Pre-amp for a tuner?

Discussion in 'Tuners' started by Rupe, Mar 9, 2019.

  1. Rupe

    Rupe New Member

    Messages:
    6
    Hi there,

    I live in a rural area with very weak radio signal. Some neighbors can pick up stations I would like, but I cannot (it's not topography, it's flat and open here, and they are less than a block away). I have a Sansui TU-666 (tuner of the beast!), which is great, except that here in Nowhere it doesn't pick any radio station up at all. I imagine my neighbors have newer more powerful tuners.

    Is there such a thing as a pre-amp for a tuner, something that would take the raw antenna signal and give it a boost so that my tuner could pick it up? Is this even how this works?
     

     

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  2. musichal

    musichal poet emeritus Subscriber

    Messages:
    11,903
    Location:
    Norman OK
    What kind of antenna are you using?

    While you can buy an antenna that boosts signal, or a booster for the antenna you are using now, they also tend to boost noise along with signal to the point that many find unlistenable.

    Sounds to me like you need to either acquire a better antenna, or move the one you are using now (increase height, re-orient for direction, or to avoid obstruction, etc.). It is also possible that your tuner needs work.
     
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  3. Rupe

    Rupe New Member

    Messages:
    6
    T-type dipole. Thanks for the reply. I can't really get one of those big outdoor deals, it's a rental. Possible the tuner needs work, but I'm not seeing evidence of that other than it's possible a tune-up would help reception; also there isn't anyone in 250 miles who could fix it, anyway.

    OK, "antenna booster" was the Google term I needed ;), does anyone have any experience with this? https://www.amazon.com/TERK-Dual-Drive-Amplified-Indoor-Antenna/dp/B00009UHYC

    Reviews are OK-ish...
     
  4. rmp

    rmp New Member

    Messages:
    45
    Rupe,

    How far away are the target stations? Can your car radio pick them up outside your house?
     
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  5. dewdude

    dewdude High on resolution. Subscriber

    Messages:
    3,160
    Location:
    Manassas, VA
    The first thing to do is look at the differences between your neighbors and your setups...both the tuners and antenna system. Are they using an outdoor antenna. How are they feeding it? Differences in tuners can make a drastic difference. Later era tuners got slightly more sensitive...modern DSP tuners are doing some really insane and neat stuff.

    How's your folded dipole mounted? Often times people don't take the proper considerations in to using a balanced-line feeder and hinder reception. The best way to operate them is with the top of the T as flat and straight as you can get it...with the rest of the feedline (the bottom of the T) being perfectly straight and perpendicular for about 1/8 wavelength.

    The thing you linked isn't a booster, it's an amplified antenna. Your folded dipole is probably cable of higher dBm values from a station than that thing. Preamps are largely good for just boosting signals to make up for additional loss in feedline...very rarely will they actually increase the SN ratio of a signal to any major degree....at least not with FM.

    https://www.amazon.com/fm-antenna-signal-preamplifier-booster/dp/b005haoab8

    Something like that is more what you might want if you already have a decent antenna. The best google term is "fm antenna preamplifier"...though any wide-band amplfier will work and those have gotten cheap due to the SDR craze.

    But I would start by examining everything in the neighbors setup...from the antenna..the placement...the tuner...and see just what is different.
     
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  6. musichal

    musichal poet emeritus Subscriber

    Messages:
    11,903
    Location:
    Norman OK
    I mentioned height and reorientation and advised not trying amplifying signal due to noise. You can often find a way to accomplish both height and relocating/reorienting a dipole without breaking rental agreements or going outdoors. It is a matter of getting the antenna to a spot where signals are stronger, even indoors. Sometimes that may be near a window an/or closer to the ceiling. Also, knowing the direction from your home of the transmitters desired for reception tells you how to am the dipole. If you affix the dipole to a wall that runs North-to-South then its arms are spread to best catch signals from East and West. From the sides you have little more than a cross-section of the wire's diameter.

    Here's a site that will help find strong channels and their direction from you:

    http://fmfool.com/index.php?option=com_wrapper&Itemid=29

    Spread the dipole to its full length, and keep the rest of the antenna wire (the feeder that attaches to the tuner) perpendicular to the spread arms for as much length as possible. Try as many placements as possible before buying anything else.
     

     

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  7. radioactive

    radioactive tube gear fanatic Subscriber

    Messages:
    8,901
    Location:
    winnipeg , manitoba
    Im old school and have this .uses nuvistors.never even hooked it up after I brought it lol.does t help the op but thought I'd show it off..
    IMG_20190311_210830.jpg IMG_20190311_210906.jpg
     
  8. Rupe

    Rupe New Member

    Messages:
    6
    Thanks for the replies y'all. I'll see what I can do with the dipole I have; other options aren't sounding hopeful.

    I'm trying to get KRBM...

    [​IMG]
     
  9. radioactive

    radioactive tube gear fanatic Subscriber

    Messages:
    8,901
    Location:
    winnipeg , manitoba
    Can you put up a flag poll.antennas can be easily hidden.?
     
  10. radioactive

    radioactive tube gear fanatic Subscriber

    Messages:
    8,901
    Location:
    winnipeg , manitoba
    I rent myself and nothing is permanent and is easily removed.have you talked to your landlord about Mabe putting up a outdoor antenna? You don't need a tower and there are portable masts that you can get .
     
  11. dewdude

    dewdude High on resolution. Subscriber

    Messages:
    3,160
    Location:
    Manassas, VA
    So...for rental purposes....let me show you guys a little something.

    https://www.mfjenterprises.com/Product.php?productid=MFJ-4601

    This is a window passthrough. They are WILDLY popular in the ham radio community for people who rent or are too damn lazy to drill holes and route cable. This sits in your window...you basically open the window enough to set it in place, close the window on top...and maybe use a little weatherstripping/weather-seal to seal up any new airleaks. But this provides you an easy passthrough for coax. You don't have to buy one...you can always make one out of a piece of properly sized/cut wood. The basic idea is just blocking out part of a window and replacing it with an object you *can* drill through. In fact...I do not recommend you buy any of the ham ones since they will not be made for any of this stuff. We use 50 ohm coax with PL-259/SO-239 as opposed to 75 ohm coax with F Connectors.

    Portable masts are great...but they still require a bit of work to leave in place; not permanent...but a hassle.

    Do you have any trees? Depending on your HOA rules, you may be able to get away with hanging an antenna from a tree; just use a slingshot and a fishing weight tied to a sinker to get a line over. This will provide you some height, which is good.

    The problem with amplifiers is they often don't do what people think. You can't increase the S/N ratio of a signal with one...unless it's a crazy LNA design and we're talking a band with hardly any noise floor to begin with. The main reason we use amplifiers is to compensate for cable loss. The standard RG-59 exhibits around 3.5dB of loss per 100ft; that means over a 100ft run of cable you will lose *half* of your signal strength. Not to mention most old houses had multiple splitters. The
    "preamp" was simply to provide a couple of dB of broadband boost...with the incoming noise and all...to compensate for this.

    My ham radio has a "preamp" function for every band...but it doesn't increase the signal-to-noise ratio...it just makes everything "louder"...which is what you want in situations where you may have a LOT of loss over your coax. It's more important in ham where...if you're lucky....you have a 100 - 200 ft tower...or your antennas are a few hundred ft away from the shack.
     

     

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  12. RxDx

    RxDx Speaker collector Subscriber

    Messages:
    1,283
    Location:
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    Leaving the window partially open was a hassle I didn't want to deal with.
    Sealing and locking took extra effort. So I went with something like this.
    Fits under the bottom of the window frame, and the window can be locked.
    Can also be used to feed signal between rooms w/o drilling holes.
    Add as many as you need. Cheap at Amazon ("flat coax")
    [​IMG]
     
    Last edited: Mar 12, 2019
  13. Rupe

    Rupe New Member

    Messages:
    6
    I won't get to this probably for a couple of weeks at this point, and interesting discussion. But for the sake of argument, let's just assume I'm not installing an antenna outside. ;)

    OK, so if the power of the amp isn't what's doing it, why do different tuners have different reception all else being equal? For example, some car radios here can get the NPR station I want, others can't. Same kind of antenna, same location (e.g. my parking spot at work, my driveway, etc.). What's the difference?
     
  14. dewdude

    dewdude High on resolution. Subscriber

    Messages:
    3,160
    Location:
    Manassas, VA
    That question is impossible to answer without cracking open every car radio.

    Cars all have different antennas. You can't assume two makes of cars have the same antenna.

    There is nothing equal really...not till you match everything. Older radios aren't as efficient. Newer radios are DSP based. Most modern cars have a DSP/SDR based system.

    That can make a world of difference
     
  15. Rupe

    Rupe New Member

    Messages:
    6
    So what are the variables then? DSP (I'll google that later) is one... What's more or less efficient? What makes two antennas of the same length and diameter different?
     
  16. radioactive

    radioactive tube gear fanatic Subscriber

    Messages:
    8,901
    Location:
    winnipeg , manitoba
    The sensitivity of your tuner is more at play than 2 identical antennas.the specs can be found in your manual for the tu-666.some tuners have better specs but specs arnt everything there's also how many stages of if and gangs on the tuning capacitor.the more the better.i will say that I own many tuners (Its my nemesis) and have owned the same tuner that you have and found that the sensitivity is not that good on that particular tuner even with a good outdoor antenna.so maybe look into getting a better tuner that has better specs or look into maybe trying out a preamp.it won't hurt to try.
     

     

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  17. BillyTheKid

    BillyTheKid Active Member

    Messages:
    343
    Location:
    The 860
    I use a giant old-school rooftop antenna with rotor, for both TV and FM reception. Even with this antenna still i get no signal unless i run at least 2 signal boosters, both having FM traps. They're very old school...Channel Master and Radio Shack. Works great, free HD tv and plenty of FM . But if i unplug either of the boosters i get nothing at all.

    Back in the day i always had good luck on FM with a pair of rabbit ears and a signal booster.
     
  18. dewdude

    dewdude High on resolution. Subscriber

    Messages:
    3,160
    Location:
    Manassas, VA
    It stands for digital signal processing. There's been a trend in the last few years of "tuners" shedding most the traditional "parts" of a tuner and instead replacing it with high speed digital circuitry, backed up with digital signal processing. The antenna, after being passed through a bandpass filter, is then digitized using a high-speed ADC. From there, it's pure digital processing to tune, clean up, demodulate, and output some audio. You eliminate a lot of things that can muck up signal acquisition in a traditional super-het...at the expense of not really having an analog radio and needing seriously fast/powerful hardware. A lot of car systems are using DSP/software-defined radio (SDR) technology for providing both AM and FM...especially in systems that have HDRadio setups. A lot of the integrated FM radios in devices are DSP/SDR based.

    But the signal processing you can do in the software domain is entirely different than what you can in the analog. This can result in "better" performance. https://dewdude.ath.cx/fmmpx.flac was recorded from a local FM station using my PC-based SDR setup. The signal on a traditional tuner with the antenna I was using would have a LOT more noise in the stereo. But my software can process the noise (to a degree) out of the difference of the matrix before decoding.

    Location, location, location. All kidding aside...location matters; so does installation. If you were to put two antennas in a huge field, at the same height, mounted and installed the exact same way; if they were too close they'd interfere with each other. Other than that, the differences would depend on things other than the antenna. Since no two installations are ever the same...one type of antenna will perform drastically different for one person than another.
     
  19. z-adamson

    z-adamson Super Member

    Messages:
    1,966
    Here is an idea that will certainly help out....

    Rather than install the antenna outside......................drum roll please.............install the antenna inside.

    Thank you very much.
     
  20. Dadbar

    Dadbar Super Member

    Messages:
    1,896
    Location:
    Waltham & Gloucester MA
    You might be able to get away with getting some flat antenna cable from Amazon and just making a longer full wave dipole. You can calculate the length needed for a full wave from your station;s frequency. Worked well at my place.
     

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