The TS 990S is a nice addition to the shack. It was added in March of 2015. It's just loaded with features. On the left hand side of the picture is the 8 button remote keypad I made for keying the memories.
You can order one from the UK but it's super easy to make one and the cost is about $20 for material. The choice of getting quality buttons was the hardest thing. I got mine from All Electronics.
The Bencher BY-2 paddles are for the TS 990S.
The Kenwood SM 220 monitor scope shown on the left is a key component. If my amp is being used, the monitor scope is on. I watch the trapezoid while transmitting. If the amp is loaded properly I will get a perfect trapezoid. It also makes tuning the amp a lot easier then using a watt meter. Meters are dampened but the scope display is not. The watt meter is only used to show my power out level once the amp is tuned.
Icom IC 705 is on the right hand side of the picture. I have always enjoyed QRP and have tried numerous QRP radios.
I also have an Elecraft KPA500 inline with the Kenwood TS590SG not shown. I have not had any problems running 500 watts, in contest conditions, out of the little Elecraft solid state amp. A Yaesu FTDX-10 was added to the primary station in Jan 2025.
Home Brew Amp:
Pictured is my home brew amplifier that uses a single 3CX1000A7 tube in grounded grid. This tube is no longer made but is one of the smallest tubes that can be rebuilt. My low voltage power supply runs 2800 volts key down. At 80 watts of drive power the amp will easily produce 1500 watts out. My higher voltage power supply runs about 3300 volts key down and the amp will easily supply 1500 watts out with much less drive power. I tried to keep the Q of the Pi-L tank system around 12. The amp will cover 10 to 160 meters and has tuned inputs. It will cover the WARC bands by putting the tuned input switch in the bypass position and using the tuner in the radio to couple the amp. The plate dissipation of the tube is rated at 1000 watts. With extra cooling the plate dissipation can be as high as 1500 watts, as per Eimac specs.
The 3CX1000A7 is an old but interesting tube. It’s kind of a cross between an 8877 and a 3-1000Z tube. It was developed before the 8877. It looks something like an 8877 but uses a thoriated tungsten filament like the 3-1000Z uses. It is a directly heated cathode, like the 3-1000Z so the tube is instant on, no waiting for the filament to heat up like the 8877.
If cooled properly the tube can easily deliver over 2000 watts in grounded grid class AB2. I run my amp around 1200 to 1300 watts out. You’ll never see the difference between 1200 watts and 1500 watts, so why bother? At that power level the tube will last longer and everything runs cooler.
