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Old 4th Oct 2018, 8:43 pm   #1
greenkit
Tetrode
 
Join Date: Aug 2007
Location: Belfast, Northern Ireland, UK.
Posts: 80
Default Murphy B40D Audio Output

Just wondering if any B40D owners out there have measured the AF output power available from their set(s)? The manual says 2.5W maximum from the 600 Ohm line. I have two of these radios, and the best clean output I've seen with an AF generator input and a directly-connected 600 Ohm resistor load is about 0.5W. With an elderly RS Hygrade transformer coupling a 4 Ohm speaker to the output line both sets do sound weaker than I would expect. The valves are good, and I've been through the AF amplifier stages of one radio: found a few carbon resistors that had drifted high by 10-20%, and replaced them, but without significant difference. The coupling caps were still good.

Thanks for looking: any comments welcome.
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