Sangean A new version of the ATS909

Boombox

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Looks like it may be all-DSP, which would make it better off the whip, and provide for some other improvements, including the variable bandwidths.
 

GB46

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That’s pretty expensive!
So was the original version of the 909x, but based on the European price of the new model, it would be $510 Canadian, which is roughly $100 more than I paid for my 909x a couple of years ago. Of course, the U.S. price would be lower, about $389, according to today's exchange rate. Our dollar has lost ground in recent years, due to various factors, including the pandemic.
 

GB46

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I just checked my invoice for the 909x. The price was actually $362, not the $412 I thought it was; that was with the freight and taxes. So the Canadian price of the 909x2 would be $148 more than that of the 909x. You can get a whole portable radio for $148.
 

Boombox

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With the present bad conditions (both solar and economic) I don't foresee this radio making banner sales any time soon. But, then again, there are hams who can still afford the latest radios, so perhaps sales of this new Sangean will be enough to keep them producing them until the sunspots improve, as well as the overall economy.
 

GB46

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DanH's earlier description of this new version lists the removal of the tuning dial detent. I've come to rely on those detents, especially because the dial is small and light and easily turned. I have a bad habit of keeping my finger on a control too long after using it, so if my hand isn't steady enough, I can easily move off the frequency by accident. The same thing happens with the R75's keypad when keying in a frequency. There's some key bounce, so I had to learn to get my finger off the button more quickly to avoid entering extra digits.
 

GB46

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Looks like it may be all-DSP, which would make it better off the whip, and provide for some other improvements, including the variable bandwidths.
Off-hand, do you happen to know where DSP is applied in the current 909X? Is it just in the audio, or in some other stages, as well?
 

Boombox

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^^^^ On the present day 909X the DSP chip is only used in the FM chain, where it replaces the FM Front End chip and the FM stages of the IF chip with DSP. The present 909X also uses discrete FETs for MW and SW, and the IF chip is used normally for MW and SW.
 

GB46

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^^^^ On the present day 909X the DSP chip is only used in the FM chain, where it replaces the FM Front End chip and the FM stages of the IF chip with DSP. The present 909X also uses discrete FETs for MW and SW, and the IF chip is used normally for MW and SW.
Thanks. The reason I asked is because the tone switch seems to do more than just make the audio bassier or more treble. For example, if I switch to the so-called "News" position on an SSB signal, not only does it cut the treble and reduce the background noise, but it actually increases the volume of the signal, so that the signal stands out from the noise -- very helpful.

The same thing happens on an AM signal if I switch to the narrow bandwidth. On the R75, that just muffles things a lot, but on the 909X the signal's volume increases significantly and overrides the noise quite effectively. This is a good thing, as there is neither a noise blanker nor a noise limiter on the 909X.
 

Boombox

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I don't know why you'd experience an increase in volume, but the 909X has the SW signal (and the MW signal as well) running through four IF cans and three to four ceramic filters. Some of what you are experiencing with SSB may be the nature of the SSB product detector. On my DX398/909, I haven't noticed increases in volume, but the filtering is very, very effective. Because I broke the bandwidth lever on my 398/909 when I took the back off to clean the controls, it's stuck on narrow, and it is an excellent MW DXer for that reason. I'm sure the 909X is much the same, as the two schematics aren't all that different (aside from the FM DSP, and there are different transistors and IF chip used -- the configuration, however, is basically the same.
 

GB46

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I don't know why you'd experience an increase in volume, but the 909X has the SW signal (and the MW signal as well) running through four IF cans and three to four ceramic filters. Some of what you are experiencing with SSB may be the nature of the SSB product detector. On my DX398/909, I haven't noticed increases in volume, but the filtering is very, very effective. Because I broke the bandwidth lever on my 398/909 when I took the back off to clean the controls, it's stuck on narrow, and it is an excellent MW DXer for that reason. I'm sure the 909X is much the same, as the two schematics aren't all that different (aside from the FM DSP, and there are different transistors and IF chip used -- the configuration, however, is basically the same.
Yes, the 909X narrow filter works great in AM mode. I'm not into MW at all, but it sure helps on SWBC. As for the circuitry, I'm totally at sea when looking at the schematics in the service manual. The only reason I downloaded it was to get more detailed specifications. The user's manual offers practically none. The specs in the service manual are very detailed, but hard to read. There are separate "electrical performance" tables for FM, SW, MW and LW.

As for your broken bandwidth lever, I've always avoided opening the cabinet on any of my radios, with a few exceptions. The R75 had to be opened up for replacing the clock battery, and, back in 2003, an internal fuse. I also opened it up when the R75 started malfunctioning last year, but I didn't actually do anything in there, and the radio hasn't acted up now for the past 9 months.

Anyway, the 909X got some bad reviews, mostly by nitpickers, so I tend to take reviews in general with a grain of salt -- sometimes it takes a whole shaker full. I'm delighted with my 909X.
 

GB46

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I did some more digging, and found the following in a review by Bob Grove in Monitoring Times, November 2011:

There has been considerable debate on chat rooms about whether or not the ATS-909X has DSP. The latest answer, direct from Sangean engineers, is that it has DSP for both FM and AM receiving modes (including shortwave), but not for SSB.
This confirms that it isn't in the audio, but only in the IF circuits. The reverse is true of the R75's DSP module: It affects just the audio, i.e. the noise reduction feature and the auto notch filter. That notch filter is very effective, making heterodynes from adjacent signals inaudible, but the NR feature is rather disappointing. The only effective means of noise reduction I've found on the R75 are the noise blanker, which works mainly for pulse noise from vehicle ignition systems, vacuum cleaners, etc., and the twin passband tuner.
 

Boombox

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I did some more digging, and found the following in a review by Bob Grove in :

This confirms that it isn't in the audio, but only in the IF circuits. The reverse is true of the R75's DSP module: It affects just the audio, i.e. the noise reduction feature and the auto notch filter. That notch filter is very effective, making heterodynes from adjacent signals inaudible, but the NR feature is rather disappointing. The only effective means of noise reduction I've found on the R75 are the noise blanker, which works mainly for pulse noise from vehicle ignition systems, vacuum cleaners, etc., and the twin passband tuner.
That's weird if it's true, about the 909X being all DSP except sideband, as Sangean's web page on the 909X says it's PLL.

Taking another look at the schematic, it's possible the MW/SW signals are fed to the DSP chip after the chain of transistors and filters, including the narrow/wide filter. I know the MW doesn't appear to have a direct connection to the DSP chip. They could be using the DSP as a final amplifier / filter. Not being an expert, I suppose DSP on everything except sideband is possible.

That said, one would think if the SW AM section is all DSP there would be more reception off the whip alone. The old 909 was not very sensitive off the whip, where DSP chipped radios can be excellent off the whip (if my DSP equipped Grundig G2 is any indication).

Either way, it seems you are experiencing is different than what I get on my 909. Glad to hear the radio is working out for you. I'd consider getting a 909X but I have enough SW radios as it is, and conditions have been so blah lately I question just how much there will be left to hear when sunspots return.
 

GB46

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Well, no doubt the 909X would benefit from a longer antenna, but I've put the reel antenna aside, because it brings in more RFI than the whip does. The main difference I experience without the external antenna is on battery power compared with AC operation. There's a big drop when I disconnect the adapter, not only in signal strength but in volume, as well. This is most noticeable if I listen out on the balcony, because street noise from cars going by makes it hard to hear the radio. This affects HF more than the other bands, and I've seen the battery indicator drop a little when I switch to SSB.

My guess is that the adapter delivers more power than the batteries, even when they're new. Maybe this is the source of all those complaints about poor sensitivity with the whip. I mainly run the radio on AC, but for portable use I favor alkalines, as they supply 1.5 volts, whereas the average rechargeable penlight battery puts out only 1.2v.

As for the DSP, the 909X circuitry probably differs somewhat from that of the 909, but I'm no expert, either.
 

GB46

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Well, no doubt the 909X would benefit from a longer antenna, but I've put the reel antenna aside, because it brings in more RFI than the whip does. The main difference I experience without the external antenna is on battery power compared with AC operation. There's a big drop when I disconnect the adapter, not only in signal strength but in volume, as well. This is most noticeable if I listen out on the balcony, because street noise from cars going by makes it hard to hear the radio. This affects HF more than the other bands, and I've seen the battery indicator drop a little when I switch to SSB.
My curiosity got the better of me, so I just ran some tests on the 909X using the 23-foot reel antenna instead of the whip. Signal strength was a lot better, which would seem to confirm the complaints about lack of sensitivity with the whip. However, when I disconnected the radio from the AC adapter, I still got a big drop in sensitivity, so it's not just the whip; lower voltage from the batteries must be at least partly responsible.

The other thing, which I can do nothing about, is that the radio picks up a very strong unmodulated carrier on 14.112 mHz if the patch cord is plugged into the laptop's microphone jack, even if the other end is not connected to the radio's line-in jack. If that's connected for decoding digital signals, a lot of hash partly covers up the signal. This doesn't happen if the radio is running on batteries.

It's complicated, because I don't get that carrier on the R75. I suspect that the differences in IF frequencies may have something to do with it, i.e. the computer is putting out on one of the 909X's IF frequencies, or perhaps the RF radiated by the computer is mixing with the radio's local oscillator.

Does any of that make sense? It wouldn't surprise me if it doesn't. :rolleyes:
 

mbott

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Just a side note when talking about the Sangean ATS-909X. A couple of years ago I conducted a small experiment with my Sangean ATS-909X and my Tecsun PL-660. This was done using the whip antennas only and fresh batteries in each. Tuning from 5000kHz to 16000kHz, I found: No signal could be found on one that the other could not tune. While on the same signal with deep fades, one might keep signal when the other lost it. Neither radio was better or worse than the other with this. The only true difference I noted was in the display of the signal strength as the Tecsun always showed a stronger signal being received than the Sangean.
 

GB46

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The only true difference I noted was in the display of the signal strength as the Tecsun always showed a stronger signal being received than the Sangean.
The S-meter is not a good means of comparison anyway, especially because the one on the Sangean is not calibrated in S-units or db, but merely has a 1 to 10 scale. I don't know about the Tecsun's meter, having never used anything by Tecsun, but I've listened to strong, clear sounding signals on the Sangean that read quite low on the meter, sometimes barely moving it. What matters most is how well the signal can be heard above the noise. BTW, what I have noticed about the meter on the 909X is a slow response to fluctuations in signal strength, especially when there is rapid fading, which the meter can't keep up with. By comparison, the meter on the R75 responds immediately, but there we're talking about a communications receiver, so it's apples vs. oranges.
 
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