Ramsey Electronics QRP20 User Manual
Page 16
QRP-20
• 16
CRYSTAL OSCILLATOR TESTING:
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Connect a key, keyer or momentary switch to J3.
◊
Connect +12VDC to power connector J4. Note that the CENTER
connection is the positive (+) side.
◊
Tune a nearby receiver to the anticipated crystal frequency.
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Make sure that S1 is set to the correct crystal position.
Keying J3 should result in a crisp, clean oscillator signal in your receiver.
Adjusting the R1 tuning control should vary the crystal frequency up to 7 KHz.
If you have installed a second crystal, test it in the same manner. Also, you will
notice that the VXO circuit usually swings the frequency down, a fact to
remember if you order additional crystals.
NOTE TO NEWCOMERS:Please be aware that even this one transistor
oscillator is itself a transmitting device, quite capable in good propagation
conditions of emitting an RF signal and HARMONICS, when and if connected
to an antenna. It is correct practice to keep your test brief and to identify them
with your callsign.
FURTHER ASSEMBLY;
The following three steps connect a simple low-pass filter to the antenna jack.
The low-pass filter prevents harmonics from the transmitter from reaching the
antenna.
37. Install C18, 220 pf (marked 220 or 221).
38. Install inductor L6, 1 uh (brown body with wire wrapped around it).
39. Install C17, 220 pf (marked 220 or 221).
BUFFER AND RF AMPLIFIER WIRING:
40. Install C8, .01 uf (marked .01 or 103 or 10 nf).
41. Install Q2, marked 2N3053. Observe the case of transistor Q3. The
small metal case tab must be oriented correctly! Please be careful.
42. Install R9, 100 ohms (brown-black-brown).
43. Install L2, 100 uh [brown-black-brown-silver]
The buffer stage is now completed and connected to the base of the power
amplifier stage, Q3.
44. Install R10, 270 ohms (red-violet-brown).
45. Install L3, 1 uh inductor [brown body with wire wrapped around it].