional
Size: 279 x 107 x 307 mm
Weight: 5.6 kg
Price: US$1050, CAN$1340, £1000, A$1850
Coverage: 100 kHz - 30 MHz continuous

Value Rating: starstarstar

Two VFO's. AM, SSB, FSK, CW. Double conversion. Keyboard entry or manual tuning. Keyboard entry takes some getting used to. 100 channel memory stores frequency AND mode. Computer control possible via RS232 interface. Aftermarket software available. Selectivity : 5.9 or 2.7 kHz at -6dB. We recommend adding the improved AM filter at the time of purchase. 100 memories. Scanning possibilities. 10 Hz is the finest tuning increment which is perfectly adequate. Good audio quality (better than ICOM IC-R72). AGC fast/slow. Timer plus dual time-zone clock. 10 Hz steps VFO. Switchable RF input attenuator.


This review was compiled independently. The Medium Wave Circle and Radio Netherlands has no financial connection with Kenwood, the manufacturer of this receiver.


 

Introduction

This set was launched in late 1987 and when it was first introduced represented the state of the art. It finally disappeared from dealers' shelves during 1988 as stocks ran out. In the meantime, sets like the AOR-7030 and Lowe HF-250E appeared, so if you're in the market for a set of this type, read the reviews of the other radios as well. Every set has its pros and cons.

The R-5000 is a table-top full coverage communications receiver. The light grey metal cabinet measures 279 by 107 by 307 mm, and it weighs 5.6 kg. An option exists to run the set off a 12V car battery i.e. in a mobile home, but it is primarily designed for use in one location. Some versions are single voltage only (i.e. in Japan), though many will accept 120, 220, or 240 volts from the AC household current supply. The set uses its own internal re-chargeable battery to keep the two independent 24 hour clocks running and retain the memory contents when the set is not connected to household current. The receiver circuitry runs cool. Even after several hours use, the back panel of the receiver only gets lukewarm. This ensures excellent frequency stability.

 

Tuning

Official coverage of the receiver is between 100 kHz up to 30 MHz continuously. An optional VHF module (installed in our example) allows additional tuning between 108 and 174 MHz. National legislation in some countries (e.g. Italy and Saudi Arabia) require that coverage is more restricted. Check details to be sure. The test sample in fact tuned down to 30 kHz. Between 30 and 70 kHz nothing could be heard except synthesiser noise. But on 77.5 kHz the time signal station in Mainflingen, Federal Republic of Germany could be heard with good strength at the test site some 500 kilometres away.

The receiver has two tuning modes, either via a manual tuning knob, or using a numeric keypad. Turning the manual knob in a clockwise direction causes the set to move up in frequency, the step being set automatically depending on the mode that has been selected. Normally this is 5000 Hz in the FM mode, 1000 Hz steps in AM, and 10 Hz steps in USB/LSB/FSK/CW. If a STEP button is switched on then tuning on AM, LSB, USB, FSK, and CW is in 100 Hz steps, 2500 Hz on FM. The steps mean accurate tuning of all modes is possible, including critical radio-teletype (RTTY) signals. For short-wave programme listening, the 100 Hz step position is preferable when tuning. This avoids the "chuffing" effect audible on the larger step. For moving fast up and down the bands, the UP and DOWN buttons allow the user to jump 1 MHz in either direction.

Keyboard frequency entry takes a bit of getting used to. The mode and antenna buttons double as the keypad, arranged in two rows of five keys. This layout is different from a standard calculator. Unfortunately, the microprocessor software is not as intelligent as on competing receivers. Whilst a frequency such as 15560 kHz can be entered immediately, 6155 kHz has to entered as "06155", and 747 kHz as "00747". Further accuracy to the nearest 10 Hz is possible, i.e. 747.15, but not usually needed. The receiver's stability is excellent, allowing easy use of the Exalted Carrier Selectable Sideband (ECSS) receiving technique. The receiver is intelligent in that no retuning is needed when switching between any combination of AM, LSB, and USB. This is in contrast to the competing, now discontinued, ICOM IC-R71 that jumps 3 kHz when swapping between USB and LSB.

 

Two VFO's and 100 memories

Operating convenience is enhanced by the use of two variable frequency oscillators. You can set one to a high frequency (say 15 MHz), and the other to a lower channel (e.g. 6 MHz). If you're using VFO A around 6 MHz and want to check conditions on higher frequencies, selecting the other VFO will allow you to jump to 15 MHz immediately. A 100-channel memory is also offered, storing the mode, and antenna number with each stored frequency. Selectivity positions are selected automatically, i.e. always WIDE for AM stations.

Scanning of the entire contents of the memory is possible, but also selected regions too. Channel numbers ending in 8 and 9 are usually reserved for setting frequency limits. Putting the receiver into "MEMORY SCROLL" mode allows the operator to scan all frequencies between the limits previously entered.

 

Signal strength meter

International standards state that "S9" on a set below 30 MHz should correspond to a signal of 50 microVolts, and each S point below that is 6 dB lower. In general, "S" meters on communications receivers of this class only provide an approximate indication of signal strength. The R-5000 meter on our production model was fairly well calibrated. At 1.6 microVolts (i.e. S 4), the meter shows S 1 on both AM and SSB modes. Under S 7, the meter readings are too low, but on higher signal levels the meter is more accurate. An RF gain control plus an RF attenuator (10, 20, and 30 dB selectable steps) are offered for very strong nearby signals. We measured this and discovered that it provided exactly the amount of attenuation as specified. Many receivers' attenuators do not. When you switch to VHF, however, the built-in converter provided extra amplification. As a result, the "S" meter becomes far more sensitive. The table below shows the results.

R-5000 S-meter

 

Features for the visually impaired

Whilst not exclusively designed for the visually impaired, two features are available (one as an option) to help users who cannot see the receiver. If the VOICE button is pushed, a female voice announces the figures displayed on the blue fluorescent digital frequency readout. It is clear, but the output only comes through at a constant level in the headphones or the internal speaker. It is not available at the RECORD output. This is a pity. Using a stereo tape recorder, one channel connected to the receiver output, and one to the clock output, automatic logging would have been possible.

In addition, pushing the MODE buttons causes a single letter Morse code message to be heard in the speaker. (i.e. A for AM, L for LSB etc.). Clever thinking.

 

Good sensitivity

In these days of 500 kW short-wave transmitters, sensitivity has become less important than good dynamic range. Nevertheless, checking to see how even the sensitivity of the receiver is over the entire range is interesting. Sensitivity on medium wave is much less than on short-wave. Kenwood have done this deliberately to avoid local medium wave stations overloading the front end of the set. The sensitivity might cause problems if you wanted to use a medium wave loop antenna for broadcast band DXing between 0.5 and 1.6 MHz. But in making a compromise, we feel that Kenwood has chosen the better solution. In the VHF area the R-5000 offers much better sensitivity that most scanners on the market.

We plotted the signal/noise ratio against the incoming signal. It is then possible to determine what level of signal is needed before an acceptable signal+noise/noise ratio is obtained. On short-wave, using the 6 kHz filter, the level was 3.45 microVolts for 20 dB S+N/N. Corresponding figures for the 2.4 kHz SSB filter were 0.9 microVolts.

 

Good selectivity

The R-5000 can be set to select the appropriate filter automatically, or a manual override is possible. The set comes with two filters NARROW and WIDE as standard for use in all modes except FM. The FM filter is 12 kHz wide at -6 dB. Because the medium and short-wave bands are very over-crowded, especially in Europe, the ability to separate the station you want from the rest is very important. The AM WIDE filter is within the manufacturer's specifications, i.e. 6.3 kHz at -6 dB, 19 kHz at - 60 dB. This is fine for general listening under minimum interference for conditions. When the going gets tough, such as when DXing, it's likely that the operator will switch to the narrower filter. The results here are 2.7 kHz (-6 dB), 4.4 kHz (-60 dB).

Kenwood (and some other smaller companies) offer other filter options. The static selectivity of the 8.83 MHz crystal filter is good.

Various methods can be used to measure the selectivity of a receiver. Manufacturers, including Kenwood, usually quote results based on the curve of the intermediate frequency filter they've installed. This is a useful guide, but it doesn't guarantee how the receiver will perform in practice. European PTT administrations use a standard method to measure Maritime Mobile receivers for professional use. We applied the same test to the R-5000. A signal generator connected to the receiver is set to 11500 kHz, and the output level set to cause a 20 dB signal to noise ratio. This is in the order of 1 microVolt on the R-5000. A second generator is set up with a 400 Hz tone and 30% modulation. Its frequency and strength is varied so that the 20 dB level on the receiver falls back to 14 dB. The difference in signal strength, measured in dBs (and often called the RF protection ratio), shows how much stronger a nearby transmitter needs to be before it causes interference. Likewise this is also a measure of how well a nearby signal is suppressed by the receiver's bandwidth filter. Optional filters exist enabling the user to select 270 Hz, 500 Hz, and 1800 Hz positions. These will appeal more to the Morse code (CW) and RTTY enthusiast.

 

Dynamic selectivity in SSB mode

When unwanted transmitters appear on -1 and +4 kHz (i.e. 1 kHz above and below the bandpass), the damping is 32 dB, mainly due to synthesiser noise. The CEPT norm is 40 dB. When the unwanted signals are at -5 and +8 kHz, damping is better at 60 dB (CEPT norm = 50 dB). The maximum suppression of unwanted transmitters operating on frequencies further away is 73 dB.

 

Good dynamic range

When two strong signals appear at the antenna input, mixing products occur in most receivers. They appear as "ghost" signals on other parts of the dial. These can be annoying, especially if a mixing product blocks out a weak signal you're trying to listen to. How strong these signals have to be before they cause problems is an important specification. The new 10 MHz amateur radio band is a source of weak signals near the strong international broadcasters around 9.9 MHz. Again using the standard CEPT measurements, the two signal generators were set to produce 0.961 microVolts, representing a signal 20 dB above the receiver's noise floor. The generators are tuned to 10000 kHz and 10020 kHz respectively, i.e. 20 kHz apart. Mixing products will occur at the same distance from both signals as their distance apart, i.e. at 10040 and 9980 kHz. The R-5000 is now set to SSB (using the 2.4 kHz filter), and tuned to one of the mixing products. The output of the two signal generators is now adjusted so that the level of the mixing product is 1 microVolt, i.e. a signal to noise ratio of 20 dB. Such a mixing product is not masked by the receiver's noise, and therefore is noticeable and annoying. The relationship between the initial and final levels of the signal generators is a measurement of the receiver's dynamic range. In brochures, Kenwood quote measurements made at 50 kHz spacing and using a 500 Hz crystal filter. This gives 102 dB. We didn't install this filter, but by measuring with the 2.4 kHz filter and extrapolating, the figure does indeed turn out to be around 100 dB. This looks good on paper, but it doesn't help the customer compare the set with other receivers. We used the 20 kHz standard instead. This gave a 3rd order intercept point of +16dBm, and a dynamic range of 90 dB. This is MUCH better than on the first pre-production R-5000 we tested way back in 1987. This is well above the CEPT minimum of 60 dB, and the old R-1000 (64 dB). The ICOM IC-R71 comes out at 97 dB using the same method, the Yaesu FRG-8800 at 90 dB. Figures for the AOR-7030 are better though.

 

Good blocking figures for shortwave

Dynamic range is a useful measure of how nearby strong signals interfere with weak signals. "Blocking" is another test to see how nearby strong signals affect a strong signal being listened to. One standard test is to feed in a signal on 7100 kHz (arbitrary) of around 1 microVolt into the receiver, enough to give exactly 20 dB signal to noise ratio. The set is tuned to 7100 kHz. On 7300 kHz a second modulated signal is also applied to the antenna terminals. The level of this signal is turned up until a level is reached when all kinds of spurious background noises are heard on the R-5000. The level in this case was 35 milliVolts (80 dB). This is a good figure and more impressive than 20 milliVolts for the (discontinued) ICOM ICR-71 and 26 milliVolts for the (discontinued) Yaesu FRG-8800. When the frequency spacing is changed to 1 MHz, the level rises to 44 milliVolts. Figures for the AOR-7030 are again better though.

 

Ten birdies

Modern frequency synthesisers inside communications receivers are not perfect. Birdies are interference products which appear on the dial as silent carriers on AM, and whistles in the SSB/CW mode (hence the name). Weak signals on the same frequency as a birdie are subject to interference. They are measured by putting a 50 Ohm dummy load across the antenna terminals, putting the receiver in a screened Faraday cage, and tuning across the entire spectrum. Most birdies on the R-5000 are so weak that they disappear below the noise level when an antenna is connected. Ten birdies on the R-5000 are however above 1 microVolt. They are heard on 1977, 8546, 8999, 14053, 17999, 18069, 23076, 25909, 26999, 29865 kHz, but fortunately most fall outside the broadcast and amateur radio bands. This may seem like a lot, but in practice the R-5000 turns out to be a quiet receiver.

 

Intermediate frequency

Like most receivers in this class, the R-5000 is a double superheterodyne design. The first intermediate frequency for the R-5000 has been chosen as 58112.5 kHz, the second is 8830 kHz. IF Rejection of these two frequencies is better than 84 and 65 dB respectively which is good. The image ratio was measured as better than 90 dB, also good. Only when FM is used does a third stage at 455 kHz become active. This design is common to other Kenwood products.

 

More tuning features

The receiver's automatic gain control can be switched between FAST and SLOW but not switched off entirely. An adjustable audio notch filter is also included in the set. It is capable of attenuating a single annoying heterodyne by some 31 dB, making it virtually inaudible. The notch is 270 Hz wide at -6 dB points. A useful pass-band tuning control is also offered, functioning in the SSB/FSK/CW modes only. The squelch control functions on all modes, but is primarily of use when listening to narrow band FM. Two independent noise blankers are included on the receiver. One is designed to eliminate the 10 Hz pulse caused by the former Soviet Over-the-Horizon Radar system, popularly known as the "Woodpecker". It is moderately effective in doing this, although the Woodpecker hasn't been heard on the air for many years now. Other forms of pulse type noises can at least be reduced with the other blanker.

 

Tape recordings

A built in timer can be used to control a tape-recorder for taping programmes when the operator is absent. The internal relay can only switch low voltages though, not the AC household current supply. The RECORD level output is perfect for most tape-recorders.

 

Computer control

An optional accessory exists, the IF-232C Interface, which fits between an RS232C interface on a home computer, and plugs into the back of the receiver. Software is available from Kenwood and a number of third-party sources.

 

Conclusions

The R-5000 is a good value communications receiver offering better performance than the Yaesu FRG-100. The audio quality is good, but not as good as the AOR-7030 or the Lowe HF-250E. The controls on the receiver take some getting use to. Some might judge them as rather clumsy. The receiver's moderate level of synthesiser noise is a slight drawback. But all the facilities you need on a communications receiver are available. In Europe, Kenwood have lowered the price of the R-5000 in some markets, but it is still above the AOR-7030 and Lowe HF-250E. In the USA, the radio is considerably cheaper than the AOR-7030 and Lowe HF-250E.

This review first appeared on the Radio Netherlands website.