Apache Labs Community Forum

I have a 100d (Angelia board) and controlling with a PiHPSDR V2 Controller.

I have plugged in a Koss SB45 headset into the front MIc/Headphone socket and using a keyboard connected (not ideal) to the controller I can press the space bar for TX.

I want to use a footswitch so, using the same headset and a footswitch, connected via the 25 way socket on the rear, PTT on 13 and 25(Gnd) , RX audio on 11 and 25 and TX audio on 12 and 25. The PTT and RX works as expected but I have no TX audio.

I also tried putting the Mic in the front port again and using the PTT via the rear and that doesn't produce and TX audio

I have tried changing the JP4,5,6 settings making no difference.

Can anyone please advise what I could be doing wrong or point in the direction of the correct configuration.

Regards Anthony G7LRQ

Front and rear PTT connections both go to the same trace on the Angelia circuit board, there is no difference between them other than the method of connection. You are smart to wire up a footswitch to the rear connector.

You cannot use the rear panel connector, Pin 12, with a microphone. It is a line level input. You need an external microphone preamplifier to go that route.

Since you cannot use the line in connector, in the piHPSDR settings you must select the mic input, not line.

Randomly changing JP4, 5 and 6 will net you random results. These jumper selections must be based on facts.

Fact: your Koss SB45 is designed for use with a PC.

By definition that means it uses an electret mic element (needs bias), signal is on the tip, bias is on the ring, and ground is on the sleeve.

Since the available documentation is all over the place, I recommended simply looking at the Angelia schematic, available from the schematics section of this forum.

Using the schematic, we see that:

- JP4 must be installed between pins 2 and 3 to feed the mic signal from the tip.
- JP5 must be installed between pins 2 and 1 to feed bias to the ring.
- JP6 must be removed entirely so that the electrical connections inside the SB45 do not short out the PTT input, i.e. unless you build an adapter of some sort to interface the SB45 to the front panel microphone connector, PTT must be accomplished with the rear panel connection (or MOX, or keyboard) and this jumper must be removed.

Because this is an electret mic, mic boost should be turned off in piHPSDR setup.

Finally, there are some PC mics that just refuse to work with openHPSDR hardware unless they are internally modified. Something to do with how the bias is connected internally, I'm afraid I don't remember the precise details at the moment.