APC7 to SMA adapter from China ok? - Page 1
Forum section: electronics / testgear

author: rfspezi
author_rank: Regular Contributor
timestamp: February 14, 2018, 09:17:06 am
content: Are these APC7 to SMA adapters on aliexpress ok for use with an 6 GHz 8753 VNA?https://de.aliexpress.com/item/10pcs-lot-Flat-Retractable-RJ45-CAT5E-Ethernet-Cable-Network-LAN-Flexibility-Extension-RJ45-Cable-2-5m/32295632285.html

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: February 14, 2018, 11:54:14 am
content: No. And yes. Well, it depends.It could be. It depends on your spec. But:The quality of connectors is vital. A precision connector like APC7 should be built to very tight tolerances. If it is not, it will give you reduced performance, mainly visible as increases S11 at the connector interface. This can swamp the DUT S11 and as such ruin your ability to accurately characterize the DUT.But that is not the main issue. The main issue is that if that connector is not built to the right tolerances, it can (and likely will) damage the "good" connector on your VNA. And once that happens, there is no way to get high precision and repeatable measurements unless you replace the connectors on the VNA - and this will cost you a lot more than just getting high-quality adapters would have.Chinese cables and connectors can work fine for basic stuff - especially if you know where to look. I use them all the time! But I clearly mark them and they only get used with adapters that are sacrificial and on connectors that don't have as tight tolerances as APC-7 in the first place. The N-to-SMA adapters (rosenberger or huber+suhner).In the case of the adapter you list: just look at the surface finish of the (supposed to be) teflon in the SMA connector. Or how dull the suposed-to-be-gold-plated contacts of the APC-7 side are.

author: rfspezi
author_rank: Regular Contributor
timestamp: February 14, 2018, 12:38:15 pm
content: Ok, thank you.I'll order some and carefully check quality/dimensions before connecting them to the VNA.I think there is no other way when it comes to low cost and amateur radio usage.

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: February 14, 2018, 12:57:10 pm
content: You can't check these tolerances by hand. You need special tools for it.I realize this doesn't really help you in your quest, but I just want to make sure that you are aware of this. Once you damage the connectors on your VNA there is no way to undo it without spending a lot of money.

author: hendorog
author_rank: Super Contributor
timestamp: February 15, 2018, 06:28:22 pm
content: Quote from: rfspezi on February 14, 2018, 09:17:06 amFWIW, A friend of mine has two of those on his 8753, from the same aliexpress page, and is very pleased with them.

author: Neganur
author_rank: Unknown
timestamp: February 16, 2018, 11:36:14 am
content: Those look used US-made ones actually. Compare to these:eBay auction: #362002502232I don’t think the polished golden ones are great anyway, most Amphenol ones are dull gold

author: sixtimesseven
author_rank: Frequent Contributor
timestamp: April 05, 2019, 02:18:39 pm
content: Quote from: hendorog on February 15, 2018, 06:28:22 pmAny chance your friend has four of them and could measure two back to back