I was testing a bunch of SMA-F to N-F bulkhead adapters from ebay yesterday. The neat thing about the SD-24 is you can test such things as fast as you can make the connections. I was putting a very good Inmet N-M load on the N-F side. The adapters came from wifi_expert.
Bear in mind In the time domain I'm testing to 20 GHz, but in the frequency domain I can only sweep to 2.9
GHz. Notice that the TDR lets you see the SMA connection and the N connection separately.
TDR using a Tek 11801 w/ SD-24 20 GHz head
Top is unmarked, but thought to be Suhner
Middle is Astrolab
Bottom is Chinese
Next is a thru cal on my 8560A from 500 KHz to 500 MHz at 1 dB/div using an Astrolab part
Chinese with same settings and using the Astrolab as the cal reference.
Next is a thru cal on my 8560A from 500 KHz to 2.9 GHz at 1 dB/div using a Suhner (?) part
Chinese with same settings using the Suhner as reference cal
I'm building an RF switch deck to automate a full annual cal run of my bench. I'll be using AR488 and Arduino Mega 2560s to control ST6P Radiall SMA relays for RF and 44421A relay cards from a 3497A for DC, AC & resistance measurements.
The Chinese SMA-F to N-F bulkhead adapters won't cut it for the cal system, but I'm also building an antenna and radio switch deck using another pair of the Radial relays. Except for playing with an SDR and an abandoned Direct TV dish, I won't be doing anything above the 70 cm band. I might use better grade adapters for those, but for HF/VHF/UHF the Chinese are just fine.
For those for whom an 11801 is out of reach, Leo Bodnar will provide his excellent BNC <40 ps square wave generator with a 1 MHz instead of 10 MHz period. Naturally that limits you to the BW of your scope, but it will test any connectors and cables you use with your scope to to full BW.
Just as you can do TDR on modern VNAs, you can do VNA by TDR with a DSO and computer. I plan on dong some examples and writing software to do that.
But I'm a severe ADD case, so no idea when that will happen. I've got a 7x12 Chinese mini-lathe awaiting further attention for making high precision RF stuff. But first I have to rebuild the lathe to work to those tolerances. That's a *lot* of work. The machines are quite impressive, but it's really just a complete kit of parts which has been assembled to make sure they didn't forget something. So for serious work they have to be completely disassembled, cleaned, critical parts replaced and then scraped by hand into alignment. The hard part is learning to measure things accurately enough.