Ramsey Electronics FT146 - Manual (Page 24)

FT146 • 24
Here's a handy reference chart for the 5 pin DIN jack
PIN # FUNCTION
1 +12 VDC power input
2 Power ground
3 Audio input
4 Audio ground
5 PTT (Push-To-Talk)
Audio level required is in the 10 to 50 mV range. PTT requires a path to ground
of less than 10K ohms.
OTHER ENCLOSURE RECOMMENDATIONS
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
boards in a single enclosure. Use of the inexpensive and attractive Ramsey
case set will give your unit that finished look and increase its resale value.
These sturdy black instrument cases are supplied with neatly-lettered front and
rear panels, rubber feet and mounting screws.
While we believe that the Ramsey enclosure option is a fine value for finishing
off your Ramsey kit transmitter, we're 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 additional
microphone, power and antenna connectors, and even a small mike. The
connectors are easily mounted at one end of such a box. It may be necessary
to cut away the molded posts which secure the tape cassette itself. These
storage boxes come in several styles, so pick one that looks truly practical as a
project enclosure.
If you wish to accomplish RF shielding, the most economical metal enclosure
nicely suited for Ramsey amateur kit boards 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.
CRYSTAL REQUIREMENTS
The FT146 transmitter uses a crystal at 1/9 the final carrier output frequency.
This is a fairly common type of crystal that is found in many of the older "rock-
bound" rigs that populate many hamfest flea market tables. You may order
additional crystals from JAN Crystal, 1-800-JAN-XTAL, specify HC-18/U holder,
wire leads, parallel resonant, 18 pf load capacitance.