18-05-2015, 11:58 AM
Apologies - 545. The B version. An easy typo to miss if you're working from home thanks to conjunctivitis 
I always understood that the problem with carbon comp resistors drifting high was mostly environmental, though I'm sure that usage is factor. I've read various theories over the years, including some interesting anecdotes from folk who have tried baking them to dry them out. And I've probably read as much about this topic on both US forums as UK ones, so the problem wasn't confined to the UK by any means. Which is why I was so impressed with the ones Tek selected for that 'scope at least. Guessing they'd be Allan Bradley, perhaps Dale?
I have a bunch of NOS carbon comp jobs that are all high - I've just measured a pack of 10k jobs and they measured between 11.5 and 13.5k, which although out of spec, actually isn't too bad. I generally only come across these in transistor radios, so they don't lead a hard life, but somehow they all go high for fun. Luckily the circuits are rarely critical, and my NOS ones are sometimes useful when I'm wanting to be "sympathetic".
I always understood that the problem with carbon comp resistors drifting high was mostly environmental, though I'm sure that usage is factor. I've read various theories over the years, including some interesting anecdotes from folk who have tried baking them to dry them out. And I've probably read as much about this topic on both US forums as UK ones, so the problem wasn't confined to the UK by any means. Which is why I was so impressed with the ones Tek selected for that 'scope at least. Guessing they'd be Allan Bradley, perhaps Dale?
I have a bunch of NOS carbon comp jobs that are all high - I've just measured a pack of 10k jobs and they measured between 11.5 and 13.5k, which although out of spec, actually isn't too bad. I generally only come across these in transistor radios, so they don't lead a hard life, but somehow they all go high for fun. Luckily the circuits are rarely critical, and my NOS ones are sometimes useful when I'm wanting to be "sympathetic".
