For Sale..New 2 meter GS-31B amplifier.
Posted: Tue Jan 29, 2013 12:14 pm
Hi all...I have finally completed the new 2 meter GS-31B amplifier I mentioned in a previous thread..
This amplifier uses a GS-31B Russian triode in Grounded Grid mode.,I have used a new custom built Toroidal multi tapped HT transformer and the standing HT is around 3500vdc...I also used a new custom made 12.6 volt Toroidal filament transformer which has a multi tapped primary allowing selection of correct filament voltage for different mains voltage..The relay supply uses a new multi tapped transformer and an LM317 voltage regulated rectifier system providing 24 volts for the bias relay and two changeover relays...The amplifier cooling system uses a 4.5 inch fan blowing straight into the sealed cathode compartment directly on to the tube filament cathode and exhausting through a small grid on the side cover..
The main cooling has a 12-28 volt Papst 285cfm fan...This runs off a separate 20 volt power supply..The top RF deck is sealed from the cathode deck....Air passes through the GS-31B cooler up through a Teflon chimney exhausting through the top cover...Air flow and cooling is excellent..The main cooling fan can be switched off manually so that the filaments can be left running when the amplifier is not in use....This allows for switch on of the main cooling fan and HT and relay supply when you need instant use..
The amplifier is just coasting at the 400 watt VK ham power limit and is also suitable for those who have a high power permit for EME use..
I have installed an input relay and a coaxial output relay on the amplifier...However for those who wish to use an external preamp relay system and sequencer I can re do the system with a direct N type socket in and out...The bias idle relay can then be activated via the switch line from the exciter..
The amplifier uses a W4ZT bias board...I run a bias control adjustable from the front panel...Amplifier idle current can be adjusted for CW or Linear mode....Plate and Grid current are metered and function lamps for 24vdc, and Operate, as well as a mains indicator on the front panel....HT, Filament and Main cooling Fan have separate switches with neon indicators.
I have run all the usual tests on the amplifier into a 1kw dummy load and all functions work correctly..
The amplifier uses an adjustable T input network on the drive input...The Plate Tuned Circuit has adjustable Tune and load capacitor...Loading is set for best operation into your antenna system...I have set it up and locked it using a 50 ohm Bird 1kw dummy load, but into your antenna system it may have to be slightly adjusted if the vswr is different than purely 50 ohms..Once set it is locked and needs no further adjustment unless your antenna resistance is changed..Tune is smooth and peaks nicely..
The amplifier is all hand made using all new components..Contact me if you need more detailed information Email or phone 0355791403....Thanks....Bob..VK3ZL..
This amplifier uses a GS-31B Russian triode in Grounded Grid mode.,I have used a new custom built Toroidal multi tapped HT transformer and the standing HT is around 3500vdc...I also used a new custom made 12.6 volt Toroidal filament transformer which has a multi tapped primary allowing selection of correct filament voltage for different mains voltage..The relay supply uses a new multi tapped transformer and an LM317 voltage regulated rectifier system providing 24 volts for the bias relay and two changeover relays...The amplifier cooling system uses a 4.5 inch fan blowing straight into the sealed cathode compartment directly on to the tube filament cathode and exhausting through a small grid on the side cover..
The main cooling has a 12-28 volt Papst 285cfm fan...This runs off a separate 20 volt power supply..The top RF deck is sealed from the cathode deck....Air passes through the GS-31B cooler up through a Teflon chimney exhausting through the top cover...Air flow and cooling is excellent..The main cooling fan can be switched off manually so that the filaments can be left running when the amplifier is not in use....This allows for switch on of the main cooling fan and HT and relay supply when you need instant use..
The amplifier is just coasting at the 400 watt VK ham power limit and is also suitable for those who have a high power permit for EME use..
I have installed an input relay and a coaxial output relay on the amplifier...However for those who wish to use an external preamp relay system and sequencer I can re do the system with a direct N type socket in and out...The bias idle relay can then be activated via the switch line from the exciter..
The amplifier uses a W4ZT bias board...I run a bias control adjustable from the front panel...Amplifier idle current can be adjusted for CW or Linear mode....Plate and Grid current are metered and function lamps for 24vdc, and Operate, as well as a mains indicator on the front panel....HT, Filament and Main cooling Fan have separate switches with neon indicators.
I have run all the usual tests on the amplifier into a 1kw dummy load and all functions work correctly..
The amplifier uses an adjustable T input network on the drive input...The Plate Tuned Circuit has adjustable Tune and load capacitor...Loading is set for best operation into your antenna system...I have set it up and locked it using a 50 ohm Bird 1kw dummy load, but into your antenna system it may have to be slightly adjusted if the vswr is different than purely 50 ohms..Once set it is locked and needs no further adjustment unless your antenna resistance is changed..Tune is smooth and peaks nicely..
The amplifier is all hand made using all new components..Contact me if you need more detailed information Email or phone 0355791403....Thanks....Bob..VK3ZL..