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Home made feed through terminator for BNC
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G7PSK:
I wanted a bnc terminator a while back, all I had was some bnc crimp on plugs. I made a half watt 50 ohm with a couple of 100 ohm through hole resistors and covered in shrink sleeve and another one using smd resistors the wattage of which I do not know but cant be much as they are so small. 
grumpydoc:
Resurrecting this thread a bit.

Inspired by the original post and the fact that a) I needed another terminator for some 'scope calibration b) the shops were shut  c) I'd just found a reel of 0.25W 200ohm 1206 resistors in the spare parts bin and d) the cheapest feedthrough terminator I could find on fleabay was still twenty quid, I thought I'd have a go at building a feedthrough terminator from a spare panel mount BNC socket and clamp-on plug myself.

To add to the gallery here are some photos of the result



And the top view


The finished article looks just the same as david77's

I'd like to be able to measure the performance of this properly but don't have the kit - however I can say that it doesn't appear to be especially stellar. Probably OK to a couple of hundred MHz but at 500MHz both this and a cheapo 50ohm resistor soldered to a BNC crimp plug (plus tee) both showed about 6dB loss compared with my scope's internal 50ohm termination.  Worse, with either connected to the 'scope, my signal generator actually complained saying "RF amp failure or unterminated" when I tried to drive them at 1V RMS - presumably the VSWR is bad enough that the sig gen sees it and sulks - from my rough understanding of VSWR I'm assuming that if the 'scope only sees half the voltage the sig gen is putting out then the rest is getting reflected so the VSWR would be 3:1  :(

I confess I did expect that it would be better than a tee plus terminator given that they don't need the tee - perhaps my construction is rubbish?

So, OK in a pinch and as long as the frequency isn't too high but not a substitute for equipment with correct internal termination. I might make a couple more for low frequency use as they're more convenient than having to use a tee
PA4TIM:
The best configuration is 2 x 100 Ohm soldered opposit from each other. This minimizes paracitic capacitance and inductance.
 
Nut for the rest nice done.

I have done some tests on feedtrough terminators with a vna and TDR. The best result was a attenuator in series with a in line terminator. This because the input impedance of the scope is decreasing with frequency. (how much is depending the brand and model (my former Rigol was only 30 Ohm at 100 MHz) Best is a scope with 50 Ohm input.
grumpydoc:

--- Quote ---The best configuration is 2 x 100 Ohm soldered opposit from each other. This minimizes paracitic capacitance and inductance.
--- End quote ---

Yes, that's why I spaced the resistors out. I didn't have any 100ohm in the parts bin so was stuck with the 200ohm ones. Well, some 1/3W through hole but they were much too large physically.
babysitter:
Inspired by your posts, I fabricated a limiter out of:
* 2 x unknown SOT23ish RF NPN transistors
* 1 x N plug
* 1 x BNC front panel mount BNC socket

Exchanging a N-BNC Adapter in a small bridge from TG to SA for transmission measurement gives a flat trace up to 150-200 MHz where it started to bobble up and down, at ~500 MHz the bobbling becomes > 1 dB.
More exact measurement when baby lets me !
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