02-02-2012, 10:48 PM
I'm probably going to annoy a lot of purists, and I try to be one to the best of my limited radio knowledge, so here goes...
I have a Philco 90 (version with one #47 tube). I restored the cabinet and chassis and they look great. With the radio itself, I replaced the filter caps eliminating the 60 cycle hum. (At least, it is much lower than it was). Used 10 microfarad 450v caps, disconnecting the original cans, but leaving them in place.
The problem is this.....When I put an antenna wire on the ANTENNA lug, I hear some scratching when I connect the wire, and that's it. No reception. Looking at the schematic, I went down the line as best as I could from the ANTENNA lug through all points on the coils and components, touching them with a screwdriver and got scratches and crackles as I went along.
With that, I assumed there were no opens, or I would not hear the scratching from the speaker? When I got to the RF GRID, the radio played crystal clear. So I clipped the antenna wire to the RF GRID and checked the reception. The volume control worked smoothly, and I picked up many stations at the right places on the dial (e.g., station 1550 tuned in at 1550 on the dial and station 600 tuned in at 600 on the dial). Also, I did not have to adjust any pots, trimmers, etc.
With that, I wound up cutting the wire that went from the ANTENNA lug to the first coil in the circuit, and re-wired the ANTENNA lug to the RF GRID, bypassing the coil circuitry before the RF GRID
Question is, how important is this circuitry? Again, volume control knob works great and dial tuning tracks. If I did not know this was done (say someone else did and I did not know about it), I would not suspect any modification of this kind was done, as the radio performs well, or as well as can be expected from an 80 year old radio with original components (except for the filter caps). Is it ok to leave the radio like this?
Thanks guys!
Joe
I have a Philco 90 (version with one #47 tube). I restored the cabinet and chassis and they look great. With the radio itself, I replaced the filter caps eliminating the 60 cycle hum. (At least, it is much lower than it was). Used 10 microfarad 450v caps, disconnecting the original cans, but leaving them in place.
The problem is this.....When I put an antenna wire on the ANTENNA lug, I hear some scratching when I connect the wire, and that's it. No reception. Looking at the schematic, I went down the line as best as I could from the ANTENNA lug through all points on the coils and components, touching them with a screwdriver and got scratches and crackles as I went along.
With that, I assumed there were no opens, or I would not hear the scratching from the speaker? When I got to the RF GRID, the radio played crystal clear. So I clipped the antenna wire to the RF GRID and checked the reception. The volume control worked smoothly, and I picked up many stations at the right places on the dial (e.g., station 1550 tuned in at 1550 on the dial and station 600 tuned in at 600 on the dial). Also, I did not have to adjust any pots, trimmers, etc.
With that, I wound up cutting the wire that went from the ANTENNA lug to the first coil in the circuit, and re-wired the ANTENNA lug to the RF GRID, bypassing the coil circuitry before the RF GRID
Question is, how important is this circuitry? Again, volume control knob works great and dial tuning tracks. If I did not know this was done (say someone else did and I did not know about it), I would not suspect any modification of this kind was done, as the radio performs well, or as well as can be expected from an 80 year old radio with original components (except for the filter caps). Is it ok to leave the radio like this?
Thanks guys!
Joe