A couple of months ago, I stumbled across NR6C, Gregory's website where he detailed a modification that he came up with that upgraded the stock tuning dials on his Ameritron AL-800H HF amplifier. What caught my eye about this modification was how fast he claimed that he could tune up his amp after performing this modification. I have the same amplifier and thought this would be a great idea for me to try, as well. In addition to the precision vernier dials, the key to this modification is the adapter plate and the shaft extensions that Gregory makes in his shop. I contacted him about obtaining the necessary parts and he was more than willing to help me out! He offered to send me the necessary parts and directed me to where I could order the precision verniers from Henry Radio on eBay, which is located here: http://rover.ebay.com/rover/1/711-5...0001&campid=5336136228&icep_item=330837447160. As you can see the the numbered dials make it easy to maintain a spreadsheet to record the exact tuning location for various locations on each band. After I received all of the necessary parts, it was time to perform the modification. The first step of the process is to remove the case cover, all of the dials on the faceplate, and then the faceplate. Once you loosen or remove the faceplate, you need to first remove the four machine screws holding the stock vernier shafts in place, shown here: You must also remove the phillips set screw on the back the vernier, as well: Now the verniers simply slide off the shaft and your case should now look like this: Now we slide on the new shaft extensions supplied by NR6C, shown in the following pic. He doesn't supply them tapped for a set screw, and it's probably not necessary, but I decided to do that anyway: Now you're ready to put the face plate back on, but you need to leave the cover off while installing the new dials. Here is a picture of the adapter that Gregory prints on his 3D printer: The vernier dials simply mount onto the adapter plate using 4-40 screws. I suggest test fitting everything before screwing it together to make sure all of the holes line up. Due to variances in the amplifiers, you should only mount one screw on the bottom of each dial, slide the dials on and then screw in the other side. After you slide the new verniers and adapter plate on, you simply tighten the set screw located behind the new dial. Before you do that, make sure and align the capacitors by hand to match the location of the dial. Here is the finished product: The first adapter plate that Gregory sent was actually too small for my AL-800H. We discovered that there is some variance in these amps, probably depending on the specific years they were produced. Going forward, to make sure you get an adapter plate that fits properly, Gregory is going to have people measure the center to center distance of each shaft so he could print the proper adapter size. Once he sent me a revised adapter plate based on the correct center to center shaft distance, the kit went together very smoothly. The whole process takes about an hour, is really pretty simple to do, and is easily reversible, if desired. The results are awesome! These new dials are super precise and smooth. Using the tracking spreadsheet that I keep on my PC desktop, I can switch bands and be ready to key in seconds due to the fine, single digit measurements on the verniers. If I happen to dial up a frequency that causes me to retune, I just add it to the tracking list for next time. There really is no comparison to the stock dials and I couldn't be happier! If you want see more details on this modification, please visit NR6C's website located at: http://nr6c.com/speed_dial.htm. Thanks again Gregory!