Dc Power Supply Considerations - Ramsey Electronics FZ-146 User Manual

good 50 ohm load. Keep these key-down tests as brief as possible.
? TX52. If you are observing at least 4 watts of RF output, transmitter
tuneup is completed. Spread coils L13 and L16 on the main board and
L12 and L22 on the low pass board for maximum RF output. These coils
are purposefully wound with a little too much inductance, so that they
can be easily "peaked" by some spreading. This is probably one of the
most important steps to get the most RF out of your rig.
? TX53. Adjust Modulation control R46 by listening on another receiver or
scanner and simply adjust for best sounding audio. See Test Procedure,
Step 8, regarding FM Deviation.
? Remember that indicated RF output also depends on the accuracy of the
wattmeter and correct DC supply voltage. Our lab measurements
consistently show 4 to 5 watts or better. If your application demands
significantly more RF output, your FX-146 transceiver will drive the
Ramsey PA-146 booster amp (factory assembled with receiver pre-amp)
to its maximum rated outputs in the 35 to 40 watt range.
? TX54. Replace the dummy load with a well designed 2 Meter antenna
and start enjoying the FM transceiver that you built yourself!
IMPORTANT:
It is your responsibility to know what band privileges are granted by
your Amateur Radio License and how to program the frequency
synthesizer correctly within the 144.00 to 148.00 MHz operating range
of the 2 Meter Amateur Band. A proper license is required for
transmitting in this band. Other FCC licensing is required for operation
of this equipment on frequencies outside the Amateur Band. It is illegal
for licensed amateurs or other persons to transmit on frequencies for
which they are not properly licensed.
ELECTRONICS, INC.
RAMSEY
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FX 146 138

DC POWER SUPPLY CONSIDERATIONS :

Your Ramsey FM Transceiver is designed to operate from any stable DC
voltage source in the 12 to 15 volt range, from typical car, boat or plane 12V
systems to a wide variety of battery packs or AC-powered DC sources. In a
pinch, you can get on the air for quite a while with 8 to 10 ordinary "D" cells!
Our lab tests show only a .93 amp current draw for 5 watts of RF output. We
have just a few points of advice and caution:
1. Your DC supply should be able to provide a minimum of 1.0 amperes in
continuous service.
2. Any battery setup capable of supplying 12-15VDC will serve quite well.
3. Use of wall plug power supplies is NOT recommended. Obviously,
12VAC output is not suitable. Most DC output units do not have
adequate voltage regulation.
4. Turn your transceiver OFF before re-starting the vehicle in which it has
been installed.
5. Replace F1 only with a 1 amp fuse.
6. If you power your transceiver from the +12V accessory voltage available
from other equipment, be sure that source is rated for the 1 amp
required.
7. Your transceiver circuit includes noise suppression at the DC input and
additional filtering at the VCO, primarily to prevent ignition/alternator
noise from being introduced into the FM modulation. If you hear ignition
noise in the receiver, the vehicle has a serious general problem. Check
your transmitted signal on another receiver before mobile operation.
Radio Shack sells a variety of noise-suppression capacitors and
chokes. The ultimate solution, which has been tested, is to run the
transceiver from a smaller accessory battery.
If you plan to build a power supply for fixed-station use, there are numerous
construction articles in ham and electronics hobby publications. A
convenient new book featuring easy-to-find components and clear
explanations is Building Power Supplies (Radio Shack 276-5025.)
FX-146
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