VEC-1120K/1130K/1140K/1180K Instruction
Manual
23
Local Oscillator Alignment:
There are several methods for aligning the local oscillator portion of the
receiver. Use the method that is easiest for you.
Using a receiver:
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1. Place the VEC-11xx direct conversion receiver next to an Amateur or
general coverage receiver that covers the band of interest. Connect a
short 3 or 4 foot wire antenna to the receiver, route the antenna wire so
it passes near the direct conversion receiver PC board.
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2. Select a tuning tool that properly fits coil L1. The 20 meter kit
requires a hex type alignment tool. The other kits require a small
blade type tool that matches the slot in the coil core, or use a small
jeweler’s screwdriver.
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3. Set coil L1 tuning core to the top of the coil form.
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4. Tune the receiver to the lowest operating frequency by turning the
tuning capacitor shaft fully CCW (counter clockwise).
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5. Set the monitor receiver to the lowest frequency you wish to receive
on the direct conversion receiver. The receiver should be set to a wide
filter bandwidth, and if it has a BFO, it should be on.
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6. Install a fresh 9-volt alkaline battery to the receiver, and turn it on by
depressing the push-action power switch.
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7. Carefully adjust the core in coil L1 until it is heard sweeping across
the monitor receiver frequency. Set the coil for zero beat, or strongest
S-meter reading on the receiver. Note that metal alignment tools will
cause some frequency shift, and interact with the tuning when removed
or inserted into the coil. You will have to adjust the coil in small
increments, and observe the point where the proper frequency is
reached when the tool is removed.
Important Note:
Allow at least a 10-kHz tuning overlap on the band edges to
compensate for aging and long-term drifting.
Using a signal generator:
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1. Set the signal generator to the direct conversion receiver’s lowest
operating frequency. Set the generator output level for a 30-uV CW
signal.
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2. Connect the generator RF output to the VEC direct conversion antenna
jack (J1) using coax cable and the appropriate mating connectors or
adapters.
