The Corsair Transmitter by Dave Martin

The CORSAIR transmitter was designed by
Dave Martin of W.N.K.R. in 2004.
It is a 10 watt AM short wave transmitter that does not need a modulation transformer,
thereby much simplifying the design.
The "Pierce" oscillator uses a common symmetrical FeT, the 2N3819.
The driver stage is a BFY 51 and is series modulated by a LM386 Audio IC.
The output stage is a very robust MoSFeT,
the IRF530.
It is possible to achieve more
output power than 10 watts.
But to give excellent audio reproduction, the power has been kept to the lower level.
On these pages we will outline versions of the "CORSAIR" for use on different bands.
At present versions have been made and used on air on medium wave through to 32 metres (9.3Mhz)

A LM386 audio IC is used to series modulate Q2. The LM386's output on pin 5, sits at half the supply voltage. But is swung plus and minus with the audio being fed to it's input.In the high current version Q4 allows Q2 to draw more current without damaging the LM386. The PA, Q3, is a IRF530 which is configured as a linear amplifier. To set up you should, by adjusting RV2, set the DC voltage at TP1 to 2.5 VDC. Then by moving the turns on L6 further apart or closer together, get the RF power to read 10 Watts. It must be noted that Q2,Q3 & Q4 must have heatsinks and that Q3 & Q4 should be mounted using a TO220 insulation kit.
The table below shows the component changes needed to the PA and Filter section to use the CORSAIR on other bands.

All the above coils are wound using 22 - 24 SWG,
enamel covered copper wire.

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