The best solution depends on the situation. Is this to build into the unit? Is it to be permanently applied? Is a DIY solution acceptable, and if so, at what level of complexity? If you happen to have a synthesized VHF generator, just run it from the same reference and set for 200 MHz - you'll already know the specs too. If you don't have one, or need one to permanently commit, you may be able to find a used one fairly cheaply, especially since you don't need high setting resolution. For example, a Wavetek 3000 or 3001 may be sufficient - I have a few of these units, and have never paid more than US$20 for one. If you end up wanting or having to go DIY, then I'd recommend building a VCXO with a 200 MHz crystal, then PLL or injection lock it to the reference. If you choose to multiply up instead, there will be a lot of RF filtering needed to get rid of the intermediate spurs, so I'd recommend having at least one crystal filter stage in there somewhere. Either way, a crystal should be involved. A good example of a 100 MHz PLXO is in the HP8566A/B - it is locked to the 10 MHz OCXO, and runs pretty much everything in the instrument. It wouldn't be too big of a stretch to make one for 200 MHz. Ed