Stealth SM3437 Power Amplifier

Recently a source of Stealth Microwave SM3437 PA modules was made available on eBay and several radio amateurs in New Zealand and Australia purchased one to complete or upgrade their 9cm equipment.

The rated power output is specified at 20W but they have been found to produce over 30W with 0dBm drive, and more importantly no modifications were needed to operate on 3400 or 3456MHz.    As an added bonus it will operate safely from 13.8V or 12V making it suitabel for shack or portable operation.

In order to operate the unit the I/O pin (TTL level) and needs to be pulled to a logic 1 or +5V, or simply connect via a 4.7K resistor to the +12V supply rail to activate the amplifier.  The unit is biases in class A operation so it pulls 8.5A with no drive.

The amplifier is well protected by a circulator on the output, and has DC monitoring outputs for forward and reverse power levels.  For my 9cm transverter the natural thing to do was to put the monitoring outputs to good use and display the output power levels and SWR using my sequencer / controller board

Stealth PA Inside View

Stealth PA Inside View

Supply current is around 8.5 Amps at 12V and it is safe to use at 13.8V as the main FETS are rated at 15V.  There is also over voltage protection contained in the PA that prevents the bias supply from activating if voltages are out of spec.

At US$187 it cannot be beaten!

The manufacturers datasheet can be found here: SM3437