johnieo

Roy, my apology for misreading my scribbled notes. 1-5/16 it is. However, from the outside I measure a pot spacing of 1-3/4 inch. The Ohmites would fit with an eighth to spare! Ohmite also makes a 12.5 Watt unit (REE15R) that is the size of the pot shown above. We considered resistors and a switch, but realize that switch contacts also wear. What about replacing the mid-pot with fixed resistors and outside taps in the manner of an AR-1 incantation? One could choose mid-driver values yielding (-3/0/+3) dB. For the hi-driver- a single 15-Ohm resistor with no pot. Alternatively, 14+1 and taps, if really fussy. We have not tried resistors yet. My pots are good--recently reworked by a perfectionist. However, one day ...

>Be careful ordering 15 or 16 ohm pots from electronic >suppliers. I've tried to get some from Parts Express and MCM >Electronics and both had oversize bodies the would not allow >two to be installed side by side at the current center >distance which, if I remember is about 2.25 inches. Are we confusing potentiometers with L-pads? I have never seen 15 Ohm potentiometers in Parts Express. P-E does sell 16-Ohm L-pads, which are well over two-inches in diameter. In any event, one would not purchase these for use an AR-3a. MCM is one distributor of Ohmite rheostats. For example, see Ohmite part number RHS15R, a 25-Watt, 15-Ohm potentiometer with an outer diameter of 1-5/8 inches and a body depth of 1-3/8 inches. These dimensions are identical to those of the AR-3a originals. The Ohmite units are dear--low volume--but considering their expected lifetime, they likely represent a better long-term investment than commercial restoration.