-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
Outdoor Loop
- Thread starter HomerBB
- Start date
Homer I was referring to the red coax not the brown rg303 coax. I'm not sure if it's 50 ohm or maybe 75 or even 90 ohm to get the swr down.
Seems a center fed 1/2 wave dipole at 180 degrees should be 72 ohms and the 5/8 could be even higher. An end fed 5/8 is close to 150 ohms so I wonder if the phasing network also matches the impedance to 50 ohms or if Sirio are using a 3/4 wave matching transformer section from the connector to the center feed point.
16 turns at 2.75 inch diameter plus 3 inches from the connector to the coil plus the 133 inches above the coil ends up right at 274", a 3/4 wave length around 27.5 if the velocity factor is about .85 like LMR400.. But if the velocity factor is 66% then only taking the coil of 16T x 2.75 inch dia + 3 inches is a half wave unless the velocity factor of the braid inside the casing also comes into play
I might take mine apart to get an exact measurement.
One thing is for certain, the gainmaster design is a serious balancing act to get it right. I am definitely impressed by the Sirio design team.
I wonder if the patent info would reveal these details?