Duel amplifier 2 and 6 meters..

[VK3ZL]

I can't sit still so I decided to put together a small amplifier for my own use..The basis of this project is an amplifier with 144mhz and 50mhz in the same case..As I don't require high power I have chosen a single GS-9B Russian triode for each amplifier..I have an old Kenwood TS-700S 2 meter 10 watt radio and a Yaesu FT-620 6 meter 10 watt radio to use as exciters..

The GS-9B tube has an anode dissipation of 300 watts and runs best on about 2000vdc..Previous experience with this tube shows it is good for 400 watts PEP output before saturation..The tubes cost $15 each and are readily obtainable from Ukraine and other sources..

The HT and aux power supplies for this amplifier are built into a separate case...Both amplifier and power supply front panel are 14 inches wide and I will make a rack panel box to put them in..The finished package will be about 14 inches wide and 14 inches high and about 15 inches deep...

The HT transformer is a compact Toroidal unit I had built especially with this project in mind and delivers 1450vac @ 500ma....Rectified through a diode bridge rectifier it will produce about 2000vdc..The tube draws 300ma peak current so this supply is more than adequate..

Both amplifiers are straight forward and simple...The 6 meter unit uses a Pi-L tank circuit in the anode compartment and the 2 meter unit uses a grounded 1/4 wavelength line..Both amplifiers are tuned with a simple flapper capacitor.. The 2 meter amplifier uses a series tuned pick up line on the output..Input to each amplifier cathode is a tunable T network..

Cooling...The anode compartments of both amplifier are sealed...I am using two 80mm 24 volt axial fans to push air into the compartments....The air exits through the tube coolers and Teflon chimney's on the top cover...Here I have made a compartment divider between the amplifiers with a screen so the air from both fans is shared between the tubes...As I will only be running one amplifier at any time the unused air outlet will be covered so that the amplifier in use gets all the air..The cathode compartment is cooled using two small 12 volt fans blowing on to the tube bases and exiting through a grid on the amplifier case sides..

Here are some pics to show what I am getting together..

Bob..VK3ZL..

[NQ6U]

Bob, if you were building an HF (80 through 10m) amp with about 600W output, what tube would you use?

[VK3ZL]

These pics are the HT power supply, 24 volt fan and relay supply and the filament transformer..The HT Toroid has a simple Relay Resistor step start...The relay and fan supply use the same transformer...I made up a simple board with a 7812 and 7824 regulator for these functions..All amplifier voltage functions are on the power supply front panel..I am waiting for the proper meter to monitor plate voltage..It is the same as the dummy meter installed at present and will be scaled to read 0-2.5kv..

Enjoy....Bob..VK3ZL..

[KG4CGC]

Awesome as always. I wish I could build stuff like this.

[VK3ZL]

Hi Carl, I would use a Russian GS-31B tube with at least 3kv HT...This tube has 1000 watts anode dissipation and at 600 watts output is only loafing along...

Bob..VK3ZL..

[mw0uzo]

Nice!

[NQ6U]

Hi Carl, I would use a Russian GS-31B tube with at least 3kv HT...This tube has 1000 watts anode dissipation and at 600 watts output is only loafing along...

Bob..VK3ZL..

Thanks, Bob!