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Re: Anyone Built the Rose 80?
Thank you for the details about the caps and transformer.
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Rob <roomberg@...>
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#400
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Re: Anyone Built the Rose 80?
John, I prefer to have these conversations within the forum Often there's somebody else with the extra info needed to resolve an issue. As Ryan says, people come to this forum because they want to see
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Jerry Gaffke
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#399
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Re: Anyone Built the Rose 80?
Hey John, You wrote " Sorry to drag the group through this, but ..." Please, please.... drag the group through it! There are a lot of people here whose joy is to read through such issues and learn
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Ryan Flowers
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#398
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Re: Anyone Built the Rose 80?
Jerry, Thanks for all your response and interesting ideas.?? My frustration beyond the fluctuation in the output over about 100 kcs, is that I don't really understand how the filter works.?? I
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John Roland <johnroland51@...>
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#397
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New QRP Labs 50W PA for the QCX (and Homebrew, I'm sure)
http://qrp-labs.com/50wpa Hans released this today- $29.50 for a 50W PA that includes filtering and heat sink. It's class C, CW only. Could be a nice addition to a rig during the solar minimum :) --
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Ryan Flowers
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#396
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Re: Anyone Built the Rose 80?
Correction:? 24-22=2mhz But you knew that.
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Jerry Gaffke
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#395
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Re: 7 MHz Oscillator Ideas
Yes, the capacitance change of a varactor per volt decreases as voltage increases. But remember that the capacitance change has more "worth" at low levels. For example, in a tank with only a varactor
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Nick Kennedy
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#394
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Re: Anyone Built the Rose 80?
Most QRP CW transmitters get by with just the output low pass filter because the oscillator is working directly at the desired transmit frequency. There is no mixer to create spurious products. The
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Jerry Gaffke
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#393
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Re: Anyone Built the Rose 80?
John, Why offline? Perhaps we can all learn something. I have no experience with this particular design. But I don't think you have a layout issue. Most CW transmitters are broadband all the way out
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Jerry Gaffke
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#392
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Anyone Built the Rose 80?
To make a long story short, I am have a problem with the output power varying a couple watts over the tuning range depending on where I peak the filter (T3 T5).? I built the rig using ugly
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John Roland <johnroland51@...>
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#391
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Re: What level math is in the RF design books?
As someone who has endured graduate level math... Don't overthink the math when designing or troubleshooting a radio. As someone else commented, high school algebra is almost overkill for the amateur
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ac7lx@...
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#390
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Re: What level math is in the RF design books?
two CR2032 batteries Roy WA0YMH
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Roy Appleton
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#389
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Re: What level math is in the RF design books?
William, Oooops, That should have been Vrms ?^2 I never could get comfortable with RPN.? I had one of the TI programmables.?That worked good for me for a while.? I *loaned* it to my son when he
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Chuck Carpenter
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#388
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Re: What level math is in the RF design books?
Chuck, Thanks! I had discovered that a long time ago and was using it in my previous message to illustrate my relative Business Administration degree ignorance of electronic theory. But, coincident
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k6whp
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#387
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Re: 7 MHz Oscillator Ideas
Here's a thought on a minimalist si5351 vfo: Could turn on a second channel at 600 hz away from the primary channel, weakly coupled into that primary channel. This should come through on most
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Jerry Gaffke
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#386
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Re: 7 MHz Oscillator Ideas
The si5351 is a great part, and only costs $1. You do need a processor to communicate with the si5351 via its i2c bus, but a low end msp430 these days is $0.50. With that, a 25mhz reference crystal,
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Jerry Gaffke
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#385
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Re: 7 MHz Oscillator Ideas
It is stable enough because of the use of the crystals. However, if this was an LC circuit, you definitely want voltage into that pot to be regulated. The voltage applied to the diode is always some
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Jerry Gaffke
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#384
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Re: 7 MHz Oscillator Ideas
Jerry, The capacitance beyond 10V changes very little.? The plotted curves by k7qo?in the attached chart show that. The MV209 is similar to the BB910 that I used. Note too that the curve for the
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Chuck Carpenter
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#383
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Re: 7 MHz Oscillator Ideas
Would it be of any value to use a Si5351 module like the Adafruit module ($7 from them or Mouser or Digikey) or a homebrew one like VK3PE makes that is a drop in replacement for the Adafruit
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Jim Pruitt WA7DUY
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#382
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Re: What level math is in the RF design books?
William, Try this:? Vrms = 0.3535 * Vpp? then, Po = Vrms*2 / 100 That's the simplest approximation. -- Chuck, W5USJ (ex K2OFN) Point, Rains Co, TX? EM22cv
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Chuck Carpenter
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#381
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