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Re: How good is the 1N4004 diode as a varactor
Please ignore my last post. I wish these things could be edited after posting, but it doesn't work that way here! I was forgetting the influence of the 270pF cap connected to pin 6 of the 602. My
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Dave AA7EE
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#9519
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Re: How good is the 1N4004 diode as a varactor
I have no experience with the 1N4004 as a varactor, but I did use a 1N4001 as one in a simple NE602-LM386 DC receiver on 40M. The inductor was 3.1?H (27 turns on a T50-7). With a voltage span of
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Dave AA7EE
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#9518
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Re: How good is the 1N4004 diode as a varactor
What circuit did you use to test?
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Doug Hendricks
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#9517
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Re: How good is the 1N4004 diode as a varactor
Thanks for the info.? Very interesting that a 5mm red led works so well.? I'm going to do some testing.? ?Again, I appreciate the help.? Doug
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Doug Hendricks
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#9516
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Re: 60 Meter homebrew rig IF frequencies
In my BITX40 I used the VFO to switch USB/LSB for digital, so high side and low side. Worked great.Could I hear the difference? Yes. The filter skirt was different. Was it equally usable? You bet it
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Ryan Flowers
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#9515
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Re: 60 Meter homebrew rig IF frequencies
But i think it? it is easy because will you hear the difference? I believe not. I cant give exact figures because I do not have the precission equipment to measure it. Yes the roll off slope is
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Kees PE7ST
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#9514
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Re: How good is the 1N4004 diode as a varactor
Hi Doug, One normally doesn't run a varactor down to 0 volts (as Han's chart showed), but at minimum 1 volts. I tested two brands of rectifier--1N4003 and 1N4007.? The 4003 at 1V was 10.6 pF and at
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Steve Ratzlaff
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#9513
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Re: How good is the 1N4004 diode as a varactor
http://www.hanssummers.com/varicap/varicapdiode.html Not that particular part but useful info here. Plus a circuit to take some data.
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Curt
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#9512
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How good is the 1N4004 diode as a varactor
What is your experience with using the 1N4004 diode as a varactor in tuning circuits?? How does it compare to the MV209? In the same circuit, what is the comparison between the 2 diodes in tuning
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Doug Hendricks
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#9511
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Re: QRP TX LPF illustration
Change cutoff to 6.1 MHz for 80M. Not quite as good as previous 40M filter. John KN5L
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John KN5L
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#9510
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Re: QRP TX LPF illustration
URL for filter design tool https://markimicrowave.com/technical-resources/tools/lc-filter-design-tool/
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John KN5L
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#9509
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Re: QRP TX LPF illustration
One way is using a filter design tool for a start, LC Filter Design Tool Select Lowpass, Elliptic, Shunt First, Order 5, cutoff 10 MHz, ripple 0.10, and stopband (dB) 37 Place calculated values into
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John KN5L
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#9508
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Re: QRP TX LPF illustration
Hi Goody, For my example I used an existing LPF and simply used each inductor to calculate what resonating cap worked at the 2nd and 3rd harmonics and picked the closest standard value cap to use. But
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Steve Ratzlaff
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#9507
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Re: 1W and 5W build guides
Thanks Chuck! I may celebrate and build my Organic 5W CW Transceiver Kit for 40m finally... I have an extra PCB and keyer chip in case I screw up.?? But just so others know - the keyer chip and PCBs
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Daniel KK4MRN
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#9506
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Re: QRP TX LPF illustration
I have a homebrew 80m CW rig I built 20 years ago that was out of spec and I'm re-doing the final PA and LPF. Did you use an online calculator to determine the values? I'd like to try this harmonic
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Anthony Good
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#9505
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QRP TX LPF illustration
We're all aware of the current FCC regs for harmonics and spurious outputs from a transmitter needing to be -43 dBc or greater below the fundamental output. Here's a 40 M LPF with the original
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Steve Ratzlaff
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#9504
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Re: Final PA Transistor
I run my 40 and 17x 5watters all the time. Awesome little radios! I need to rig up an attenuator knob for the 17 because the filter is so tight/narrow that it rings horribly on strong signals. I
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Tim Tyler II
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#9503
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1W and 5W build guides
Forgot.? Old links at kitsandparts.com are for the old call.? Here are the new links. <https://www.aa7fo.com/5w.pdf> <https://www.aa7fo.com/1w-108.pdf> <https://www.aa7fo.com/onewatter.html> and I
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chuck adams
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#9502
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Final PA Transistor
Here is one used in the 1W and 5W xcvr of KitsAndParts designed by Diz, W8DIZ<sk>. I bought a 100 and tried them in a 20m 5W and a 12m 1W and got the exact same output as non-fake parts.? Go look at
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chuck adams
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#9501
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Re: 60 Meter homebrew rig IF frequencies
*Hallas Rule ( https://soldersmoke.blogspot.com/2015/05/sideband-inversion.html ) :? Sideband inversion only occurs when you are subtracting the signal with modulation FROM the signal without
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hwstar
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#9500
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