Re: Front End Protection Diodes?
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That's the term we have been using for ages. It means that one diode is placed with the cathode connected to one side of the circuit and the other connected the other way round so that they clip both sides of an AC voltage. (A DC voltage will also be clipped by the forward biased diode) Taking the input of a receiver, one diode would have its cathode connected to the antenna input with the anode connected to earth. The other diode would have its anode connected to the antenna input and its cathode connected to earth. Guess that different terms are used in different parts of the world. Regards.
On Thu, Jul 27, 2017 at 9:53 PM, Dexter N Muir <dexy@...> wrote: Back to back? I think not! That gives avalanche/breakdown voltage, and that can be up to kV depending on device. Try Head to tail - and across the input. +/-0.6V max, turn-on (forward-bias) voltage of silicon junction. 0.3V or so for germanium. If you're worried about capacitance, point-contact. This, of course is for RX ONLY! Tx into that will blow either the diodes or the Final! Not quite sure how it fits in the BITX scheme, probably in amongst the antenna relay circuitry.
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