Home brew 10m amp - HomeBrew Forum at eHam.net

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Home brew 10m amp	Reply
by K5DVW on January 31, 2002	Mail this to a friend!
I am currently contemplating building the two transistor (MRF454) HF amplifier avaiable here http://www.communication-concepts.com/eb63.htm It's a pretty simple design, says it's capable of 140W with less than 5W drive. Of course I'll have to follow it with a LPF of my choice and possibly a VSWR protection circuit. My question is has anyone else built this "kit amplifier" or built anything with these transistors and if so, what are your impressions. My intention is to use it either on 17m or 10m. K5DVW

RE: Home brew 10m amp	Reply
by WB2WIK on February 4, 2002	Mail this to a friend!
I've built several EB-63 amplifiers. If you buy the CCI "kit," it does not come with a chassis, heatsink, RF connectors, fuse holder or DC power connector -- you must provide those items, yourself. But it does come with the printed circuit board and all the electronic components. I don't like the original (Motorola) RF sensing circuit used to key the T-R relay, so I always modify that and use my own, which has more gain and pulls in more reliably with low drive. (I use a full-wave RF voltage doubler driving a Darlington transistor -- tons of gain.) If you use a large enough heatsink on the PA transistors, you won't need a fan; otherwise, you will. If you intend to use the amp on only one band, then a LPF can be very effective. The problem is, this amp has lots of gain from about 3 to 30 MHz, so an LPF for, say, ten meters, does absolutely nothing to filter 80-40-30-20 meters, and probably little to filter 17-15-12. A single-band version with an LPF tuned to just above the actual operating band will be far more effective and result in a truly "legal" signal! 73 de Steve, WB2WIK/6

RE: Home brew 10m amp	Reply
by K5DVW on February 6, 2002	Mail this to a friend!
Thanks for the info here and on the other thread about this amp. In my application, I have a TX line, so I'll be driving the relay off that instead of off detected RF energy. One less thing to worry about. K5DVW

RE: Home brew 10m amp	Reply
by K5DVW on February 6, 2002	Mail this to a friend!
Thanks for the info here and on the other thread about this amp. In my application, I have a TX line, so I'll be driving the relay off that instead of off detected RF energy. One less thing to worry about. K5DVW

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