02-27-2012, 01:20 AM
I couldn't get the presets to work properly and eventually found this bad 370 pF mica cap (#10 on the schematic).
It works with the adjustable coils to set the LO oscillator frequency.
[Image: http://farm8.staticflickr.com/7067/69342...bce9_z.jpg]
Each preset slug only covers a portion of the BC band as shown on the chassis.
[Image: http://farm8.staticflickr.com/7048/69342...8250_z.jpg]
Replacing it with a 390pF got the presets working, but I couldn't tune below 800 kHz on the first four presets. I bumped it up to 500 pF which go me down to 680 kHz.
I suppose I could increase the capacitance even more, but I'd like to know why the tuning range is so far off ?
[Image: http://farm8.staticflickr.com/7178/67880...e752_z.jpg]
It works with the adjustable coils to set the LO oscillator frequency.
[Image: http://farm8.staticflickr.com/7067/69342...bce9_z.jpg]
Each preset slug only covers a portion of the BC band as shown on the chassis.
[Image: http://farm8.staticflickr.com/7048/69342...8250_z.jpg]
Replacing it with a 390pF got the presets working, but I couldn't tune below 800 kHz on the first four presets. I bumped it up to 500 pF which go me down to 680 kHz.
I suppose I could increase the capacitance even more, but I'd like to know why the tuning range is so far off ?
[Image: http://farm8.staticflickr.com/7178/67880...e752_z.jpg]
