FX 146
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14
GUIDE TO PC BOARD I/O CONNECTIONS:
In addition to primary interconnections required for jacks and controls, etc.,
your FX-series Transceiver PC board provides additional access to
operating voltages and circuit features to make later customizing as neat
and easy as possible. All these points are plainly marked on the board itself
and highlighted on the facing page, with a few other components for
FX-146
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133
8.
While speaking in the microphone, adjust modulation level (R46) for the
best sounding speech. "Best" is not necessarily the maximum: see the
following note. NOTE: R46 adjusts the FM deviation of the transmitted
frequency. Deviation is carrier frequency swing in step with voice
modulation. If you "over-deviate," your signal will not be stronger.
Instead, the speech will become distorted and "splash" over to adjacent
channels. Deviation is a very important adjustment: "best sounding
speech" will usually result in the proper 5KHz deviation used on VHF
FM.
9.
Disconnect power and proceed with completing the transmitter section
(Steps TX15, etc.)
IMPORTANT: If you do not achieve the test results discussed above, there
is no point in doing more work on the transmitter section until the problem is
solved. If you are not able to transmit at least within the same room and
receive on any desired frequency, finishing the transmitter is not going to fix
the problem.
CONTINUE TRANSMITTER ASSEMBLY:
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TX15. Install RF choke L19 (prepared in Stage TC). Notice that the
holes are diagonal from each other. If the choke was wound correctly,
L19 will line up nicely as illustrated.
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TX16. Coil L16 was also prepared in Stage TC. Insertion may stretch the
windings very slightly. Gently press L16 in as close to he top of the
board as possible, leaving about 1/8" clearance. The coil windings must
not, of course, touch the solder plane.
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TX17. Install C61, .001 uf.
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TX18. Install C66, 3.9 pf.
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TX19, Install C79, also 3.9 pf.
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TX20. Install C78, 22 pf.
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TX21. Referring to step TX16 and Stage TC as needed, install L15, the
other 5/16" 2.5 turn coil.
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TX22. Install L18, a .33 uh inductor with axial leads. (L18 looks like a
resistor body with wire wrapped around it and is marked by 2 orange
dots.)
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TX23. Install R45, 82 ohm (gray-red-black), R45 is larger than the other
resistors in your kit, it is a 1/2 Watt size resistor.
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TX24. Install L14, .015 uh, small pre-wound 1/8" 1.5 turn coil.
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TX25. Install C60, 220 uf electrolytic, observe polarity.
