Ramsey Electronics QRP20 User Manual
Page 14
QRP-20
• 14
18. Install R14, 10K ohms [brown-black-orange].
19. Install Q4, be sure to orient its flat side correctly as shown.
20.Install C15, .01 uf (marked .01 or 103 or 10 nf).
So far, here's what we've accomplished. First, we've got over a third of all the
parts soldered onto the board, which should make you happy, and you should
be used to locating the correct component holes with increasing ease by seeing
them in relation to previously installed components. Secondly, the keying circuit
is completed and would be usable, if there was something to key.
From here, we could proceed one of two ways. It would be quite easy to start
filling in the holes around the antenna jack, and the project could be done in
perhaps another hour. We'd like to suggest a better approach, which is to build
up the VXO stage (variable-crystal-oscillator) around Q1 and test it before
finishing the rest of the transmitter.
BUILDING THE VXO (VARIABLE CRYSTAL OSCILLATOR):
Your QRP transmitter comes complete with one crystal in the CW range,
usually the suggested QRP international calling frequency. S1 permits your
choice of any two installed crystals, the one that comes with your kit and
another which you may add on your own. If you plan to add a socket for your
own crystal, it should be wired to the "A" crystal position.
The PC board used in your kit is common to all the QRP transmitters in the
Ramsey Kit line. This means that there are some component locations on the
PC board that may not be used on your kit. Please be aware of this and install
your parts carefully. The parts layout diagram is quite clear regarding this. (The
reason for these holes is that different frequency bands require various styles of
inductors and capacitors for correct VXO frequency and shift).
Now, since we have gone to all this explaining, let's install some more parts!
21. Install L1, 2.2 uh inductor (green body with two red bands).
22. Install C1, .01 uf (marked .01 or 103 or 10 nf).
23. Install R2, 1 megohm (brown-black-green).
24. Install Varactor diode D3, observe correct placement of the flat side.
(Varactor diodes act as a variable capacitor whose capacity is varied by the
voltage applied across it).
25. Install varactor diode D4, observe flat side placement.
26. Install R3, 1 megohm (brown-black-green).
27. Install R4, 10K (brown-black-orange).
28. Install C2, 68 pf.