The objective of this project is to provide a pair of multiple-input audio channels for my various receivers and transceivers: one HF channel, and one VHF channel. These channels will have:

• simultaneous, multi-receiver (source) capability

• separate output amplification-per channel

• master volume controls per channel

• multiple-and simultaneous-filter selection options, including an NIR-12 dual-DSP processor per channel (e.g. one HF & one VHF)

• SSB squelch capability

• VU-meter level monitoring

• multiple speaker (destination) selection

• muting-on-transmit of both, either, or neither output channel

• Line-level (600 ohm) output for multiple TUs with TU selection

• Programmable switch-relay/connector capability via WW board

• Recording via 2 Philips DCC decks w/remoting of operational functions

The physical design will use a 19 inch rack cabinet, and will incorporate relay switching for virtually all input and output lines. The unused inputs will be switched to ground through 20 ohm 2W resistors as loads. All audio I/O lines will use gold-plated RCA-type jacks, and most other lines will use gold-plated connector contacts. There will be internal power supplies for +48VDC, +28VDC, +13.2VDC, and -12VDC. There will also be a +24VDC line that will be available regardless of the Power Switch status.

Tape & RTTY Line-Level outputs will be available, as well as RECORD and Transmit/Receive Switch-Sense-Lines brought through the unit (with RECORD originating within the unit.) While individual connector-relay sets will be hard-wired, the relationship between which relay responds to which switch-closure will be programmable via a Wire-Wrap matrix, to facilitate logic adaptability, and the rerouting of the path, should a connector or relay fail.

Other features include a dot-matrix display of relay-activation status; Bi-color LEDs to indicate Audio-channel ON (Green-to-Red transition) which provides instant indication of which channels are on; momentary-up/center-off/on-down mini-lever switches for all 16 channels of audio switching; 8 position rotary switches for HF speaker select; VHF/UHF speaker select; and for RTTY destination (e.g. TU) select. All switching will be designed to "fail-safe-through" to a safe state during either power-loss or relay failure. All audio signals will be carried on TFE-shielded cables. Most relays will be 24VDC/28VDC 'crystal-can' MIL-spec (surplus) relays. All relays will have a 1N4001 in reverse across their coils (except in the case of a 48V relay, which will get a 1N4002 or better.) The AC line will have a suitable input filter, and all I/O lines will have at least a ferrite bead.

Finally, all the drawings will be in Adobe ACROBAT .PDF format. If the resolution fails to be sufficient on any drawing, just ask. Also, if you see an error, I would greatly appreciate knowing about it. These drawings are my own except as noted. Please feel free to reproduce them as long as credit is given to their source.

Once again a reminder:

I am including the AF Controller here as it is developed, as an example of Project Design and Implementation. Be very careful to keep in mind that the circuits are not final until described as finished!

2001 04 15:  Basic design is essentially frozen! Final schematics and block diagrams here as finished.

2002 03 28:   Mixer design change...

2002 09 25:   a) Single Channel Switching / Indicator... b) Mixer design still being worked on...

2002 12 26:   Mixer design change LOOKING GOOD...

Overview Diagram Block Diagram

8-Input Dual-Output Mixer - NOTE: This will be changing AGAIN shortly-AND hopefully FINALLY to a set of four SSM2164s and a pair of OP176s-all from ANALOG DEVICES.

Single Channel's Switching Diagram

  Red-Green (Bipolar) Relay-Activity Indicator

... more to follow