06-02-2016, 09:04 PM
The HT capacitor reforming process was a success. There is 300 volts at the reservoir capacitor and the supply to the detector and RF amplifier is about 210 volts.
Performance is disappointing, I'd expect a lot better from a Murphy receiver. There is a nice loud hum when the grid of the leaky grid detector is touched, so we know that all is well in that part of the set. The set is fitted with a Mazda AC/VP1 vari-mu pentode as the RF amplifier, it's certainly not the original, it's more likely the A3A was supplied with an RF tetrode such as the MS4 or AC/SG. An MSP4 was tried and the results were even worse.
Of course these sets were intended to work with a long wire aerial, perhaps I'm expecting too much from ten feet of wire.
Geordie McBoyne.
Performance is disappointing, I'd expect a lot better from a Murphy receiver. There is a nice loud hum when the grid of the leaky grid detector is touched, so we know that all is well in that part of the set. The set is fitted with a Mazda AC/VP1 vari-mu pentode as the RF amplifier, it's certainly not the original, it's more likely the A3A was supplied with an RF tetrode such as the MS4 or AC/SG. An MSP4 was tried and the results were even worse.
Of course these sets were intended to work with a long wire aerial, perhaps I'm expecting too much from ten feet of wire.
Geordie McBoyne.
