50+ Watts am for QCX... More light hearted

#33824

My first job in life was fixing things.? Involved film projectors and related products. Grew to fixing electronic flashes.? Was fixing one and had to reform the capacitor. Was within 6 inches of it and the main capacitor blew up.? So loud it affected my hearing for a couple days.? High frequencies sounded low and vise versa.? On my work bench I had a AM radio powered by No 6 dry cells.? My boss came in and saw this and referred it to a FLQ Bomb.? This is Canadian thing, some may remember this from years ago.? Lastly, as a kid, I made a breadboard with a few terminal strips, built a regenerative AM radio and was able to pick up a radio station in Victoria BC from Vancouver.??It used?a couple 2N170 transistors, remember those. Have also built several of the Genesis SDR radios but have moved on. ? My last projects were 2 QCX radios.? Thumbs up on these. 50 years later I'm still fixing things...

Cheers 72/73

Ray VE7AVG/VA7SK

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From: Steve Ireland <vk6vz@...>
To: [email protected]
Sent: Tuesday, April 23, 2019 6:52 PM
Subject: Re: [QRPLabs] 50+ Watts am for QCX...

Hi Hans

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I applaud your ingenuity and QRO does have its place alongside QRP – a lot of us do both.

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In regard to exploding mosfets, about 15 years ago a good friend, with my dubious assistance, built a couple of versions of Dave Pick G3YXM’s Throbbatron amplifier – see ?

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In the original version, after eating a couple of FETs, my mate got the amplifier working nicely and stably on 160m CW by using quite a lot of bias, but I foolishly and insistently kept pressing him to get it working on SSB as well.

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He then rebuilt the amp with lots of safety features, removed the bias and, hey presto, it ate IXFH58N20s in a fairly spectacular and absolutely continuous manner.? The amp now sits in a corner of my shed looking sad.

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There is a lot of black magic and luck when it comes to making FET amps. What we learnt is if you get one working, don’t change the design!!!

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Vy 73

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Steve, VK6VZ/G3ZZD

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From: Hans Summers

Sent: Wednesday, April 24, 2019 12:29 AM

To: [email protected]

Subject: [QRPLabs] 50+ Watts am for QCX...

?

Hi all

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A lighthearted intermission, that I hope you enjoy, discussing first "WHY" then the story of explosions, fireworks... and finally a successful and simple junkbox amplifier producing over 50W RF from a QCX-40.

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See

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73 Hans G0UPL

Virus-free.

Chris Baker

#33850

About exploding caps... I worked at Power One for awhile way back before switching power supplies and every once in awhile the line people would put in an electrolytic capacitor in backwards. I remember one time one of them exploded and embedded the shell in the ceiling 20 feet up. Another time I got hit in the shoulder hard enough to make a bleeding bruise. Those things are dangerous if installed incorrectly or if they just decide to go bang for no discernible reason.

On Wednesday, April 24, 2019, 11:42:57 AM EDT, Ray Worrall via Groups.Io <grimmerstreet@...> wrote:

My first job in life was fixing things.? Involved film projectors and related products. Grew to fixing electronic flashes.? Was fixing one and had to reform the capacitor. Was within 6 inches of it and the main capacitor blew up.? So loud it affected my hearing for a couple days.? High frequencies sounded low and vise versa.? On my work bench I had a AM radio powered by No 6 dry cells.? My boss came in and saw this and referred it to a FLQ Bomb.? This is Canadian thing, some may remember this from years ago.? Lastly, as a kid, I made a breadboard with a few terminal strips, built a regenerative AM radio and was able to pick up a radio station in Victoria BC from Vancouver.??It used?a couple 2N170 transistors, remember those. Have also built several of the Genesis SDR radios but have moved on. ? My last projects were 2 QCX radios.? Thumbs up on these. 50 years later I'm still fixing things...