FU-29 Xuel Making, Fu-29 Power Amplifier
Keywords: tube, amplifier, Fu-29
FU-29 is 829b foreign models, which is originally used in high frequency fields, making short-wave oscillations and high frequency launches, and is mostly used in military fields. It is said that the MiG 15 aircraft is to use this tube to transmit tubes. FU-29 It turns out that there is a lot of money, but there are many people who have flowed in the people in recent years, and the price is low, and one can be bought around 20 yuan. If you don't have the original price of 1/10. It is estimated that the unit is eliminated and inventory is more inventory, but also because this tube is very small in the audio sector, there is only a 560 model in the domestic finished electronic pipe machine, and the amateur use is also used. Nor did it form a popular, so the price of this tube is not specified. In fact, many non-audio-specific RF tubes have excellent performance in the field of audio, such as Fu-32, FU17, etc., Fu-29 is one of them.
I. Circuit introduction From the performance of Table 1, Fu-29 is a double-bundled four-pole power tube, with a higher pressure, extreme value of 750V, and has a large screen power consumption and screen Current, good linear, low saturation pressure drop and high crosscomers. From Fig. 1, the characteristic curve of Fig. 2 indicates that this is a highly efficient power tube. There are two identical beam tubes inside the tube, with 600V screen pressure, 200V curtain pressure, 13.75 kΩp-p load in standard state. A FU-29 output power can reach 44W, a large couple of 6P3P, and a pair of EL-34, KT66, slightly smaller than KT-88, but the current price is much lower than KT88, so Fu-29 is one Only worth "playing" tubes. Be
Table 1 Performance of FU-29
Filament voltage
Filament current
Input capacitor
Output capacitor
Maximum anode voltage
Parallel 6.3V, series 12.6V
Parallel 1.9-2.6a, in series 0.95 ~ 1.3A
13-17 PF
5-9 pf
750V
Maximum second gate voltage
Maximum anode dissipation power two quadrupole
Maximum second gate dissipation power
Maximum operating frequency
Be
225V
40W
7w
200MHz
Be
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The difficulty of making Fu-29 is primarily in the operating voltage and making impedance comparison output transformers. Of course, 600V is nothing wrong with the amateur masters that have been done 211, 845, 805, but it is a challenge for primary enthusiasts for experience in experience. Impedance 13.75 kΩ Output Transformer can't find finished products on the market. The way to solve the one is to find a business that can provide custom services, and the second is to wind with your own ability, but because of its high working voltage, insulation is worth noting. The output transformer parameter of this unit is shown in Figure 3, as shown in FIG. The high quality output transformer is a basic guarantee for the success of the electronic tube power amplifier. Figure 5 is a FU-29 power amplifier circuit diagram we made, which is a quite "classical" circuit form, overall highlights the characteristics of balance. Transformer B1 inputs, sharp off five-pole 6J4P, the transmitting tube FU-29 acts as power amplification, transformer B2 is output impedance conversion.
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