[hpsdr] Testing linear amplifiers with HPSDR

[FRANCIS CARCIA]

Hi All,
I built a directional coupler with a second pick up coil on a .87 inch type 61 toroid. I wound 50 turns of #28 wire wrap wire for the pick up inductor. I connected the two ends to a BNC chassis connector with a 47 ohm 3 watt noninductive load across the connector. (you generate very high RF voltage without the load resistor) I then use a series of pads around 50 dB to reduce the level low enough for the Hermes RX input. The output of the attenuator pads goes to the NO contacts of a SPDT coax relay. Hermes RX input goes to the common and RX antenna to the NC contacts. Then I put PSDR in dupe mode so I can see my TX signal on the display. When I go into TX I power the coax relay.
This is a very efficient set up that allows me to check an amp 160 through 6 meters at multiple power levels in about 15 minutes. I have a Bird 43 in series with the dummy load to measure RMS power.
Frank WA1GFZ 
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