Radio Alignment

Ran into a fellow company Driver yesterday at a Loves and he asked me for a radio check because he had just installed a brand new Cobra 29 LX, well I could barely hear him so offered to help him. First thing I did was listen to his radio and heard very little static or incoming signals so Im thinking antenna system is bad because he is driving a Volvo with over 400,000 miles. Normally the stock antenna system, from my experience, works pretty well on a volvo but if it is old the coax or the Rami box could be bad, so we installed a new antenna using Volvo bird perch, 18 feet of RG 58, and a Frances antenna and the radio now had much better receive but modulation was still low so I adjusted VR 4 almost all the way counter clockwise. ( it was only half way) and now the radio was loud and clear , even with stock mic. I know there has been alot of discussion about peak and tune , but I think , from this experience, it might be a goid idea to at least get an alignment per service manual guidelines.

 

I have read that the reason the modulation level is set so low by the manufacture from the factory is so the wattage level does not exceed FCC limits if they were to check a shipment, but I guess I thought they were mainly concerned with carrier wattage not exceeding 4 watts and increasing the modulation level should not affect the carrier, or are they also concerned about the pep swing?

 

The service manual for a Cobra 29 says to set modulation level at 100% and with the limiter intact I dont think there is any risk of overmodulation,but I do agree it would be better to adjust it with the use of a scope and SA so you know exactly where to set it instead of guessing.

 

That radio should have a variable RF power control knob, was 2watts on low or high power? There is an adjustment pot for high and low carrier as well as modulation, so once again another example where it would be beneficial to have a proper alignment done for best radio performance.