09-27-2015, 10:07 AM
Hi Todd,
What I would do is listen in another radio for the local osc signal. Easily done by using a little "shirt pocket" xsistor set. Would tune the Philco to 1000 kc. Listen for the osc around 1460kc on the xsistor set. Place it near the 36 mixer tube. The osc is operating at 460kc above the incoming signal. With the Philco dial at 700kc osc should be at 1160kc (700kc+460kc= 1160).
This holds true for pretty much all superhet sets (frequency on dial + the IF frequency= local oscillator frequency) Some sets the LO runs below the incoming frequency (frequency - the IF frequency= local oscillator frequency). This would be the exception rather than the rule.
So if you find that you LO is conking out towards the low end of the dial you'll need to add a few more turns to coil you just rewound ( tickler or feedback winding). You don't need to remove what you already wound just solder a length of 38g wire to what you have and add 3 more turns to it. That should put you in good shape.
I would suspect that the 710mmfd condenser is OK. For a four tube set they are good performers, but alignment of the IF is critical for good sensitivity. By adjusting the sensitivity trimmer on the rear apron of the chassis just below the point of oscillation will give you the best sensitivity, selectivity, and audio frequency response. The model 84's are a little better as they use a 8" spkr rather than your 6"er.
Oh and one other thing about the 80 and sets of it's ilk it works a lot better with a good earth ground to the chassis. You'll find that without a good ground the volume control won't be very effective. The VC is connected to the antenna and varies the amount of signal going into the set. Without a good gnd the VC doesn't have a good way the lower the amount of RF signal coming into the set.
Whenever I attach pics they always are out of order. Philco 81 w/xsistor set and xsistor set to listen for LO.
Are they still making Willys jeeps over there???
GL
Terry
What I would do is listen in another radio for the local osc signal. Easily done by using a little "shirt pocket" xsistor set. Would tune the Philco to 1000 kc. Listen for the osc around 1460kc on the xsistor set. Place it near the 36 mixer tube. The osc is operating at 460kc above the incoming signal. With the Philco dial at 700kc osc should be at 1160kc (700kc+460kc= 1160).
This holds true for pretty much all superhet sets (frequency on dial + the IF frequency= local oscillator frequency) Some sets the LO runs below the incoming frequency (frequency - the IF frequency= local oscillator frequency). This would be the exception rather than the rule.
So if you find that you LO is conking out towards the low end of the dial you'll need to add a few more turns to coil you just rewound ( tickler or feedback winding). You don't need to remove what you already wound just solder a length of 38g wire to what you have and add 3 more turns to it. That should put you in good shape.
I would suspect that the 710mmfd condenser is OK. For a four tube set they are good performers, but alignment of the IF is critical for good sensitivity. By adjusting the sensitivity trimmer on the rear apron of the chassis just below the point of oscillation will give you the best sensitivity, selectivity, and audio frequency response. The model 84's are a little better as they use a 8" spkr rather than your 6"er.
Oh and one other thing about the 80 and sets of it's ilk it works a lot better with a good earth ground to the chassis. You'll find that without a good ground the volume control won't be very effective. The VC is connected to the antenna and varies the amount of signal going into the set. Without a good gnd the VC doesn't have a good way the lower the amount of RF signal coming into the set.
Whenever I attach pics they always are out of order. Philco 81 w/xsistor set and xsistor set to listen for LO.
Are they still making Willys jeeps over there???
GL
Terry
