SDR Cube Transceiver
Online Assembly Guide
Detailed construction notes for building and testing each of the SDR Cube kit modules
Bill of Materials
RXAMP Multi-Rx X-LPF Internal Cable Set External Cable Set Main Enclosure Accessory Enclosure
Digital Subassembly Test Final Assembly RF Functional Test
|Building the Internal Cable Harness ... (Section version 1.0b: Larger pin numbers in wiring diagram)|
What Is It?
The Internal Cable Set is comprised of the 40-wire flat cable that connect the DSP and I/O boards ("Cable 1"), and the 6 smaller ribbon cables that interconnect the DSP board with the internal Softrock. A DB-15 connector is provided to fill the hole in the rear panel of the Enclosure - otherwise there is no need to connect anything to that DB-15.
[____] STEP 1: Inventory the supplied parts
Check to make sure you received the CABLE-Kit-Int bag and all the components that are pictured below. (Click on any photo to see a larger image.)
Designator QTY Description Source INTERNAL SOFTROCK CABLE HARNESSES Cable-1 1 DSP-to-I/O Cable J101, J102 2 CONN 40POS IDC SOCKET 10GOLD (connector and clamp) Cable-2 1 ATTEN Cable (4-wire, 5.5") J103, J104 2 Receptacle, 2x2, 0.1", cut from 20P 2ROW STRT SOCKET Cable-3 1 LINE-IN Cable (3-wire, 6") J105 1 Receptacle, 2x2, 0.1", cut from 20P 2ROW STRT SOCKET J106 1 Receptacle, 1x3, 0.1", cut from 36P 1ROW STRT SOCKET Cable-4 1 CLOCK Cable (3-wire, 4") J107 1 Receptacle, 2x2, 0.1", cut from 20P 2ROW STRT SOCKET J108 1 Receptacle, 1x3, 0.1", cut from 36P 1ROW STRT SOCKET Cable-5 1 LINE-OUT Cable (4-wire, 10") J109 1 Receptacle, 2x2, 0.1", cut from 20P 2ROW STRT SOCKET J110 1 Receptacle, 1x3, 0.1", cut from 36P 1ROW STRT SOCKET J116 1 Receptacle, 1x2, 0.1", cut from 36P 1ROW STRT SOCKET Cable-6 1 SOFTROCK POWER Cable (2-wire, 6") J111, J112 2 Receptacle, 1x2, 0.1", cut from 36P 1ROW STRT SOCKET Cable-7 1 RF Cable (2-wire, 2") J113, J117 2 Receptacle, 1x2, 0.1", cut from 36P 1ROW STRT SOCKET Cable-8 1 Bandswitch Cable (2-wire, 6.5") J118, J119 2 Receptacle, 1x2, 0.1", cut from 36P 1ROW STRT SOCKET J115 1 D-style, 15p, female, panel mount 2 Machine screw, pan phillips, #4-40x3/8" 2 Nut, #4 18 Heat Shrink Tubing & Sleeves FP-301 1/8 X4' RED 32 Heat Shrink Tubing & Sleeves FP-301 1/8 X4' BL
STEP 2: First build Cable1, the 40-position flat cable that connects the DSP and I/O boards ...
This is the goal ... create a 40-wire flat ribbon cable that is 2.5" long, with IDC connectors on either end, pointing in opposite directions Hold the pieces in place ... Start by holding the two connector halves (connector and the thinner clamp) in place with the ribbon cable in between. The ribbon cable should come right to the end of the outside of the connector (i.e., don't go too much past the end such that it sticks out the other side of the IDC.) The connector sides have little ridges that tend to center the ribbon cable in the right position when you press the connector halves together with your fingers. (Hence the name of this IDC connector: Insulation Displacement Connector.) Pressing Method #1 ... Using wide hand clamp (e.g., from Harbor Freight) ... Making sure the ribbon cable stays in position, press the two halves together with the hand vise until the connector pins "bite" through the wires and the ends of the thinner plastic clamp snap onto the end knobs of the connector. Pressing Method #2 ... Using a bench vise (preferred method) ... Making sure the ribbon cable stays in position, press the two halves together with the bench vise until the connector pins "bite" through the wires and the ends of the thinner plastic clamp snap onto the end knobs of the connector.
(Harbor Freight ... http://www.harborfreight.com/4-inch-jaw-capacity-drill-press-vise-30999.html)
(harbor Freight ... http://www.harborfreight.com/2-1-2-half-inch-drill-press-vise-5927.html)
The completed Cable #1
NEXT ... The Internal Cable Set Construction! ...
NOTE: Before you start, be aware that Cable 6 (SR Power) really needs to be about 6" long, not 3" as supplied with the initial run of kits. We're now shipping a 6" cable, and we're sending a 6" replacement ribbon cable in the Service Pack ... But if you want to make progress right now, just grab two 6" lengths of hookup wire or ribbon cable and use it instead of the 3" ribbon cable provided. The cable just supplies 12V power (~300ma) to the SR-base - no special precautions are necessary.
STEP 3: Separate the wires at each end of each cable such that about 1" of each wire in the ribbon cable is free and separate.
STEP 4: Strip off about 1/8" of the insulation for each wire on each end of the cables, and tin the exposed wire
STEP 5: Organize the supplied ribbon cables according to the diagram above for the right length of cable, the right connector for each end, and the red and blue shrink tubing.
5a) One way of organizing things is to get a piece of paper and put down 6 lengths of double-sticky tape. This will hold the cables in position.
5b) Label each one so you know which cable is which: Cable 2 through Cable 7. Go in the order of the diagram above - it will be a big help!
5c) Press each cable down along its respective "row of tape" on the paper.
5d) Cut the length of RED heat shrink tubing into 13 pieces. Each one should be no longer than 1/4" .. actually a tad less than this will make it easier for you. The purpose of the red shrink is to denote "pin 1" on each connector, and to protect the bare wire connection you will make to those pins.
5e) Cut the length of BLUE heat shrink tubing into 23 pieces. Each one should be no longer than 1/4" .. actually a tad less than this will make it easier for you. The purpose of the blue shrink is to denote "the other pins" on each connector, and to protect the bare wire connection you will make to those pins.
5f) Your sheet of paper should look like the photo below at this point ...
STEP 6: Using the pin numbering for each connector, insert the correct color heat shrink over each wire and carefully solder it to the correct pin for each connector.
The pin numbering for each 2x2 pin connector is the standard Z-pattern, as seen from the rear of the connector (solder tail side), with pin 1 in the upper left and pin 2 to the right of it, etc.
For example, let's walk through the wiring for Cable 4, J107 ...
- Grab the wire at the outside edge of the ribbon cable, slide a piece of red shrink on it, and solder it to J107-pin1.
- Grab the very next wire next to the one you just attached, place a piece of blue shrink on it and solder it to J107-pin 4.
- Grab the third wire in that ribbon cable, slide another piece of blue shrink on it and solder it to J107-pin 2
- That's it for that connector. J107-pin 3 will not have a wire connected to it. This connector might look like the following:
STEP 7: Apply heat to all the shrink tubing on the end of each cable.
After all wires on the cables have been soldered to their respective connectors, with their pieces of heat shrink still loose, apply heat with a hot air gun or with the tip of your soldering iron. The tubing will shrink neatly to form nice, tightly-insulated and reinforced connections on the pins. See the photos below ...
STEP 8: All done! It will look like this ...
And don't forget to keep track of which end of the cable goes to the DSP board (left side) and which goes to the Softrock (right side)!
Here's an idea for keeping track of your cables, as once they leave the sticky tape on the paper here, they all start looking the same. Plus, it's pretty important to remember which end plugs into the DSP card (vs. into the SR-Base).
I slipped a larger yellow shrink tube over an end of each cable and applied heat to bring it down to a size that would keep it on the cable (i.e., not have it slip off the end.)
Then, I wrote the cable number on that yellow shrink tube and a "band" (like the cathode marking on a diode) on one end of the yellow shrink as a reminder for the end that plugs into the DSP card.
Of course, you can apply any label of your own choice using paper, tape, etc.
The internal Cable Set construction is complete! Set it aside and next move on to testing the RF Sub-assembly.
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Page last updated: Dec 31, 2010