Here I go again..New prototype 2 meter amp..

[VK3ZL]

I decided to take a slightly different approach to the RF deck design of my 2 meter EME amplifiers...The originals work well but there is a lot of work setting up the RF deck, hand making and assembling the parts...Ya can't buy this stuff off the shelf..

I have cheated a bit this time...Friends got a good look at a commercial amp and took a few pics and ran the ruler over the plate line etc for me...I started this amplifier on Monday and I have nearly completed the whole job now..I will post more pics next week..

The plate line is a simple sheet of brass sheet bent to the dimensions given to me along with the tune flapper cap and pickup line...I have only used the brass plate line and set up my own flapper capacitor design using a 2 inch Teflon disc I machined up with a 3/8 offset to make it work as a cam....I used an old 3-1 shaft drive on the chassis front sub panel and the flapper combination tunes this little bugger from 143-147mhz smoothly...I put in a GS-31B tube in this amplifier but I can change it to a GS-35B tube in 5 minutes if I want...

The Pickup wire runs across the cold end of the plate line with a small series tuning capacitor to load the amplifier into the antenna coax relay..My Analyser tells me that the combination Tunes and Loads at 144.250 into 50 ohms using a plate resistance of 2200 ohms so we are in the ballpark...Will probably need some adjustments under fire no doubt..

I will present this amplifier at the SERG convention HB competition for comment next month..The amplifier will be primarily for EME work, moderate power probably 800 watts JT65 and data modes and 1200 watts SSB/CW...I am waiting on a shipment of new power transformers so may have to use a compromise trannie if they don't arrive..

I have completed the front panel ready to wire in and I am keen to see the end result...

Pics show the pre assembled case..17x17.5x9.5 high...The amplifier will use a 12-28volt 6 inch Papst fan 285cfm in my usual setup air pressurising the RF deck exiting through the tube cooler then a Teflon chimney on the top cover..The cathode compartment uses a small fan blowing air over the filament/cathode assembly..I have used this combination of cooling on a number of my amplifiers and it is very efficient..

Enjoy..Bob..VK3ZL..

[K7SGJ]

Very nice, Bob. Do post some completed pix.

[NQ6U]

Have some mercy and stop making all the rest of us look bad, Bob.;)

[N2CHX]

Awesome as always!

[K7SGJ]

Have some mercy and stop making all the rest of us look bad, Bob.;)

You and I don't need Bob to make us look bad, we do pretty well by ourselves.

[NQ6U]

You and I don't need Bob to make us look bad, we do pretty well by ourselves.

Good point. Let me rephrase that, then:

Have some mercy and stop making all the rest of us look even worse, Bob.

How's that?

[K7SGJ]

Good point. Let me rephrase that, then:

Have some mercy and stop making all the rest of us look even worse, Bob.

How's that?

Works for me. I wouldn't change a word.

[KC2UGV]

Good point. Let me rephrase that, then:

Have some mercy and stop making all the rest of us look even worse, Bob.

How's that?

I concur.

[NQ6U]

By the way, Bob, this came in this morning's mail:

Attachment 9661

My first 10m SSB QSO to Oz.

[VK3ZL]

I dunno....These UHF guys always trying to outshine the Topband where real men take a stand..

Dunno the bloke but lot's of 6 meter hams hang around 28mhz...Congratulations...

Bob..VK3ZL..