LDG QRP Assembly Manual - page 3

QST, 225 Main St., Newington CT 06111. We've included the charts and tables from the article (modified for

the QRP version) needed to build the kit in this manual.

Before getting the soldering iron out, go through all of the parts in the kit and familiarize yourself with

each component and its placement. Most of the parts are common, but a few of them may be new to some

builders. There are about 150 parts and 500 solder connections, so take your time.

Once familiar with the parts, start with the nine T-50 toroids (they are red and just over a half inch

in diameter). Take care to not drop them, they will break. Use the number #24 gauge wire provided to wind

L1-8. For consistency, we count one turn when the wire passes through the center of the toroid. L1-4 just

loop at the bottom of the toroid (figure 2). L5-8 are evenly spaced around (figure 3). L8 is a double toroid,

two toroids held together with the winding around both of them. Use the inductor table to cut the wire to length

(figure 4). Wind each toroid in the same direction as shown in the diagrams. Note that L1-4 wind in one

direction and L5-8 wind in the other. The PC board is laid out with offset solder pads for the toroids. If you

wind them backwards, the offset will not match. Trim the wire to about 1/2 inch and scrape away the

insulation from the end. Don't solder them in until later.

Next, wind T1 with 10 turns (figure 5). It is the small, black toroid and just under 1/2 inch in

diameter. The windings use the smaller #28 gauge wire and are made bifiliar. This means to use two lengths of

wire and wind them at the same time. It doesn’t matter if you twist them together or just wind them side by

side. Connecting Green 1 and Red 2 together forms the center tap of T1. Be sure to note that the wire on the left

side comes from under T1 and the wires on the right side comes over the top side of T1. Trim the wire to about

1/2 inch and scrape away the insulation from the end. Do not install T1 until later.

Notice that some of the silk screen markings on the PC board may have been drilled away when it was

fabricated. Use the Parts Placement layout in the back of this manual to assist in locating where parts are

installed.

The 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.

After the resistors are installed, install the 1N4148 diodes. Then, the larger 1N4001 (D3). Be sure to

note the band polarity on both types. Next, install the groups of monolithic and ceramic caps. This includes the

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