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Thread: Sirio SY-3 or SY27-3

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    Sirio SY-3 or SY27-3

    Manuals (PDF file) for the SY-3 and SY27-3 are very similar but may lead to a measure of confusion. I've posted this as it may be of value. One or the other may be the "upgrade".

    05.22.22 SY-3 Tuning Specifications
    Freq. MHz [A] Reflector [B] Driven [C] Director L1 L2
    27.0 806 535 474 952 518 +/-5
    Difference 53/ 48/ 47/ 38/
    27.200 785[30.9"]7/8 516[20.3"]5/16 455[17.9"]7/8 937[36.9"]7/8 518 [20.39"]3/8
    27.250 779.5 511 450 933
    27.5 753 487 427 914 519 +/-5
    Element Comparison
    Source Reflector Driven Director Spacing
    waoooo.com
    rfwireless-world.com
    mapleleaf.com
    Sirio SY-3


    [1-3] AVG
    18' 6"
    17' 10.8"

    18' 5.04"

    19' 2.88"

    18' 3.24"
    .5
    .9

    .42

    .24

    .27
    17' 5"
    17' 1.44"

    17' 4.68"

    18' 4.32"

    17' 3.72"
    .42
    .12

    .39

    .36

    .31
    16' 7"
    15' 10.8"

    16' 4.32"

    18' 1.92"

    16' 1.36"
    .58
    .9

    .36

    .16

    .28
    4' 5"
    4' 6 1/4"

    7' 1/2"

    4.7/4.07
    Reflector Tuning Section length of 806mm (31.73"), as indicated above for 27.000mHz, is longer than the actual measured length of 800mm (31.496"); which does not include the 72mm length of the Tuning section inserted into mid section S2; when combined the full length of the Tuning section is 34". Which can also be said for the 535mm and 474mm lengths within the table, also for 27.000mHz for Driven and Director elements. Hence, element lengths in table include the 72mm insertion portions, which were not included in the following measurements:
    Sirio SY-3
    Element Measurements
    S3 108cm
    S2 105cm
    S1:
    Reflector 80cm (31.496")
    Driven 52.4cm (20.63") Questionable. Measure again.
    Director 46.2cm (18.19")
    Center Boom Connector 15cm width.
    5700 or 18.7', maximum Reflector Element length.
    5,148mm, 16.89', maximum Driven Element length . Questionable. Measure again.
    5,024 maximum, 16.48', Director Element length.,
    Therefore, derived Tuning section lengths for 27.200mHz elements in table above must include that 72mm portions, not included in measurements, otherwise.

    Three online 3 Element Yagi Antenna Calculators used to arrive at [(1-3) AVG] element lengths. Sirio indicates all elements considerably longer, for 26.500mHz. There is similarity with element spacing, with mapleleaf.com, the exception. Sirio's specificity in element spacing is apparent in boom sections, with near 7" greater distance between reflector and driven elements.

    Calculating element tuning section length begins with known tuning lengths for known frequencies, specifically 27.000 and 27.500mHz and establishing the target frequency 27.200mHz. The frequency difference of 50kHz is multiplied by 40% to obtain the desired target of 20kHz. Subsequent 40% and known values for each element tuning segments and the differences between the associated frequency lengths; indicated in the previous table in green, and 40% of the difference is subtracted from the larger value. The control is 27.250mHz, 50%.
    Last edited by Alabama Buckeye; 05-25-2022 at 12:24 PM. Reason: 34"; cor S3/S2 L
    All answers are opinions and may, or may not be technically correct.

  2. #2
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    Of note is the SY-3 pdf Manual includes a Table of significant value whereas the SY27-3 manual does not. The table constructed providing length of Tuning Segments lengths is relation to a small handful of frequencies beginning with 26.5mHz. Sirio suggests cutting Tuning Segments to length whereas I would prefer not doing so. There is the alternative of sliding the unnecessary portion of Tuning element within the S2 tubing and drilling new anchor holes. See original post wherein S3, S2, S1 element section identifications are established.

    Confusion begins with full SY27-3 Reflector length of 5740mm 26.1-27.7mHz while the SY-3 Reflector length is 5942mm 26.5-30mHz; shirley the 7" greater length of the SY-3 is not for sake of the slightly broader and higher frequency range shift. Must be a Euro conversion I'm not aware of?
    Last edited by Alabama Buckeye; 05-22-2022 at 03:04 PM.
    All answers are opinions and may, or may not be technically correct.

  3. #3
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    Reflector *-72 mm Inches Driven *-72 mm Inches Director *-72 mm Inches
    18.27' 5568 3.24 17.31' 5276 3.73 16.28' 4962 1.37 Objective
    5886 5336 5216 Native
    Tuning Sections 27.200mHz Objective
    30.9"/28.07* 713* 785 0.07 S3 Objective
    872 S3 Native
    20.3"/17.48* 444* 516 +1/2 S2 Objective
    596 S2 Native
    17.9"/15.08* 383* 455 0.08 S1 Objective
    534 S1 Native
    Full Element Lengths
    18.84' 713 5741 17.07 444 5203 16.67' 383 5081
    Out of the Box Lengths
    19.31' 5886 17.5' 5336 17.11' 5216
    *Tuning Section Corrected -2.8"

    Inches explained: Reflector L 18.27' is 18' 3.24"
    Last edited by Alabama Buckeye; 05-25-2022 at 12:10 PM. Reason: corrections
    All answers are opinions and may, or may not be technically correct.

  4. #4
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    A long time CBer of zilch for knowledge in the finer points of radio shite. I'm now apprised in the knowledge the difference between 10 and 13 dDi gain. 10X versus 20X signal gain at the receiver, according to internet information, and you know how I stand on such; 66.6% BS; until proven irreputable.

    Had I opted for the SY-4 I'd be granted with 13dBi gain, all things being theoretical true. Instead I chose the SY-3 for sake of manageability, a three versus 4 element Yagi. My original SD27, a vertical, was already a handful when a homegrown reflector was added; I could have called it SD27-2; but, I didn't have the understand of a beam antenna and I'm sure I'm still not there. It didn't work out as expected.

    The Sirio SD27 is quite successful in DX hearing. Last night "747 Texas" sounded as though I were in an auditorium with him. It's not so great for the locally area due to it's current meager 18' AGL height. On first assembly, adjusted overall length for 27.205mHz and Gamma Match as manual prescribed, the SWR has been flat from Channels 1 > 40. I'm quite excited that my SY-3 Yagi will be just as remarkable, as it reaches 1 full λ height.

    My understanding in achieving elevated heights above full λ matter little; and, since I've heard no rebuttable thus far I'll press forth, if in ignorance, then so be it.

    I make no adjustment to neither L1 nor L2, Gamma Match L, past the original frequency specific alteration.
    Last edited by Alabama Buckeye; 05-25-2022 at 12:37 PM.
    All answers are opinions and may, or may not be technically correct.

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    Fistfulladirt (05-26-2022)

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