CAT & audio interface version 3 by pa5ca
Ham radio is a continuous process of learning.
After using the V2 interface during numerous contests I decided you build a new interface
The V2 interface was not bad but it had shortcomings!
- Audio-levels where hard to adjust and sensitive to Hum.
- I only could use one type of microphone (electred)
- The headphone output was only for VFO A or A + B.
- It had too many connectors.
- Only one PTT output.
One of the major disadvantages was the voice keying using the V2 interface. We became lot of complains about our voice keying during
SSB contests, the shack surrounding noise was most of the time louder than the voice keying so steps need to be taken.
Another issue was the need for connecting RX antenna's to the rig.. in order to avoid frying the mixers
an adequate muting of the RX input was a must.
The most convenient way was to use a sequencer.
Last but not least… I own a FT2000 and one of here mishaps of this rig is the lag of sufficient headphone audio.
We at
PA6Z do not have the direct capability for setting up multiplier stations so most of the time we use the second receiver for that purpose .
In that case separate audio control and VFO audio control would be most convenient.
So enough input for the drawing board…
I've build an interface using the above input_
- Two stereo high-performance Headphone audio amplifiers.
- Two channel selectable audio output, VFO A both speakers, VFO B both
speakers and VFO A + VFO B.
- Each output has his own volume control.
- Audio sequencer, microphone input muted while voice keyer active.
- Microphone input, selectable dynamic or electred and mute.
- PTT sequencer with two PTT output switching the PTT like, di da, da di. Relay controlled
- The sequencer can be disabled or enabled, indicator showing the on or off state.
- Les connectors due to combining in and outputs.
- Accurate audio level adjustment.
- Extra relay controlled PTT can handle high voltages and up to 1 Amperes.
It took me some time too build it but the result was above my expectation. Pictures and schematics are posted here.
Please contact us if more info is needed,
Front panel view, at the right the two separate headphone controls, middle section, microphone input and mode control. The TRX and PC audio control. Left main power switc and PTT, CW indicator, at the bottom the PTT sequencer control switch and indicator.
2* 5V power supply, the 12V tap in the secondary section is used for the CAT TRX pull-up.
2* 12V power supply, needed for the audio amplifier and PTT sequencer.
Audio TRX and PC control board and microphone audio sequencer.
PTT control board, controlling the TRX PTT, microphone sequencer control, PTT sequencer control. Input pinning is according to N1MM logging program.
CW TRX contoler, input pinning is according N1MM logging program. With the diode it the controller also works with DTR control.
RS232 TRX CAT controler. note the 12V pull-up input from the secondary 5V power supply.
