On 28/4/19 3:25 am, John Ackermann N8UR wrote: > I have a large box of 8140 pods (well, I call them "taps"). They are > quite handy for stringing distribution points around a large room, > provided ultimate phase noise performance isn't required. > > You *don't* need an 8140 main box to use these. All the 8140 does is > put 12V DC bias on its output connectors, and the taps couple their > power off the coax with an RC choke. When I was using my setup, I built > a bias-tee box that was inserted right after the frequency source and > that worked fine. Earlier in the project I just built some test boards with a tee, a DC block and space for a regulator, which have proven to be handy little things, allowing me to use whatever source is handy for testing, plus my precision DC supplies so I can actually meter the power.
> However, one note: for best performance, you want to terminate the end > of the distribution line in 50 ohms, but since there's a DC voltage > present, you need to include a DC block (series capacitor) so you're not > burning 3 watts in the load. Building a set of those terminators, and then having them not actually terminate was one of the reasons I picked up the VNA, for now I'm running with values I came to using LTspice, but once I get the test sets I plan to measure and see if I can do better. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.