[Elecraft] Transmit noise gating

[Wes Stewart]

Although I continue to await the arrival of my K3, I'm pleased to see the incorporation of the noise gating feature.  I started using something similar almost 30 years ago.

Shortly after the publication of my article, "Split-band Speech Processor" in the September 1979 issue of the old Ham Radio Magazine, I received some justifiable criticism for the use of the Plessey SL1626 compressor chip. (Also, while available locally, around the rest of the world this device was made of unobtainium instead of silicon).

Consequently, I redesigned the compressor portion of the circuit and since I had a couple of op-amps left over, I added a threshold detector and FET switch to disable the audio output below a preset level.

For those of you with class A-B amplifiers, a related function (and heat reduction and power saving) can be realized by incorporating electronic bias switching in the amplifier.

ps. IMHO, the split-band approach is still a preferred clipping method and is incorporated in the sweet sounding TS-870, my current transceiver.