TS-590SG_review_RC_2015.pdf

16 Kenwood TS-590SG An update for a well-respected HF for a full description of all the features and functions, refer to the earlier review in the January 2011 RadCom. NEW FEATURES AND FUNCTIONS. The TS-590SG includes a number of hardware changes and firmware upgrades. Some small cosmetic changes have been made to the knobs, lettering and trim to complement the style of the top-end TS-990S. LCD backlight colour selections have been increased from two to ten, all variations on amber and green. A Morse code data decoder is now built in, displaying up to eight characters in the space on the display normally allocated to the split operating frequency. It tracks over a reasonable range of speeds and up to quite high values but, as with all such decoders, it is only effective on really accurately sent Morse (eg from a computer) with low levels of noise and interference. Its greatest use is perhaps in building confidence on receiving Morse code. The low-level drive output connector, originally provided for transverter drive or LF transmission, can now be assigned to provide an antenna feed to an external receiver. This yields a 3dB loss on both paths if enabled. The number of programmable function keys on the front panel has been increased from two to six by allowing the RIT, XIT and The TS-590SG looks almost identical to its predecessor, the TS-590S: the improvements are all under the skin. CW decoding is now included and characters appear in the sub display area. 17 Equipment Review March 2015 l RadCom Peter Hart, G3SJX l peterg3sjx.freeserve.co.uk CL keys to be reassigned for this purpose and fitting the MULTI click-step rotary with a push-button. In split frequency operation it is now possible to enter split shifts directly in integer kHz units up to 9kHz. Two different methods are used to set the IF channel bandwidth, using dual concentric rotary controls. In the original design, these controls provided independent tailoring of the low and high cut-off frequencies on voice modes as a means of setting the overall bandwidth. On CW and data modes, these controls set the bandwidth and centre frequency (shift). With the TS-590SG, both methods of control are available on SSB voice and SSB data modes by setting an appropriate menu item. However, the finer control provided by the original method is more appropriate for voice modes and is the default setting. A number of minor circuit changes have been made to improve the overall performance. In the original design, some slight power overshoot was seen on the first CW transmit character. In most situations this was not a problem but some users with linear amplifiers driven to near full output experienced over-power tripping. Kenwood produced a fix for this issue, which was implemented in production models from the beginning of 2014. In the SG version, the ALC circuitry has been redesigned to eliminate this problem. Some redesign of the circuitry around the first mixer and synthesiser has been made to improve further the close-in dynamic range. In the original design, strong close-by signals falling inside the roofing filter bandwidth could desensitise the receiver by capturing the IF element of the AGC. The AGC is applied in several places. In the SG version, the AGC has been re-optimised to avoid this problem. MEASUREMENTS. I limited my detailed measurements to those areas that had been addressed by circuit changes. In other areas a brief check showed a similar performance to the measured results for the TS-590S. Dynamic range figures for intermodulation and reciprocal mixing at greater than 10kHz spacing were broadly similar to the TS-590S. These are excellent figures in line with the top end radios currently on the market. Close-in there was no sign of AGC desensitising but there was a drop-off in dynamic range as the roofing filter sides were approached, perhaps rather more than I was expecting. With the earlier TS-590S review, AGC affected the close-in measurement and resulted, I realise now, in false high measured figures. The overall AGC attack and decay performance was similar to the earlier model, with a 5 to 10ms hole inserted in the signal on the attack response. Commonly seen on many DSP implemented radios, this can degrade readability of weak signals in noisy situations. Backing off the RF gain control and turning off the AGC may help in these specific situations. The receiver is generally very clean from spurious responses. The weak birdie on 1827.5kHz in the 160m DX sector reported in the earlier review is still there, although on the review SG radio it is at a lower level than the earlier model and unlikely to be an issue. On transmit, the keying envelope was nicely shaped with no overshoot visible at any power level. The default rise/fall times are 6ms and this gives a clean result but faster times down towards 1ms give noticeable clicks on adjacent frequencies and even further out. Transmitter noise output is similar to the TS-990S and better than some recent introductions. CONCLUSIONS. The TS-590SG performs in a similar fashion to the earlier model. It is an excellent all-round radio, packed with useful features, is easy to operate with well thought out and friendly ergonomics and has a very readable display. The on-air performance was very good with clean results on weak and strong signals and it received good transmission reports. The changes and additions enhance an already excellent radio. Some of the enhancements have also been implemented in a firmware update to the earlier model. Available from the usual retailers for around 1350, the TS-590SG is excellent value for money. ACKNOWLEDGEMENT. I would like to express my gratitude to Kenwood Electronics UK for the loan of this radio. CLOSE-IN INTERMODULATION. 500Hz BANDWIDTH. PREAMP OFF -RX1 on 7MHz- -RX2 on 10MHz- 3rd order 2 tone 3rd order 2 tone Spacing intercept dynamic range intercept dynamic range 1kHz -10dBm 81dB -18.5dBm 76dB 1.5kHz -4dBm 85dB -18.5dBm 76dB 2kHz -1dBm 87dB -18.5dBm 76dB 3kHz +5dBm 91dB -12.5dBm 80dB 4kHz +9.5dBm 94dB -9dBm 82dB 5kHz +12.5dBm 96dB -6dBm 84dB 7kHz +17dBm 99dB 0dBm 88dB 10kHz +27.5dBm 106dB +10dBm 95dB 15kHz +35dBm 111dB +28dBm 107dB 20kHz +30dBm 107dB +28dBm 107dB 25kHz +31dBm 108dB +28dBm 107dB - RECIPROCAL MIXING 500Hz BANDWIDTH - Transmit Frequency RX1 RX1 RX2 noise offset 7MHz 21MHz 16MHz 7MHz 1kHz 89dB (-116dBC/Hz) 85dB (-112dBC/Hz) 73dB (-100dBC/Hz) -100dBC/Hz 2kHz 99dB (-126dBC/Hz) 95dB (-122dBC/Hz) 79dB (-106dBC/Hz) -107dBC/Hz 3kHz 104dB (-131dBC/Hz) 99dB (-126dBC/Hz) 82dB (-109dBC/Hz) -110dBC/Hz 5kHz 110dB (-137dBC/Hz) 106dB (-133dBC/Hz) 87dB (-114dBC/Hz) -112dBC/Hz 10kHz 117dB (-144dBC/Hz) 112dB (-139dBC/Hz) 98dB (-125dBC/Hz) -120dBC/Hz 15kHz 120dB (-147dBC/Hz) 116dB (-143dBC/Hz) 105dB (-132dBC/Hz) -126dBC/Hz 20kHz 122dB (-149dBC/Hz) 117dB (-144dBC/Hz) 108dB (-135dBC/Hz) -132dBC/Hz 30kHz 123dB (-150dBC/Hz) 120dB (-147dBC/Hz) 110dB (-137dBC/Hz) -133dBC/Hz 50kHz 116dB (-143dBC/Hz) 118dB (-145dBC/Hz) 108dB (-135dBC/Hz) -134dBC/Hz 100kHz 127dB (-154dBC/Hz) 125dB (-152dBC/Hz) 115dB (-142dBC/Hz) -136dBC/Hz - BLOCKING PREAMP OFF - Frequency RX1 RX1 RX2 offset2.7kHzroof500Hzroof2.7kHzfilter 1kHz noise limited noise limited noise limited 2kHz noise limited noise limited noise limited 3kHz noise limited noise limited +2dBm 5kHz +17dBm +20dBm +2dBm 10kHz +17dBm +20dBm +6dBm 15kHz +17dBm +20dBm +14dBm 20kHz +17dBm +20dBm +20dBm 30kHz +17dBm +20dBm +20dBm 50kHz +17dBm +20dBm +20dBm 100kHz +17dBm +20dBm +20dBm ThecleanTS-590SGrearpanelisunchangedfromtheTS-590S.