03-23-2007, 01:43 PM
All,
I am presently in the process of restoring a Model 640. Initial startup on a Variac yielded the all too familiar hum with no reception. Recapping the filters yielded weak reception. Replacing the non-bakelite block paper caps resulted in functional volume and tone controls with good reception on three of four bands (not much on the old police/utility band these days). Only wish I could get 1936 radio broadcasts.
At this point I have several questions. First, The filter caps I replaced were 2 Sprague "600" Line 16 MFD electrolytics that didn't function. The Philco schematic and parts list indicate an 8MFD (30-2025) and a 12 MFD (30-2117). I assume the Spragues would have been replacements by someone and not original equipment. I liked the old paper labels.
Second, the 640 has a shadow tuning meter which appears to function properly (moves with varying signal strength). However, I appear to be missing a part of the illumination system. Comparison to photos of the older style shadow meter appears to indicate that all parts are there except for some type of holder (slide on ?) that goes around the round base portion of the bulb and holds it to a mounting. Does this sound right? If so, is this part difficult to find, old or repro? Has anyone created something from scratch?
Third and final. Being a member of the "if it ain't broke, don't fix it club", based on members experience, other than the electrolytic and paper caps I replaced, are there any other components the would be candidates for outright replacement based on age/reputation? I appear to be getting good reception on the three bands I previously mentioned, but since I don't know what a properly functioning 640 should sound like, I have nothing to compare to.
Any help would be greatly appreciated.
Thanks,
Tad
I am presently in the process of restoring a Model 640. Initial startup on a Variac yielded the all too familiar hum with no reception. Recapping the filters yielded weak reception. Replacing the non-bakelite block paper caps resulted in functional volume and tone controls with good reception on three of four bands (not much on the old police/utility band these days). Only wish I could get 1936 radio broadcasts.
At this point I have several questions. First, The filter caps I replaced were 2 Sprague "600" Line 16 MFD electrolytics that didn't function. The Philco schematic and parts list indicate an 8MFD (30-2025) and a 12 MFD (30-2117). I assume the Spragues would have been replacements by someone and not original equipment. I liked the old paper labels.
Second, the 640 has a shadow tuning meter which appears to function properly (moves with varying signal strength). However, I appear to be missing a part of the illumination system. Comparison to photos of the older style shadow meter appears to indicate that all parts are there except for some type of holder (slide on ?) that goes around the round base portion of the bulb and holds it to a mounting. Does this sound right? If so, is this part difficult to find, old or repro? Has anyone created something from scratch?
Third and final. Being a member of the "if it ain't broke, don't fix it club", based on members experience, other than the electrolytic and paper caps I replaced, are there any other components the would be candidates for outright replacement based on age/reputation? I appear to be getting good reception on the three bands I previously mentioned, but since I don't know what a properly functioning 640 should sound like, I have nothing to compare to.
Any help would be greatly appreciated.
Thanks,
Tad
