Why do you need at least half watt?For a Heathkit VTVM, need 1% resistors at least 1/2 watt, 7 and 9 megaohms.
Any idea where to get them, Mouser and Digikey no have.
TY
Scott
strantor said:Why do you need at least half watt?
It would take at least 2,100V to dissipate 1/2W into a 9Mohm resistor.{/quote]
With a 1000 V input (guessing) and a 2x safety factor, that isn't to bad.
I had to buy a 1 Meg 200 W resistor once and on the other side of the scale a 0.5 ohm adjustable resistor rated at 1000 W and I did buy a few 400 M resistor onec.
When I googled "Heathkit VTVM" I saw a bunch of VOMs that only measured up to 15VDC.With a 1000 V input (guessing) and a 2x safety factor, that isn't to bad.
They are reference resistors for the vacuum tubes. I think 1/2 watt is recommended to limit heat extremes of "properly" sized resistors and limit heat effects on accuracy.When I googled "Heathkit VTVM" I saw a bunch of VOMs that only measured up to 15VDC.
Got it, thanks!They are reference resistors for the vacuum tubes. I think 1/2 watt is recommended to limit heat extremes of "properly" sized resistors and limit heat effects on accuracy.