IW3SGT 630m 5-15W amplifier (work in progress)

IW3SGT home page: www.iw3sgt.it 
Here is a simple class D amplifier with an inexpensive IRF510 that costs less than 1 Euro.

What does D class mean ?
D class is like C class with square wave input signal. IRF510 (same for IRF520/530) requires 0-8V gate level for interdition-saturation condition but high Cin values requires a low impendance/high current driver. I use a TC428 driver by Microchip then input signal can be simple TTL signal.

Why D class ?
Because in MF and LF Ham use only digital mode like WSPR, OPERA, JT and slow CW (QRSS3 and more) then linearity is not necessary in the amplifier's stage that complicates the schematic and less efficiency.

Have a look at this interesting document bu Paul NA5N about D, E and F class: ClassDEF1.pdf

For the MOS cooling I used a surplus Intel P4 CPU heatsink, the fan is not necessary for normal operations.

During long key down at 15W out (24V power supply) some capacitors become slightly warm, but I did not observe variations in the power out. I have done a test with 27, 30 and 32V and I see efficiency degradation and C10/C11 became hot.
Here is the schematics:

click here or in the pictures for enlarge it

Here the prototype:

Microchip TC1428 driver close up

Prototype measurements
    475kHz TTL IN
power s.     power OUT
 9V 375mA        2.2W
12V 492mA        3.8W
15V 609mA        5.8W
18V 725mA        8.4W
21V 843mA       11.4W
24V 961mA       15.1W
27V 1.11A       17.8W*
30V 1.47A       20.7W*
32V 1.65A       23.0W*
* not recommended

Useful info

IRF510 datasheet
IRF520 datasheet
IRF530 datasheet
IRF540 datasheet
TC1426 TC1427 TC1428 datasheet

Mini Ring Core Calculator by DL5QWB: http://www.dl5swb.de/html/mini_ring_core_calculator.htm
Elsie by Tonne Software: http://tonnesoftware.com/elsie.html
Soon to be done:
- change the MOS with IRF520/530 (target 10W at 12V)
- harmonic distorsion measurement (Is a 5 pole low pass filter enough ?)
- put it in a box

73 and good DX in the 630m band !
IW3SGT home page: www.iw3sgt.it


È vietata qualsiasi utilizzazione, totale o parziale, dei contenuti inseriti nel presente portale, ivi inclusa la memorizzazione, riproduzione, rielaborazione, diffusione o distribuzione dei contenuti stessi mediante qualunque piattaforma tecnologica, supporto o rete telematica, senza previa autorizzazione scritta di Alessandro Kosoveu IW3SGT (e-mail: iw3sgt_@_libero.it   remove _).
Any use , total or partial , of the content posted on this site, including the storage, reproduction, editing, distribution or dissemination of the contents by means of any technology platform, support, or computer network are forbidden without the written permission of Alessandro Kosoveu IW3SGT (e-mail: iw3sgt_@_libero.it   remove _).