AT-11 Datasheet, PDF (4/15 Pages) List of Unclassifed Manufacturers – AT-11 Automatic Antenna Tuner

Parts are installed and soldered in order of height, from shortest to tallest. With the PC board blank, it
is easiest to install all of the resistors first. Be sure to check the values with the parts list. Most of the
resistors are 1/8 watt and may be hard to read. Use an ohmmeter to verify the values if you have trouble
identifying them.
Next, install the 1N4148 diodes. Then, the larger 1N4001 (D20). Be sure to note the band polarity on
both types. Next, install the monolithic and ceramic caps. The SIP resistor can also be installed. Be sure to note
the orientation of the SIP resistor. A small line (or dot) on the side with writing marks pin 1.
Next install U2, the 34064 (use the parts placement sheet for orientation). Then U3, the 78L05. Next,
install Q1-17. Note the orientation. Then, the variable resistors VR39 and 40. Then the Variable capacitor
C35.
Now install T1. It lays flat against the PC board and the #18 wire from the SO-239 (installed later)
will pass through the center. You may wish to use a small amount of silicon RTV or glue to hold T1 in place, but
wait until after the unit is tested before applying it in case there are problems.
Now install the socket for U1. Note the orientation of the socket. The flattened corner goes in the upper
left, toward the oscillator. Do not install the 68HC11 until later. Then the 8 MHz oscillator. Three of the
corners are rounded and one corner is square on the oscillator. The square corner is pin 1.
Next, install the tuning capacitors, C58-67. Be sure to match the values from the capacitor chart
(figure 6). Then the electrolytic capacitor, C51, on the power input, note the polarity. Then the power jack.
Now, relays K1-17 can be installed.
Lastly, inductors L1-8 can be installed on the PC board. Note that the mounting holes are offset slightly
on L3-L8 to help keep the inductors straight after installation. The inductors can be pushed in until the
windings touch the PC board. Don't forget to scrape some the insulation off the ends before trying to solder. The
#18 wire is stiff enough to support L3-L8, but RTV or hot melt glue may be needed for L1 and L2 to hold them
in place. The RTV or hot melt glue should be used if you plan to use the unit in a mobile application.
The circuit should be "power on" tested once all the components except for U1 (the 68HC11 chip) have
been installed. Apply 12 to 14 volts DC to the power input. Check for +5.0 volts on the output of the 78L05
(pin closest to U1). Current draw should be around 20 mA (anything less than 30.0 mA is acceptable). If the
volts and amps look good, you can proceed to mount the unit in the case and begin wiring the user interface. Do
not drill the mounting holes on the PC board to make them larger.
Just about any metal enclosure that is 5.5 inches deep by 8 across by 2.5 inches high will work. See
the front panel layout for ideas (figure 7). LDG also has custom finished enclosures available for around $30.
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