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National NCL-2000 amp
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Anyone figure out a good way to modify the NCL-2000’s keying circuit so that a modern transceiver can safely key it?
The amp uses the 13.8 VAC filament supply at approx 500 ma for keying. Keying AC with a transceiver’s open collector keying circuit is a no no. I’d rather not use an outboard adapter. Doug/WA1TUT? |
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Doug - I just saw this post and you may already have a solution. If not, then you could use a triac to switch the ac relay and a PNP transistor to switch the triac. The transistor would be turned on by pulling the base to negative through the open collector output of your transceiver. You would need to make a simple dc supply powered from the 13.8 vac supply in the amplifier. All of the new components could probably be mounted in the amplifier. Let me know if you want to pursue this.
Jack, KO?T? |
开云体育Hello Jack,Thanks for your input. I’ve got two NCL-2000’s. For one I bought “Radio Dan’s” kit of an external keying box with a design similar to what you suggest. It works fine and presents a keying voltage of about 3 volts with just a few milliamps to the transceiver. For the other amp I simply installed in series with the relay a diode, current limiting resistor and a small filter cap. The keying voltage is now about 19 volts DC, although I’m sure with a lot of ripple. Nevertheless it seems to work fine with my Ten-Tec Jupiter which uses an open collector keying circuit. 73, Doug/WA1TUT? On Dec 13, 2022, at 9:39 AM, KO0T Jack Werthman via groups.io <jwerthman@...> wrote:
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