UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - First Radio Build

ms660 · 17th Jul 2017, 6:40 pm

Sometimes it's printed or stamped on the case, Log, Lin, sometimes it's a letter code such as A or B, with those codes though there's no definite rule, in most cases A will be Log and B will be Lin but for whatever reason it can sometimes be the other way round.

If a pot isn't marked Lin or Log you can check which type it is by measuring the resistance between one end of the pots track and the pots wiper then the other end of its track and the wiper, both measurements taken with the pot's shaft set to the mid rotation position, if those two resistance measurements are in or roughly in agreement then it will be a Lin pot, if the two resistance measurements differ by a factor 9 (approx.) then it will be a Log or Anti log pot, Log pots are the most common type compared to Anti log pots.

For more info do a google image search for...... log lin pot curve ......plenty to look at and read about.

Yes, volume pot would be a log pot.

Lawrence.

17th Jul 2017, 6:40 pm	#29
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: First Radio Build - 12V HT system Sometimes it's printed or stamped on the case, Log, Lin, sometimes it's a letter code such as A or B, with those codes though there's no definite rule, in most cases A will be Log and B will be Lin but for whatever reason it can sometimes be the other way round. If a pot isn't marked Lin or Log you can check which type it is by measuring the resistance between one end of the pots track and the pots wiper then the other end of its track and the wiper, both measurements taken with the pot's shaft set to the mid rotation position, if those two resistance measurements are in or roughly in agreement then it will be a Lin pot, if the two resistance measurements differ by a factor 9 (approx.) then it will be a Log or Anti log pot, Log pots are the most common type compared to Anti log pots. For more info do a google image search for...... log lin pot curve ......plenty to look at and read about. Yes, volume pot would be a log pot. Lawrence.