08-12-2017, 12:25 PM
You've already established that the problem is signal level dependent and you say it has an internal linear PSU.
Do you have a suitable external PSU that you could try in place of the battery? If this works - with the PSU as close to the radio as possible, of course - this would point to a problem with the internal PSU. Check any suppressor capacitors on the mains input, that any electrostatic shield in the transformer is grounded OK. It's a long shot but I wonder of faulty rectifier diodes could cause a problem?
Do you have a suitable external PSU that you could try in place of the battery? If this works - with the PSU as close to the radio as possible, of course - this would point to a problem with the internal PSU. Check any suppressor capacitors on the mains input, that any electrostatic shield in the transformer is grounded OK. It's a long shot but I wonder of faulty rectifier diodes could cause a problem?
