5 out of 5
Alpha R-V38-XL Potentiometer - Alpha, Linear, 3/8" Bushing
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Product Description
Manufacturer Part Number: R-V38-XL
Standard fit for most vintage American made tube amps.
For similar pots with tighter 10% tolerances, see R-V38-10TOL-XL.
Measurements and Specs
Files
Standard fit for most vintage American made tube amps.
For similar pots with tighter 10% tolerances, see R-V38-10TOL-XL.
Measurements and Specs
| Body Depth | 11.5 mm | ||
| Body Width | 24 mm | ||
| Bushing Length | 6.5 mm | ||
| Bushing Thread | 1 MΩ version | R-V38-1ML | 3/8"-32NEF |
| 1 kΩ version | R-V38-1KL | 3/8"-32UNF | |
| 2 MΩ version | R-V38-2ML | 3/8"-32NEF | |
| 5 kΩ version | R-V38-5KL | 3/8"-32UNF | |
| 10 kΩ version | R-V38-10KL | 3/8"-32UNF | |
| 25 kΩ version | R-V38-25KL | 3/8"-32UNF | |
| 50 kΩ version | R-V38-50KL | 3/8"-32UNF | |
| 100 kΩ version | R-V38-100KL | 3/8"-32UNF | |
| 250 kΩ version | R-V38-250KL | 3/8"-32UNF | |
| 500 kΩ version | R-V38-500KL | 3/8"-32UNF | |
| Hex Nut Thickness | 2.2 mm | ||
| Hex Nut Width | 12.6 mm | ||
| Insulation Resistance | >100 MΩ at 500VDC | ||
| Life | 15,000 cycles | ||
| Manual Soldering Max Temp for 3 sec. | 350 °C | ||
| Max. Working Voltage | 500V | ||
| Max Rotational Stopper Strength | 6Kgf | ||
| Operating (Useable) Temperature | -10 °C to +70 °C | ||
| Rated Wattage (Power) | 0.5W | ||
| Rotational Torque | 20-200 gf-cm | ||
| Shaft Diameter | 6.35 mm | ||
| Sliding Noise | <47 mV | ||
| Tap Residual Resistance | ≤100 Ω | ||
| Taper | Linear | ||
| Tolerance | 1 MΩ version | R-V38-1ML | ±30% |
| 1 kΩ version | R-V38-1KL | ±20% | |
| 2 MΩ version | R-V38-2ML | ±30% | |
| 5 kΩ version | R-V38-5KL | ±20% | |
| 10 kΩ version | R-V38-10KL | ±20% | |
| 25 kΩ version | R-V38-25KL | ±20% | |
| 50 kΩ version | R-V38-50KL | ±20% | |
| 100 kΩ version | R-V38-100KL | ±20% | |
| 250 kΩ version | R-V38-250KL | ±20% | |
| 500 kΩ version | R-V38-500KL | ±20% | |
| Total Rotational Angle | 300° ±5° | ||
| Total Shaft Length | 15 mm | ||
| Washer I.D. | 9.7 mm | ||
| Washer O.D. | 16 mm | ||
| Washer Thickness | 0.4 mm | ||
| Withstand Voltage | 500 VAC for 1 min. |
| Packaging Dimensions | 1.3 in. × 1.1 in. × 1 in. | |
| Weight (Packaging) | 0.024 lbs. |
Files
| Specification Sheet for 1 MΩ | R-V38-1ML |
| Specification Sheet for 2 MΩ | R-V38-2ML |
| Specification Sheet for 1 kΩ | R-V38-1KL |
| Specification Sheet for 10 kΩ | R-V38-10KL |
| Specification Sheet for 100 kΩ | R-V38-100KL |
| Specification Sheet for 25 kΩ | R-V38-25KL |
| Specification Sheet for 250 kΩ | R-V38-250KL |
| Specification Sheet for 5 kΩ | R-V38-5KL |
| Specification Sheet for 50 kΩ | R-V38-50KL |
| Specification Sheet for 500 kΩ | R-V38-500KL |
Attention CA Residents: Prop 65 Warning
WARNING:
This product can expose you to chemicals which are known to the State of California to cause cancer, birth defects, or other reproductive harm. For more information, go to www.p65warnings.ca.gov.
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Customer Reviews
By Gizzmo
Date: November 28, 2025
These variable potentiometers fixed my power supply
Rating: 
[4 of 5 Stars!]
[4 of 5 Stars!]
By Noah Niesen
Date: November 15, 2025
For anyone interested in using this with an arduino-like project, the potentiometers that I received are wired incorrectly. It seems that the black wire is to be connected to the analog pin, the yellow wire to ground, and the red to positive. They work fine with 3.3V as well.
Rating: 
[5 of 5 Stars!]
[5 of 5 Stars!]
By bobby
Date: November 12, 2025
they work for the speed control on my pride maxima mobility scooter . It does not replace the forward or reverse potentiometer. That is a separate part. Amazing it worked just fine for what it is and what little they cost .
Rating: [4 of 5 Stars!]
[4 of 5 Stars!]
By Emily Bennett
Date: October 08, 2025
These arrived with washers but no nuts! Also, one of the three was a 10K instead of 50K potentiometer!
Rating: [4 of 5 Stars!]
[4 of 5 Stars!]
By Adam Zaccaria
Date: June 26, 2025
I needed a new potentiometer for my welding machine. Ordered these, installed it, and it rans AMAZING for 10 secs, then never worked again. Tried a different one (10k to 5K, same brand) and again, worked AMAZING for about 10 seconds and then never worked again.
Rating: [5 of 5 Stars!]
[5 of 5 Stars!]
By BlindPilot
Date: May 16, 2025
I did not notice but it is clear in the picture. The yellow wire is supposed to be in the center. The yellow wire is place on the connection, the Red wire is on the ground connection and the black wire on the variable resistance output. Caused a big problem, nothing worked. The red is supposed to be the , the black, the ground and the yellow the signal wire, should be in the center. I bought these for the plug connection, not expecting them to be wired incorrectly. I had to cut the plugs off which makes them not worth the price for 3.
Rating: [5 of 5 Stars!]
[5 of 5 Stars!]