What is the function of the loading coil on the early Trirdyn sets. It was eliminated on the later models.

Hello Edd,

Thanks for the excellent explanation. I've noticed that the early production Trirdyns use the loading coils, while later production is very similar to the referenced 5-38. In other words, its operation would be similiar to the AK tap switch on the mdl 20's, correct?

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: : : : : : : : : : :Sir Bill. . . . . : : :If you will look at the 3 shared Crosley circuits on that Trirdynes schematic page, you will find different treatments to the antenna coupling aspects to the other separate receivers on the page. : : : :There is the 5-38 model with its tap on the primary of the antenna coil which gives provisions for the matching to either a short or a long length of antenna . . . . .errr . . . aerial wire. : : : : :Then the model 51 has a series arrangenent of the antenna coil pair, where either a lower amount of input coupling capacitance can be incorporated with the compensation for tuning then being made wiith using a tap that selects a graeater amount of inductance to work with it in resonating to the desired station. : : :The tuning alternative would be that a higher amount of input capacitance was selected, with one then correcting by the selection and use of a tap that has less inductance. Then, in either situation, the variable capacitor, is fine tuned in to optimize on the desired received station tuning. : : : : :Lastly, is the mentioned Trirdyn circuit, which has both the antenna initially going into a loading coil with taps such that one can then tap select the optimum series inductance that the antenna length agrees the best with. :Then the loading output has the option of then connecting to the top end of the antenna coil or else the tap that is a bit lower down on the antenna coil. : : :This latter arrangement of the Trirdyne certainly offers the greater possibility of matching to a very short antenna length . . . . . . . .but where is the point of inadequate returns . . . as, at least a certain length of aerial wire is needed for adequate signal pickup in feeding these simple little RF frontal stages. : : : :So basically, the frontal loading coil of that design only will be required if working with a short antenna length at the lower frequencies that would actually benefit from its use. : : : : :A later case in point of series loading inductance being associated with an aerial was the advent of the automobile receiver, as one had limited real estate area on the length of a car, and a " long trailing wire" aerial was not quite in order on an auto. : : :That ideal solution was admirably served by the use of a 2-3 foot antenna staff that fed into a shileded line for fighting ignition related static noise. Then the use of a loading inductance and a series tuned circuit, made that antenna staff perform and "think" that it was a 50 ft unit and then the additional feed into a tuned RF stage finalized matters. : : : :Just my thoughts . . . . : : : :Tech Referencing: : : : : : : : :73's de Edd : : : :

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:Hello All,
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: What is the function of the loading coil on the early Trirdyn sets. It was eliminated on the later models.
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