Amplifier

Jun
21

Homebrew 20 Watt Linear Amp

Jason Milldrum on June 21st, 2009

QRP is tons of fun on CW, but it gets a bit rough trying to work other stations on SSB with 5W, especially when you are using antennas that are low to the ground. I had been eyeballing the nice RF MOSFETs from Mitsubishi for a while, and since I got a hankering to get [...]

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Design, Homebrewing, Operating 1 Comment »
Dec
12

W8DIZ 5 Watt CW Amplifier Analysis

Jason Milldrum on December 12th, 2008

I finally got the proper binocular ferrite cores that I needed to build the W8DIZ 5 watt amp correctly. You can see my previous post on this amplifier here. In my last post, I noted that I was seeing some strangeness in the drive level circuitry. I found that I had a very bad connection [...]

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Homebrewing, QRP 3 Comments »
Dec
7

W8DIZ 5 Watt CW Amplifier

Jason Milldrum on December 7th, 2008

A few days ago, W8DIZ made a post on qrp-l.org announcing a new addition to his RF Toolkits line. This one is a 5 watt CW amplifier using a push-pull 2SC5739 pair as the PA (my new favorite full QRP gallon transistor). I built my own version of the circuit using parts that I had [...]

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Homebrewing, QRP 1 Comment »
Jul
9

Dual Gate MOSFET Investigations - Gain and AGC

Jason Milldrum on July 9th, 2008

Having determined some basic characteristics of the biasing of the BF998 dual gate MOSFET in a previous experiment, it was now time to look into the gain and AGC performance of the amplifier. A few changes were made to the original circuit to turn it into a proper RF amplifier. Test Equipment Power Meter: M3 [...]

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Design, Homebrewing 3 Comments »