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Leon Crampin · 12th Sep 2013, 9:08 pm

Michael, I've restored a couple of these and know some of the wrinkles. Change all the usual capacitor suspects, but especially, the RF bypass connected to the rectifier anode, 50nF I think. There may well be a blown 250mA fuse and a knackered U404 to greet you.

The U404 can be replaced by a UY41 without any wiring changes, but it would be polite to add 90 Ohms of heater ballast to maintain the correct current. A convenient place to add this is at the heater connection to the FM front end box.

The audio is not brilliant on these sets due to the tiny 'speaker and there is some hum caused by magnetic coupling between the heater and output transformers. As usual from Murphy, the RF performance is good - on AM it comfortably out-performs the offerings from Bush.

Leon.

12th Sep 2013, 9:08 pm	#1
Leon Crampin Octode Join Date: Nov 2005 Location: Surrey, UK. Posts: 1,874	Murphy A372 Michael, I've restored a couple of these and know some of the wrinkles. Change all the usual capacitor suspects, but especially, the RF bypass connected to the rectifier anode, 50nF I think. There may well be a blown 250mA fuse and a knackered U404 to greet you. The U404 can be replaced by a UY41 without any wiring changes, but it would be polite to add 90 Ohms of heater ballast to maintain the correct current. A convenient place to add this is at the heater connection to the FM front end box. The audio is not brilliant on these sets due to the tiny 'speaker and there is some hum caused by magnetic coupling between the heater and output transformers. As usual from Murphy, the RF performance is good - on AM it comfortably out-performs the offerings from Bush. Leon.