NC40A revision B power measurements


From: Wayne Burdick (
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.


Search QRP-L Archives

[ QRP-L Archive | ]
[ 1993 | 1994 | 1995 | 1996 | 1997 | 1998 | 1999 | 2000 ]


This archive was generated by hypermail 2b29 on Fri Jun 02 2000 - 11:28:07 EDT