The SR-705 (Speed Reduction) knob makes tuning easier for magnetic loop antenna.
The SR-705 has been designed in Autodesk‘s Fusion 360 by our engineers and takes 3 1/2 hours for our equipment to build. Each thermoplastic polyester unit is then finished off by hand to fit on any round 1/4 inch nylon shaft. This provides a perfect fit for the Icom AL705 antenna.
How the SR-705 (Speed reduction knob) works
As you will see below, a lever that is made 3 times the size of a standard knob is the same as having a 6:1 reduction drive installed on a variable air capacitor with a 360 degree turning radius.
As an added benefit, the silver rod can be positioned to point left when the loop is tuned for 10 meters and right when tuned for 40 meters.
A 180 degree turn with a reduction of 3:1 = a 360 degree turn with a reduction of 6:1
180/3 = 360/6 or 60/1 = 60/1 or 6:1
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A knob that is 3 time the size of another equals a reduction of 3:1
SO/SI = dO/dI
Increase the speed the load moves with a Class 3 lever
Since the load or output length (dO) is longer for a given lever length, the Class 3 lever would result in a greater speed mechanical advantage and be able to project the object faster.
Speed equation
The relationship between the effort speed and load speed is dependent on the ratio of the arms of the lever, according to the equation:
SO/SI = dO/dI
where
- SO is the resulting speed of the output or load
- SI is the speed of the input or effort
- dO is the length of the output or load arm
- dI is the length of the input or effort arm
Note that SO/SI is the speed mechanical advantage of the lever.
Example: As the AL-705 uses a variable air capacitor with a 180 degree turn, using the 3:1 reduction offered from our SR-705, provides you the equivalent of a 6:1 reduction on a 360 degree turn.
Specifications, prices, and descriptions are subject to change without notice.
I could not believe the difference in tuning, it made fine tuning possible, great product!
This ingenious speed reduction knob installs easily and allows fine tuning of my Alpha Antenna Mag Loop.
I recently read a magazine article mentioning the use of the Alpha SR-705 knob and quickly ordered it for my Alpha Loop, Jr. It arrived in a couple days and I easily installed it in minutes. It’s amazing how little effort it now takes to precisely tune a loop antenna. Thanks Alpha Antenna for providing this needed accessory.
Great improvement over the standard tuning knob