If adding shunt C reduces the VSWR, then the relays are adding
inductance in the line. When you have series L and shunt C you get
a network that changes the impedance. If the inductance is low
enough, the impedance shift is small and you end up with low VSWR.
If the inductance (or should I say reactance) is higher, the
impedance change is higher and you can't get back to 1:1 VSWR.
It's much easier to explain on a Smith chart :-)
Try a series C in the through path.
Steve
> With just RG214 to the relays & RF in/out
> connectors, I get a whopping 3 to 1 SWR with amp in bypass. I tried various
> silver mica caps, and low value trimmers to ground from the NC to NC coax
> connection- lowest bypass SWR I can get is 1.3-1.4 to 1 with a single 47pf
> silver mica to ground.
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