Drake L7 Monobanded, Variable Bias, on the bench before finishing her up and putting her away. скачать в хорошем качестве

Drake L7 Monobanded, Variable Bias, on the bench before finishing her up and putting her away.

This is my clean Drake L7. It had a bandswitch problem and more, and since I have another L7, not as clean though, but has full Ham Bands in it, I decided to go ahead and destroy, errr I mean mud duck, errrr I mean Mono Band this one. It is set up to work on 10-15 meters including 12 meters with no band switching. The Input tune is variable and the output tank circuit has enough bandwidth to tune from 10-15 meters. The Bandswitch has been removed and in its place is the Pot for the variable Bias PCB. Though the amp runs best with about 10v's of bias, the Bias can be varied from 5-20v's. Hence it can be setup to run from heavy class AB all the way to C. The caps in the separate HV power supply have been replaced and slightly upgraded from 200uf to 220uf's. I probably will in the future replace the 220's with 330's but at the time I was playing with it, I only had 220's laying around. Other than the monobanding, caps replaced, and variable bias PCB, the rest of the amp is stock. The Drake L7 was the later version of the Drake L4B amplifier. The L7 came out in 1980 with the CB boom still going on and the FCC crackdown happening at the time. The FCC outlawed any amp maker making an amp that was capable of being operated on the 27mhz CB band. I have said this many times: Any amp that will work on 10 meters will work on 11 meters unless it has a specific circuit to block 11 meters. I had known for decades that the Heathkit SB-221 was a SB-220 that not only took out 10 meters, it also had a circuit on the input side of the tubes called a Filter which sole purpose was to block 11 meters. The 'Filter' was a notch filter that notched out 11 meters only. Since there are not a lot of Drake L7's and not a ton of info on them, I did not know until I got one that Drake did the exact same thing with the L7. There is some info on the net on it, but if you look at the schematic, there is a filter circuit on the input which is also an 11 meter notch filter. Drake replaced the blower/chimney cooling that the L4B had and went with a standard muffin fan. At least the muffin on the L7 does direct some air to cool the pins, but still not as effective as the blower/chimney combo. Drake also cheapened the bandswitch on the L7 and that is a known problem of the L7's. Drake did improve the looks of the amp with the pretty meters, lights and pushbutton switches. It looks almost like a nice stereo piece. The Drake L7 is just a nice 2 piece dual 3-500z amp. It runs the plate pretty low at 2700v high and 1900v low. Many amps push those 500z's a lot harder than that nowadays, but again, IMHO for how long? The more you push stuff, the less it lasts. If driven hard, it will do 2kw peak and around 1400 average, but I don't push my stuff hard. In the video its cruising at 1400 peak and a kw average with about 100 watts drive in. Running nice, smooth and clean. I Likkie Clean. I've always had love/lust for the Drake L4'/L7 since I missed out on one as a kid. At 16, Dad was going to get me one to keep me in the house and off the streets of Detroit, but when the seller said make sure you run it on 220v, Dad said No Nooo and took his check back. It took me years after that to get one and when I don't have one, I don't feel complete LOL.