I tested 10 each of the three transistors currently available--2SC5706, 2SD822, 2SC2078 (from Las Vegas seller). (It takes about 5 minutes per transistor....) I used the same NC40A test fixture and 12.8VDC as before and the first transistor was same as before, note the AWG setting and output level is slightly different from yesterday. I kept the same AWG setting but noted the output level--this is quicker to do for multiple transistors.

Steve AA7U

2SC5706 (from kitsandparts.com)

1. -5.0 dBm in for all, 28.5 Vpp out, 2.03W

2.? 28.5 Vpp, 2.03W

3.? 28.5 Vpp, 2.03W

4.? 28.1 Vpp, 1.97W

5.? 29.9 Vpp, 2.24W

6.? 27.5 Vpp, 1.89W

7.? 27.6 Vpp, 1.90W

8.? 29.6 Vpp, 2.19W

9.? 28.9 Vpp, 2.09W

10. 28.0 Vpp, 1.96W

2SD822 (from Tayda)

1. -1.5 dBm in for all, 28.6 Vpp, 2.04W

2.? 28.6 Vpp, 2.04W

3.? 28.9 Vpp, 2.09W

4.? 28.1 Vpp, 1.97W

5.? 28.0 Vpp, 1.96W

6.? 28.8 Vpp, 2.07W

7.? 28.0 Vpp, 1.96W

8.? 28.3 Vpp, 2.00W

9.? 28.7 Vpp, 2.06W

10. 28.5 Vpp, 2.03W

2SC2078 (from eBay Las Vegas seller)

1.? -3.2 dBm in for all, 28.4 Vpp, 2.02W

2.? 28.8 Vpp, 2.07W

3.? 28.4 Vpp, 2.02W

4.? 28.9 Vpp, 2.09W

5.? 28.5 Vpp, 2.03W

6.? 28.7 Vpp, 2.06W

7.? 28.7 Vpp, 2.06W

8.? 28.2 Vpp, 1.99W

9.? 28.6 Vpp, 2.04W

10. 28.3 Vpp, 2.00W

On Thu, May 15, 2025 at 9:45?PM Steve Ratzlaff via <ratzlaffsteve=[email protected]> wrote:

Here are some output PA transistors I tested in the 7 MHz NC40A buffer, driver, PA circuit, with the function generator adjusted to give 2 watts output (28.3 Vpp) across the 50 ohm dummy load; power supply set to 12.8 VDC. My function generator can show the level in dBm but many do not so I've included the mVpp value too. I've listed the results in lowest drive level (better) to highest (poorer). The BSC 2N3553 is an eBay find from BSC--Boca Semiconductor Corp in Florida--I've tested several eBay 2N3553s and this is the only one I've found that compares well with the genuine old Motorola 2N3553 I have. .? If I left out your favorite 1.5-2W PA transistor, let me know and if I have it I'll test it too. Schematic of the test circuit attached. I didn't install the output zener diode since this is a bench test with 50 ohm dummy load and won't see an antenna.

73,

Steve AA7U

1. Motorola 2N3553 -6.5 dBm 299 mVpp (old genuine Motorola transistor)

2. 2SC2314 -6.1 dBm 313 mVpp (old genuine CB driver transistor)

3. BSC 2N3553 -5.6 dBm 332 mVpp (from eBay seller Boca Semi)

4. 2SC5706 -4.8 dBm 364 mVpp (from )

5. 2SC2028/2 -4.6 dBm 372 mVpp (old genuine CB driver transistor)

6. 2SC5739 -3.5 dBm 423 mVpp (genuine, not from eBay or Amazon)

7. 2SC2078 -3.0 dBm 448 mVpp (from eBay Las Vegas seller I've mentioned before--Chinese transistor)

8. 2SD882 -1.2 dBm 551 mVpp (from Taydaelectronics.com)

9. Central Semi 2N5109 -0.5 dBm 597 mVpp (genuine Central Semi transistor)

9. Central Semi 2N2219A -0.5 dBm 597 mVpp (genuine Central Semi transistor)

10. 2SC2078 -0.3 dBm 611 mVpp (from Dan's Small Parts and Kits)

11. 2SC2078 +6.1 dBm 1.277 Vpp (from ME 40M kit)