HPSDR Hermes
J16 Breakout Board


This board provides access to the audio and keying lines available on the HPSDR "Hermes" transceiver's 26-pin J16 rear panel connector. Specifically, it provides these outputs:

and these inputs:

The board and parts kit is now available from TAPR.

The board is designed to be as small as possible (about 1.25 x 1.5 inches) because there is little room on either side of J16, and I didn't want to increase the required clearance behind the radio any more than I had to.

It plugs directly into J16 and extends horizontally behind the radio. On the left side, CON1 is a right-angle, PCB mount, female, unkeyed, 26 pin connector that mates with J16. It mounts on the top of the PCB and has its pinout mirrored to match the actual layout of J16 (which is NOT the same as shown in the Hermes schematic!). If the pinout doesn't make sense, remember that it's a right-angle connector, so the row of pins closest to the edge of the board ends up connecting to the bottom row of J16.


There are five 3.5mm audio jacks; three are on the top of the board, and the other two are on the bottom. The spacing allows cables to be plugged into all five jacks, but it can be a tight squeeze. If you can use cables with thin connector shells, you'll find an easier fit.

(Click on the image to see a full-sized version.)

The 10-pin header (SV1) carries the 7 open-collector output signals on pins 1 though 7. The "open collector reference/flyback diodes" signal is on pin 8. Pins 9 and 10 (which are oriented nearest to the board edge) are ground.

Two-pin headers labeled PTT_IN and PTT_OUT provide access to the PTT and amp keying signals. On both headers, the ground pin is closest to the edge of the board. PTT_IN is closest to the radio; PTT_OUT is closest to the row of 3.5mm jacks.

Somewhere along the way, a design error crept in. The intention originally was to allow the LINE_IN jack to optionally use one circuit for another PTT_IN signal (so that it would work the same way as the Hermes MIC input does by default). However, I goofed up and the PTT_OUT (amp keying) signal got routed there instead. Sorry about that.

Assembly Notes

Some notes on building the Hermes breakout board: