Transmitter Circuit

This TV transmitter will handle frequencies up to about 250MHz , so it will work perfectly if you have on your telly. In principle, the transmitter should work up to 500MHz or more, using the BF959 bipolar transistor. You should be able to generate a signal on UHF channel 21, but I have not (yet) tried this with the first rats-nest version. TR2 and TR3 may be difficult to get, but you need to select a small-signal transistor with an ft= 1.1GHz (1100MHz). For 50/200MHz bands you may be able to get away with 2N2369 , but I have found this to be a ... Read Full Story

The circuit is very simple, it just has three transistors, but the transistor types have been changed for VHF/UHF transistors. You can use 2N2369, BSX19 or BSX20, or any small signal transistor with an “ft” of typically 400MHz or more. The transistor DC biasing is a little more tolerant to varying transistor types than the old V5 (FM) TR1 is a simple audio transistor, such as the BC547, BC108, or 2N2222. This transistor provides absolutely no gain, but it inverts the video modulation from the camera. Without it the video would have a negative modulation characteristic. The 4K7 pot adjusts the video level and ... Read Full Story

This RF power amplifier is based on the transistor 2SC1970 and 2N4427 . The output power is about 1.3W and the input driving power is 30-50mW. It will still get your RF signal quit far and I advice you to use a good 50 ohm resistor as dummy load. To tune this amplifier you can either use a power meter/wattmeter, SWR unit or you can do using a RF field meter . RF Amplifier Assembly Good grounding is very important in a RF system. I use bottom layer as Ground and I connect it with the top with wires to get a good grounding. ... Read Full Story

This is a 6m band RF power amplifier (50 MHz) with 100W output. It used with my FT-736R and drive from 10W for the 6m SSB DX. The Building information comes from Japan CQ Magazine. The Toshiba RF bipolar power transistor will be used in it. RF Power Amplifier Schematic and PCB Grounding If you want to construc this rf amplifier, it's the better way if the double side PCB use for increase the grounding and current transfer. The TX power can be tune to 120W. RF Amplifier features: Input Power: 10W Output Power: 100W Operating Frequency: 50-52MHz Operating Mode: FM- SSB Operating Voltage: ... Read Full Story

This 30W RF amplifier circuit provides an appropriate power boost with an input of 4-6 watt operating on the VHF FM Broadcast Band with 88-108 MHz frequency. However, the circuit is very stable and provides a clean-output through 7 element Butterworth low-pass filter (LPF). Circuit Explanation This VHF RF power amplifier circuit uses 2SC1946A VHF RF power transistor . The transistor is specifically designed for operation in frequencies up to 175 MHz, with very good results. As you can see, the power line is well decoupled. The amplifier current can be over 5 amps. All the coils are made from 16 gauge laminated wire ... Read Full Story