Hi, I had these NOS resistors from military surplus market. I have no idea about manufacturer and type (CF, MF, etc.). They measure 1% (actually better) tolerance range. Non-magnetic. I'm familiar with Beyschlag resistors but these ones are quite different in shape and color. Also doesn't look like Piher's but I'm not sure.
Dimensions are 14x4x90mm. The leads are very thick for such sized resistor. Lead diameter is 1mm.
Dimensions are 14x4x90mm. The leads are very thick for such sized resistor. Lead diameter is 1mm.
Don't know the mfr, but thick leads can allow the resistor to be smaller for the rated power, because they act as a heat sink.
The leads are copper in that case, you got lucky, most are tin plated iron these days.
If you got an assorted lot, just sort them by rating and use them.
As for origin, the supplier may not be around any more, or an exclusive mil grade supplier...see if the packaging has any information.
If you got an assorted lot, just sort them by rating and use them.
As for origin, the supplier may not be around any more, or an exclusive mil grade supplier...see if the packaging has any information.
I scraped another one with 930ohm value. It seems that these resistors are qualitatively made. Resistive material is shiny black. Speaking of pitch black resistive material, I guess these are high grade Carbon Film ones. What is your opinion?
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Metal film have light blue case, normally. If a strong acid doesn't disolve the track its likely to be carbon.
Mystery solved:
Manufacturer: Electrosil
Type: TR5, 1/2 Watt
Composition: Glass-tin-oxide ("glass" explains the dark shiny look)
https://mullard.org/products/electrosil-tr5-0-5w-2-glass-tin-oxide-resistors
Manufacturer: Electrosil
Type: TR5, 1/2 Watt
Composition: Glass-tin-oxide ("glass" explains the dark shiny look)
https://mullard.org/products/electrosil-tr5-0-5w-2-glass-tin-oxide-resistors