So, being a heartless butcher I opened up one of the HP 8-port GPS splitters (forget the number) and removed the sawtooth filters so the unit would pass both L1 and L2.
I found that to bridge the filter pads even the smallest cap I had (I think 7pf) caused problems. I ended up making "gimmick" capacitors out of a couple of inches of #26 magnet wire twisted together. That has worked well; there's a little difference in gain between ports, but not enough to worry about. John ---- On 4/30/20 11:39 AM, Bob kb8tq wrote: > Hi > > At 1.5 GHz something like a 50 to 100 pf NPO is probably the best > pick for a blocking cap. > > Why? It does a fine job at the intended frequency. It acts as a high pass > down lower where lightning energy is a bit higher …. > > Bob > >> On Apr 30, 2020, at 9:25 AM, Ben Hall <[email protected]> wrote: >> >> On 4/30/2020 7:33 AM, Bob kb8tq wrote: >>> Pretty much all the Mini Circuits splitters will pass DC. >> >> Hi Bob and all, >> >> That's absolutely correct. Something you might consider is what I did - I >> got a pair of Mini-Circuits ZC6PD-1900W's cheap on the e-place. >> Frequency-wise and loss-wise, not perfect, but good enough for me. Problem >> was, like you note, all the ports are DC-pass, and I wanted only output port >> 1 to be supplying DC to the antenna. >> >> So I opened mine up, carefully cut the trace going to outputs 2 and up, and >> bridged them with, IIRC, a 0.01uF ceramic capacitor to block DC. >> >> Before and after plots on the VNA at work showed very little increase in >> loss after the mod compared to before the mod. >> >> Just some food for thought. :) >> >> thanks much and 73, >> ben, kd5byb >> >> >> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
