Interesting how this thread started talking about 3-500Zs and ended up with a discussion about Camaros and communism......
"Gettering" this thread back on track, I put a set of RF Parts Taylor branded and matched 3-500s in my Amp Supply LK-500 and they have worked just fine for over 5 years now. Others have the same experience, but everybody is entitled to their own opinion.
But, they are not priced at $135 either. Sometimes you actually get what you pay for.
Honestly, as far as I know all Chinese tubes come from one of only 2 factories in China. As we all know The Chinese are copy cats so I would assume that either factory probably makes pretty much the same product. I have spoken with Merit Arnold from RF Parts and as you may know he sells or did sell three levels of 3-500 tubes. Each level used to or still does vary about $10.00/tube. The tubes were branded thus. Low level just said 3-500ZG tube. Next level was Taylor brand. The upper level are RF Parts branded. So you ask, what is the difference in the levels? You can distinguish with a simple test what tubes out of a group of tubes will produce more power. By using a simple test jig with a milli ammeter that reads 0 to 200ma with 1 ma increments you can measure the ZSAC of the individual tubes down to a 1ma tolerance. Typically a tube that will draw a little bit higher idle current will make a bit more power output because it has a bit more gain. If you test and sort a 100 tubes for example, you would take the bottom 33 tubes with the lower current draw and they become the cheaper tubes. The second 33 become the mid grade and the higher 33 become the top level. Then you group all the like tubes and they become a matched set when chosen. There is another facet of all this as well. Depending on the amount of tubes you order from the factory and if you opt to have them test them or not changes the unit price. If they don't have to test the tubes they give you a cheaper price. Then when you get them you weed out the bad ones and you do the testing and matching. It is probably not unusual for someone like RF Parts to order up 1000 tubes at a time. Ever since we have had free trade with China you can become any kind of dealer you want. Have you ever heard of Alibaba.com? If you haven't, you should check it out. You can start a business of selling any type of widget you desire. You can go to Alibaba and have a keyboard chat with any number of hundreds of manufacturers of products and get a quote and break point prices on those widgets. You can become your own distributor of product over night. If you recall years ago there were several different companies that you could go to and get a rebuilt transmission put in your car. There was AAmco, Lee Myles, and so on. When you went there they presented you with the good, better, and best transmission. They all had a different price depending on the length of the warranty. One year was the cheapest, 5 years and then 10 years or whatever. They made you believe that the more expensive transmission with the longest warranty was a better transmission. It wasn't. You paid X amount of dollars more for the same transmission as the cheapest for the most expensive. The higher price for the same quality transmission with the longer warranty covered their labor cost of putting in another transmission if it failed in the warranty period. Rebuilding the transmission cost them next to nothing, it's the labor to R&R it in a failure.