Date   

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


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.

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


Re: Coil forms, Q, and instruments

Bobby Drummond
 

They look great.  Love the ability to wind them with consistent spacing.  Great job, Jim!

Bobby - AK4JA

On Jul 23, 2021, at 12:12 PM, Ted via groups.io <k3rta@...> wrote:

That's some nice work.  Do I see an antenna kit idea?    

Ted





On Fri, Jul 23, 2021 at 9:33, Jim, N5IB
<n5ib@...> wrote:
Thanks, Johnny,

Didn't notice the photo was blurry... here's a better one

Jim, N5IB








Electroluminescent receiver

David Wilcox K8WPE
 

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


Re: Coil forms, Q, and instruments

Ted
 

That's some nice work.  Do I see an antenna kit idea?    

Ted





On Fri, Jul 23, 2021 at 9:33, Jim, N5IB
<n5ib@...> wrote:
Thanks, Johnny,

Didn't notice the photo was blurry... here's a better one

Jim, N5IB







Re: Coil forms, Q, and instruments

Jim, N5IB
 

Thanks, Johnny,

Didn't notice the photo was blurry... here's a better one

Jim, N5IB


Re: Coil forms, Q, and instruments

Johnny AC0BQ
 

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,

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





--
Check out the 4SQRP website at 4sqrp.com


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


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








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



Virus-free. www.avg.com


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








Re: Coil forms, Q, and instruments

Jim Sheldon
 

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.

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


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


Re: 40 AND 80 Meter Net reports

AC5WT <anwj@...>
 

Look up W4C for your answer about Cuban jamming.


Re: 40 AND 80 Meter Net reports

Michael Fletcher
 

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


Re: 40 AND 80 Meter Net reports

Matthew Halsey
 

I hear a lot about Cuban jamming on 40m?

Matt
KC3OIV

On Jul 22, 2021, at 8:11 AM, 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


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


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
JOHNNY AC0BQ  ..



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


40 AND 80 Meter Net reports

Johnny AC0BQ
 

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
JOHNNY AC0BQ  ..


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