Ramsey Electronics FR6 - Manual (Page 18)

FR6 • 18
TESTING, ALIGNMENT AND ADJUSTMENT
To prepare the FR6 FM VHF Receiver for reliable monitoring operation, you
will need these basic tools:
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1. A useful 6 meter signal source.
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2. Hexagonal, non-metallic coil slug alignment tool for L3.
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3. Small screwdriver to adjust L4.
1. Signal source: This signal can be from your test bench equipment or from
a "live" source such as a local repeater. The "live" signals are best for fine-
tuning, but they also have that VHF communications character of being fast
and to the point. Good test bench signal sources include your own 6-meter
tranceiver, if you are licensed to use it, a signal generator or grid-dip oscillator.
If TV channel 2 (54-60 MHz) is active in your area, you may use its
characteristic video sync “buzz” as an indicator of receiver operation. Do not
expect to hear the audio portion clearly, since TV sound signals are fairly
wideband FM (75 KHz) which is too much for our narrow-band FM ceramic IF
filter.
2. L3 Alignment Tool: If you do not already have a set of plastic or nylon coil
alignment tools and do expect to try further Ham radio or electronic hobby
projects, such tools are worth having and can be found inexpensively at any
electronics store including Radio Shack. While a metal Hex key wrench can fit
the coil slug, the metal itself would damage the coil inductance drastically and
therefore should not be used. With patience and sandpaper, a useable tool
might be formed from a wood or plastic rod.
ALIGNMENT PROCEDURE
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1. Make sure the power switch is off.
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2. Connect the antenna, earphone or speaker and battery.
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3. Turn the slug of L3 until it is even with the top of coil the form.
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4. Now, turn the slug of L3 clockwise 1 1/2 turns back into the form.
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5. Turn the slug of L4 until it is flush with the top of the coil and then turn it
2 turns back into the coil.
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6. Turn all three controls to the left, fully counterclockwise.