Commonalities among the GSB-100 and the HT-37

Discussion in 'Amplitude Modulation' started by AC0OB, May 5, 2021.

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  1. AC0OB

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    From K4KYV above:

    If each one of the two transformers in the GSB directly feeds a balanced modulator (either diode switching or class-C), then technically they are modulation transformers. A matter of semantics; what's important is that you found the transformer(s) you need.

    With all respect, this is not a matter of semantics, but of functionality, i.e., correctly designating the transformers as to their respective functions. Both the T2 and T3 transformers in the GSB-100, and the T102 and T103 transformers in the HT-37 serve as impedance matching "Quadrature" transformers, with each transformer providing 90 degree out-of- phase or quadrature audio drive to their respective balanced modulator circuits which follows these stages.

    It is the T105 transformer in the HT-37 and the L3 transformer in the GSB-100 transmitter that can only be rightly called the "modulation" transformers, because it is here where the Balanced Modulator circuitry functions, and only for this "Phasing" system of modulation.

    Both Balanced Modulators, interestingly enough, receive a 9Mhz RF signal that is mixed with the quadrature audio, but implement the circuits somewhat differently, I suspect, to avoid infringements.

    However, both are "adaptations" of various Collins circuitry.


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