[Amps] Need some 220K 2 watt carbon resistors

[k7fm]

"Is there any procedure to test them, if no datasheet is available"

Some years ago, I needed some resistors that were good at low uhf.  I tested 
some 2 watt carbon composition resistors.  When I ran them at 2 watts, then 
cycled them down, they kept changing resistance.  I thought they would 
stabilize, but they never did.  So, I ran them at 1.5 watts and they still 
did the same thing.  I abandoned their use and used some glass film 
resistors.  Unfortunately, the type I used are no longer available so I need 
to try them all again.

Some years later, I learned that carbon composition are hygroscopic (absorb 
water).  And, as Ian pointed out, they change resistance just sitting on the 
shelf.

Years ago I watched the ALC zero point keep varying on my Collins KWM-2.  I 
figured it was a capacitor and kept changing them.  Finally, out of 
desperation, I started changing resistors and that was it.

I think most of the resistors today are stable - except the old carbon 
composition, so they all should work well in a power supply - if they meet 
the voltage rating.

73,  Colin  K7FM