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Re: Coil forms, Q, and instruments
Jerry Brown
Does anyone see a roller inductor in the making??? They are hard to come by these days and the last one I bought was for a club build project linked here....a LC matching network for end fed half wavelength verticals.... A QRP version would be nice! 72, Jerry N4EO, ex-YI9EO
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Re: Coil forms, Q, and instruments
WA4EFS
Hello Jim. Very nice work on the coil form. I test printed your .stl file and it came out perfectly.
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If you don't mind my asking which CAD application do you use? Some time ago I attempted a similar project in FreeCAD. However, I encountered difficulties and set it aside. 73, -Lloyd (wa4efs)
-----Original Message-----
From: main@4SQRP.groups.io [mailto:main@4SQRP.groups.io] On Behalf Of Jim, N5IB Sent: Friday, July 23, 2021 8:50 AM To: main@4SQRP.groups.io Subject: Re: [4SQRP] Coil forms, Q, and instruments Hi David, Here's the STL file, attached, and a photo. It's such a thin tube it needs a "brim" for buildplate adhesion There's a tiny hole at each end to pass the wire through to secure the turns. I plan to make another with multiple holes to accommodate different turn counts. Jim, N5IB
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Re: Coil forms, Q, and instruments
Bobby Drummond
They look great. Love the ability to wind them with consistent spacing. Great job, Jim!
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Bobby - AK4JA
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Electroluminescent receiver
Perchance does anyone have the old electroluminescent receiver (kit or built) that they might want to part with? Please contact me directly at Djwilcox01 at gmail dot com.
Dave K8WPE David J. Wilcox’s iPad
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Re: Coil forms, Q, and instruments
That's some nice work. Do I see an antenna kit idea?
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Ted
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Re: Coil forms, Q, and instruments
Jim, N5IB
Thanks, Johnny,
Didn't notice the photo was blurry... here's a better one Jim, N5IB
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Re: Coil forms, Q, and instruments
Gm Jim You do amazing work with that printer. These are really nice! 72 Johnny
On Fri, Jul 23, 2021 at 7:49 AM Jim, N5IB <n5ib@...> wrote: Hi David, --
Check out the 4SQRP website at 4sqrp.com
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Re: Coil forms, Q, and instruments
Jim, N5IB
Hi David,
Here's the STL file, attached, and a photo. It's such a thin tube it needs a "brim" for buildplate adhesion There's a tiny hole at each end to pass the wire through to secure the turns. I plan to make another with multiple holes to accommodate different turn counts. Jim, N5IB
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Re: Coil forms, Q, and instruments
davemrtn
ALso, I'd like to see your STL
file for the spreaders. David Martin - NA1MH - Mountain
Home, Ar.
----------------------------------------- Wherever I go, there He is.
On 7/22/2021 2:25 PM, Jim, N5IB wrote:
With too much free time for my own good, I did an experiment with 3D printing some spiral grooved coil forms. I was curious if the PLA plastic material used to print would degrade the Q of the coil. 16 turns AWG24, about 1" diameter, about 1" long on a hollow, grooved PLA tube Short answer, no noticeable Q degradation when I inserted a rod of the PLA material into the center of the coil. The effective inductance of a coil wound on the form is a few percent lower than the "air wound" formulas predict. prediction: 5.6 uH, measured: 4.8 uH But that's to be expected because of the increased inter-winding capacitance due to the dielectric constant of the form's PLA material (about 3). We see the same effect with toroids when spreading/squeezing turns - changing the spacing changes the inter-winding capacitance. Made a series trap with the test coil and a 200 pF dipped mica cap, and measured the 3 dB frequencies. The interesting finding is that when I did the Q measurement with a $1000+ spectrum analyzer, I got Q=185. The on a whim, repeated the measurement with a $65 Nano VNA , and got Q=180 Darn ! 2.7% low ! I think there is a lesson hiding here LOL Jim, N5IB
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Re: Coil forms, Q, and instruments
Kent Trimble, K9ZTV
Before buying any antenna
analyzer you intend to use in the field, make sure the screen is
legible in bright sunlight. Many, advertised for the outdoors,
are not.
73, Kent K9ZTV
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Re: Coil forms, Q, and instruments
davemrtn
Good experiment Jim, Thanks for sharing.
David Martin - NA1MH - Mountain
Home, Ar.
----------------------------------------- Wherever I go, there He is.
On 7/22/2021 2:25 PM, Jim, N5IB wrote:
With too much free time for my own good, I did an experiment with 3D printing some spiral grooved coil forms. I was curious if the PLA plastic material used to print would degrade the Q of the coil. 16 turns AWG24, about 1" diameter, about 1" long on a hollow, grooved PLA tube Short answer, no noticeable Q degradation when I inserted a rod of the PLA material into the center of the coil. The effective inductance of a coil wound on the form is a few percent lower than the "air wound" formulas predict. prediction: 5.6 uH, measured: 4.8 uH But that's to be expected because of the increased inter-winding capacitance due to the dielectric constant of the form's PLA material (about 3). We see the same effect with toroids when spreading/squeezing turns - changing the spacing changes the inter-winding capacitance. Made a series trap with the test coil and a 200 pF dipped mica cap, and measured the 3 dB frequencies. The interesting finding is that when I did the Q measurement with a $1000+ spectrum analyzer, I got Q=185. The on a whim, repeated the measurement with a $65 Nano VNA , and got Q=180 Darn ! 2.7% low ! I think there is a lesson hiding here LOL Jim, N5IB
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Re: Coil forms, Q, and instruments
Ha Ha! Yup, for amateur use, spending 1000+ on a spectrum analyzer vs $65 on a Nano VNA or even maybe a bit more on a "Tiny" spectrum analyzer is pretty huge "overkill" LOL.
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I have both the Nano VNA and the tiny Spectrum Analyzer and have gotten super good results from both of them. I sold my expensive spectrum analyzer. The only thing the two little ones don't have is a "tracking generator" and I never found the TG to be super necessary for most of my normal SA measurements. Jim, W0EB
------ Original Message ------
From: "Jim, N5IB" <n5ib@juno.com> To: main@4sqrp.groups.io Sent: 7/22/2021 2:25:26 PM Subject: [4SQRP] Coil forms, Q, and instruments With too much free time for my own good, I did an experiment with 3D printing some spiral grooved coil forms. I was curious if the PLA plastic material used to print would degrade the Q of the coil. 16 turns AWG24, about 1" diameter, about 1" long on a hollow, grooved PLA tube Short answer, no noticeable Q degradation when I inserted a rod of the PLA material into the center of the coil. The effective inductance of a coil wound on the form is a few percent lower than the "air wound" formulas predict. prediction: 5.6 uH, measured: 4.8 uH But that's to be expected because of the increased inter-winding capacitance due to the dielectric constant of the form's PLA material (about 3). We see the same effect with toroids when spreading/squeezing turns - changing the spacing changes the inter-winding capacitance. Made a series trap with the test coil and a 200 pF dipped mica cap, and measured the 3 dB frequencies. The interesting finding is that when I did the Q measurement with a $1000+ spectrum analyzer, I got Q=185. The on a whim, repeated the measurement with a $65 Nano VNA , and got Q=180 Darn ! 2.7% low ! I think there is a lesson hiding here LOL Jim, N5IB
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Coil forms, Q, and instruments
Jim, N5IB
With too much free time for my own good, I did an experiment with 3D printing some spiral grooved coil forms.
I was curious if the PLA plastic material used to print would degrade the Q of the coil. 16 turns AWG24, about 1" diameter, about 1" long on a hollow, grooved PLA tube Short answer, no noticeable Q degradation when I inserted a rod of the PLA material into the center of the coil. The effective inductance of a coil wound on the form is a few percent lower than the "air wound" formulas predict. prediction: 5.6 uH, measured: 4.8 uH But that's to be expected because of the increased inter-winding capacitance due to the dielectric constant of the form's PLA material (about 3). We see the same effect with toroids when spreading/squeezing turns - changing the spacing changes the inter-winding capacitance. Made a series trap with the test coil and a 200 pF dipped mica cap, and measured the 3 dB frequencies. The interesting finding is that when I did the Q measurement with a $1000+ spectrum analyzer, I got Q=185. The on a whim, repeated the measurement with a $65 Nano VNA , and got Q=180 Darn ! 2.7% low ! I think there is a lesson hiding here LOL Jim, N5IB
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Re: 40 AND 80 Meter Net reports
AC5WT <anwj@...>
Look up W4C for your answer about Cuban jamming.
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Re: 40 AND 80 Meter Net reports
One suspect is Cuba. Mike KL7IXI
On Jul 22, 2021, at 07:12, Jim Linsenbardt <jim.linsenbardt@...> wrote:
73's to all! The past two or three weeks, when I tune into the 40m net, there's been some type of strange digital QRM that seems to swamp everything out. It spans several KHz. Makes it almost impossible for me to hear QRP (or even QRO) CW signals. Dunno if anyone else has been hearing this QRM? Jim KD0WF 4SQRP #960
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Re: 40 AND 80 Meter Net reports
Matthew Halsey
I hear a lot about Cuban jamming on 40m?
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Matt KC3OIV
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Re: 40 AND 80 Meter Net reports
Jim Linsenbardt
73's to all! The past two or three weeks, when I tune into the 40m net, there's been some type of strange digital QRM that seems to swamp everything out. It spans several KHz. Makes it almost impossible for me to hear QRP (or even QRO) CW signals. Dunno if anyone else has been hearing this QRM? Jim KD0WF 4SQRP #960
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Re: 40 AND 80 Meter Net reports
n4mj
Sri I missed the nets. NAQCC Sprint took priority. hi hi 73 de n4mj//glenn “PLEASE REMOVE all email addresses before you send it on and use BCC option when forwarding" Thank you!
On Wednesday, July 21, 2021, 09:01:14 PM CDT, Johnny AC0BQ <jomatlock@...> wrote:
Ge Group Bands were in pretty good shape. Lot's of check in's! Check in's were: 40 METERS WD4CFN STEVE N4ELM DAVE W5ESE SCOTT AB9BZ DAVID N3COB GLENN KK5IB DARRYL KA5ZBP JOE (POSSSIBLE QRO) 80 METER CHECK IN'S WERE: N0YJ BERT WA0ITP TERRY NK80 CHARLES N4ELM DAVE KL7IXI MIKE WB0QQT STEVE. Thanks everyone, have a good week. Please stay cool, Summer has returned! 72 Johnny AC0BQ 72
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Delta Mike Romeo Net
Robert
Tonights Check in's N0RSR ROGER N9EGT WAYNE AC0BQ JOHNNY NA1MH DAVID WA9BNZ BILL KC0PP KEITH NK8O CHARLES WG5F ED WA2TOP MIKE 73'S Bert N0YJ
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40 AND 80 Meter Net reports
Ge Group Bands were in pretty good shape. Lot's of check in's! Check in's were: 40 METERS WD4CFN STEVE N4ELM DAVE W5ESE SCOTT AB9BZ DAVID N3COB GLENN KK5IB DARRYL KA5ZBP JOE (POSSSIBLE QRO) 80 METER CHECK IN'S WERE: N0YJ BERT WA0ITP TERRY NK80 CHARLES N4ELM DAVE KL7IXI MIKE WB0QQT STEVE. Thanks everyone, have a good week. Please stay cool, Summer has returned! 72 Johnny AC0BQ 72
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