This latest Radio Tale comes from a series of Service Calls in the last month or two.
The Saga... Two-way Radio Customers often replace their own fuses when something causes their unplanned departure. Often a dead car battery jump start can be the source of a radio/equipment fuse vacation. We also see a lot of wrong size 20 or 30 amp fuses used "just for a temp fix"... left in line until something worse happens. And of course we know "worse does happen"... One not so cute problem we've seen in the last month are a number of "half-blown" slow speed (aka "slow blow") 3AG Auto fuses. The customer reports a radio doesn't work right/well. Initial inspection finds the radio farts out (fails) on tx. The radio receives 13 volts dc as measured but acts like the vco fails lock in tx mode. Well... after much head scratching one of the techs found an additional customer installed fuse holder in the wiring harness (outside the truck) with an inline 3AG slow blow fuse. The fuse was half blown.. allowing low current through the internal resistor (old fuse type 3AG glass slow-blow fuse with the visible internal resistor) although the main fuse internal current path had properly opened. Radio TX mode caused the resultant voltage drop and related tx problems. Replaced the whacky fuse and the tech put the event off as earned experienced. **** Onward... We make and install Kenwood portable vehicle chargers similar to "converta com' or pocket chargers, which are provided by us with new Pyramid Vehicle Repeater Systems (we install). One customer reported a problematic drop-in portable charger. I replaced the reported trouble pocket because it was brand new and shouldn't give us grief. Sometimes it's better to simply replace a new unit vs an on site repair with a busy customer standing around possibly getting mad. A week later the customer reported the second new charger pocket had the same non-completing charge problem as the first replaced charger unit. Go figure... the measured voltage to the charger pocket voltage "appeared normal" with a multi meter. To wrap things up... the charger pocket was problematic because of the same half-open 3ag fuse trick installed by the customer after his last truck jump-start. He didn't admit to replacing the fuse until after the half-blown slow blow fuse was located and replaced. Older slow blow fuses are not always 100%. The half blown fuse is a serious problem/issue in a high voltage power supply circuit. At low voltage operation they tend to only cost time and money. The question is... who's time and money should it be? cheers, skipp skipp
