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Thread: ADS Tech RDX-155 Instant FM Music

  1. #21
    Join Date
    May 2009
    Location
    Blaine, MN
    Posts
    395

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    I have been playing with the tuner for most of the day. It barely gets 100.7 out of Gillette (80+ miles) which is pretty good in my book, and that is with the included crap antenna. The antenna is it's biggest downfall. I also noticed something odd happening to one of my locals, 92.7. Every so often, what sounds like a paging tone comes across, totally dampening the station. I have attached a sample to this post. This is the only station where this occurs. Could it just be a paging tower close to the receiver?
    Attached Files Attached Files
    Justin W. - Blaine, Minnesota (EN35)
    Most used radios in order: Sony XDR-F1HD, Subaru Impreza Factory radio with RDS (not stock antenna though), Grundig G8, or Grundig S350.
    DTV dx: Insignia Tuner that everyone else has.
    DTV dx2: Vizio 24" DTV built in 2011 (hooked to Insignia).
    DTV dx3: Emerson 40" DTV built in August of 2015.
    FM Antenna: 4 Element Beam similar to the FM-6 just missing two elements.
    TV Antenna: RCA Suburban VHF-HI/UHF on the same mast as the FM antenna.

  2. #22
    Join Date
    Jul 2009
    Location
    Northern NY
    Posts
    642

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    Do you have a strong signal near the FM band or something that could possibly give off harmonics in the FM band. It sounds like it lowered the gain quite a bit for some reason. I haven't noticed anything like this. The only weird noise I get is around 96Mhz, something I've noticed on other Si470x chips as well which may be caused by a harmonic from an internal oscillator/clock.
    DX Radios:
    Sony XDR-F1HD
    Sony XDR-S10HDiP
    Tecsun PL-390

  3. #23
    Join Date
    May 2009
    Location
    Blaine, MN
    Posts
    395

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    To me it sounds like a medical pager of some type. There are a bunch of them here. It only happens if the antenna is in one position. If I move it around, it doesn't do that. Not a big deal, more annoying than anything.
    Justin W. - Blaine, Minnesota (EN35)
    Most used radios in order: Sony XDR-F1HD, Subaru Impreza Factory radio with RDS (not stock antenna though), Grundig G8, or Grundig S350.
    DTV dx: Insignia Tuner that everyone else has.
    DTV dx2: Vizio 24" DTV built in 2011 (hooked to Insignia).
    DTV dx3: Emerson 40" DTV built in August of 2015.
    FM Antenna: 4 Element Beam similar to the FM-6 just missing two elements.
    TV Antenna: RCA Suburban VHF-HI/UHF on the same mast as the FM antenna.

  4. #24
    pjdyer Guest

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    Amazon gave me an estimated Jan 18 delivery date (USPS) for it.

    As far as that pager effect, without knowing what the tuner has for a local oscillator it's hard to say if it might not be responding to a harmonic of the l.o. beating against something to produce the i.f. freq. My SX-62 in the 40-50 MHz range would reproduce faint local FM broadcast signals, like (40.1+10.7) x 2 = 101.6 -10.7 = 90.9 MHz. Or, if the pager is close/strong enough it could be intermod overload effects.

    73, Pat - WA5IYX
    Last edited by pjdyer; 01-15-2013 at 04:17 PM. Reason: added info

  5. #25
    Join Date
    Jul 2005
    Location
    Enfield, CT
    Posts
    1,180

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    Today (1/15) I took my new ADS Tech Inst. FM music stick out of the box and plugged it into a free USB port and loaded the software.

    With the included piece of garbage antenna I found that I could not even hear my local LPFM (WACC 107.7) even though it's just 5 miles away across town. Some of the Hartford stations could be heard but no RDS.

    I checked the antenna connection to the dongle. I cut off part of the antenna wire and checked both wires against the connector for continuity with an ohmmeter. Ground had no continuity.

    After trying a few ideas which didn't correct the problem, I took apart the dongle. I soldered a wire to the shield at the board and soldered another wire to the center conductor at the board. The dongle then worked a little better with a few stations showing RDS. But it was nothing spectacular and not even as sensitive as my G8.

    I then wondered how it would react when fed from an APS-13. I soldered on a female F connector and took the laptop downstairs to try it.

    Click image for larger version. 

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    The dongle works great with locals. RDS is quick. To my south, WPLR was there with its RDS. WEZN there but without RDS. The Long Island Spanish station on 98.5 was there weak and WALK 97.5 was in okay but no RDS. WYBC 94.3 was weak. Could never get a strong signal out of WRKI 95.1.

    I needed the outdoor antenna to get a good signal out of WACC-LP (local), WEBE 107.9, WIHS 104.9, our local La Bamba translator on 97.1, WZBG 97.3.

    I was unable to get much of anything out of WSRS 96.1, 93.9 in Greenfield and Lazer in Northampton 99.3 which should be a local! Providence stations WWLI, WPRO-FM and WHJY, which are good on my NAD tuner, were barely there.

    I will say that selectivity with this stick is very good. But I'll also say that sensitivity is NOT good. It's better with the E4000 dongle, even though that thing will overload forcing you to turn down the RF gain at times. Sensitivity is not even as good as the Grundig G8. You are going to need some monster tropo to see it on this dongle. Overload, though is not a problem.

    I'm not disappointed in this dongle because I only paid $2 for it. My only use for it is to take it with my laptop on vacation and check out local stations RDS. That's about it. Or maybe for listening to local FM wherever I am. To get any results out of this radio you do need an outdoor antenna, but even then you'd probably do better with a G8 or something similar.

    I have added one last picture of the interface, which is pretty good. The radio tunes in 200khz steps and uses much fewer resources than my E4000 dongle, which tends to stutter a little on FM using the laptop, even with some of the settings changed.

    Would I recommend it? No, not for DXing.

    Click image for larger version. 

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    Mike B.
    Enfield, CT
    -72 30' W/41 59' N
    FN31RX

    Online since 1999 and still going at
    mikesdx.com

    Archives: The Original Mike's TV/FM Page with Tuner Mods and Lots of Old Stuff

  6. #26
    Join Date
    May 2009
    Location
    Blaine, MN
    Posts
    395

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    I wonder if it varies per unit. I have KGWY in (tropo enhancement) weak but there right now on the ADS. The Sony is picking up KGWY with 2 bars, sometimes showing three and is much stronger with just the dipole. I have wrapped the unit (minus the air holes) in aluminum foil, connecting the outside of the antenna to the USB ground which helps. The antenna is wrapped around a set of rabbit ears, which sits right on top of my TV antenna indoors. I agree Mike, it would be a good unit to take on vacation to check out local RDS. We'll see what happens (if anything) when Es comes around. In the meantime, I am going to get an MCX to F coax connector and ditch the worthless antenna.
    Justin W. - Blaine, Minnesota (EN35)
    Most used radios in order: Sony XDR-F1HD, Subaru Impreza Factory radio with RDS (not stock antenna though), Grundig G8, or Grundig S350.
    DTV dx: Insignia Tuner that everyone else has.
    DTV dx2: Vizio 24" DTV built in 2011 (hooked to Insignia).
    DTV dx3: Emerson 40" DTV built in August of 2015.
    FM Antenna: 4 Element Beam similar to the FM-6 just missing two elements.
    TV Antenna: RCA Suburban VHF-HI/UHF on the same mast as the FM antenna.

  7. #27
    Join Date
    May 2012
    Posts
    48

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    The unit arrived earlier in this week, shipped from the San Marcos, California. A five minute test yielded significantly better results on FM than both the Elonics & Fitipower tuners via SDR connected to same antenna. The Silabs device was also a couple of bucks cheaper. Both were connected to a long USB extension cable to minimize RFI emanating from the laptop. FM performance is also better than the expensive Winfast TV2000XP PCI card which is quite satisfactory. Please keep in mind that rigorous testing has not been undertaken, these are initial impressions only. Your mileage may vary significantly. With foil shielding, sensitivity of the unit (whilst making allowance for the airholes) may be even better.

    When connected to a combination antenna, this Silabs tuner permanently receives powerhouse signals [that is, 80 - 100 kilowatts ERP] at 145km (90mi) from the south and 142km (88mi) from the west. In the peak of jet traffic, it will receive powerhouse signals at 222km (138mi) from the north west off the back of the antenna. RDS PS and Radio Text decoding is fast. Selectivity is identical to the Tecsun portable I own, with satisfactory adjacent channel selectivity on the low side next to locals. At least one frequency (96.1 MHz) was affected by spurious emissions from the device making reception of a station at 90mi on that frequency impossible. Images were heard on 93.9 MHz (moderate, two mixing products) and 99.3 MHz (weak).

    Like Spunker, 'out of the box' performance was very frustrating. I wanted to introduce the device to an outstanding 'repair tool' known as the hammer! It would not receive anything unless I squeezed the plastic exterior with my hand and this was with a rooftop antenna connected. This was indicative of a shielding problem so easily fixed.

    I found a thick piece of wire [rated at 25 amps for car automotive applications] in my electronics component compartment. Using this wire, I connected the metal exterior of the pictured USB connector to the coaxial cable ground [the metal exterior of the crimped F plug on the coaxial cable]. Instantly, performance roared into life on weaker signals.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Last edited by fmdxing; 01-16-2013 at 09:27 PM. Reason: aesthetics

  8. #28
    Join Date
    Jul 2005
    Location
    Enfield, CT
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    Hey fmdxing...I want to thank you for posting a few minutes after I posted. I went back to the dongle again today and did what you did...I soldered in a wire between the USB connector shield and the connector shield on the other end. Then I wrapped the entire thing in aluminum foil (I pulled off the plastic housing on the USB side to give the board some ventilation).

    I noticed that the semi-locals I couldn't hear well suddenly came out of nowhere. With the APS-13 connected I had a couple of Boston stations and three Providence stations. The WHMP translator on 96.9 is okay now and WHAI is there with RDS. The LPFM in Northampton on 103.3 is there now, although weakly. WCCH 103.5 and WKNE 103.7 are there now. 93.9 is audible now and WRKI is now in fine but without RDS.

    So I'm changing my mind on his. It's better than I thought. It's not an XDR-F1HD but it's not bad. Just do the little wiring mod to it and you'll be okay. It's like the Grundig G8 now. The only reason the G8 seems better is because you can walk around with it and find the "sweet spot" where a station will come in. What I need to do is make a dipole with a lead-in long enough to move it around so I can find the "good spots" for reception.
    Mike B.
    Enfield, CT
    -72 30' W/41 59' N
    FN31RX

    Online since 1999 and still going at
    mikesdx.com

    Archives: The Original Mike's TV/FM Page with Tuner Mods and Lots of Old Stuff

  9. #29
    Join Date
    May 2009
    Location
    Blaine, MN
    Posts
    395

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    I have continued playing with the unit, taking some of the suggestions on this thread (see picture) but I'm too chicken to open up the unit and wire it for coax. I'd rather get a MCX to F connector, as I don't trust my soldering abilities as much as I used to. I re-wrapped the unit in aluminum foil, making sure the foil connects the USB side to the antenna side. Reception jumped up considerably. Lower power locals came in much better. I am happy with the unit, but I doubt it would be able to receive Es. Stranger things have happened. Also of note, with this mod, the strange noise on 92.7 is much weaker. It still affects the signal from time to time, but it isn't as strong as that audio file I posted earlier.

    Click image for larger version. 

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    Justin W. - Blaine, Minnesota (EN35)
    Most used radios in order: Sony XDR-F1HD, Subaru Impreza Factory radio with RDS (not stock antenna though), Grundig G8, or Grundig S350.
    DTV dx: Insignia Tuner that everyone else has.
    DTV dx2: Vizio 24" DTV built in 2011 (hooked to Insignia).
    DTV dx3: Emerson 40" DTV built in August of 2015.
    FM Antenna: 4 Element Beam similar to the FM-6 just missing two elements.
    TV Antenna: RCA Suburban VHF-HI/UHF on the same mast as the FM antenna.

  10. #30
    Join Date
    Jul 2009
    Location
    Northern NY
    Posts
    642

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    It depends what kind of ES you are going after, but these units have decent selectivity and overload protection plus the sensitivity isn't terrible so I don't see why they couldn't be used for unattended DX recording. It may not be as good as the XDR-F1HD but its a lot cheaper and easy to record from since its already hooked to a computer.
    DX Radios:
    Sony XDR-F1HD
    Sony XDR-S10HDiP
    Tecsun PL-390

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