sceiv

make it easier to remove, you can mount a
19-pin SIP (Single InIine Package) socket
directly to the FX-146 board and anach a
19-pin header to the EPROM board. If you
use individual header pins, you can line them
up by sticking them in the SIP socket and
lining them up with the holes on the EPROM
board . Then just solder the pins in place.
Youcan use a 2Q-pin socket and header and
just CUI them down to 19 pin.s (see the parts
list). You'll have to wire the EPROM board
up 10 +5 volts and ground points on the
FX-146 board as well.
I attached the 19-pin header to the component
side of the EPROM board so it can be
plugged directly into the FX-I46 board. The
foil side of the EPROM board should face up
towards you when ir's in place (see Photo C).
If you plan to mount the thumbwbeel frequency
select switches on the front panel just
CUi out a hole in the panel 10 allow a snug fit
for all five switches. Just run wires from the
thumbwheel switches over to the EPROM
board as shown in Photo B.
Power up the Ramsey transceiver and you
should now have a very versatile 2 meter rig
with direct frequency input.
Since the diode matrix area of the FX·I46
seems to be relatively free of RF, the board
worked well as shown. However, if you
should have any problems, you may want to
add 0.01 IJF ceramic capacitors from each
address line to ground.
Programming the EPROMs
How arc the contents of the EPROM determined?
A BASIC program that yields the data
is included in the sidebar. The -600 kHz
duplex bit is set for 145.10-145.49 MHz and
146.60--146.99 MHz. The +600 kHz duplex
bit is set for 147.00 to 147.39 MHz.
For the faint-of-heart who don't want to
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FX-146
©
10/91 REV 1.3
CIRCLE 4 9 ON READfR SERVICE CARD
14 73 Amateur Radio Today. June, 1992
. •
Flgur~ 4. Anach the EPROM board to thefrequency programmmg lmes as shown hu e In the
diode maim area ofRamsey FX-J46 PC board. You can either use a SIP socket to mount the
EPROMboardjust above the FX-/46 circuit or ron wires from the EPROM board to the points
shown here. +5 volts andgroundare easily obtainedfrom the Ramsey board as well. Diagram
counesy of Ramsey Electronics.