If the bridge design is basically the same as others, there is coax on one side, and the other side is only wound for symmetry purposes, so it doesn't matter if there is the same coax or solid wire of the same outer diameter.
If the through line behaves like a high pass, there is probably an open circuit or hair crack that acts as a small capacitance.
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--- In hp_agilent_equipment@..., "Peter Bunge" <bunge@...> wrote:
The A3 Directional Bridge (Port 1) has a pair of toroids on each side. The pair with brown "wire" is wound with coax. Is the grey "wire" on the other pair also coax?
I have an 85046A S parameter test set with identical faults on both directional couplers (I did not believe it either) and looking at the inside of one seems suspicious as the "Bridge" does not appear balanced in construction. Each end of the grey "wire" out of the toroid pair ends in a solder blob. I cannot see if it is/was a coax.
I looked at the coupler on the VNA from input to output after doing a B/R thru calibration and it starts at -20dB and climbs exponentially to -2dB at 1GHz, stays there then drops off a bit at the 3GHz end. I used a Transmission/Reflection Test Set with "Test" feeding the Transfer Switch end and with the Port 1 end on "B" on the 8753B. Coupler port terminated but it does not change anything.
When connected to the 8753B S11 and S22 with the ports open have identical shapes with two humps starting at -70dB rising to -15dB,and separated by a notch going to -55dB around 2GHz. When terminated they both rise exponentially from -70dB to -20dB at around 2GHz then flatten out. (this has nothing to do with the other thread I started, this is a different 85046A)
I have eliminated the splitter, attenuator, and Transfer Switch because I thought it had to be something in common to both Directional Bridges. I am now looking at the A3 as a separate component.
I can send a full description .docx file with pictures if I have an email.
Main question: is the grey "wire" on the toroids a coax?
