Two comments here:
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- Yes, the ProgRock2 (nor the original) have coupling capacitors on their outputs.? If you aren't sure if you need one, add one!? Don't go overboard with the capacitance - perhaps a value that will provide an Xc (reactance) equal to or greater than 1/3 of the expected load impedance at the lowest frequency.?
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- Even though they are "rated" for "12 volts" don't even think about running one at that voltage:? I'd avoid going above 10.0 volts.? Either put a voltage regulator there (anything from 5 to 10 volts is fine - there's no point in more than 5) or if you do have a fairly stable 10-12 volts, a 47-68 ohm, 1/2 watt resistor in series with each (expect 40-60mA consumption - do the math) to limit the voltage.? I "discovered" that even when running from 12.0 volts (from a 7812) that the ProgRock ran very hot - and two of them failed in quick succession, hence the warning.? 5.0-9.0 volts is more or less the sweet spot.
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73,
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Clint, KA7OEI
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