Upgrading a cassette with spares

[alig]

I'm currerntly using a HG50 12-25 (9 speed)
Rather than pay 80-100$ for a new cassette (I'd like a 11-25), I'd like to purchase the 11T cog and lockring instead

My question is, can I use a 11T CS-6500 9 speed cassette cog, with a dura-ace 7700 11T lockring on a HG50 cassette?

 

[alfeng]

I'm currerntly using a HG50 12-25 (9 speed)
Rather than pay 80-100$ for a new cassette (I'd like a 11-25), I'd like to purchase the 11T cog and lockring instead

My question is, can I use a 11T CS-6500 9 speed cassette cog, with a dura-ace 7700 11T lockring on a HG50 cassette?

Yes, you can use the Ultegra cog & DA lockring ...

BUT, because you apparently don't have either of the fore mentioned components, you'll find it will be much more cost effective to buy & cannibalize an 11-32 LX cassette for whichever cogs/spacers/lockring you need.