23cm Amplifier SBB2088Z - More Navel Gazing

It occurred to me some time after I had prepared the PCB layout that I had left out the small input "stability" resistor in the transmission line version. Since the minimum resistance needed to ensure stability was 1 ohm I wasn't too concerned. Just putting 1 ohm into the actual circuit wouldn't change much would it?

Well, it turns out it did.I started from scratch and derived a circuit with a 1 ohm resistor and transmission line matching. I found that the capacitors adjacent to the 50 ohm ports were reduced by around 50%. And the transmission lines were around 20% different in length. Now 1 ohm is a really small amount of resistance and these are significant changes.

So I inserted a 1 ohm resistor into the original transmission line version and compared the two.

While there is a small variation in gain, all versions will be substantially the same in practice. Should I be concerned that 1 ohm made such a difference?

I put the difference circuits giving almost the same result as comforting in that the matching will be smooth and relatively insensitive. I look forward to receiving the boards to find out if this is indeed the case.

73's
Richard