#16
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Shielding is indeed very important, especially in TRF sets. Any feedback that can happen will happen and will produce distortion and funny noises. <--Murphy's Law of TRF.
Shielding prevents feedback and interference. If you get it shielded up and there is still distortion pull the detector tube and inject audio downstream of it...Remember HiFi wasn't a thing until the late 30's (and then was only a thing on high-end sets). If speech is reasonably understandable it is probably about right. That Philco dates from a time where having a paper cone loudspeaker was a new technology just being grasped by manufacturers.
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Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
#17
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OBTW it's not uncommon for the primary winding on the rf coils to be open. This could but the cause of the garbled sound via the ant coil. Easy to repair, abt 50T of 34-38G magnet wire will do the trick. It's not too fussy as it's not part of the tuned circuit.
Terry |
#18
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Sorry, forgot to mention that I had the shields once I started getting a hum in the speaker. I had almost completely forgotten about them, as this set has been sitting for awhile now.
As to the audio quality, The one's I had seen online have better quality that what I'm getting. I'll make sure to replace the other filter with Mylar caps and I'll check the coil as well. Haven't really gotten the opportunity to troubleshoot much and I don't think I'll have much time this weekend.
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"If it isn't broke, you aren't trying hard enough" |
#19
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Well, finally got back to the bench during daylight hours. Replaced the 2uF electrolytic with mylar caps and was able to isolate the garbling/noise issue down to a cold solder joint on the speaker terminal. Reflowed it and was able to get a much cleaner sound. Proceeded with an alignment, and now the set works like a beauty. It's amazing what a 4ft antenna does for this set, I've been listening to it for the past hour picking up a station about 50mi that broadcasts classic music.
Workbench lights don't help much with RF interference. Seems to affect this set more than others I've had. Thanks all, Zach
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"If it isn't broke, you aren't trying hard enough" |
#20
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Old radios are a beautiful thing. It's sad that two radios are in the shop and one radio is dead. I need a fix!
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Rick (Sparks) Ethridge |
Audiokarma |
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