I'm trying to find suitable connectors for a PCB I'm designing and it's been rather difficult. I usually use Molex because their website makes it easy to find matching male female connectors. However, I'm looking to get some JST connectors this time since they're much cheaper than Molex.

However, I'm having trouble confidently picking two connectors which I know are going to be compatible. I'm looking to get the following 4 pin JST header to go on the PCB (Part No S4B-PH-K-S).

enter image description here

This connector has a pitch of 2mm so I looked for 2mm wire assemblies on Digikey (Since I don't have the tools to make them myself) and I found the following which I think might fit (Part No A04KR04KR26E51A)? enter image description here

However, I'd be lying if I said I was confident they are compatible. Is it enough to say since they have the same pitch that they'll fit? Where does JST document which connector mates with certain header or where can I find out?


2 Answers 2


You would first look at the datasheet for the connector. It would list the mating part numbers. Then you can look for a harness that has that mating part.

Digikey makes it easier. On the product page it has various things broken down. First is the series. It's a PH series. The assembly you pulled up is a KR series. It won't mate properly. Except... it does. The PH datasheet doesn't say it but the KR datasheet explicitly says that it's interchangeable. PHR uses crimped connections while the KR uses displacement (stab in wire) connectors.

The second is that they cross reference to the mating parts at the bottom of the page. Which includes the KR.

  • \$\begingroup\$ Ahh right. So at the bottom of the header page on Digikey I found the part CABLE-PH04 which should be the correct connector right? So it's really about making sure they're the same series as well as pitch of course? \$\endgroup\$ Commented Aug 18, 2023 at 11:39
  • \$\begingroup\$ @SwissGnome yes exactly. But see my update. The PH datasheet doesn't mention it but the KR one does. Which is also why digikey lists them in the mating section. \$\endgroup\$
    – Passerby
    Commented Aug 18, 2023 at 11:42
  • \$\begingroup\$ Ah ok. Yes that's a bit tricky. So the main process to follow is choosing a header the finding the correct housing that mates with the header which Digikey lists, and then find an assembly with the correct housing. \$\endgroup\$ Commented Aug 18, 2023 at 11:44
  • \$\begingroup\$ Correct. Normally you stay in the same series or family but here the ph header is compatible with many connector types, who only differ in how they are assembled. \$\endgroup\$
    – Passerby
    Commented Aug 18, 2023 at 11:53

Forget about Digikey and go straight to the source jst.com. Typing in your exact partno S4B-PH-K-S makes the KR family pop up (among others). JST's site is a fair bit confusing since they list straight, right-angle headers together with the mating socket parts (not all of them).

The KR one proposed appears to be 04KR-6H-P which is a 1x4 similar to the left one on your pic - these are known as IDC. Whereas the right one on the picture is known as crimp. Either will fit. As noted in another answer, the crimp version is named PHR, or specifically PHR-4 for 4 pin crimp.

Crimp is more suitable for mass production through a contractor and IDC is more suitable for small series or when you need to rewire them yourself (but you do need the IDC tool then).

Also note that Würth is a decent second source for these, although with an equally confusing web site.


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