If you do this with relays, I believe it would work but you want to make sure you get low capacitance relays, like RF-switching relays. Otherwise, they might still allow signal propagation in some cases when open (or for the DPDT case, they might allow crosstalk between the two selectable signals). I ran into this once when I made a remote antenna tuner (for receive only). It used a binary sequence of capacitors (e.g., 1024 pF, 512 pF, 256 pF, etc.) to synthesize the required capacitance to match the inductive antenna. The purpose was both for pre-selection and matching to minimize coax cable losses and the degree of effect which the cable had on the tuning of the antenna.. When I tried to do it with regular telecoms relays, they had something like 20pF of capacitance across the contacts when open. This did not greatly affect the larger values but down in the 10pF range, it made a huge difference. I ended up using mostly telecom relays but one (more expensive) RF relay to isolate a bank of the larger capacitors+relays when small capacitance values were commanded. It worked well! Sean On Mon, Jul 14, 2014 at 11:07 PM, Robert Rolf wrote: > You can probably get away using relays that have a very flat & short > geometry.NAIS make many that are suitable. > DPDT, tiny geometry. Split the cable out in pairs, and put a pair on > each relay. You'll need 4 since GBE uses > all 4 pairs. If your cable run isn't near the length limit, the losses > introduced will have negligible effect. > You'll lose about 1" of 'twist, but you lose nearly that much with > each plug on a Cat6 cable. > > There are micro relays (MEMS) used in cell phones, if you want to keep > the impedance perfect > and are good at doing strip line board layouts. > > Manual switches also exist to do this. You didn't say if you needed > electrical control. > http://secureswitch.com/ManualABswitches.htm > > and electrical one > > http://www.blackbox.com/Store/Detail.aspx/Pro-Switching-System-1U-NBS-RJ-= 45-A-B-All-8-Pins-8-Port/NBSALL8 > > You need to search for "gigabit failover switch". > > Lots of info on 'copper A/B switching' here. > http://img.pr.com/release-file/1108/343451/AB_Switches_5028-02.pdf > > > Robert > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .