HFU HF Underground
Technical Topics => Equipment => Topic started by: mondomusique on December 11, 2011, 1603 UTC
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I have a Palstar R-30A radio and enjoy listening to shortwave DX. I'm thinking of spending the $695 to get the audio improvements the Sherwood SE-3 sync detector promises. The SE-3 would fit well with my afterdark headphone monitoring and daytime speaker listening.
Of course I'm wondering if I should instead put the money toward an SDR like one of the RF Space units. The SDRs offer a lot, I could view the waterfall window on my TV (pc connected), but it would be not as usable as the Palstar and phones for middle-of-the-night listening.
So I have two questions: is the Synchronous AM detector on the SDR radio software typically any good? and can you envision a way that a Sherwood SE-3 hardware sync detector could be used with any SDR's out there?
Opinions requested about these hardware choices...
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You can't use external hardware with an SDR. The SDR is the entire radio (minus the final demodulation which is done in your computer in software).
With an SDR, you can do sync detection in software. I find it to be comparable to ECSS mode on my JRC NRD 545.
For the same $695, there's no question in my mind that you'll get a lot more out of an RF Space SDR than a sync detector. You can record an entire 200 kKz band to disk, and go back and listen to individual stations later. You can view the waterfall while it is running, and see stations pop up instantly. Indeed, you can view a good portion of a SWBC band and see what's on, without having to tune around to each possible station.
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Good info on SDRs Chris. You know it's always great when you can build on your existing equipment to get more features.
Like how RF-Space offers their IF-2000 board for the Yaesu FT-2000 and FT-950 tranceivers so you get the required IF output to use their SDR-IQ as a panadapter. Or this webpage where W1VD modded a Collins R-390A to get the required IF output to use a Softrock SDR as a panadapter:
http://www.w1vd.com/R-390ASoftRockdetails.html
Unfortunately, the Palstar R-30A has no known mods that would provide the required IF output to add an SDR as a panadapter (though I think it should be possible). Although the Palstar is a nice traditional radio it is not known for mods or even circuit documentation.
Which is to say, I would have to agree that SDR is where the new developments and upgrades are happening for radio. It's remarkable that the RF-Space SDR-IQ radio will be out for five years as of January 2012, and that product has gotten more useful over that time via software upgrades.
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Generally you use a VHF or UHF radio as a panadapter for viewing a spectrum or listening to VHF/UHF comms, taking the 10.7 MHz IF output. With the SDR-IQ, it directly receives 0-30 MHz, so there's no need for another radio in front of it.
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Zane has a Sherwood sync unit with his Palstar and might offer some user experience. I've heard some of Zane's off-air recordings comparing reception with/without and the sync detector does help. So does the sync detector on my Sony ICF-2010. Ditto the online web-controlled Drake R8-series I've compared with and without AM sync.
Does it help $695 worth? Not on my budget. I'd need a quieter location and good outdoor antenna to make it worth that little extra bit of advantage.
For that kind of money I'd look for a receiver that already has a sync detector built in: Sony ICF-2010 (which is also overvalued now on the used market); some of the high end Grundig portables; Drake R8-series tabletops; some JRC NRD-series; Lowe HF-150 and 225. The Icom R-75's sync detector reportedly didn't work well so study some user reports before buying that one for the sync detection.
And I'm satisfied enough with my Palstar R-30C as-is. For weak AM signals switching to sideband and the narrow filter works about as well as the Sony 2010 with AM sync.
Incidentally, that's the main advantage I've found with sync detection - picking out weak AM signals. Passport to World Band Radio and other reviews often talked about "distortion." Eh... to me, DXing always sounds distorted - fadey, scratchy, etc. That particular characteristic seemed to be overemphasized. Most diehard DXers have built-in brain filters that help us ignore distortion and noise. Any sane person would have given up the hobby after a week.
The real advantages to AM sync detection are:
- Ferreting out weak AM signals and making them just audible enough to get an ID.
- Sorting out competing signals on the 49m band where stations are only 5 kHz apart.
Even the stock Sony ICF-2010 handles those challenges well enough. Several times when I've been unable to ID an AM pirate with the Palstar R30-C on an indoor loop, I've switched to the Sony 2010 with just the whip by a window and snagged just enough of the carrier to get a station ID.
For $695, I'd look for a good used Drake R8-series, or Lowe HF-150 (which offered an unusually flexible AM sync detection), if I wanted a conventional receiver with sync detection. I've tried some online web-controlled Drake R8's on various AM signals - weak and/or in crowded bands - and it really does make a difference.
If you'd like to test drive one, there's an online web controlled Drake R8 (http://www.chilton.com/scripts/radio/R8-receiver) in Virginia - probably the oldest continuously available shortwave receiver. It's limited by an indoor attic loop so reception is comparable to mine at home. And rather than a continuous audio stream you can choose only 10 or 60 seconds worth of audio sampling. But it's very handy for comparing the benefit of AM sync against non-sync AM, or sideband tuning - and the disadvantages, as tuning is a little fussy with AM sync. You'll often need to adjust the tuning up or down a bit to get it to lock. Meanwhile, it'll whine as it struggles to lock on. An excellent challenge is WBCQ on 5110, which is only nominally on 5110 and kinda-sorta AM. Depending on day and moon phase, it's center freq is somewhere between 5109-5111, and it's AM/USB only. Lately, with my ordinary AM receivers, 5110 is almost unlistenable - with heavy selective fading it sounds like trying to tune a sideband signal with an AM receiver. Switching to USB helps. But it's best with the Sony 2010 in AM sync, with the tuner set to around 5110.1 to ensure it locks onto the upper sideband. So WBCQ's Area 51 block on 5110 is the single best challenge to test driving a receiver's AM sync detection mode.
But as Chris pointed out, a good SDR offers huge advantages to a dedicated DXer. Even in my area, an RFI-plagued suburban neighborhood, an SDR would offer certain advantages in flexible notch filters and noise reduction. And being able to record a wide swath of a band at once - pretty cool if you're seriously into pirates, numbers or mysterious DXing. :o
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I agree with Lex, sync mode definitely improves audio quality; I run it whenever I can. It does seem to help pull weak signals out of the mud.
My own take is that for the same $695, I'd get the SDR with sync detection (assuming it works as well as the Sherwood unit you're considering, I have no experience with one). Maybe if I can get the chance I'll run some tests with the SDR in normal AM and sync mode and post the recordings. If I get real ambitious, I'll record audio from the NRD 545 at the same time for comparison.
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I've read about what the Sherwood SE-3 can do, listened to the audio clips online, plus Zane sent me some recordings, no doubt it's the real hardware deal for synchronous AM detection. It would be a nice improvement to have the audio remain intact when the carrier fades especially for the faraway DX like Radio Argentina Exterior (11710khz) or Radio Mali (5595khz) (two I listen for). Sometimes fading is heavy enough to make voice unintelligible and music not enjoyable.
But it's hard to justify $695 for the one feature, when an SDR offers a plethora of features.
Maybe some people with SDRs can post some reception clips with Synchronous AM toggled off and on, and we can see which software has a good S-AM implementation. As with hardware, all implementations of Sync Detection are likely not created equal.
I still might look on e-ham for a used SE-3 for a cheaper price.
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Here's a quick comparison I did with SpectraVue running a netSDR, the first 15 seconds is normal AM, the second is sync. Ideally you'd probably want to hear what it sounds like under various conditions, including deep fades.
http://www.hfunderpants.com/mypics/AM_VS_SYNC_SDR.WAV (http://www.hfunderpants.com/mypics/AM_VS_SYNC_SDR.WAV)
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I can't comment on the Sherwood compatibility with an SDR. I will say that I've been extremely happy with the SE-3 combined with my Palstar. Yes, it's as much money as the Palstar, but I think I easily have twice the radio.
The features I really like are:
Quality of the lock - once locked, it just doesn't lose lock.
The AR mode - New on the MK IV, it allows the unit to quickly self-lock on a carrier without manually having to bring it to lock with the up/down arrows. The AR mode was designed for amateur radio AM nets where each carrier may not be on exactly the same frequency. In the pirate radio world, it re-locks itself quickly on those transmitters with shifty carriers.
Offsets - If you have an AM signal being bothered by another nearby signal, you can lock the signal you want and walk it away from
the interference. The adjustable BFO also allows you to play some games with interference on SSB signals. You can again offset the frequency on your radio and the BFO adjust acts like a passband filter.
When the SE-3 MK III was out of production, I tried several times to bid for an older unit on an ebay auction and was never successful. When Rob Sherwood announced that they were going to be available again (they almost weren't), I decided to go for it. I figured I could unload it easily enough if I ended up disappointed. I'm not.
The example recordings I sent to MM had a lot of periodic deep fades, so it's hard for me to compare to Chris' recording which sounds more like a filtering effect to my untrained ear.
Z
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Hi Zane:
You've sold me on the merits of the SE-3 once again! I typically buy a piece of equipment each year so in 2012 it will be the SE-3 mk IV for $695 :P
My rationale is that my goal is to hear the DX better, not see the DX better which is the main SDR advantage (though SDRs do many things well). The Palstar radio is a solid receiver as is, and matches well with the Sherwood sync detector, resulting in optimal shortwave audio.
Of course, if I was still using my old Sony portable and didn't have the Palstar radio already at hand (bought it used in 2011), I would go directly to an SDR as you can't argue with the features and value SDRs bring to the table.
Here's my favourite Palstar R30/Sherwood SE-3 webpage... Vic's Weblog... by a Japanese SWL... which I run through google translate:
original page: http://blog.goo.ne.jp/vic142178/c/a1dd141467dffcec39693bf0db1ed974
translation page: http://translate.google.ca/translate?sl=ja&tl=en&js=n&prev=_t&hl=en&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Fblog.goo.ne.jp%2Fvic142178%2Fc%2Fa1dd141467dffcec39693bf0db1ed974
MM
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Can't really add much to what's already been said, but I love my MK III. It really shows it's stuff on weak stations especially for europirates where once locked, you can go off frequency for better copy like an EQ adjust for audio intelligibility.
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Just an update, I bought a used Sherwood SE-3 (mk III) Sync Detector (paid more than I should have) and have been using it for the past two weeks. It's the bomb, it gives incredible control over AM signals, a really well thought out piece. For Palstar R30 owners it's the next level, the perfect complement to the Palstar's excellent front end, AGC and Collins filters but otherwise limited feature set.
For anyone with a 455khz IF output on the back of their radio, there is at least one Sherwood SE3 on Eham classifieds right now if you are interested.