[Amps] Bypass SWR RJ1As

[Steve Thompson]

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.