Sencore SG-165, or something else?

Discussion in 'Tuners' started by deniss, Jan 17, 2014.

  1. deniss

    deniss AK Subscriber Subscriber

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    Location:
    Ewing, NJ
    I've been given a gift of $200 over the holidays to spend on my electronics hobby. I have a nice scope (Tektronix 2246A), and I have a budget audio signal generator (REK RAG-101). What I've been wanting is to get some tuner alignment equipment, so I could ease into aligning tuners in the receivers that I restore.

    I've read that Sencore SG-165 is a good enough piece of equipment to get for a hobbyist, while some characterized it as "has every functionality in it but does nothing really well." I've also read recommendations for HP 8640B, but they also seem to be sort of mixed, and that HP unit generally sells closer to $300 on the auction site.

    I very much welcome opinions and recommendations for other equipment, too -- I may have easily overlooked other options in my review.

    Also, what would be a reasonable price for the SG-165 or the 8640B, and how do I find HAM meets in my area? I hear this sort of equipment sells for more reasonable prices at HAM meets.
     

     

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  2. chazix

    chazix AK Subscriber Subscriber

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    Curiously enough, I have both SG-165 and HP 8640.

    For FM alignment work, my opinion is that the SG-165 is OK for an unmodulated 10.7MHz reference signal, IF sweeps, and baseband MPX signals. I think its real weak points are its lack of a low-distortion audio generator, and its not-too-linear FM modulator. Because of that, I don't use it for detector linearity adjustment (I use the HP and a distortion meter), and I generally only use its stereo-modulated IF/RF outputs for break/fix work, not for alignment.

    If I had to get along with only one of the above, I'd probably go with the Sencore, but I'd be shy about doing detector linearity adjustments. If I had to adjust linearity, I'd use the IF sweep function and 'scope the "S curve" at the detector output.

    If all the above is gobbledygook to you, I'd definitely go with the SG-165, because its user manual is quite good. I believe the manual can be found on the web these days. If/when you go shopping for one, try to get one that comes with its specialized cables. In particular, if you don't get the cable that has a built-in RF detector, you'll need to buy or make a detector probe.

    Regarding other equipment, what about a frequency counter? That's needed for one common alignment task (on tuners with a phase-locked-loop MPX section, anyway).

    Regarding HAM meets, web-surf for "hamfest" and I think you'll hit paydirt.

    Good luck,

    chazix
     
  3. chazix

    chazix AK Subscriber Subscriber

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    Oh - forgot to mention that the SG-165 is just fine (IMHO) for AM alignments.

    (The HP would be, too, and would have the added benefit of a trustworthy frequency readout.)
     
  4. deniss

    deniss AK Subscriber Subscriber

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    From what you say, another valid point to consider is that the HP unit does have a frequency counter built in, while the Sencore unit would require me to purchase a stand-alone frequency counter.

    So with that, plus if the HP unit has significantly better FM modulation performance, it may be a better idea for me to hold out and wait until an 8640B unit comes up for a decent price.

    I've understood most of what you said, not all, but enough to figure out that the HP unit may be a better investment for longer-term use as my knowledge and experience with alignment will eventually grow.
     
  5. ZombyWoof

    ZombyWoof Active Member

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    157
    If you could find an SG165 for < $100 it's decent enough. As Chazix said you have to be aware of it's limitations and work around them.
    I have only used it on old Marantz recievers and it's done a decent job. For FM detector alignment I use a spectrum analyzer and adjust for minimum THD. I wouldn't attempt to use it on any newer, synthesized, receivers.
    The HP is a fine piece of equipment and would do all you need. But you're not likely to find a deal on one.
    It has a mechanical weak point. The vernier adjustment for frequency is coupled to the tuner with a plastic "straw" deal. It will break if forced beyond the stops. It can be replaced but is a real bugger to get to...
     
  6. deniss

    deniss AK Subscriber Subscriber

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    Location:
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    For my purposes, I'm not looking for anything "laboratory grade", since I'm not a tech doing this professionally -- I just enjoy this hobby of restoring older discrete-component receivers, tuners, and amps. If I can occasionally make a nice sale, it helps the hobby pay for itself, but otherwise it's a hobby rather than a business venture. I just enjoy being able to learn new things and being able to do a good job with my projects.

    Mostly, we're talking about 1960s and 1970s solid state tuners and tuner sections from receivers of that same era. I do have a couple of tube tuners that I have in my collection - but I'm not touching those until I get some practice on solid state. So far during my restorations, I've left the tuners alone. Once, I did a careful tune-up/touch-up on the Marantz 2238B tuner section, by ear, and the buyer wrote me back a year later to tell me how much he's enjoying listening to the radio on that unit and how clear and strong the reception is.

    Now I'd like to have the guidance of appropriate equipment next time I will want to check alignment of a tuner. :D

    Now, the spectrum analyzer -- is that the same tool that's also called "distortion analyzer" that folks use to check the THD of audio amps?
     
  7. amptramp

    amptramp Active Member

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    Location:
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    I think the Sencore would be adequate for most vintage units. You should have a frequency counter as well, but I believe you can get a counter plus an SG-165 for less than the HP. I am a member of the London Vintage Radio Club (in London, Ontario, Canada) and a lot of test equipment trades at rock-bottom prices. I think my SG-165 was $10 (good working condition) and my counters were each less than that. (I have two counters, a B&K and a Heathkit). You may need to mod the generator to get a signal for the counter before it goes through the attenuator or you may find you have no ability to count.
     
  8. ronaldw441

    ronaldw441 Well-Known Member

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    arrl.org

    Click on the "Hamfest" link in the What's Popular section.
     
  9. deniss

    deniss AK Subscriber Subscriber

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    This is slightly off-topic, but do you guys know if I need a membership with ARRL in order to attend a HamFest and in order to browse/buy there?
     

     

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  10. electronjohn

    electronjohn Plug it in & see!! Subscriber

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    Nope. There MIGHT be an admission fee (nominal). Who knows...you might end up becoming a ham!
     
  11. amptramp

    amptramp Active Member

    Messages:
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    Location:
    Mississauga Ontario Canada
    I doubt you need either a membership or a license. Hamfests are for trading equipment and the best prices happen if there are a lot of interested customers, so they don't tend to put any roadblocks in anybody's way (other than maybe an admission charge).
     
  12. ConradH

    ConradH Addicted Member

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    Location:
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    I have the SG-165, the HP8640B and an ancient Leader LSG-231 FM Stereo Generator found at a hamfest. The first thing you have to remember is all this stuff is as old as a lot of the equipment you'll be working on. That means you'll have to work on the test equipment first. IMO, the SG-165 manual is super. I paid a lot more than $100 for mine, but still had to change out every electrolytic cap and repair some other problems. And calibrate it. So right there you need a few things that might not be on your test bench. All tuned up it's really pretty good, other than the distortion not being low enough to do the best possible job with the better tuners.

    The HP8640B is a gem, but not for the faint of heart. It has known failure modes with cracking plastic gears, contacts that fall off the rotary switches and an unobtainium output amplifier that has a history of debonding inside the metal transistor case. Calibration of the thing again might require equipment you don't own. Working properly it can't be beat, but it's not unit you want to pay a huge amount for unless it has a warranty.

    Even my old Leader was DOA when I got it- bad opamp in the audio oscillator. It does however, have very low THD and I use that for the final tune up.

    FM alignment ought to be easier, but there's no cheap simple solution. Possibly one of the more modern generators found on eBay is the answer, but finding documentation of the various Meguro, Goldstar, Jung Jin, Kikusui, Panasonic or other generators is near impossible, so it's hard to know what to buy.

    The Sound Technology 1000A is very nice, but again it's old and may need service. They also don't show up very often and are way outside my budget. Finally, you'll probably want a distortion analyzer. Fortunately, if you have a PC, that can be free- download a copy of Visual Analyser. That gets you THD, spectrum analysis, plus a lot more.
     
    Last edited: Jan 18, 2014
  13. deniss

    deniss AK Subscriber Subscriber

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    Location:
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    Conrad, I've thought of the some of the same points you brought up... That the Sencore unit would need to be restored first (e-caps replaced) and checked for proper operation, and then I'd have to pay a tech who can properly calibrate it.

    So I will wait until the next HamFest in my area and see if someone's got this Sencore unit for below 100 bucks, which will leave some money for restoration costs.

    Most likely, the Sencore unit will be good enough for my purposes, at least to start with and learn on. If I wanted to upgrade at some point, looks like these units retain their value on eBay.
     
  14. ConradH

    ConradH Addicted Member

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    BTW, if you haven't seen the Sencore in person, don't be surprised at the size and weight of the thing when it arrives. I know I was expecting something quite a bit smaller, even though I had seen lots of photos! They can sell for anything and I bought mine at the peak of the market. Buy high and sell low, that's my motto.
     
  15. Westy56

    Westy56 A symphony of paradox

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    I'll stick with buy low, sell high. :D

    Paid $50 for everything.


    [​IMG]
     
  16. ConradH

    ConradH Addicted Member

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    Dang, nice haul!
     
  17. Westy56

    Westy56 A symphony of paradox

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    I happened across the stuff through dumb luck. Turns out the guy is an AK member.

    Talk about Good Karma. :yes:
     

     

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  18. jdurbin1

    jdurbin1 Tandberg enthusiast Subscriber

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    Nice haul indeed... but I am still quite chuffed with my own $50 haul. Only one box, but it does say ST 1000A on it. :banana::banana:


    John
     
  19. dgta

    dgta Active Member

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    Location:
    Michigan
    Does anyone have experience with the Leader LSG-231? How does it compare with the Sencore?
     
  20. ConradH

    ConradH Addicted Member

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    Location:
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    Yes, I use a LSG-231. I think it has lower distortion and I use it for the final adjustments, but it doesn't have all the features of the SG-165. It won't help you for IFs. There seem to be two versions of it and I had to get the later schematic direct from Leader in the US, who had to get it special from Japan. It's a n-generation copy and just barely readable. Like the SG-165, the LSG-231 also quite old, older than you'd think from its appearance.
     

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