I picked up a no name dovetail jig but there is no information about what size bushing collar and type of router bit to use with the jig. I tried it with 7/16 and 1/2” collar and 14°, 1/2” bit but the tails are much too small to in 1/2” material. The comb has 5/8” between the combs and the combs are 1/4” wide. By my calculations I think I need a 9/16 collar but haven’t been able to find one. Am I on the right track or am I barking up the wrong tree.

5/8 guide bushing should work.
As for bit, bring the bit up shallower makes them looser, and deeper > tighter.

Don’t just start on the left and work to the right, because you’ll get splintering out on the front. So start on the right, and come across with a light climb cut until you get across before entering the comb.

Let me be honest. That jig is just about the biggest piece of crap you could buy and try to make money with. The clamps are undersized and are so far from the comb on top, that just the slightest cupping in the stock will not get pressed out and that will allow the comb to rise up or not lay parallel and ruin the fit. The one I tested when I worked for Woodworker's Journal Magazine was formed sheet metal and not bent square, so drawer stock was not held square in machining. You need something that is machined, not stamped. The locating tabs are also stamped steel, so again no precision. I'd estimate you'll get about 5 good joints out of 10. Sell that thing on Craigslist and buy a quality jig. Buy a Keller, older cast Omni Jig, or one of the jigs from Leigh.

Christopher Kearney:

I agree with both Keith and Rich. You probably need a 5/8" guide, and your bit may need to be 1/2" to 5/8" below your router base, for 1/2" material. You will need to play with it, and if you hit on the right combination, you may want to leave the router set up and dedicated to cutting dovetails, and keep a cutoff of your stock for future sizing of material. All of this assumes that the existing adjustments are correct, and that your comb is not too far in or out. You may also find that your drawers will need to be in specific incremental sizes to accommodate the pin offsets.

Having said that, that jig really does look like a POS. You might consider something like the Porter Cable 4212, especially if all you are doing with it is small scale drawer fabrication. Pretty inexpensive in the scheme of things, and it has the added benefits of an instruction manual and available parts.

I looked at your website, and I would have thought that the North Bennet Street School would have taught you to hand dovetail. But you do need to charge for that, and not everybody wants to pay for it, as I found out. Perhaps you have found that out also.

Hope this helps.
TonyF

Maybe the North Bennett St School taught him to prepare his work flat so the jig doesnt have to mash the flat out of a cupped piece? Or maybe he is making a move into ply?

For odd stuff we run a Leigh jig just for the variable spacing but it wont mash a piece of paper down flat even with clamping the crap out of it. But it does a great job for small odd runs and on-of's. Tons of people swear by fixed comb jigs. If the parts are flat there isnt a lot to it and even on dedicated machines most everyone is still doing a bit of filler/putty work prior to sanding if they are outputting clean dovetails. They are rarely dead perfect off even a modestly reasonable machine (5-8K)

I get dead perfect off a Keller every single time. The template is adjusted to the bit when you buy it, and that's the last adjustment made. Just set the bit for the stock thickness and run stock. Who doesn't want dead flat stock? But when you have a fixture that changes the fit when the height of the comb is even changed by a few thousandths, you introduce a quick error. If the OP bought that jig, I doubted he had a wide belt to dress the drawer stock.