¿ªÔÆÌåÓý

ctrl + shift + ? for shortcuts
© 2025 Groups.io
  1. Loopantennas
  2. Messages
Single Messages Topics Expanded Polls

Re: Ikin Norton 9 dB preamp tested with several transistors

 

I use -61 material ferrite beads, Fair-Rite 2661000101, mouser.com carries it. The -73 material binocular cores, 302 size, are Fair-Rite 2873000302, also carried by mouser.com. The -73 material is conductive. The transformer windings must NOT have the insulation abraded so it touches the core otherwise the IMD will suffer greatly. After stripping the ends of the finished windings, use an ohmmeter to check from all windings to the core--they must read infinity or you'll need to rewind the core and try again. I use a thin Teflon tubing spacer for all my binocular cores using -73 material. I buy it from China on eBay. The proper size is 3.0 x 3.4 mm, in type 9L. Here's one seller of it . (I use #30 AWG magnet wire for these transformers and the insulation easily abrades and touches the core if I don't use the Teflon spacers.)

73,

Steve AA7U

On 11/1/2024 9:48 PM, Steve Ratzlaff via groups.io wrote:
I tested three different transistors in the Ikin Norton 9 dB circuit--2SC5551, BFU590QX, 2SC3357 (all SOT-89 package). I used Everett N4CY's PCB. All were tested at 12.0 volts supply and bias set for 70 mA. Since the 2SC3357 has a max 12 volts Vceo; this circuit with 12.0V supply and 70 mA had 10.3V emitter to collector so is running below the Vceo 12V limit. IMD tested with my standard 3/4 MHz test tones set for 0 dBm each tone at output of the preamp----2IMD checked at 1 and 7 MHz; 3IMD checked at 2 and 5 MHz. P1dB tested with 50 ohm load at 1 MHz. Gain swept with DG8SAQ VNWA--all three had fairly flat response from about? 50 kHz-30 MHz. Noise figure tested on HP 8970B.

1. 2SC5551??????? IMD--1 MHz +93 dBm OIP2, 7 MHz +89 dBm OIP2. 2 MHz +50 dBm OIP3, 5 MHz +49.4 dBm OIP3.? P1dB--0.585 watts, +27.7 dBm.??? 10 MHz noise figure 1.82 dB. (The transistors are from what I purchased several years ago when Rochester Electronics still had them.)

2. BFU590QX???? IMD--1 MHz +84.5 dBm OIP2, 7 MHz +83.5 dBm OIP2. 2 MHz +50.1 dBm OIP3, 5 MHz +49.3 dBm OIP3.? P1dB 0.585 watts, +27.7 dBm.??? 10 MHz noise figure 1.87 dB. (I got the transistors from mouser.com, NXP made them.)

3. 2SC3357???? IMD--1 MHz +89 dBm OIP2, 7 MHz +89 dBm OIP2.??? 2 MHz +49.9 dBm OIP3, 5 MHz +49.6 dBm OIP3.?? P1dB 0.63 watts, +28 dBm.??? 10 MHz noise figure 2.15 dB. (I got the transistors from digikey.com, EVVO (Chinese) made them.)

All three transistors gave similar IMD and P1dB. 2SC5551 is no longer available but the other two are currently being made. If you're careful not to exceed the 2SC3357 Vceo 12V max, it would also be suitable.

73,

Steve AA7U
Join [email protected] to automatically receive all group messages.