Operation CHARM: Car repair manuals for everyone.

Checking Lead-In Cables

In case of continued reception or noise complaints, always check the lead-in with an ohmmeter, see Figure 1 and Table 1.

Figure 1 - Checking Lead-in Cables:




Table 1 - Lead-in Cable Resistance Values:





On some long lengths of lead-ins, such as power antennas, capacitance is added in the tip. This results in a resistance reading of approximately 100,000 ohms.
When checking resistance, cautiously wiggle the lead-in tip and cable. The above readings should always be obtained. If not, some portion of the lead-in is intermitted and lead-in should be replaced. Also try:
1. Running a braided ground strap to the antenna lead-in.
2. Changing the antenna lead-in.
3. Disconnecting the lead to check resistance.