Custom Products for the Digital Radio Amateur Enthusiast

Click here for Parts List.
The parts list includes several construction notes too! Be sure to reference it along with this article to minimize the possibility of construction mistakes.

Please read through this article and the parts list at least once before starting your assembly. It will bring your attention to things that need to be done in order to prevent assembly errors.

Assembly can be done by personal choice, but you may find it easier to build in a vertical height order - installing the shortest components first, building toward the tallest, and finish with the connectors on the ends. The LEDs will need to have their leads bent similarly to the way they are on your original board so they will fit into their holes and mount properly. With the exception of the LEDs, all other components are installed tight against the circuit board.

Install all resistors. Some resistors color bands may be hard to make out. If in doubt, use an ohm meter to verify the value before soldering it in place. Bend both of the resistor leads sharply at the body at a 90 degree angle.

Install the crystal - tight against the board. Use the supplied plastic spacer under the crystal to insulate the metal body from the traces under it.

Install the diodes and shortest capacitors, observing polarity on all diodes and the polarized capacitors! The square pads are the banded end of the diodes and the + of the electrolytic capacitors. Small capacitors are identified as follows: "47" or "470" = 47pF, "103" = 0.01uF, "104" = 0.1uF, "105" = 1uF, and "107" = 100uF. In other words the first two digits are the value and the third digit (if present) is the number of zeros you add to determine the final value.

There are five Tantalum capacitors that are polarized and need to be installed the correctly. This circuit board has silkscreened outlines for the Tantalum capacitors that were altered to make the installation easier. The outlines of these components look like an oval race track. One of the longer straight lines is printed heavier (wider). The Tantalum capacitor is inserted so the printing on the capacitor is on the same side as the wider line. Look at the outline for C17 (the large yellow Tantalum) in the photo above for an example. Notice C3 and C5 install in opposite directions from one another. Do NOT install the 100uF Tantalum at this time, as it's quite a bit taller, and will be placed later in vertical order.

Install the 10k Trimpot.

Install the IC sockets - match the notch to the silkscreen.

Next, install the transistors (flat to flat on silkscreen). The silkscreen has a letter inside the outline of the part.
The N stands for NPN (2N2222), and P for PNP (2N2907). F stands for FET (2N7000) and D stands for Darlington (MPSA13).

Install the two, three and four pin headers - observing their colors and positions as noted on the parts list.

Install the relay. It doesn't really matter which way it's oriented, but it looks better if the printing is toward D5 so you can read it.

Install the 8-pin ICs - 2 - LM386s and 1 - LM555 observing correct orientation. Match the dot on the IC to the notch end of the socket.

Next, install the larger capacitors. You may need to bend the leads of these straight so they sit down tight against the board.

Install the 100uF Tantalum capacitor observing polarity. The printing goes on the side of the silkscreened outline that's printed wider.

Then, install the Mini-DIN-6 and USB "B" socket connectors.

Install all shaft potentimeters. Make sure they are tight against the board, and pushed back into their holes (and away from the boards edge) while keeping the alignment straight.

Then, install the 2 LEDs. NOTE the flat on the LEDs lens and the circuit board outline to insure the correct orientation of the LEDs. The LEDs have their leads pre-bent so they will fit into their holes and mount properly through the panel. Use your front panel to get the alignment right while soldering them in place.

Put the jumper shorts over the headers per the DRA-100-DIN6 jumper document.

Three small plastic washers get sanded to a final thickness of .031". One is placed onto the threaded body of each pot - - not now, in the next step.

Go to the article about installing the board into the case.

Information on the CM119A.
Click here to download a manual for the C-Media CM119A.

Email Kevin Custer for support.
 

DRAC-12 - 6-foot Mini-DIN-6 Radio Cable  can be added optionally to connect several data capble radios to the DRA-100.

Product of Masters Communications, all rights reserved.
Specifications may change without notice.
Images property of Kevin Custer - Masters Communications.
Board layout by Kevin Custer - W3KKC
HTML February 14, 2022, W3KKC All Rights Reserved!