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Chassis 26 Heater string - Printable Version

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Chassis 26 Heater string - radeonut - 01-23-2017

    Okay, so I've completed the electrical (cap and resistor) restoration of this chassis #26 radio I mentioned in my first thread, but I'm having a real Ohm's Law brain freeze with the series heater string. Unlike most models like this, the series dropper consists of 175 ohm and 103 ohm (pilot tap)  instead of the more common 175 ohm and 53 ohm. Either way, I figure with 120 volt line and tube drop of 89 volts, the drop across the resistors together is 31 volts. Assuming 150 mA current, the resistors should total 207 ohms, instead of my 278 ohms or the seemingly more common 228 ohms.
This all came about because after I complete the re-cap and power up, I like to check voltages. I found two things: the voltage across the pilot (#47) was about 3.75 volts, and more curious, the heater voltage on the 35A5 was 30 volts. All other heaters were normal. Any suggestions?
One other thing is the coil-capacitor combo, part #4 was missing (probably from a previous butcher job). Is this item necessary, and if so, how would I build one?

RE: Chassis 26 Heater string - Carl Travis - 01-23-2017

In reference to item 4, it can just be replaced with a cap, coil winding not necessary.
Where did you find the schematic?

RE: Chassis 26 Heater string - Radioroslyn - 01-23-2017

You missed the fact that #31 and 32 don't really equal 278 ohm as the lamp is a much lower resistance than the resistor it's in parallel with.  The 103 ohm section is lower than 103 ohms, if you remove the bulb it is.

RE: Chassis 26 Heater string - radeonut - 01-23-2017

(01-23-2017, 05:26 PM)Carl Travis Wrote:  In reference to item 4, it can just be replaced with a cap, coil winding not necessary.
Where did you find the schematic?

Thanks, I'll do that. This is a Canadian radio and I have a full set of RCC manuals, hence the schematic

RE: Chassis 26 Heater string - radeonut - 01-23-2017

(01-23-2017, 06:30 PM)Radioroslyn Wrote:  You missed the fact that #31 and 32 don't really equal 278 ohm as the lamp is a much lower resistance than the resistor it's in parallel with.  The 103 ohm section is lower than 103 ohms, if you remove the bulb it is.

Hmm. Okay thanks I'll check that. Just wondering why most schematics show the parallel resistor to be 53 ohms. Perhaps the pilot lamp is of a different rating other than the 47 I'm using? I haven't been able to find anything about the lamp in any parts lists.