John Popelish wrote:

Digikey carries a pretty broad line of Steward long form ferrite bead
cores. You can check the specifications at http://www.steward.com/

For instance, core HFB143064-300 has an impedance of about 180 ohms at
146 MHz. Type HF is their highest frequency material.

Core 28B0562-200 (same size in the lower frequency, 28 material)
produces an impedance of about 360 ohms per core.

I think both of these would fit over RG8X and are about an inch and an
eighth long.

By the way, if you want the convenience of the snap around cores in a
plastic retainer, part # 28A0593-0A2 provides 450 ohms per core at 146
MHz.. They cost about $2 plus shipping. They are about 2 and 1/4
inches long.