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Models with indication of signal level in dBµV

Discussion in 'Tuners' started by xkdb, Oct 23, 2018.

  1. xkdb

    xkdb New Member

    Messages:
    7
    Hello,

    I am looking for high-end / TOTL FM tuners (both "digital"/synthesizer and analog) with signal level readings in dBµV or dBf. [ dBf = dBµV + 11.2 (75Ω) OR 5.2 (300Ω) ]
    Deviation and multipath readings, or at least multipath outputs for oscilloscope are desirable as well. Searching through all manufacturers and models listed on fmtunerinfo is very time consuming and will likely not give reliable results, so I am open to all kinds of suggestions.
    NOTE: It must be a European model / EQ timeconstant 50µs or switchable.

    Here are some examples:

    --- dBµV ---
    Sony ST-SA5ES, ST-SA50ES
    Technics ST-G7 ?
    JVC FX-1100, FX-1010
    Onkyo T-4711 (at the bottom of the list)
    Media Engineering ME-TUN (professional Swiss 1U FM tuner, hard to find and quite expensive)

    --- dBf ---
    Onkyo T-9990, T-9090II
    Kenwood KT-917
    Accuphase T-105, T-103
     
    Last edited: Nov 3, 2018

     

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  2. jdurbin1

    jdurbin1 Tandberg enthusiast Subscriber

    Messages:
    8,872
    Location:
    San Diego
    Tandberg's 3000-series analog tuners (3011/3011A/3001/3001A) have meters displaying µV level, and the TOTL 3001/3001A models also have detector and hor/vert multipath outputs.

    John
     
  3. xkdb

    xkdb New Member

    Messages:
    7
    Thanks, John! I like Tandbergs, too, will definitely consider them.
     
    Last edited: Oct 23, 2018
  4. steerpike2

    steerpike2 Super Member

    Messages:
    3,332
    Location:
    Transvaal, South Africa
    The revox B760 , B260, B261 all fit your requirements I believe.
     
  5. Nick_G

    Nick_G Active Member

    Messages:
    498
    Location:
    Whitchurch, Hampshire, UK
    The BW Broadcast RBRX Encore receiver shows the received signal in dBµV, accurate to 1 decimal place. Very useful for finding the precise direction to point at a wanted station. It also has switchable de-emphasis of 50µs, 75µs or off. It's another expensive one though, and I'd guess that the Media Engineering ME-TUN model would be the closest equivalent on the OP's list.
     
  6. jlovda

    jlovda Things I loved from the 60's and 70's Subscriber

    Messages:
    3,461
    Location:
    NE Ohio
    I believe several Technics tuners such as the ST-G5, ST-G505 and ST-G707 also had a digital signal strength mode. I have an ST-G7. It's a pain in the butt to switch back and forth between freq and signal strength since they share the same display.
     

     

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  7. PabloTincho

    PabloTincho Active Member

    Messages:
    102
    Location:
    Salt Lake City Utah
    The Hitachi ft-5500 ll and also the Sony st-sa50es
     
  8. FauxHall

    FauxHall Super Member

    Messages:
    1,590
    Location:
    Abu Dhabi, UAE
    Besides my Sony ST-SA5ES, the Sony ST-S3000[ES] had a digital signal level indicator. They read pretty close to the same values with the same antenna connection and arrangement. Both pegged out high at 70 dBf.
    DSC_7047.JPG
     
    Last edited: Oct 31, 2018
  9. xkdb

    xkdb New Member

    Messages:
    7
    Thank you all for the suggestions.

    Nick_G, BW Broadcast RBRX Encore is great, but quite expensive as a high-end professional re-broadcast receiver. I have a few others of the kind on my list, by DEVA, ProfLine, 2wcom, also WCS. Second-hand is preferable as they are more affordable.
    FauxHall, ST-SA5ES and SA50ES are among those high in my list. I was not aware of ST-S3000. (If I remember correctly from the manuals, they display the level in dBµV, not dBf.)
     
    Last edited: Oct 30, 2018
  10. Nick_G

    Nick_G Active Member

    Messages:
    498
    Location:
    Whitchurch, Hampshire, UK
    The Kenwood L-1000T also shows the received signal in dBµV as well. I thought it was slightly different to the RBRX Encore, but if the IF bandwidth on the Kenwood is set to Super Narrow then the readings pretty much match, so it must be pretty accurate.
     
  11. xkdb

    xkdb New Member

    Messages:
    7
    If the IF bandwidth affects the signal level reading that much, then the metering circuitry must be cheap. But L-1000T is somewhat cheaply build and relies only on the remote control. Good, but over-rated tuner IMO. I have owned other synthesizer Kenwood tuners and am far from impressed. While Kenwood's RF section is great, their audio section is not. KT-1100SD, KT-3300D, KT-5020/990D are TOTL or near-TOTL, but sonic performance is not satisfactory for a TOTL tuner; not without modifications. And the build is quite cheap, mostly 5020/990D. It is beyond me how fmtunerinfo rated KT-5020 so high. This only confirms my initial thought that their claims should be taken with a grain of salt as not very reliable.
     
    Last edited: Nov 3, 2018

     

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  12. xkdb

    xkdb New Member

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    7
    <repeated by mistake>
     
  13. FauxHall

    FauxHall Super Member

    Messages:
    1,590
    Location:
    Abu Dhabi, UAE
    BTW, the only tuner I've discovered to have a owner-switchable de-emphasis constant is the Yamaha CT-7000. According to the service manual, it is located inside on a circuit board.

    As my local station uses the European standard, I have the choice of either buying European, buying in the US and having a tech swap out the appropriate capacitors, or else buying a switchable tuner.

    For the McIntosh MR-77 I bought in the States, I had it shipped to MikeX to do the job, along with refurbishment, realignment, and LED lights.

    Anyone know of other models with switchable de-emphasis? The power voltage differences are easy with a transformer for tuners and other light loads.
     
  14. Nick_G

    Nick_G Active Member

    Messages:
    498
    Location:
    Whitchurch, Hampshire, UK
    Well the same thing happens with the Sony ST-SA5ES (Euro version), in that the readings are affected by a nearby strong signal, particularly in wide mode. With the L-1000T the reading increased going from WIDE to NORMAL to NARROW, presumably as it 'homes in' on the signal. I've had a couple of other domestic tuners that all do similar things if they have a signal strength reading. The RBRX Encore is more-or-less immune from these sorts of quirks.

    As for the L-1000T being cheaply built, it weighs 10 kg! How many other tuners from the 90s are as heavily built as that?
     
  15. Ronald.C

    Ronald.C Active Member

    Messages:
    246
    Location:
    Brazil
    Sansui G-22000!:rockon:
     
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  16. Bob@FM

    Bob@FM Active Member

    Messages:
    355
    Location:
    NE NY
    If you look at the tuner schematics, you'll see most tuners use the standard IF chip to drive the signal strength meter/reading. Most of these IF chips have a log amp built in, but usually it has limited dynamic range - i.e. it's not the best, buts works fine over a limited range, and hopefully the range works for most users. These are usually calibrated during alignment at one RF amplitude set point.

    A few tuners have a dedicated separate signal strength meter circuit, complete with their own IF filter and wide dynamic range log amp (separate from the IF chip). The Kenwood 600T and KT-917 are good examples, although both use meters, they are highly accurate over a wide range of RF signals.
     

     

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  17. Bob@FM

    Bob@FM Active Member

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    355
    Location:
    NE NY
    Well, everyones taste is different, and what is "good" or "great" in audio greatly depends on the reviewer. At fmtunerinfo there are Jim's shootouts, and it is well stated this is one man's opinion.
    But the main tuner reviews usually encompass experiences from a number of long time users, who have experience with many different tuners. In the case of the KT-5020, you have comments from 5 different people, plus Jim, talking about that unit. This is usually the consensus on that model from others on different discussion groups.
    http://www.fmtunerinfo.com/kenwood.html

    here's an interior shot of the L-1000T - note the power supply - big potted audio transformer, huge caps, hefty heat sinks, and separate 2nd transformer for digital circuits.
    The large thick copper shield on right between RF and IF sections, plus the full cover over the 6 RF gangs. I would never call a tuner built like this a "cheap build". I mean c'mon, if this is "cheap", what digital tuned unit would be "well built"?

    [​IMG]
     
  18. FauxHall

    FauxHall Super Member

    Messages:
    1,590
    Location:
    Abu Dhabi, UAE
    As to adjacent or alternate channel interference in the signal strength meter, here's the circuit in the ST-SA5ES to mull over (lower right corner.) Of course, that's not exactly what Nick_G said which was "nearby strong signal" which might not be the same thing.

    Looks like a discrete circuit fed by the first IF amp stage which comes AFTER the front end tuning and mixing section. Tell me if I misinterpreted the circuit.

    Sony ST-SA5ES signal strenght meter circuit.JPG
     
  19. PabloTincho

    PabloTincho Active Member

    Messages:
    102
    Location:
    Salt Lake City Utah
  20. bobschneider

    bobschneider AK Subscriber Subscriber

    Messages:
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    Location:
    Back in Chicago

    30 years ago, when I lived in Singapore I bought an Onkyo (T-4700?) which had switchable deemphasis on the back panel. This went along with a power supply which could be switched between 120V and 230V AC input. It wouldn’t have made much sense to be able to switch one without the other, after all.

    Service manuals often show that manufacturers made several versions of the same tuner, typically including a Japanese market version, a US market one, and a European market one, each with the appropriate AC voltage, deemphasis, and frequency band. They often also made a “universal” version, with back panel switches to select each alternative, to be sold in other markets.

    I recently bought a European version of a Japanese tuner which is very hard to find in the US. I knew that the input voltage could be readily changed (the transformer connections which needed to be swapped were clearly labeled), but thought it might be tough to change the deemphasis, since the manufacturer won’t release service data. But I was able to get the data sheet for the MPX IC, which had suggestions for deemphasis cap and resistor values for both 50uS and 75uS. Sure enough, the manufacturer had followed the datasheet, so changing to 75uS was just a matter of swapping two caps.
     

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