23cm Amplifier Musings - SBB2089Z

While I got myself organized to order PCB's for testing the SXB4089 mentioned in the last few posts, I thought it would be worth looking at some of the other devices. The first of these I turned my attention to was the SBB2089Z, a 100mW device.

What I found, if you study the large image below, was that the bare device was acceptable for 6m through 70cm. However, at 23cm the output was not as good a match to 50 ohms as I had hoped (RL= 8dB ).

As expected, matching to 50 ohms at 23cm introduces loss of gain at other frequencies. There was also some slight chance of instability hence the series resistor in the second version to prevent these.

I'm going to get two boards fabricated for testing: one for 6-70cm using just the MMIC, and one for 23cm using transmission lines.


73's
Richard