Hi Arun,
I can vouch for Mini Circuits transformers. I had Mini Circuits build some custom 100 Ohm balanced hybrid splitters for a VDSL broadband startup project in Australia.
We used 100 Ohm Cat5 cable for the "last mile" and these were used to split one physical VDSL port into two isolated VPN ports.
The splitters consisted of one of their standard 50 Ohm unbalanced hybrid splitters with 50-100 Ohm balancing transformers on each of the three ports, all in a 16 pin DIL package.
Excellent performance over 1MHz-30MHz, better than 26dB between output ports if I recall.
It is your choice, but the general consensus on these forums seems to be to use a centre tapped balanced secondary. You can then chose to connect the centre tap to the 50 Ohm unbalanced port ground or not.
You will need to make up an appropriate cable termination jig and to make up your own O-S-L-T terminations for calibration at your chosen test impedance.
Be aware that how you support the cable will affect the measurements. Just be consistent about how you support and orient the cable if you intend to compare various results.
If you intend to use one of the NanoVNA computer apps, then a ferrite decoupled USB cable is also highly recommended to minimise counterpoise effects.
Regards...Bob VK2ZRE
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On 29/08/2023 5:01 am, Arun wrote:
Has anyone used a NanoVNA to characterize a Twin wire twisted Balanced line like say a CAN bus line or an ISO-SPI balanced 120 ohm line?
If so what interface hardware has been used or is recomended?
