Drake L-4b Linear Amplifier+power Supply Highly Customized Read On

  

Up for sale one of the best amplifiers I have ever owned, highly customized. Amplifier was given a lot of TLC. Band switch is impeccable with no slack; verniers are absolutely smooth with no backlash. Fan was oiled and vacuumed twice a year ; absolutely quiet. See rear pictures not a speck of dust in the impeller. Front panel does not have a single mark on it, nor any letter/digit worn out. Tubes are Eimacs, with FULL output - see Daiwa meter (NOT included in the sale); amp is keyed on 14.225 MHz, cw with 60 wpm dits, meter on PEP mode, on a 2Kw dummy load. Custom work done on it. Grounding of the 3-500Z tube grids. That turns off the current when amp is not keyed. This lowers the quiescent current to a bare minimum extending the life of the tubes, and runs the amplifier much cooler when not keyed. If you are not familiar. With the advantages of this mod do. Most serious L4B owners have had that change made. ALC has been removed and the RCA plug is wired to key the amp. Biasing resistors were a continuous, high source of heat. Not sure why Drake did that but certainly deviated from Eimac's recommended way to run their tubes (grounded grids). Search for Eimac App-Note and see yourself. Harbach power supply installed ; new caps and bleeding resistors. Caps are 105 degrees C not 85.

Glitch resistors added to power supply to limit b+ current and protect the power supply. Back to back diodes were installed on both analog meters for protection.

Soft start board with a front panel on/off switch - so you leave the power switch of the amp ON all the time and control it from the PS. You will never need to replace the original power switch. Umbilical power feed and power cord were moved to the back of the PS instead of from the side.

That allows the PS to sit next to the amp see pics. Digital amp/volt meter added on the front of the PS that shows the input voltage and current see pictures. Added an output to an external large analog meter that mimics the grid current of the amplifier.

This is the reading you should always keep an eye on when on the air as grid current indicates the health of the tubes. The external meter (sitting on top of the Daiwa) and cable IS included on this sale. The meter has a magnetic base to attach to any metal cabinet etc. The amp , tubes/chimneys and power supply will be professionally packed in separate boxes. If you plan on opening or doing anything to this amplifier have a professional qualified electrician do it for you. There are lethal voltages inside that WILL kill you even if the power plug is off the wall. Wired for 240V with the proper plug installed. If you revert the amplifier to 120V BAD idea... You will need to remove the soft start board because it is for 240V. NOTES: the amplifier must be used with the supplied power supply as others will have the biasing voltage on. Treat this amplifier well, don't abuse it and will outlast you. The perforated covers are a bit rusted in the corners and there are scratches. Amp cover has a small dent on the cover in the rear. The seller is "nisemboim1" and is located in Wilmington, Vermont. This item can be shipped to United States, Canada, United Kingdom, Denmark, Romania, Slovakia, Bulgaria, Czech republic, Finland, Hungary, Latvia, Lithuania, Malta, Estonia, Australia, Greece, Portugal, Cyprus, Slovenia, Japan, China, Sweden, South Korea, Indonesia, Taiwan, Belgium, France, Hong Kong, Ireland, Netherlands, Poland, Spain, Italy, Germany, Austria, Bahamas, Israel, New Zealand, Singapore, Switzerland, Norway, Saudi arabia, Ukraine, United arab emirates, Qatar, Kuwait, Bahrain, Croatia, Malaysia.

• Brand: Drake
• Model: L-4B