Parts List for One Channel

If you are not familiar with how wire sizes are specified and what wire gauges mean, you can find that information here.

Version 4.4/4.5 of the Amplifier

Transistors (Starred types are preferred.)

I tend to prefer Motorola if available. Motorola has spun off its semiconductor division, and it is now called On Semiconductor. In the process, they have discontinued many products. I have seen some mystery brand transistors that have really bad characteristics. If the transistor is labeled with a name brand manufacturer, it should give no problems. For Q1 - Q11, the first NPN type should be used if the first PNP type is used, etc. This also applies to Q16 - Q17 and to Q18 - Q21. I have seen students use all of the types of transistors that I have listed below with no problems. If you look at the specs, however, you will see why I prefer the starred types. Transistors can be substituted, provided the substitutes have similar specs to the ones below.

I have been told that the MPS8099/MPS8599 are no longer a "complementary" pair because the PNP is discontinued. ON Semiconductor states that the direct replacement for the MPS8599 is a MPSA56. In March 2003, I was told that the MPS8599 is back. ON Semiconductor is now supplying them.

Other possibilities for the MPS8099/MPS8599 are the ZTX651/ZTX751 which are available from Digi-Key.

Q1, Q2, Q5, Q7, Q9, Q10 BVCEO IC(max) PD(max) at 25o C ambient hFE(min) fT(min)
MPS8099* 80 V 0.2 A 350 mW 100 150 MHz
MPS8098 60 V 0.2 A 350 mW 100 150 MHz
MPSA06 80 V 0.5 A 300 mW 50 50 MHz
MPSA05 60 V 0.5 A 300 mW 50 50 MHz
2N5210 50 V 0.05 A 310 mW 200 30 MHz

Q3, Q4, Q6, Q8, Q11 BVCEO IC(max) PD(max) at 25o C ambient hFE(min) fT(min)
MPS8599* 80 V 0.2 A 350 mW 100 150 MHz
MPS8598 60 V 0.2 A 350 mW 100 150 MHz
MPSA56 80 V 0.5 A 300 mW 50 50 MHz
MPSA55 60 V 0.5 A 300 mW 50 50 MHz
2N5087 50 V 0.05 A 310 mW 200 30 MHz

Q13, Q14 BVCEO IC(max) PD(max) at 25o C ambient hFE(min) fT(min)
2N3439* 350 V 1 A 1 W 40 15 MHz
2N3440 250 V 1 A 1 W 40 15 MHz
NTE396 350 V 1 A 1 W 30 15 MHz

Q12, Q15 BVCEO IC(max) PD(max) at 25o C ambient hFE(min) fT(min)
2N5415 200 V 1 A 1 W 30 15 MHz
2N5416* 300 V 1 A 1 W 30 15 MHz
NTE397 350 V 1 A 10 W 30 ?

I have not tried the NTE396 and NTE397 transistors. They are specified to be a complementary pair. The spec sheet for the NTE396 has two power ratings - 1 W and 5 W. It is not clear why they specify two. The spec sheet for the NTE397 only has one power rating and it does not give the gain bandwidth product fT.

Q16 BVCEO IC(max) PD(max) with case at 25o C hFE(min) fT(min)
MJE15030* 150 V 8 A 50 W 20 30 MHz
2N6474 120 V 4 A 40 W 15 4 MHz

Q17 BVCEO IC(max) PD(max) with case at 25o C hFE(min) fT(min)
MJE15031* 150 V 8 A 50 W 20 30 MHz
2N6476 120 V 4 A 40 W 15 4 MHz

Q18, Q20 BVCEO IC(max) PD(max) with case at 25o C hFE(min) fT(min)
MJ15003* 140 V 20 A 250 W 25 2 MHz
MJ15001 140 V 15 A 200 W 25 2 MHz

Q19, Q21 BVCEO IC(max) PD(max) with case at 25o C hFE(min) fT(min)
MJ15004* 140 V 20 A 250 W 25 2 MHz
MJ15002 140 V 15 A 200 W 25 2 MHz

Do not use plastic insulating caps over Q18 through Q21. These will keep the screws that hold the power transistors to their sockets from making contact to the transistor cases. The case is the collector and there will be no power supply voltage on the collectors. I had a student use these caps, and R41 through R44 caught on fire on his board, and he blew Q16 and Q17.

Apparently the 2N3439/2N3440 and 2N5415/2N5416 transistors are getting difficult to find. A possible manufacturer who has them listed on its web page is STMicroelectronics. The STMicroelectronics transistors are available from Arrow Electronics and Mouser Electronics. I would be interested if anyone knows of other sources for these transistors. I have been told that ON Semiconductor no longer makes these and transistors with the ON Semiconductor label may be counterfeit. The transistors are currently made by ST Microelectronics and Central Semiconductor.

As of June 2000, RadioShack.com has all of the transistors at good prices. They can be ordered through the web. You can see a list of their part numbers and prices here. In spring 2002, students told me that RadioShack.com was selling its inventory at steep discounts and would soon be out of business. Formerly Tech America, this is the parts division of Radio Shack and is not connected with the retail stores.

The 2N3439/2N5415 pair is the one that I originally used for my prototype amplifiers. It is the complementary TO-5/TO-39 case pair recommended in the RCA Power Transistor Manual for audio amplifiers. For all practical purposes, the 2N3440 and 2N5416, respectively, are equivalent to the 2N3439 and the 2N5415 for the Low TIM amplifier.

Q12 - Q15 can run a little warm. I have never had problems with these running too hot. With the Version 4.4/4.5 amp, I have reduced the bias currents in these transistors just a little to keep them cooler. Although I don't think they are needed, you can put TO-5 clip-on heat sinks on them. There is not much room on the circuit board for the heat sinks, so they must have small fins. Another type of heat sink which will fit is in the shape of a flag (about 1 inch high by 3/4 inch wide) with rounded clips on one end that clip around the transistor. If you can't find them, they are easy to make from sheet metal flashing. The clips should make good mechanical contact to the transistor for good heat conduction.

Diodes

Capacitors (First type listed is preferred.)

Some of the capacitor types specified below are ceramic. I have seen some of these exhibit non-linear effects, so I don't recommend them unless the mica types cannot be found. The ceramic dielectric in the capacitors can exhibit a piezoelectric effect which causes the spacing between the plates to vary with applied voltage. This causes the capacitance to vary with voltage. Indeed, on one occasion I could hear a ceramic capacitor "sing" when excited at its resonance frequency.

Resistors (1/4 W 5% carbon film or 1% metal film unless specified otherwise. Please use an ohmmeter to check the value of all resistors before soldering them to the circuit board.)

If you do not use the specified power supply voltages, you can calculate the values for R13 and R14 from the formula R13 = R14 = (V - 40)/8.2, where V is the power supply voltage. For example, for V = 58 V, the formula gives R13 = R14 = 2.2 kohm. Use the nearest 5% resistor value. (For the Ver. 4.3 amplifier, calculate the values for R13 and R14 from the formula R13 = R14 = (V - 38.2)/5.42, where V is the power supply voltage. For example, for V = 57.7 V, the formula gives R13 = R14 = 3.6 kohm.)

Miscellaneous

Some Recommended Parts Suppliers.

Newark and Allied have regional sales offices in many metropolitan areas. There are many surplus electronics companies which advertise in electronics hobby magazines. The catalogs from as many such companies as possible should be obtained before acquiring parts for the amplifier. Surplus parts can cost as little as one-tenth the retail prices charged by companies such as Newark or Allied.

Power Supply for Two Channels

Screw Hole Sizes

So many students have asked me what the correct hole sizes are for machine screws. For a clearance fit for a number 4 screw, use a number 31 drill bit (0.12 inch diameter). For a clearance fit for a number 6 screw, use a number 27 drill bit (0.144 inch diameter).

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