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| Banggood 50 ohm BNC feed-through terminator - a quick review |
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| MF-jockey:
I received the full refund without having to return the parts and then opened the parts. There was nothing in it but a wire, see the pictures. Speak about this: https://www.eevblog.com/forum/testgear/banggood-50-ohm-bnc-feed-through-terminator-a-quick-review/msg2078935/#msg2078935 Now I ordered 2 of the P57 should be good enough for use with my 100 MHz oscilloscope. |
| kerouanton:
Reviving this old thread ! I've been using the good old BNC-T + 50ohm terminator when feeding RF signals to my Hi-Z scope, but was wondering about changing to more convenient R&S HZ22 or Aliexpress P57 units. --- Quote from: Microcheap on January 01, 2019, 01:56:24 am --- --- End quote --- Wondering if anyone has done a VSWR measurement of those "new" P57 cheap terminators up to 1GHz, as they claim it's rated. --- Quote from: TheSteve on July 08, 2017, 06:53:05 am --- --- End quote --- And by the way, I'd be curious to see the same measurement for the R&S HZ22 terminators for comparison, as they also claim 1GHz too. Upon searching on Internet I found a long thread on a german forum with measurements and so, but I had to resort to deepl automatic translation. Anyway this thread looks interesting :-+ https://www.mikrocontroller.net/topic/204806 |
| TERRA Operative:
Looks like a prime candidate for a replacement PCB with a greatly optimised layout.. Something like a continuous central 50ohm microstrip or similar with 4x 200ohm 1% decent wattage resistors, two hanging off each side tied to a bottom layer ground plane. |
| mawyatt:
Looks as if the PCB can be utilized as an attenuator as well as a 50 ohm thru. Might be a good project for someone to roll a PCB and 3D printed case. Somewhere I recall that using two 100 ohms chip resistors across for each other produced a better load than 3 or more resistors. Here a 2D field solver might be useful in getting the best configuration & layout. Best |
| shapirus:
Another variant of the same "P57" thing from Aliexpress: I have no idea how to measure VSWR, and very likely no means either, but I think a comparative estimate can be made by looking at the overshoot at the rising edge and the undershoot at the falling edge of a pulse with fast edges (presumably 300-500 ps) when the terminator is connected between a pulse generator and a 1M scope input. With this one the over/under -shoots were significantly higher than with a handmade terminator that I made from two BNC connectors of opposite genders. No screenshots, unfortunately, as I didn't make them before I broke my DIY terminator: two of the four 200-ohm SMD resistors cracked from mechanical stress, as there was nothing but them that would be holding the center conductor in place, axially, against the outer shell (and the plastic was not going a good job at it, because I overheated it too much during soldering). So I now have a useless 100 ohm terminator. So this Chinese thingy has a nice enclosure, but a poor PCB. And an unforgivably high price of $6-7 currently. I think I'm going to make a proper board for it and then do a before/after comparison. |
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