VK3ZL
10-19-2013, 04:49 AM
I had just delivered the last GS-31B 6 meter amplifier to it's new owner and I received mail from VK4 requesting a 2 meter unit..I collected the aluminum panels a week ago and started this new project last Monday..
This is pretty much after the same design as my last 2 meter GS-31B amp..The aluminum panels in this amp are anodised grey satin finish so I had to carefully remove the anodising from all metal to metal joins and earthing points so that the chassis was bonded together as a common ground...This was especially important around the RF deck...I used a high speed wire wheel to remove the anodising along all the joins down to bare aluminum, carefully, as I didn't want to disfigure the interior of the case...Using 12mm aluminum angle I re assembled the case and it looks pretty good..
The RF deck uses a 1/4 wavelength plate line grounded at the cold end...The Plate blocking capacitor is a 10kv/20kva doorknob 200pf...Hopefully the DC will never find it's way through that capacitor..
Plate tuning uses a grounded cam operated Flapper at the hot end of the Plate line and the Loading consists of a wire loop with a series to ground 20pf variable capacitor the other end goes to the output relay..
The Cathode circuit is simple, a tunable T network and can be adjusted from the back of the amplifier..
The front sub panel has a simple resistor relay step start for the high tension transformer..The tube bias setup uses a W4ZT designed board adjustable from the front panel and all the bias wiring, cutoff resistor/relay also on the sub panel..
I am about to wire in the front panel and will show further construction pics as I progress...I am held up waiting for a new batch of HT transformers and electrolytic capacitors but expect them soon..
Enjoy....Bob..VK3ZL..
This is pretty much after the same design as my last 2 meter GS-31B amp..The aluminum panels in this amp are anodised grey satin finish so I had to carefully remove the anodising from all metal to metal joins and earthing points so that the chassis was bonded together as a common ground...This was especially important around the RF deck...I used a high speed wire wheel to remove the anodising along all the joins down to bare aluminum, carefully, as I didn't want to disfigure the interior of the case...Using 12mm aluminum angle I re assembled the case and it looks pretty good..
The RF deck uses a 1/4 wavelength plate line grounded at the cold end...The Plate blocking capacitor is a 10kv/20kva doorknob 200pf...Hopefully the DC will never find it's way through that capacitor..
Plate tuning uses a grounded cam operated Flapper at the hot end of the Plate line and the Loading consists of a wire loop with a series to ground 20pf variable capacitor the other end goes to the output relay..
The Cathode circuit is simple, a tunable T network and can be adjusted from the back of the amplifier..
The front sub panel has a simple resistor relay step start for the high tension transformer..The tube bias setup uses a W4ZT designed board adjustable from the front panel and all the bias wiring, cutoff resistor/relay also on the sub panel..
I am about to wire in the front panel and will show further construction pics as I progress...I am held up waiting for a new batch of HT transformers and electrolytic capacitors but expect them soon..
Enjoy....Bob..VK3ZL..