Welcome Guest! Be sure you know and follow the Phorum Rules before posting. Thank you and Enjoy! (January 12) x

Thread Closed
Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Resistor questions (wattage and ohms)
#1

So I am still working on my 38-12 and I am attacking some nasty looking resistors. I noticed alot of posts regarding what wattage and a link to Philco Bench but when I click on it I get an error that page could not be found. Is there another resource? Also, if I can't get the exact ohm rating for a resistor, can I go a bit higher or lower? Example: if the schematic calls for a 200 ohm resistor, can I use a 220? Thanks for helping with these questions. Also, in line with the wattage question, I am shopping for a kit with single wattage assortment of resistors and are there any recommendations on this?
#2

You can always go higher in wattage than the original resistor, but you should try to match the specified resistance as closely as possible, or at most don't go more than 10% over or under. If the resistor is the old body-end dot type with no metallic color on the other end, it is 20% tolerance. If it has silver it is 10%, or gold is 5%. With resistors with bands the tolerances are the same, just 3 bands, 20%, a 4th band that is metallic colored means the same as the colors above. I buy modern 1% resistors of the proper resistance and rated higher in wattage. A modern metal film resistor that is 2 watts will be about the same size as an old 1/2 watt. I buy assortments of these on eBay in both 2 watt and 3 watt, which I use for 1/2 watt and 1 watt respectively, and then order specific resistances in 2 watt if I need to to get the ones I need that are not in the assortment. I also order specific resistances in higher wattage when needed, as when replacing those of a candohm. By the way, here is a horse to remember the resistor color code that I learned in the Navy many years ago, before women were allowed to be on ships, and before "political correctness"...
Bad        black        0
Boys      brown        1
Rape      red            2
Our        orange        3
Young    yellow        4
Girls        green          5
But        blue            6
Violet    violet            7
Gives      grey            8
Willingly  white          9
Get        gold            5%
Some    silver            10%
Now        none          20%

This is another horse we used to remember sine, cosine, and tangent when doing resonance and reactance problems...
                                Oscar (opposite)
Sally (sine)      =     ________
                                Has (hypotenuse)

                                 A (adjacent)
Can (cosine)   =      _________
                                Hard (hypotenuse)

                                On (opposite)
Tell (tangent)  =      _____________
                                Always (adjacent)
#3

Good stuff. Thanks much for the input. I have several radios I am working on and was trying to consolidate my purchasing. This 38-12 I am working on has been "violated" previously and I am trying to bring it back to the original schematic.
#4

Yep, I learned the same mnemonics. I think it's the Navy one.

People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.




Users browsing this thread: 1 Guest(s)
[-]
Recent Posts
Restoration of the Canadian General Electric A-87
Great job on the cabinet. PS. In the US notation, "kenotron" refers to specific type of tubes; we call re...morzh — 08:24 AM
Part numbers to model cross
This document has at least some tables of models and parts used. Example: Choke 32-7572, used in 604 radio. Search f...morzh — 08:19 AM
Restoration of the Canadian General Electric A-87
I also checked all the radio tubes on my Hickok 530 tube tester. The 5Z3 kenotron turned out to be faulty, all the other...RadioSvit — 08:02 AM
Restoration of the Canadian General Electric A-87
Well... While the varnish is drying up, I started repairing the chassis... Of course I started by replacing the pa...RadioSvit — 07:12 AM
Philco Model 38-7: what caps & resistors do fail typically?
Hello Martin, Welcome aboard our little community what great Model 38-7 Sincerely Richardradiorich — 12:30 AM
Philco Model 38-7: what caps & resistors do fail typically?
Welcome to the Phorum Martin. I count about 9 paper caps, the 3 electrolytic caps and 2-Y2 safety caps to replace th...RodB — 09:44 PM
Part numbers to model cross
Jim, We have this index put together by Dale Cook but I don't think that is quite what you are looking for. The Parts...klondike98 — 09:37 PM
Philco Model 38-7: what caps & resistors do fail typically?
Yep the dim bulb test is OK but I'd definitely replace all those electrolytics before I did it. Since those #47 conden...klondike98 — 09:18 PM
Philco 42-345 Restoration/Repair
The resistor is a 2.2 Meg, it was the last one I hadn't replaced. The broadcast is coming in after replacing it.osanders0311 — 09:09 PM
Philco 42-345 Restoration/Repair
What does the resistor measure? I think it should be 3.3 Meg. If the oscillator coil has continuity and the resistanc...RodB — 09:03 PM

[-]
Who's Online
There are currently 1312 online users. [Complete List]
» 1 Member(s) | 1311 Guest(s)
Avatar

>