2W output with 2SC1815 * 4 AMP

JJ1WKN made the 7MHz transceiver and the transmitter generates 2W with four parallel 2SC1815. Here is his blog for 2W transmitter. The schematic diagram of 2W amp is quite simple.

KEM-TRX7-CW video by JQ1BWT

JQ1BWT uploaded the KEM-TRX7-CW video. He compared with his FT-2000d on the video. KEM-TRX has a good performance.

7MHz MicroVert by JA1SCW

This web page describes the MircroVert for the 40m band. The length of the radiator is only 143cm and the length of the coax cable for the counterpoise is 8.3m. You need to attach the 29.4uH coil for the radiator and the choke coil of the FT240-43 between the counterpoise and the coax feed to the transceiver.

The antenna is quite small for 40m band and can install it on the small space. I've made one for my QRP rigs and have a good performance to the domestic CW communication.

Circuit - 7MHz trasmitter - CQ Ham Radio July 2009

You can look at the circuit diagram of 7MHz trasmitter on the July issue of CQ Ham Radio in 2009. The collpits oscillator generates the 7MHz signal and the PA stage increases the RF power to 200mW with 2SC1815GR. The LPF consists of two coils and three capacitors. There is the full break-in capability with 2SA1015GR (PNP transistor) .

The VXO with the 20pF capacitor can move the frequency between 7.000MHz and 7.003MHz.

Parallel 2SC1815GR for 7MHz PA - 500mW

The 7MHz transmitter of the CQ Ham Radio July issue can be upgraded with parallel 2SC1815GR. The orignal PA has only one 2SC1815GR, but JM6QAL has been changed to two 2SC1815GR at PA stage. You can look at the parallel 2SC1815GR which can generate over 430mW although the single one is only 200mW.

I've got one board and made this transmitter with parallel 2SC1815GR. I need to have the receiver that can work with the transmitter.

The 2SC1815 is the typical transistor in Japan. There are sub-alphabet like O, Y, GR, BL for different hfe.