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Post by w1ans on Feb 15, 2021 16:43:44 GMT -5
No receive in am or ssb a little static at full volume and can get it to him if volume switch wiring is touched. And ideas??
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Post by 2600 on Feb 17, 2021 2:19:38 GMT -5
Mark 4 radios seem to come in two varieties.
First, the radio that's "clean enough inside to eat off of". Nobody asks why the radio was never used or removed from the carton long enough to get dirty in 44 years. The reason is that it broke the first week and got boxed up immediately. By the time they called the factory about warranty repair, the company was circling the drain.
Second variety belonged to someone who found the transmitter's digital selector/PLL would "crash" only when the radio was turned on cold. Once it stabilized on his home channel, it would work as long as it was turned on. This radio will be burned to a crisp because it remained powered up 24/7 until it stopped working. This version of the radio will have way more dollars' worth of trouble than the one that never worked for more than a week.
First place to look might be the relay in the transmitter. If it comes loose from the socket, you won't have a receiver. Oxidized spring contacts in the tube sockets would be the next thing to check for.
And if you see darkened components that reveal years of heat stress, there are probably multiple faults to clear, probably including tubes.
The Mark 4A is not a bad radio if maintained appropriate to its age. The Mark 4 is a train wreck with more bad habits than I care to cover here.
73
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