NC40A revision B power measurements

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From: Wayne Burdick (burdick@interval.com)
Date: Thu May 25 1995 - 16:26:58 EDT


These measurements were taken with the NC40A revision B circuit changes
that I just made, which include changing the transmit buffer to a J309
(this device is HOT--about twice the transconductance of the 2N4416, and
even a bit higher than the J310).

Typical numbers for the NorCal 40A running at 14 volts are:

  - 2 watts out with drive set to about 80% clockwise,
      PA collector current 185mA, PA efficiency approx. 77%,
      Total transceiver current on transmit: 221mA

  - 3 watts out with drive set to max clockwise
      PA collector current 285mA, PA efficiency approx. 75%,
      Total transceiver current on transmit: 323mA

Of course, many will run the rig off 12 to 13 volts, in which case the
maximum output will likely be closer to 2 watts than 3. Also, you could
probably get up to 5 watts by using a 2:1 broadband transformer rather than
the RF choke at the PA collector; this would provide a better match from
the PA to the low-pass filter at higher power levels. There was a QRPp
article last year on this modification as made to a NorCal 40.

73,
Wayne


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