Voice Keyer for Icom transceivers

This voice keyer came into being as a logical successor of the Voice Keyer for FT897.
It uses the same logic and behavior and adds the following features:

• Imbedded speaker to check the correctness of the recording
• Quindar Tone ("roger beep")
• Selectable delay between playbacks
• Level of the output, loudness of the speeker, and level of the quindar tone settable with trimmers
• Ready to send the supply voltage to MIC (some MICs require this)
• Highly protected against RF

Overall view of the box. The box is metalic to protect the device against RF.	Bottom view of the device. Mind the holes for the speaker.	Front panel: Green button - trigger a playback Yellow button- play repeatedly Red button - record Spkr - switching the speaker on/off Qundar Tone - switching the roger beep on/off Delay Long/Short - toggling between two delays. More options by jumpers on the board. Rec Enabled/PTT Enabled - enables/disables recording/PTT
Rear panel: Left is the MIC connector. A standard Icom microphone (such as HM-36) comes here. Right is the connector for a short shielded cable to TCVR (to MIC input of the TCVR).	Interior of the device.

Schematics

Upgrade for muting (8/2015)

Even that the relay for switching AF path was wired for not switching any DC current, it still produced a slight "click" at the moment when PTT on MIC was depressed. It caused problems mainly when PA was attached to the TCVR.
As a cure a switching FET was added to shorten the AF output. The output is muted when no playback is in progress and PTT button is released. If either PTT is depressed or the playback is commenced the FET keeps the output muted for some 100 milliseconds.
This way the click produced by the relay as well as any other instability that may occur due to switching from RX to TX is safely muted.

The added parts are painted in red:
Partial schematics

It was realized on a tiny PCB.

The PCB was soldered above the relay.

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