(Information provided by Joseph Ruggieri)

75W Linear RF Amplifier Board 2.3-2.35 GHz

This is a 75W linear amplifier board as removed from a new Spectrian power amplifier which is optimized for 2.30-2.35 GHz but is also useful up to 2.45 GHz at reduced power an gain.

This amplifier board does not require any tuning for use on the ham band!  Required supply voltage is +24-26 VDC at about 17A.

Input drive required for 75W output power is 1.25W.  Power gain is 18 dB.  Saturated power is 80W+.

This is the final revision for this board design (Rev. A) which has larger plated through holes and the holes have been sealed so the silicon grease does not come through the top side when bolting the board down to the heat-sink.  The earlier revisions were all "number" revisions with open vias.

I sell the older "number rev boards" at a lower price on other auctions.

The sweep photo shows one of these amps putting out 80W with about one watt input at 2304GHz.  The output (CH1) reference is set for 100W (+50 dBm)with a scale factor of 5 dBm per division.  Channel 2 is the input power with it's reference set for 10W (+40dBm) with 5 dBm per division.  Sweep is from 2.2-2.6 GHz with 50 MHz per division.

Looking at the output plot, you will see the level 1 dB down from +50 dBm or 80 Watts and the input +9.4 dBm down from 40 = 30.6dBm, slightly over one watt.  Looking at 2450 MHz you can see the output is down 4 dB from 50 - 46dBm = 40W.  Note the preamp I am driving this PA with is not linear with frequency over this full range as indicated by channel 2.

Circuit board is on an integral .062" solid copper heat spreader.  Both the board upper surface and the heat spreader surface are heavy gold plated.  Board needs to be mounted on heat-sink using silicon grease and 7ea. 4-40 screws in existing holes.

RF input and outputs are 50 ohm strip-line and will butt up to a standard SMA or N launch connector.  Good quality SMA connectors are rated to 400W @ 2 GHz and work very well for this amp.

The XRF286 Lateral MOSFETs used on this board can handle a 10:1 VSWR at full power so isolators are not required.

Board dimensions are 1.25 x 5.9 inches.  Weight is 6 ounces.

DC Connector Pin-Out

1: Temperature output = 10 mV per °F

2: PTT = +12V to enable all three power FETs

3: Drain current monitor for Q1.  1 volt out per amp of drain current

4: Drain current monitor for Q2.  1 volt out per amp of drain current

5: Ground

6-10: No Connection

Additional Info