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Technical Topics => The RF Workbench => Topic started by: stationqrp on April 20, 2021, 0938 UTC
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After about a year of working on GU-50 shortwave tube transmitter project, I finally finished! Download it, build it, enjoy it as much as I enjoyed it.
https://stationqrp.com/data/gu50transmitter.pdf (https://stationqrp.com/data/gu50transmitter.pdf)
73s
Twitter: @StationQRP
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I haven't read it all yet but thanks for the nice write up. I have had a lot of experience with tube (valve) equipment a long time ago and I love the feeling and light in a room full of warm, glowing filaments but my professional experience is strictly in transistors and I appreciate the compact efficiency of them. I probably won't go back. To each his or her own.
Just to be sure the No. 2 ‘scope probe was transferred to the input of the power amplifier and all was perfect there at any volume level. So it appears that these amplifiers do not like to power into the nasty reactive load of a modulation transformer, only a loudspeaker!
I have had similar experiences. I've had more problems at low frequencies where the impedance of the transformer changes the most but I guess you could have probelms at any frequency depending upon the model. It's good to do frequency sweeps and look for unexpected things.
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Very nice work!
Hard to beat the durability of hollow state stuff!
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After about a year of working on GU-50 shortwave tube transmitter project, I finally finished! Download it, build it, enjoy it as much as I enjoyed it.
https://stationqrp.com/data/gu50transmitter.pdf (https://stationqrp.com/data/gu50transmitter.pdf)
73s
Twitter: @StationQRP
Very nice. Did you design this circuit?
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The design is based on approved (Germany, Denmark and UK) xmtr for use on MW and SW. The approved version has 4 GU50 tubes.
There where 2 demands; parts must be available for years to come and had to comply with international
standards so HFCC membership could be applied for.
73s
Jack