C. Crane Antenna Measurements - +12 dB!

Discussion in 'Tuners' started by FauxHall, Jul 13, 2017.

  1. FauxHall

    FauxHall Super Member

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    Just got my C. Crane dipole antenna. I'm running a Sony ST-SA5ES which has a digital signal strength meter.

    I had two prior indoor antennae for my favorite station, Abu Dhabi Classic 91.6 FM. One is a simple wire folded dipole in a T-configuration. It has a balin to match the 75 ohm connection on the tuner.

    The other was a metal rod I borrowed from a Tivoli Model Two radio. It was already 75 ohm. The metal rod used a 75 ohm coax to get it closer to the south facing window where I presume the transmitter is at and to hide it. The T-wire hung right over the tuner. I'm on the 32nd floor of a concrete apartment house with metal framed windows.

    Both the rod and the t-wire would pull in 51 dB at their best. When I connected the C. Crane dipole, the signal shot up to 62-64 dB!. One factor was the coax as the new antenna was direct connected without the extra coax. Other testing lost may 4-6 dB with the coax but I didn't try to optimize at a new, more distant location.

    To me, this is objective evidence that the $20 USD I spent on the C. Crane antenna (plus $25 mailing it Abu Dhabi!) was money well spent.

    Here's the C. Crane antenna as-tested:
    DSC_1798.JPG

    Here's the rod antenna but re-installed on the Tivoli:

    DSC_1797.JPG
     
    Last edited: Jul 13, 2017
  2. RWood

    RWood The future is not what it used to be Subscriber

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    Thanks for the info - I ordered one.
     
  3. c.coyle

    c.coyle Fighting the Dunning-Kruger Effect Subscriber

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    Not surprised that the signal is stronger. But, I wouldn't trust the calibration of your s-meter. 12db is a lot of gain (I am understating) for a diople. EDIT: What you are getting is a relative reading on the meter.

    I hope this doesn't come across as raining on your parade. Better reception is always a good thing. C. Crane products are always a good value.
     
  4. FauxHall

    FauxHall Super Member

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    Rain in NOT allowed in Abu Dhabi this month and it's too darn hot for parades.

    The quoted gain was NOT the antenna gain in absolute terms. It was the relative increase in detected and measured signal strength within the tuner compared to the two prior antennae. I didn't expect anyone to be confused on that point! I suspect that better impedance matching of the antenna to the tuner front end is the secret to the increased signal strength.

    No, my Sony's signal strength meter is not calibrated to National Bureau of Standards references for absolute level over the scale so far as I know. The owners manual recommends at least 50 dB for stereo sound quality. It sounded fine with the lesser antennae but there's a noticeable betterment with the C. Crane antenna.

    Here's a portion of the Sony ST-SA5ES schematic. The signal strength meter circuit is in the lower right.

    DSC_1799.JPG

    Update: I compared the signal strength meters in the ST-SA5ES, Sony's TOTL digital tuner, and their smaller ST-S3000ES tuner, using the new C,Crane antenna. The SA5 displayed 61 dB while the S3000 showed 59 dB. The later also used to show 50 to 51 dB as the best from the prior antennae.
     
    Last edited: Jul 14, 2017
  5. RWood

    RWood The future is not what it used to be Subscriber

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    I got mine and it made a big improvement. I don't know from dBs as the radio I"m using only has a seeing eye tube, an EM85 fan-shape. The station my wife likes to listen to carries BBC news; it is not a distant one but it is a low powered station.

    With the built-in antenna the station was faint and did not register anything on the tube. With the Crane installed the eye tube (a fan-shaped EM85) now responds and closes about 2/3 of the way (all the way closed is strongest possible reception). Wife is pleased, she says "buy two more for the other radios". Yes, dear!
     
  6. FauxHall

    FauxHall Super Member

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    I played with other locations last night. I used a Sony ST-3000ES tuner. I inserted some 75 ohm coax and moved it to the window. When I had it tucked into curtains in a vertical orientation the tuner signal strength pegged high and it kicked in the antenna attenuation!
    That means over 70 dB signal.

    I'm super impressed now.
     
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  7. rmp

    rmp New Member

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    What makes the Crane antenna different from common dipoles?
     
  8. Pio1980

    Pio1980 AK Member Subscriber

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    Probably nothing. Any rigid VHF Yagi with a rotor would be preferable.
    Location and orientation mean everything.
     
  9. mhardy6647

    mhardy6647 AK Subscriber Subscriber

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    Yeah, I wonder about this myself. The only thing about it (other than the price!) that's really, obviously different compared to a DIY or dime-store ;) folded* center-fed ("T") dipole is the use of a 75 ohm "downlead". I presume this means there's a 300 to 75 ohm balun between the antenna and the downlead, too.

    http://www.ccrane.com/FM-Antennas/FM-Reflect-Dipole-Antenna

    __________

    * I assume the CCrane antenna's a folded center-fed dipole.
    http://www.antiqueradios.com/forums/viewtopic.php?f=2&t=186963
     
  10. mhardy6647

    mhardy6647 AK Subscriber Subscriber

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  11. N8Nagel

    N8Nagel AK Subscriber Subscriber

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    Hmm. I've got quite a few of the Radio Shack dipoles, would a C.Crane make a noticeable improvement?

    Sadly, I'd love to put up a roof antenna and a distribution amp, but that's not in the cards as I currently do not own my house.
     
  12. FauxHall

    FauxHall Super Member

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    There is no transformer that I can detect in my example. It is well constructed and the insulated conductors are thicker than expected.

    My guess is that the impedance is better matched to the tuner somehow. It ends in a regular 75ohm F-connector.

    Right now I'm getting TOO much signal as the tuner automatically puts attenuation in the path.

    A dedicated exterior yagi would improve multipath IF THAT WAS THE PROBLEM. But it ain't. Besides, I'm on the 32nd floor of a urban highrise with no balcony so ANY exterior antenna is out of the question. For a California ranch house it would be great. When I lived in a California ranch house in California I had two and a j-pole.
     
    Last edited: Sep 11, 2017
  13. FauxHall

    FauxHall Super Member

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    You didn't read the initial post where I described in detail my testing or else you just went with your prejudices.
     
  14. Pio1980

    Pio1980 AK Member Subscriber

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    The pic afaik shows a folded T dipole as the CC, no booster box or tuner, like I'm presently using here on two systems. What am I missing?
     
  15. FauxHall

    FauxHall Super Member

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    The pic looks funny to me as the usual dipole is a balanced signal (+ and -) for the 300 ohm antenna input while the C.Crane design is unbalanced (+ and ground) and 75 ohm.

    Still no explanation for the superior performance I measured with the Crane. Perhaps my test was flawed - my base dipole was pretty crappy - but others also observed better RF performance.

    The mystery continues.
     
  16. Pio1980

    Pio1980 AK Member Subscriber

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    Whatever gives good reception within the constraints is good.
     
  17. Pio1980

    Pio1980 AK Member Subscriber

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    I have an outdoor Yagi on my cobbled together AV system that is generally more reliable for the stations preferred.
     
  18. rmp

    rmp New Member

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    I think I've got it. The Crane website talks about bending the arms to pick up circular transmissions. That's easy with a simple dipole, but not with a folded dipole. Secondly, a simple dipole has a 75 ohm feeder. That means you can directly attach an F connector and not have to lose dB going through a balun.
     
  19. mhardy6647

    mhardy6647 AK Subscriber Subscriber

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    Yes, true indeed if not a folded dipole (see the figure I posted earlier) -- but the images I've seen of their antenna sure look like the "arms" are twinlead (???).

    Maybe the OP could post a good photo of his (or hers, as the case may be)?
     
  20. I LIKE MUSIC

    I LIKE MUSIC Super Member

    It does not contain a balun transformer.

    I took one apart a years ago and it is somewhat different than a basic FM broadcast band antenna, but nothing really new. The basic design has been around a long time in various forms, although it is not all that common for FM broadcast band antennas.

    IIRC? (sorry for the quick diagram) it is something like this, not necessarily to scale.

    upload_2017-9-11_15-57-49.png

    It has the slightly more broad banded characteristics of a folded dipole antenna with an intrinsic feed point impedance of 75 Ohms due to its design so it can be used with 75 Ohm coaxial cable.

    The 300 twin lead of the basic folded dipole antenna needs to be kept unbunched and away from other wires/cables and metal by several inches to avoid additional signal loss and or antenna pattern degradation. This is often not the case in normal use. The coaxial cable of the C. Crane antenna does not have this issue do to the nature of coaxial cable.

    The coaxial Double Bazooka antenna is a close cousin in its various forms. There is a lot written about it, both pro and con.

    Remember that when it comes to antennas, location can be important and no two locations are likely to be the same.

    You are missing the fact that the C. Crane is not just a plain folded dipole antenna.

    I am going by memory and I could be thinking of different antenna.































     

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