2M Bandpass Filter from RG213 Coax

So RG142 coax proved unsuitable. Perhaps RG213, which has a larger diameter, would work?

Initial results were encouraging. Loss was now about 1.5dB, a  1dB improvement just by switching to a wider coax.

 

Circuit

The filter was loosely based on the RG142 filter. With all the practice I had tuning up such filters I didn't stick to this religiously. My coax was a few cm longer and resonating capacitors adjusted to suit. I still need to revise the terminating capacitors since I have less capacitance than the original circuit  required.

 Initial Results

Prior to Changing 4.7pF Terminating Capacitors

I didn't persist with this because I spotted a length of LDF4-50A, a half inch coax which was wider in diameter than RG213, so I thought I would give that a go.

More on that later.