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Do you have any hints on how to wire a lavaliere mic to a TA5F connector so the connection won't fail quickly?


Here are some things we've found that will strengthen and protect the connection:

  1. If the mic cable is much smaller than the strain relief boot, use a very flexible sleeve to increase the effective size of the cable. Allow about an inch of this sleeve to stick out of the TA5F boot. What you are looking for is a gentle curve in the cable when it is pulled at right angles to the TA5F boot. A stiff sleeve will cause a sharp bend right at the sleeve and effectively do nothing. We use a soft silicone shrink tubing here. Silicone model airplane gas line is very flexible and will work well. There is a self fusing silicone tape that can also be used. Taper the thickness around the cable as it comes out of the boot so that the cable makes that gentle arc as described above. If you start the wrapping at a point away from the connector and then work toward the pins, the loose end will be trapped in the connector. This will also give you a natural taper if you decrease the wind angle as you get close to the pin end. It is not necessary or desirable to put the tape under the crimp tabs. You are only trying to increase the bend radius where the tiny cable exits the TA5F boot.
  2. The metal strain relief crimp tabs in the TA5F are very critical to the longevity of your connection. There are two sets of tabs. The tabs closest to the solder pins should be used to crimp over the shield of the cable but not the outer insulation of the mic cable. This shield grounding will also give the best protection against RF from the transmitter. (The shield still needs to be soldered to pin 1). The second set of tabs, farther back, should crimp over the insulation of the cable. This requires fairly exact placement of the cable but you can and should have slack in the inner wires of the cable before they are soldered to the pins of the connector anyway. By assembling the connector this way, you have strain transferred to the outer insulation by one set of tabs and strain placed on the inner wires by the other set. The tabs should be firmly mashed into the insulation and cables but not so much as to puncture the wires. There is some judgment required here. There should be some deformation of the insulation but not enough to cause failure. You want to crimp the strain relief tabs enough so that a good pull on the main cable does not move the cable past the strain relief.
  3. As mentioned in note 2 above, there should be some definite slack in the internal wires when the crimping and soldering is all done. The shield is normally a fairly stout wire and only a little slack is necessary but the other wires should have a definite "kink" so there is no chance of cable movement transferring force to the soft solder connection or to the small signal wires. All force should be taken up by the strain relief.
  4. When stripping the wires and the insulation of the cable, use a good round hole wire stripper or even a thermal stripper so that the wires and the shield wires are not nicked. If they are nicked they will break easily when even slightly flexed. Don't use too small a stripper setting for the same reason. When in doubt, flex the wire(s) a few times; if strands break off, the wire has been nicked. You might as well just start over.
  5. Don't overheat the shield. This is usually the largest wire in the bundle and can easily conduct enough heat to melt through the insulation of the audio and bias wires. Since all the wires have to be short to get them into the small connectors, heat can be conducted quite quickly up the wire, melting adjacent insulation. Pre-tinning the end of all the wires before attempting assembly will keep the ends from fraying and enable you to solder much faster. This will help prevent insulation melt through. Along the same lines, don't heat the metal strain relief in any way after the tabs are crimped down. We had one dealer that soldered a chip resistor to the strain relief tabs after they were crimped to the cable. This melted the insulation and caused many mic failures days and weeks after the connectors were wired.


Posted 1 year agoby LectroAdmin