Ramsey Electronics QRP20 - Manual (Page 20)

QRP-20 • 20
is the Ramsey CW-7 CMOS Keyer, with built-in sidetone.
This transmitter is an ideal travel companion to the growing number of portable
shortwave broadcast receivers which feature digitally synthesized tuning,
memories and other features, provided that a BFO for CW-SSB reception is one
of the features. In most cases, transmitter keying can be monitored directly from
such receivers without too much overload, though it may be necessary to rig a
simple switch to mute or attenuate the audio or short the antenna input to
ground while transmitting.
THE RAMSEY ELECTRONICS CASE, KNOB & HARDWARE
OPTION:
Your finished transmitter can be installed in a variety of enclosures of your own
design and choosing. You might be planning to combine several Ramsey circuit
kit boards in a single enclosure. Use of the inexpensive and attractive Ramsey
case and knob set will give your unit that nice finished look and increase its
resale value. These sturdy black instrument cases are supplied with printed
overlayes on front and rear panels, knobs, rubber feet and mounting screws.
OTHER ENCLOSURE RECOMMENDATIONS:
While we believe that the Ramsey enclosure and knob option is a fine value for
finishing off your Ramsey receiver or transmitter, we are happy to give you a
couple of additional suggestions and our reasons for them. If your first goal is
economy and rugged portability, you will find that the circuit board can be
mounted nicely in a standard VHS videotape storage box, which also gives
room for storing cables, a small homemade keyer, etc. The controls are easily
mounted at one end of such a box. It may be necessary to cut away the molded
posts which secure the tape itself. These storage boxes come in several styles,
so pick one which truly looks practical as a project enclosure. To accomplish RF
shielding, the most economical metal enclosure nicely suited for Ramsey
amateur kit board is Radio Shack No. 270-253A. This metal utility cabinet can
accommodate both a receiver and transmitter board, plus speaker, with room
for various refinements you might like to add.
NOTE ON CHOOSING, ORDERING CRYSTALS:
When ordering crystals for Ramsey QRP transmitters, specify 32 picofarad load
capacitance, parallel resonance, HC-6/U or HC-18/U holder, although virtually
any crystal will work. The back of Ham magazines have ads for many different
crystal suppliers (one source is JAN Crystals, 1-800-JAN-XTAL), any of whom
are excellent. A variety of crystal styles may be used, but do not expect to get
satisfactory output and keying from surplus crystals in the old WW-II, FT-243
holders which may have been opened and modified over the years.