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Re: Elmer 101
Sorry guys, I posted the copies here without permission so I need to remove them.? Please google online yourself if you want to read them. 73, Mark.
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Mark - N7EKU <n7eku@...>
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#553
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Re: Magloop prototype
What do you mean by ¡°daily drivers?¡± Can you also share some data that Teflon is lossy at rf? Thanks for the help. Kurt
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Kurt Loken <kurt.loken@...>
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#552
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Re: Magloop prototype
Historically, Teflon hasn't been suitable for "daily drivers" over time, whether trombones or otherwise. It's fine for proof of concept, but it's far from ideal and it's lossy at RF. Not when used in
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Kirk Kleinschmidt, NT0Z
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#551
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Re: Magloop prototype
Hello Jerry, My 3D printed cap isn¡¯t wholly dissimilar to what you describe. I think the stability issue could be mitigated by having an overlap system rather than a hinge but that causes
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Kurt Loken <kurt.loken@...>
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#550
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Re: Magloop prototype
Yes, if bandwidth is maybe 10khz, mechanical stability will be a real concern. My laminate thing, like a lot of mag loops I see, could be a bit floppy. But perhaps an advantage, distort the circular
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Jerry Gaffke
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#549
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Re: Magloop prototype
The stability issue is real and controlling overlap with a motor is a challenge of engineering in and of itself. For myself I consider it a challenge and part of the fun. Also...I have really come to
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Kurt Loken <kurt.loken@...>
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#548
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Re: Elmer 101
Hi, Typo there.? The journal issue which has the Elmer 101 book is QRPp Journal Volume 6 Number 3.? I just added a folder in the files section for copies of the journal and broke up volume 6 into
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Mark - N7EKU <n7eku@...>
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#547
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Edited
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Re: Magloop prototype
I still like that laminate strip with a copper foil glued to it, a teflon sheet for the dielectric?where the foil overlaps?to form a cap.? The overlap is held firmly in place by a couple bare FR4
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Jerry Gaffke
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#546
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Re: Fwd Bias LEDs as Varicaps/Varactors
A bench test, sort of... Using a 30m Rx**, 10.116 crystal?and a BB910 vs a small LED I adjusted the LED bias?for about the same measured?C range as the BB910 The read-out on my FT-847 Rx and 25Hz
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Chuck Carpenter
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#545
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Re: Fwd Bias LEDs as Varicaps/Varactors
There is of course a nice exponential relationship between forward voltage and current. But forward current is much easier to measure.
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Jerry Gaffke
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#544
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Re: Elmer 101
Mike Yep, I have seen it there and plan to use for my6 builders. The PC boards are coming from China based on some Gerbers I found. But I did see a book at one of the web sites so I thought I would
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stephen white
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#543
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Re: Fwd Bias LEDs as Varicaps/Varactors
Seeing a forward voltage of 12v applied across a 1n4001 got my attention as well. From the webpage:? "NOTE: the voltages measured are at the wiper of the potentiometer, which is NOT now the voltage
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Jerry Gaffke
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#542
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Re: Fwd Bias LEDs as Varicaps/Varactors
It IS. The "combined" graph had a hover feature to show forward bias voltage, but it isn't working for me either... if I am not mistaken... 73, Gary WB6OGD
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wb6ogd
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#541
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Re: Fwd Bias LEDs as Varicaps/Varactors
Hi All, I gotta ask... How can you forward bias a 1N4007 diode greater than 0.6 volts? I must be missing something? Diz
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w8diz
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#540
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Re: Norcal 40a Toroids
Thanks Richard, I think Santa is bringing me a NanoVNA. I'm looking forward to learning what it can do for me. Cheers, Paul VA3ZC
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Paul Egan
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#539
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Fwd Bias LEDs as Varicaps/Varactors
Read the Info from Hans, http://hanssummers.com/varicap/varicapfwd.html And especially this comment with calculations at the bottom...(Jerry) *Adam SQ5RWQ * Note that connecting two LEDs in series
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Chuck Carpenter
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#538
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Re: Elmer 101
Steve, It's been over 20 years, but the original info is still on my qsl web page http://qsl.net/kf4trd. You are welcome to print and use the info as you wish, just not for profit. Good luck Mike
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Michael Maiorana
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#537
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Re: SMT Varactor vs Thru Hole
Eric, Good info, makes sense when you relate the shape to functional applications.? On the O/T about the capacitor plates.? In my Vast Experience (or maybe Half-) I knew that tapered plate style as
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Chuck Carpenter
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#536
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Re: Norcal 40a Toroids
5% is 1.45uH so 0.6uH is well within tolerance. I've been analysing a 20m LPF with my NanoVNA and I found I had to remove a total of 4 turns off the 3 toroids to get a decent return loss and minimise
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Richard Tomlinson G4TGJ
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#535
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Re: Magloop prototype
One good reason to use teflon as a capacitor dielectric, it's easy to know when it has failed. Search for the word "explosively" in this discussion:
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Jerry Gaffke
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#534
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