CORSAIR CIRCUITS by Dave Martin

The Corsair 2007.

The Corsair 2007 is merely a refined version of the original Corsair.
Lessons learned & feedback from others who have built the circuits have led to the circuit you now see above.
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.

Intro

HomeBrew
Pirate radio

BAND	L6 Turns	L7 Turns	Core type	C17 pF	C18 pF	C19 pF	C20 pF
1.5MHz	17	30	T-50-2	1290	4610	1800	1800
1.9MHz	14	30	T-50-2	1290	4610	1800	1800
3.7MHz	10	21	T-50-2	560	2680	720	720
3.9MHz	10	21	T-50-2	560	2000	720	720
6.2MHz	7	14	T-50-2	560	2000	470	470
7.0MHz	7	14	T-50-2	560	1360	470	470
9.3MHz	5	12	T-50-2	700	1150	300	300

The second circuit shows the optional VFO. Values given will work over 6 to 8 MHz. The Corsair should be built with the crystal first.
VFO Values for other bands are shown below.

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

Clip on heatsink for Q2.

TO220 Insulation kit for Q3.

BAND	L Toko Number	VC1 pF	C1 pF	C2 pF	C3 pF	C4 pF
1.8MHz	KANK3333	75	120	560	1000	1000
3.5MHz	KANK3334	75	100	560	1000	1000
7.0MHz	KXNSK4173AO	25	47	270	560	560
10.1MHz	KANK3335	25	68	220	680	680
14.0MHz	KANK3335	25	68	68	220	220

Last updated, 16/09/2007.

Remove Xtal from socket
when using VFO.

If the LM386 gets hot try this version of the circuit, here.