On Air Transmitter Testing of the N3FJZ MAX SSB . 2023-01-10

I've finally got the PA wired and operational, and in this video I'm using an on-line SDR to perform on-air testing of the rebuild of the MAX-SSB (formally known as the ZX-SSB-II) HF SSB transceiver.
You can perform on-air testing of your transmitter and actually hear what your rig sounds like, on-air, to other by using an on-line SDR. In this case I used the W3HFU Westminster, MD, USA on-line KiwiSDR (sdr.hfundergrou...) to perform the on-air test.
The MAX-SSB is a multi-band SSB transceiver based on many homebrew designs I've seen on the web. It includes a built-in GPS disciplined frequency counter used to calibrate the Si5351 PLL oscillator, a GPS derived real-time-clock showing UTC and local time, thermistors mounted on the PA final transistors to monitor their operating temperature, a Stockton Bridge to monitor the forward and reflected power at the PA's output connector. Using the thermistors and Stockton Bridge, the MAX-SSB Front Panel controller is able to shut down the transmitter if the SWR or PA temperatures rise above user preset threshold levels. Controller is the Arduino Mega 2560 with color display. The RF deck is based on Ashhar Farhan's (VU2ESE) Bitx20 with Wes Hayward's (W7ZOI) and Bob Kopski's (K3NHI) Termination Insensitive Amplifiers. The GPS module is the Ublox NEO-6M.
Schematics and Arduino sketch (source code) for the original ZX-SSB-II available at: www.remmepark.c...
www.remmepark.c...
Schematic of the temporary Front Panel on breadboard:
www.remmepark.c...

[@Paul_VK3HN]

Your Tx monitoring is working very well. Smooth and intuitive. The advantage of using a Mega over Uno or Nano is you don't hit the latter's limits on GPIO lines or memory. The Rx sounds excellent too. I think you've taken care to get each stage working really well. Congratulations!

[@paultomlinson528]

I would love to try this as my next project

[@R2AUK]

❤ 👍