An experimental HF 6-band SSB transceiver – Part 8: Transmit/Receive Switch

This unit is a very simple one. I did not want to use more relays than necessary. The consequence was to save at least the one commonly used in the transmit-receive switch unit. Here 2 p-channel MOSFETs do the job:

DK7IH 6 band QRP SSB TRX 2019 - Transit/Receive Switch Unit
DK7IH 6 band QRP SSB TRX 2019 – Transit/Receive Switch Unit

Hint: The “PTT” in the radio here leads to a PIN of the MUC switching the transmitter on. For general purposes a “PTT” has been drawn into the schematic.

Function: When Gate (G) is “hi” (i. e. close to VDD) the S/D channel goes to nearly infinite ohms. Resulting current is 0A apart from some uA leakage current.

When S is pulled to GND, or, to be more exact, some volts lower than VDD the S/D channels switches to a value very close to 0 ohms. Pushing PTT pulls G of the left MOSFET to GND thus switching on the transmitter. G of the right MOSFET is now pulled to VDD (via 10k) which means that the right MOSFET becomes non-conductive and receiver is turned of. A dual-LED (red and green) in the front panel shows the current status.

Vy 73 de Peter

Author: Peter (DK7IH)

Radioamateur since 1987, constructor of radio hardware, software developer, science teacher in secondary education.

One thought on “An experimental HF 6-band SSB transceiver – Part 8: Transmit/Receive Switch”

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.