The PHILCO Phorum
line dropping - Printable Version

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line dropping - applepicker - 08-08-2014

question for a 46/200-1225v38778.I have found on the radio chassis a candohm power resister, my schematic identifies it as a 80 ohm 5 watt line dropping ,(what ever that is ) I have a Dale 10w 1 ohm resister could I replace the 80 ohm 5 watt with this ,if so how to I wire it.: crazy:

RE: line dropping - morzh - 08-08-2014

No you can't.

Has to be the same Ohms and same or higher wattage.
Resistors are first about Ohms, and only then about Watts.

RE: line dropping - tab10672 - 08-08-2014

Think of it in electric volts, if your tv operates on 120v but all you have is a 240v outlet what would happen to the tv? The 80ohm resistor "resists" the voltage so if the original resistor cuts down the voltage "80" times the 1ohm resistor only cuts it "1" time. If any of that makes sense.

RE: line dropping - codefox1 - 08-08-2014

Schematic is here:
http://www.nostalgiaair.org/PagesByModel/591/M0013591.pdf

Is this what you have? If so, and you are operating from 120 volts, no line dropping resistor would be needed, and none is shown on the above referenced schematic.

Please post a copy of your schematic if it is different, or tell us what modifications were done, i.e. using different tubes, etc...

RE: line dropping - Ed Locker - 08-09-2014

http://www.antiqueradios.com/forums/viewtopic.php?f=6&t=252527

RE: line dropping - tab10672 - 08-09-2014

Seems like all this was covered in that forum? I doubt if anyone will ever say the 1ohm is ok to use.

RE: line dropping - applepicker - 08-09-2014

The 80 ohm 5watt line dropping ,does not show on the Riders schematic ,its on the photo fact folder , when looking at the two is when I found it ,I will replace it with the same or go a little higher, depends on what I can find on net ,Radio Shack does not have any

RE: line dropping - morzh - 08-09-2014

According to the tubes lineup they need 115 - 120V for their filamens which means if you drop voltage your tubes will not heat up properly.

Is your tube lineup as shown in that sch?

RE: line dropping - David - 08-09-2014

Good afternoon Reiders list the fellowing tubes 7A8,14A7,14B6.50L6,35Y4. Beitman list the fellowing tubes 7A8,7B7,7C6,50L6,35Z4. Beitman shows the 80 ohm resistor. The Beitman sch is under 1947 sorry not able to download the one page can only figure out how to do the whole year from my documents. Sometimes I am real stupid with computers. David

RE: line dropping - klondike98 - 08-09-2014

Here's Beitman's schematic:
[Image: https://dl.dropboxusercontent.com/u/54621529/46-200_schematic_Beitman.jpg]

RE: line dropping - Arran - 08-10-2014

So in other words one version has 12.6 volts more drop across the filament string, though that still does not add up to 120 volts, that would come to 116.5 volts, but they typically designed around a 117 volt working voltage, though it should still have a dropping resistor. The loctals like a 7A8, 7C6 are actually 6.3 volt tubes, but with a current draw of 150 milliamps, the loctals like a 14A7, 14B6 are 12.6 volt filament tubes, also with a current draw of 150 ma.
Regards
Arran

RE: line dropping - David - 08-10-2014

Good morning to find ohms take deisred voltage drop divided by amps 12volts divided by .150amps(150millamps) equals 80 ohms. to find the wattage of the resistor watts = volts x amps 12x.150=1.8 watts. You want a safety factor of 3 to 5 so use 10 watts. Hope this helps. David

RE: line dropping - codefox1 - 08-10-2014

Well, the post WW11 sets used up whatever tubes available at the right price, so if they came up with 106 string for a 115 or whatever fr a few thousand sets, a dropping resistor could be used. 80 ohms would be just right. A 100 ohm resistor wouldn't be bad considering today's higher average supply. If the tube lineup is so, a 10 watter would be fine, dress it against the chassis to dissipate heat. But --- any reason why original failed?

RE: line dropping - morzh - 08-10-2014

Heat would be my guess Icon_lol

RE: line dropping - applepicker - 08-10-2014

tube line up 7A8 14A7 14B6 50L6 35Z5 they are in the radio (the photo fact for the 46/200 tube line up is 7A8-7B7-7C6-50L6-35Z5GT ) the Riders does not match with the photo fact schematic. the schematic posted by Klondike98 is a lot more detailed but different tubes .when I bought the radio two tubes were missing ,got the riders ,ordered the missing tubes 14a7 and14b6 .removed one resister at a time and matched it with a new one and re installed it same with the electrolytic capacitor .so I guess will start over again check voltage ,but with the help I get here will get it done just takes time,