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Sunday, 28 June 2015

Fitting the SPF Amplifier in the 23cms BiQuad antenna

Today I installed the SPF amplifier in the dicast box on the back of the BiQuad antenna.

The new amp is MUCH smaller than the old one. Since I want to run the amp from a 12V supply I added the recommended 180 ohm series resistor, however I found that the Voltage across the amp was heading for over 5V once the supply exceeded 12V, so I  upped the value to 220 ohms to be on the safe side. The instructions contain warning about not letting the voltage on the drain of the chip exceed 5V. I'm not happy about the pig-tail on the coax going to the F-connector, but I can't think of a better way of terminating it yet.
At the other end, I kept the ends of the coax as short as possible at the feedpoint of the biquad.

Hopefully, with the nice weather, I might get a chance to try the aerial out this week.
73 Hugh

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