VK Logger Ham Radio Forum Archive

Hi all, once more it is head down and tail up putting together another 2 meter GS-31B amplifier..Started just a week ago and making good progress..As usual waiting for some components drags the job out..

This amplifier case is built entirely from anodised aluminum sheet..I have used a high speed rotary wire wheel to carefully remove all anodising from metal to metal contact especially around the RF compartments....I use 12mm aluminum angle to join all panels....I did this with a couple of 6 meter amplifiers a while back and they turned out fine...It just takes a little more care to do a good job..

This amplifier uses a grounded 1/4 wavelength plate line, tuned with a cam operated flapper capacitor and has a tunable loading pickup..This design is very simple and easy to resonate on 144Mhz...I assemble the RF deck then use my Grid Dip meter to establish the line is resonant around 144 Mhz..That is pretty much all that is needed..

I am currently just finishing the Cathode compartment...This uses a tunable T input network..In this particular job the input relay is a small bladed 24 volt SPDT unit...The common on the relay is connected directly to the input coax plug...I will post pics when I have this completed..

The amplifier has all the usual controls, Step Start High Tension, front panel Bias adjust, manual and remote PTT operation.
All the control wiring is done and I will be ready to wire in the front panel shortly..

Enjoy....Bob..VK3ZL..

Parts finally arrived this week and I have been able to complete this amplifier..It has now been fully run and tested for reliability and everything works perfectly..

These few pics give an idea of the finished amplifier...At 400 watts output the amplifier hardly gets warm in all modes and is loafing along at this output..It takes about 20 watts to achieve 400 watts..

The amplifier is now ready for use....Bob..VK3ZL..

You gotta quit posting this stuff Bob otherwise I might have to raid the Super fund!!

Another fine job mate, well done!

Gidday Andy..Thanks for the compliments..I just love using my hands on these things..I am back on a 70cm amp at the moment and hoping I can have that running properly before starting another 2 or 6 meter amplifier..

Meanwhile I am building two small amplifiers into one case, 6 and 2 meters which will share the one power supply.. These are low power amps probably only 350 watts output..I am using single GS-9B tubes in each amplifier..This amplifier is for my own use and if I get it done in the next month or so I may appear on both bands...

Never a dull moment..Cheers..Bob..

Keep it up OM...you are a shining example of what TRUE amateur radio homebrewing is about!

Now then, you need to build me a 6m kW amp which will be no wider than 410mm.

Cheers Bob!

This amplifier is complete and in the hands of the new owner...I have enough components on hand to do a 6 or 2 meter amplifier if anyone is interested...

73....Bob..