TelePost LP-100, Manual

Page: 11 / 36

11
Assembly cont’d
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Install miscellaneous parts such as resonator, Piezo transducer, transistor, diodes, etc. NOTE: Remove the protective covering on
the transducer before using. Also, the “+” lead goes to the side with the jumper, per the placement guide. The outside leads of the
resonator are interchangeable. Do not install chokes yet.
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Install connectors and switches, except for J4, the DB9 connector. You will probably have to prop sections of the board up to
ensure that the parts are flush with the board. Install the header on the PLED PCB. The header is installed on the back side of the
PLED PCB with the long pins pointing away from the board.
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Install 7805 regulator. Attach heatsink to the regulator before installing on PCB, using 4-40 x ¼” (6.35mm)” machine screw and
small hex nut. It doesn’t matter which side the nut is on.
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Install T2 near C43. This xfmr is made up of 10 bifilar turns of #28 enameled wire wound on a FT37-61 core. Wire is supplied in
red and green to make wiring a snap. Bifilar means that the two wires are wound as a pair. See diagram above for wiring. It does
not matter if the wires are parallel or twisted. A turn is defined as a pass through the center of the core. You will wind up with three
leads, which will be inserted into the three holes indicated on the silk-screen. The lead with two wires goes to the center hole in the
PCB. Make sure that the enamel is removed from the leads before soldering to ensure good contact.
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Install L4 and L6. The remaining chokes will be installed as part of the initial checkout of the board, in order to enable powering up
of circuits individually. These may be brown or green, but are smaller than the other chokes.
NOTE: If you check the chokes with a
meter like the AADE, the readings may be low. This is because the chokes use ferrite cores, and the L varies with frequency. The
little meters tend to test at very low frequencies.
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The jumpers for the PTT connector can be wired now. The normal wiring is shown on the component placement diagram at the
beginning of this chapter, and below. This provides for a normally closed connection between the center conductors of the two
RCA connectors. This will work for most rig/amp combinations. For more options for PTT wiring, check out the SteppIR Tuning
Relay section of my webpage.
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Attach J4, the DB-9 connector to the PCB using 4-40 x 3/8” (9.53mm) screws, lockwashers and small hex nuts. The lockwashers
and nuts go on the bottom of the board. Solder the pins after tightening the screws to avoid stressing the pins after soldering.
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You can install RL1 at this time. The correct positioning is with the two separated pins toward the back of the board, next to the
snubber diode, D5. The notch in the top is also positioned next to the diode. See the component placement illustration. I used to
supply a socket for this, but have decided that there’s really no need for it, and there’s a risk of the relay working loose during
shipment.