3-400Z Homebrew questions

Discussion in 'Amateur Radio Amplifiers' started by AC0LA, Aug 20, 2012.

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  1. WA7KKP

    WA7KKP Ham Member QRZ Page

    Looks like a fairly nice homebrew amp, and I'm assuming it is probably 80-10 meters.

    This is no problem to convert to 160 -- just add a toroid coil to the plate tank, and you'll have to add padding capacity to both the tune and loading capacitors to get it there. As for 6 and 2 -- fuggetaboutit. You're better off with a separate unit for each band. 6 meters is where most HF tubes get a bit quirky for stable operation. Output capacity (those pf values) of the tube itself becomes a critical matter; I remember one design that had NO plate tune cap -- it was tuned with a rotating shorted turn inside the tank coil. 2 meters -- you will need to have a whole different tank design period, and a different tube.

    Look up in older ARRL handbooks for amp construction projects, and better yet, get a late-model copy of the W6SAI (Editors & Engineers) Radio Handbook. Bill Orr was an Eimac employee, and one of the best gurus on PA design.

    Gary WA7KKP
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