IRF510을 사용한 7MHz 출력10W 증폭기, PLL
This is a very interesting transmitter from MicroHobby Lab. Reference
MICROHOBBY Nº2 Transmisor excitador de 10W CLASE E
The output stages in 74HCxxx devices are designed to
have equal pull-up and pull-down transistors.
This minimises even-order harmonics, simplifying the rig's output filtering.
The 74HC240 can directly drive a power MOSFET amplifier (IRF510).
MICROHOBBY Nº1 Preamplificador ecualizador. http://www.qsl.net/lu8eha/lab_ref1.html
XTAL = Cristal de Frecuencia Fundamental
IC1 = Requiere pequeña aleta disipadora
SINT = Entrada de oscilador externo requiere 0 / 8V de pico
CH1 = 30 espiras de alambre 0.25 sobre ferrite de 6 mm de O
L1 = ajustar para que de 10 W de salida con 12 VAC y 1Amper
C1, C2, C3 = Mica Plateada > de 100V
IRF510 송신기는 E급으로 효율이 90%이다.
DATA SHEET: IRF510 POWER MOSFET TRANSISTOR
Manufactured by Harris Semiconductors
Available at most Radio Shacks (although incorrectly labeled "IFR510")
Cost: $1.99 at Radio Shack (Cat. No. 276-2072)
The IRF510, IRF511, IRF512 and IRF513 are n-channel enhancement-mode
silicon-gate power field-effect transistors.
These power MOSFET's are designed for applications such as
switching regulators, motor drivers, relay drivers, and drivers
for high-power bipolar switching transistors requiring high speed and low gate-drive power.
These types can be driven directly from integrated circuits.
MAXIMUM RATINGS IRF510 IRF511 IRF512
Vds Drain-source voltage 100v 80v 100v
Vdgr Drain-gate voltage 100v 80v 100v Rgs=20K
Vgs Gate-source voltage +/-20v +/-20v +/-20v
Id Continuous drain current 5.6A 5.6A 4.9A
ELECTRICAL CHARACTERISTICS (All types unless otherwise stated)
Igss Gate-source leakage 500nA (forward) -500nA (reverse)
Idss Drain current, Vg=0v 250uA
Id-on On state drain current 5.6A IFR510, IFR511
4.9A IFR512, IFR513
Rds-on Drain-source "on" Res. 0.4-0.54 ohms (device ON resistance)
Cis Input capacitance 135pF (at Vds=12v, Cis=180pF)
Cos Output capacitance 80pF (at Vds=12v, Cos=130pF)
Td-on Turn-on delay time 8-11nS ) These parameters define
Tr Rise time 25-36nS ) how fast the MOSFET turns
Td-off Turn-off delay time 15-21nS ) on and off when gate is
Tf Fall time 12-21nS ) driven with a square wave
Vsd Diode forward voltage 2.5v (dropped across the source-drain
due to the internal diode)
SOME DATA FROM THE PERFORMANCE CURVES
Output drain current (Id) vs. gate-source voltage (Vgs) at Vd=+12v
Vgs=4v Id= 0A
Vgs=5v Id= 1A
Vgs=6v Id= 2.8A
Vgs=7v Id= 4.8A
Vgs=8v Id= 6.8A
NOTE: Therefore, for a 5W QRP power amplifier, the gate-source voltage should not exceed 5-6v;
otherwise excessive current will attempt to flow.
A continuous applied Vgs >7.5v will cause Id to exceed the maximum drain current rating of 5.6A (IRF510).
This will cause "catastrophic substrate failure" (commonly known as smoke!).
What is the maximum frequency? Max. frequency is not specified,
but since Tr= 36nS (rise time) and Tf = 21nS (fall time),
a total device delay of 57nS occurs, worse case. f=1/t = 1/57nS = 17.5 MHz.
Total "typical" device delay is 25+12ns= 37nS for f= 27 MHz.
This does not take into account L/C loading of the output filter, etc.,
which will lower the maximum frequency which the MOSFET will toggle on and off.
GL de Paul NA5N
For a 5-15 watt transmitter, the IRF510 is a pretty good choice.
Its Drain-source breakdown voltage is 100V which gives a reasonable amount of headroom.
(on mod peaks the supply voltage will be 24V , assuming a 12V powersource.
The RF voltage on the FET will be something more than 2 times
that, say peak voltage of 60-70 Volts.
The input capcitance of the IRF510 is quite low (Ciss ~= 150PF)
which makes it easy(er) to drive than larger mosfets with higher gate capacitance.
Why not try to get more out of the IRF510? The problem is Rds - the on Resistance, which is 0.4 ohms for the IRF510.
The output impedance seen by the FET is roughly V*V/2P where V is DC supply voltage and P = power out.
If P = 10 and V=12 then the output impedance is about 12*12/2*10 = 7.2 Ohms
If P = 20 and V=12 then the output impedance is about 12*12/2*20 = 3.6 Ohms
As the value of Rds gets larger relative to the output impedance the efficciency drops
and you stat producing more heat and less RF.
At the small end of the scale, you could try MTP3055Es.
They are tested at 7 Mhz, but they are gate capacitance is about 3 times that of the IRF510,
and thier breakdown voltage is rated at 60 Watts.
If you can drive them you may be able to get more out than an IRF510,
assuming you adjust the output network ...
MICROHOBBY Nº3 Modulador clase A http://www.qsl.net/lu8eha/lab_ref3.html
MICROHOBBY Nº4 Sintetizador. http://www.qsl.net/lu8eha/lab_ref4.html
예 1: 3625 kHz = 3200 + 320 + 80 + 20 + 5
예 2: 7255 kHz = 6400 + 640 + 160 + 40 + 10 + 5
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