After a lot of listening to various SWBC stations, I've come to the conclusion that the Sony SW7600GR has a better synchronous detector than the Tecsun PL-660's, though not by any great amount. Both receivers will sync and and hold sync equally well (it really is amazing how equally both behave in this department). The Tecsun's sync seems to introduce some distortion into the audio when locked, as opposed to the 7600GR's sync which reduces distortion. An unlocked sync on either receiver just adds noise.
While on the subject of the synchronous detectors, both radios howl when tuning away from a locked signal, with the Tecsun howling like a cat in heat! Seriously, if the author of the above article thinks the 7600GR is worse in this department, then he must have a defective radio. When sync is not locked or lost, both receivers make noise and I find it far more productive to tune around in an ssb mode. Now, mentioning that the Tecsun's sync adds some distortion isn't saying that SWLing with the 660 is unpleasant, far from it.
The 660 has very good audio for a unit its size. It's wide filter is very wide and is only useful for powerful broadcasts without interfering signals on either side. I did all my testing with the 660's narrow filter. The Tecsun has the better audio section and that helps the intelligibility of badly buried signals. And to state the obvious, a good set of headphones does wonders for both receivers. Ergonomically the Tecsun is better than the Sony.
However there are a few caveats. First and foremost, my number one complaint is the detent in the fine tuning control. I like to do ECSS and that little detent makes it more difficult than it needs to be and also interferes with tuning ssb. It was a very bad design decision. The tuning knob is very handy but it could be wider. The attenuator switch is handy, but I prefer a variable control like the one present on the Sony. This is a very minor quibble. On the 7600GR it's easy to "trick" the sync into locking by switching to ssb and then turning on the sync. I was delighted to find that I could also do this on the 660! When it comes to the display the 660 has it all over the 7600GR. No comparison. Lots of info and a wonderful backlight and it displays the clock at all times! I don't care for the long rectangular numerical keys; the round buttons on the Sony are easier to hit, though I've been using this configuration since '94 with the SW7600G, and old habits are hard to break.
I love that the ssb and sync controls are on the front and that the status of these controls are clearly shown on that wonderful display. It's nice that the 660 has two bandwidths, unfortunately the wide setting is nigh useless except for powerful signals in the clear, and I mean very powerful and very clear. The narrow filter is very good and comparable to the Sony's excellent single filter. It would have been very interesting if the 660 had multiple DSP based filters like the lesser 380/39x series. I have yet to do more work with the memories, LW,MW,FM and AIR and will report on those soon (although I'll probably wind up ignoring the air band as I don't even concern myself with it on my scanners). Incidentally, I'm running both receivers on Energizer L91 Lithium batteries. Speaking of batteries, the Tecsun came with 1000 mAh NiMH cells! What is this, the '90s? I've seen AAA NiMH that are spec'd at 900 mAh! Mark
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