30-Meter QRP (CW)by P. Wyns, ON7WP (Belgium)

This transmitters' intended purpose is for morse-code only in the 30 meter band (10Mhz). It is a low-powerQRP type and needs to be connected to your existing tranceiver. The harmonic rejections on the prototypewere measured at 40dB on 20Mhz and 50dB on 30Mhz.

Component Layout.

30-Meter QRP (CW) http://www.sentex.ca/~mec1995/circ/30m.htm

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1-5/16" x 2" (34mm x 52mm) double-sided.

Parts List

R1 = 100K C1 = 22nF L1,L3 = 820nH BNC connector R2 = 4K7 C2,C5 = 1nF L2 = 1.8H Coolrib for Q2 R3 = 12K C3 = 100nF L4 = T-94-2 (Amidon) Morse-key, single pole R4 = 18 Ohm C4 = 100pF Q1 = BC547 All-metal casextal = 10Mhz C6,C7 = 330pF Q2 = 2N2219(A)

Additional NotesThe transmitter is build as a Colpitts Oscillator with a strong 2N2219(A) transistor. HF-output of the oscillatoris 100 to 500 mW, depending on the supply voltage of 5 to 20 Volts. The transmit frequency is stabilized withthe 10Mhz crystal. A slight detuning is possible by putting a 150pF trimmer capacitor between C2 and thextal. The oscillator signal is taken from the collector of Q2 by induction and via a low-feedthrough filter andguided to the output. This particular filter is called "Chebychev" and uses standard E12 type values. Theoscillator is keyed by Q1, which biases as long as the morse-key is open and the base of Q1 is at ground level.By keying the morse-key Q1 is blocked and allows Q2 to freely oscillate. For best results, use the doublesided pcb as shown above. Coil L4 exists of Primary 6 turns and secundary 3 turns of 0.5mm magnet wire ona Amidon T-94-2 donut. Outside diameter is 24 mm and inside diameter is 14mm; the A(l) value is 84H per100 turns and permeability of 10. Q2 needs a coolrib! The whole circuit needs to be mounted in anall-metal/aluminum case. If you're unable to obtain an all-metal case, then use a roll of self-sticking aluminumtape (available from your hardware store), just make sure that all individual pieces of aluminum-tape areconducting with each other. Works fine. Don't forget the coolrib on T2.

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30-Meter QRP (CW) http://www.sentex.ca/~mec1995/circ/30m.htm

2 de 2 27/01/2016 18:59