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Alabama Buckeye
05-22-2022, 02:14 PM
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
Driven
[C] Director
L1
L2


27.0
806
535
474
952
518 +/-5


Difference
53/
48/
47/
38/



[B]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%.

Alabama Buckeye
05-22-2022, 02:31 PM
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?

Alabama Buckeye
05-24-2022, 09:33 AM
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"

Alabama Buckeye
05-24-2022, 10:09 AM
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.