Unloading the D104 cartridge makes more sense as the lower transmit passband width is extended.? For transceivers with a conventional 300 Hz to 2.4 kHz transmit bandwidth, the low-end response is restricted by the SSB crystal or mechanical transmit filter.? Adjusting the carrier set point to allow an increased low-end response only robs articulation at the upper end.?
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As Jim points out, 470K in series with the cartridge is a reasonable value for bandwidth-limited transmitters.? Interestingly, the input Z of Astatic's 2-transistor circuit (i.e., T-UG8 stand), also computes to approximately 470K.??
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For typical AM and ESSB transmit bandwidths, the JFET transformer can extend the response to below 100 Hz.? There's no reason to extend below about 75 Hz.? That's the lowest fundamental I've measured using FFT software from Charlie Van Dyke's voice, a well-known voice-over talent.? Anything measured lower, is the result of non-voice factors like vibration, rumble, and breath sounds.??
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Paul, W9AC
Paul Christensen