There are a couple of alternatives that I have used succesfully:
1- Use small strips of bycicle inner tube less than 1/2 in wide rolled up to adequate thickness and push them between adjacent fins down to close to the fin base (shoot for this dimension when you roll the strips not the outside gap between fins). If you choose to do this in the lower part of thew vertical fin they'll be hardly noticed with several advantages, it´s a reversible tweak, tube is black as the fins are if needed can be done at middle height, add more etc. The effect on convection is minimal and you can kill the vibes.....
2- Use a small wire or better a small aluminum piece and adhere it to the fins with a hot melt adhesive gun in the underneath the lower portion of fins.
3- You can also bridge the fins with the holt melt adhesive and decrease the ringing acordingly.
Some options are far more effective than others and easier to implement depending on how careful you are the other too can be used but there's more potential problems So weight the options and the compromises you might get into.
I prefer the first one since it´s easy and totally reversible.
Have fun and kill the ringing.
1- Use small strips of bycicle inner tube less than 1/2 in wide rolled up to adequate thickness and push them between adjacent fins down to close to the fin base (shoot for this dimension when you roll the strips not the outside gap between fins). If you choose to do this in the lower part of thew vertical fin they'll be hardly noticed with several advantages, it´s a reversible tweak, tube is black as the fins are if needed can be done at middle height, add more etc. The effect on convection is minimal and you can kill the vibes.....
2- Use a small wire or better a small aluminum piece and adhere it to the fins with a hot melt adhesive gun in the underneath the lower portion of fins.
3- You can also bridge the fins with the holt melt adhesive and decrease the ringing acordingly.
Some options are far more effective than others and easier to implement depending on how careful you are the other too can be used but there's more potential problems So weight the options and the compromises you might get into.
I prefer the first one since it´s easy and totally reversible.
Have fun and kill the ringing.