Tecsun PL-606 1 kHz DSP Ultralight-- More Information

Gary DeBock

Hello All,
     Tecsun's newest DSP Ultralight was taken for a "test drive" during TP-DXing this morning here on the west coast, primarily to check out the compact little radio's "soft mute" level, and MP3 audio recording quality. Asian signals weren't exactly booming in, but there was a fair signal around 1420 UTC (0720 PDT) from 738-BEL2, Taiwan's 100 kw "big gun."
     The new PL-606 was inductively coupled to the 9' PVC loop (which brought Taiwan's signal on the PL-606 up from inaudible to fair), and 1 kHz frequency offset tuning was used to check the radio's "soft mute" signal drop off. ULR transoceanic DXers frequently use this 1 kHz offset tuning to get further away from domestic splatter, so long as the DX signal drop off on their ULR is not too severe (as in the case of the PL-380, and the CFJ455K5 IF-filtered E100's and SWP's). In this morning's test, BEL2 was tuned in on its 738 kHz frequency on the PL-606 for the first 20 seconds of this MP3 (along with a 2 kHz heterodyne and 740-KCBS splatter), while the second 21 seconds were recorded on 737 kHz  http://www.mediafire.com/?p8kkulbnnpdhp2s . Although the 1 kHz offset tuning did remove the heterodyne and 740 splatter, it also removed most of Taiwan's signal, a result similar to the PL-310's "soft mute" behavior.
     Further testing against both the PL-310 and PL-380 confirmed that the PL-606's soft mute behavior is very similar to that of the PL-310, although because the new radio's AM sensitivity is significantly superior to that of the PL-380, even with its greater "soft mute" drop off, the new PL-606 can usually match the PL-380's TP-DX station signal quality when 1 kHz detuning is used. Surprisingly, the compact PL-606 has been matching the larger PL-310 in AM sensitivity on all frequencies from 530-1700 kHz.
     The lack of a direct-entry keypad on the PL-606 makes it necessary to rotate the thumb wheel multiple times in order to shift from the low band to high band, unless stations are already stored in memory. Another quirk (at least in my PL-606 review model) concerns accessing the LW band. In a PL-360-style mystery system, the PL-606 lacks any front-panel indication that it can even tune the LW band, nor does the current user manual tell you how to access the frequencies. The method is to turn off the radio, press the 9/10 kHz control down until "9 kHz" disappears (and the clock comes back), then press the "MW" control down until "LW On" disappears (and the clock comes back). Although that is the LW-band access procedure, in the case of my review model, the radio still has a quirk somewhere that is preventing LW reception.
     The PL-606 is noticeably smaller and lighter than either the PL-310 or PL-380, and probably shares a lot of compact circuitry with the tiny, vertical-form PL-360. The new model can be reasonably pictured as a horizontal form PL-360 with far superior AM sensitivity, and with all the Si4734 DSP filtering options. That's a very effective combination of sensitivity, selectivity and portability on the AM band-- with a pretty low price as a bonus.
73 and Good DX,
Gary DeBock
(Photo below is also at  http://www.mediafire.com/?b2biy0s21zgo5dc )

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