Bifurcated (forked) terminals: soldering tips, safety, and use cases

Article summary

Bifurcated terminals, also called forked solder posts, were once common in military electronics and high-power transformer applications. This article presents a modern use case along with safety tips and links for additional learning.

Introduction to bifurcated terminals

A customer recently inquired about a high-voltage power transformer manufactured by Hammond. This transformer, as shown in Figure 1, is part of Hammond’s Peter W. Dahl Co’s line of custom transformers.

It features bifurcated terminals for the input power. These slotted solder posts are marked as terminals 1 and 2 in Figure 1.

Figure 1: Picture of a high-voltage transformer featuring bifurcated terminals for input terminals 1 and 2.

Author’s personal experience: As you see in my bio, I served in the U.S. Coast Guard for 27 years. My formative years were spent as a service technician for a high-power radio transmitter. I remember rebuilding the transmitter’s exciter which featured half a dozen 6146B beam tubes and a 500 VDC regulator with a trio of heavy graphite-plate 6336 tubes. Figure 2 is a good representation of the solder connection styles used in that transmitter.

I will forever be thankful for the opportunity to service that equipment. The experience including water cooling (plumbing), analog circuitry, and a 100-rung ladder logic controller was in the critical path leading directly to my current position as a DigiKey application engineer.

Where can I learn more about bifurcated terminals?

Let me leave you with a few helpful soldering resources. First, I recommend you download a copy of NAVAIR 01-1A-23 (STANDARD MAINTENANCE PRACTICES
MINIATURE/MICROMINIATURE (2M) ELECTRONIC ASSEMBLY REPAIR). This “unlimited distribution” U.S. government document provides detailed instructions for wire connections to a variety of solder posts. Figure 2 shows several solder terminal types including four different ways to solder to bifurcated terminals.

Figure 2: Picture shown quality wire to solder post connections from the NAVAIR 01-1A-23 document.

Secondly, now that you know the term “bifurcated terminal” you can search for videos, such as Video 1, provided by Pace worldwide.

Video 1: Video showing how to solder bifurcated terminals.

Tech Tip: Note that the bifurcated terminal allows entry from above or from the side. From a safety perspective, it may be better to run the wire from the top and then cover the joint with heat-shrink. This is a good step toward achieving a touch-safe design for line-powered equipment.

Happy soldering,

APDahlen

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About this author

Aaron Dahlen, LCDR USCG (Ret.), serves as an application engineer at DigiKey. He has a unique electronics and automation foundation built over a 27-year military career as a technician and engineer which was further enhanced by 12 years of teaching (interwoven). With an MSEE degree from Minnesota State University, Mankato, Dahlen has taught in an ABET-accredited EE program, served as the program coordinator for an EET program, and taught component-level repair to military electronics technicians. Dahlen has returned to his Northern Minnesota home and thoroughly enjoys researching and writing articles such as this.