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I am making up a parts order for my 116B, noticed the cathode resistors for RF tube and 1st IF are listed as flexible resistors. Was there any electronic reason for using them instead of carbon comp. Thanks
Hank
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Philco flexible resistors are wire-wound on a fiberglas core. Slightly higher heat dissipation and bendable to get into tight places and used as replacements for any radio. Came in 1/3, 1/2, 1, and 2 watt sizes. Marked with standard color code.
If you can fit a modern resistor in it's place (if out of tolerance or bad) with the same wattage rating, then there is no need to replace with a flex part.
Chuck
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I heard it was also a better way to manufacture resistors with low values back then. Any verification of that?
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I'v also heard that way back then it seems that getting anywhere near precise value with carbon resistors was tricky, especially when handling 1 or more watts continuously, so they used wire as in "power resistors."
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(12-17-2014, 07:22 PM)Hank G Wrote: I am making up a parts order for my 116B, noticed the cathode resistors for RF tube and 1st IF are listed as flexible resistors. Was there any electronic reason for using them instead of carbon comp. Thanks
Hank
If they are in good condition physically, I would leave the flexible resistors alone, they don't drift as far as I know. The most common failure with flexible resistors I see is that the cloth casing burns through, falls apart, and you end up with a slinky of nichrome wire falling out of them posing a short circuit hazard.
Regards
Arran
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AS Arran said wire wound and they are either right or open. If right, leave them alone unless the insulation is falling off.
Jerry
A friend in need is a pest! Bill Slee ca 1970.