08-27-2018, 05:57 PM
Hi,
I am a new member of the Philco Phorum and I am pleased to have discovered this website.
I have replaced all of the electrolytic capacitors and all of the wax/paper capacitors. In addition I replaced any resistors that had drifted out of tolerance. I also discovered that the primary of the output transformer had been previously burned out. So the output transformer has also been replaced. Then I peaked all of the IF coils and antenna/RF circuits.
The AM band works quite well and has good sensitivity.
However, on the SW band (8.9 to 12 MHz) all I get is a loud hum - almost like motorboating. It is not 60 Hz or 120 Hz power supply hum as the B+ is nearly ripple free. The noise seems to have peaks and valleys evenly spaced along the SW band. Any Ideas on what is causing this and how to cure it?
Also, should the local oscillator frequency be set above the desired station frequency or below it? Currently it seems that the local oscillator for the SW band is operating below the desired station frequency.
Any help and advice will be greatly appreciated.
I am a new member of the Philco Phorum and I am pleased to have discovered this website.
I have replaced all of the electrolytic capacitors and all of the wax/paper capacitors. In addition I replaced any resistors that had drifted out of tolerance. I also discovered that the primary of the output transformer had been previously burned out. So the output transformer has also been replaced. Then I peaked all of the IF coils and antenna/RF circuits.
The AM band works quite well and has good sensitivity.
However, on the SW band (8.9 to 12 MHz) all I get is a loud hum - almost like motorboating. It is not 60 Hz or 120 Hz power supply hum as the B+ is nearly ripple free. The noise seems to have peaks and valleys evenly spaced along the SW band. Any Ideas on what is causing this and how to cure it?
Also, should the local oscillator frequency be set above the desired station frequency or below it? Currently it seems that the local oscillator for the SW band is operating below the desired station frequency.
Any help and advice will be greatly appreciated.
