I recently had troubles with KCD-11 switches I bought on aliexpress (
https://www.aliexpress.com/item/1005001513148147.html), they had 100s of ohms ON resistance. I don't think I used them much, maybe few hundred times. I dissasembled it and found that the seat have worn spots in nickel plating where the botom of the plate is touching the center pin. I did paid $1/10pcs free shipping so, I don't know what I expected. Rant over.
Here's frequency measurement before (yellow) and after switch replacement (cyan)
Yeah definitely don't go too cheap on switches, bad contacts, melty cases, etc.
Mechnical contacts can be tricky with small signals. A good low ohm contact may need a certain minimum current to flow.
The switch could well be OK for other uses (e.g. to switch a light or possibly even mains).
The construction looks cheap, with no extra contact material. The problem may not be the worn spot, but possibly just an oxidized or oily contact surface.
Mechnical contacts can be tricky with small signals. A good low ohm contact may need a certain minimum current to flow.
The switch could well be OK for other uses (e.g. to switch a light or possibly even mains).
X2. The OP should look up the term "sealing current" or "wetting current". I found out about this early in my career when I tried to use a normal AC switch in a low current digital circuit. A digital rated switch was about 3x the price but it worked and a standard switch simply wouldn't, even when brand new.
Also on those Chinese made switches it very likely that the contacts were made of steel and had a very thin layer of tin on them and that the plating wore through very quickly. I've found that to be VERY common in cheaply made wire, bulbs, sockets, switches, etc.