Date   

Re: Are LEDs a noise source

Neil Smith G4DBN
 

Back on to the original topic for a second, there are some articles showing what appears to a forward-biased LED used as a noise source. The author in this piece says the noise was about 6dB down on a zener in the same topology (two-transistor amplifier). http://www.n5ese.com/noise.htm

I did wonder if the LED was drawn incorrectly and it was actually being used in reverse breakdown.  The diagram towards the end of the page definitely shows it drawn in the forward conduction direction.

LEDs do show some rising levels of shot noise and 1/f noise below 10 kHz, but that is at low levels. However, at high currents, the authors found a correlation between the LF noise and the brightness fluctuations of the LED in that frequency range.

https://www.researchgate.net/profile/Michael_Shur2/publication/268362232_titleLow_frequency_noise_of_light_emitting_diodes_Invited_Papertitle/links/54bcea0f0cf29e0cb04c55e3/titleLow-frequency-noise-of-light-emitting-diodes-Invited-Paper-title.pdf

There is another article using a totally different topology where a LED and photodiode are used to generate noise with 7dB ENR up to about 100 MHz, but it hits the usual 1/f noise issues. https://electronicprojectsforfun.wordpress.com/making-noise/noise-sources-i-have-built/a-led-photodiode-noise-source/

I've done this at extremely low light levels to make a "Quantum" random pulse generator, but that's well away from the OP's question.

Neil G4DBN


Re: Are LEDs a noise source

KENT BRITAIN
 

I was also done along the Gulf of Mexico in the 1970's using Xenon flash tubes and
light intensifiers.   No digital processing and got 300 km on clear nights.  
Sea level to sea level, just scatter.
Certainly another 30 or 40 dB more power in the sources.
Be sure to have deep 100 Hz and/or 120 Hz filters.
Hard to think of a common incandescent light bulb as a frequency doubler, but they
do respond to both peaks in a sine wave. 
I have 6 systems we used several times during VHF/UHF contests.
We used the Lasers out of CD players.   IR and power adjustable.
The best detectors were made by Texas Instruments for Laser guided bombs,
but a panel of solar cells also worked well.   LOTS of capture area.

Kent

On Sunday, January 24, 2021, 10:25:33 AM CST, Andy G4JNT <andy.g4jnt@...> wrote:


No, It WAS done yonks ago in Oz, using WSPR just after it first came out

They used 60W of red LEDs, WSPR on a subcarrier and got 200km plus on cloud scatter.

I keep thinking I really ought to have a go at this, get some really big high power RED LEDs and find some suitable optics.    It's difficult getting a non point source into a narrow beam though, needs physically big and thick lenses.



On Sun, 24 Jan 2021 at 16:22, John Fell <john.g0api@...> wrote:
-45dB would probably relate to the developmental WSJT-X software yet to be released .(Done in VK ?)

I have had Transatlantic decodes at -44dB/noise , using JST4W-1800 on 137kHz  - that seems to be the limit but up in the realtime nano metre wavelengths , with massive path scattering a 65 tone or more system would need to be used .
Andy JNT knows more about the Shannon theory ....but all the LEDs in his right side are aching again .I blame the Snow .

It's Bloody clever stuf .

73
John
G0API

On Sun, 24 Jan 2021 at 16:09, Robin Szemeti - G1YFG <robin@...> wrote:
Speaking of which ... there was a rather excellent article in DUBUS a while ago about some chaps resurrecting a 90's LED optical transceiver and adding JT65 or similar to it and getting phenomenal performance ... hundreds of kilometres over non-line-of-sight paths, just relying on atmospheric scattering and recovering signals at -45 dB S/N

On Sun, 24 Jan 2021 at 14:53, Andy G4JNT <andy.g4jnt@...> wrote:
Especially white ones.



On Sun, 24 Jan 2021 at 14:34, John E. Beech <john@...> wrote:
It could be argued that LEDs produce noise at nanometer wavelengths.

de John G8SEQ

>  -------Original Message-------
>  From: Andy G4JNT <andy.g4jnt@...>
>  To: UK Microwaves groups.io <UKMicrowaves@groups.io>
>  Subject: Re: [UKMicrowaves] Are LEDs a noise source
>  Sent: Jan 23 '21 20:36

>  LEDs do not generate noise. Being forward-biassed, there is no noise
>  generation mechanism.
>  Gordon. you are referring to regulators, aren't you. They suffer from
>  instability if not decou[led.

>  Specs call-up minimum of 0.22uf on the output and a few uF on the
>  input if more than a few cm away from the supply.
>  The Question was about LEDs

>  Andy
www.g4jnt.com

>  On Sat, 23 Jan 2021 at 20:27, Gordon REASON via groups.io
>  <gordonj.reason=virgin.net@groups.io> wrote:

>  > Yes , Rick , should be decoupled with a 10 or 22 nF and a 4.7 uF .
>  >
>  >> On 23 January 2021 at 19:27 "G8ZHA via groups.io"
>  >> <g8zha-1=blueyonder.co.uk@groups.io> wrote:
>  >>
>  >> I have just built a G4DDK PGA-103 preamp to use for ADSB receive
>  >> on 1090MHz. The preamp will be mounted up on a pole, directly
>  >> underneath a PCB antenna, in a plastic tube. I feed 12V up to the
>  >> preamp and have 5V regulator next to the preamp. I usually include
>  >> a LED on the 5V shining down at the ground, so I can confirm that
>  >> the preamp is powered.
>  >>
>  >> Do LEDs generate any noise?
>  >>
>  >> Rich G8ZHA
>  >
>  >>








--
Robin Szemeti - G1YFG


Re: cling film?

John Fell
 

Ah yes ,
A mini olde style Fylingdales Radome would work .You may find /p operation would bring more attention than you would like and if it was windy ........

Good to see the next generation working through the systems Engineering we had to do on narrowband 10GHz back in the late 1980s ,Such Fun .
73
John
G0API

On Sun, 24 Jan 2021 at 16:34, militaryoperator via groups.io <Military1944=aol.com@groups.io> wrote:
Hi Ben,
Polystyrene boxes and cling film are OK for temp /P .
Keep up the good work .
73
John
G0API


Thanks John. 

Should do a little better this year, didn't start in this field until April last year so should get 3 months of extra points, hi.
Thinking on keeping rain off the radiator, a balloon would be good, blown up to cover but not touch the elements but can't get it on, hi. 

Need like a sphere, in two halves, bottom has coax though it first, connected, then bottom and top halves joined together to keep the rain off the radiator, hi. 

All good fun!

Ben 


Re: Are LEDs a noise source

John Fell
 

Yes , I know it was done Yonks ago , but the new software was mentioned in the last issue of the EME Newsletter as one of the "other" uses used to test the software system before general release - using more modest light sources .

I saw a video on TV (Winterwatch) showing a man flushing Starlings out of Italian Trees to prevent Poomagedon .Looked like a solid torch but emitting narrow beamwidth Laser light ?
Now a bit of websearching and modulation interfacing it could be possible to do some handheld OTH comms ....

John


On Sun, 24 Jan 2021 at 16:25, Andy G4JNT <andy.g4jnt@...> wrote:
No, It WAS done yonks ago in Oz, using WSPR just after it first came out

They used 60W of red LEDs, WSPR on a subcarrier and got 200km plus on cloud scatter.

I keep thinking I really ought to have a go at this, get some really big high power RED LEDs and find some suitable optics.    It's difficult getting a non point source into a narrow beam though, needs physically big and thick lenses.



On Sun, 24 Jan 2021 at 16:22, John Fell <john.g0api@...> wrote:
-45dB would probably relate to the developmental WSJT-X software yet to be released .(Done in VK ?)

I have had Transatlantic decodes at -44dB/noise , using JST4W-1800 on 137kHz  - that seems to be the limit but up in the realtime nano metre wavelengths , with massive path scattering a 65 tone or more system would need to be used .
Andy JNT knows more about the Shannon theory ....but all the LEDs in his right side are aching again .I blame the Snow .

It's Bloody clever stuf .

73
John
G0API

On Sun, 24 Jan 2021 at 16:09, Robin Szemeti - G1YFG <robin@...> wrote:
Speaking of which ... there was a rather excellent article in DUBUS a while ago about some chaps resurrecting a 90's LED optical transceiver and adding JT65 or similar to it and getting phenomenal performance ... hundreds of kilometres over non-line-of-sight paths, just relying on atmospheric scattering and recovering signals at -45 dB S/N

On Sun, 24 Jan 2021 at 14:53, Andy G4JNT <andy.g4jnt@...> wrote:
Especially white ones.



On Sun, 24 Jan 2021 at 14:34, John E. Beech <john@...> wrote:
It could be argued that LEDs produce noise at nanometer wavelengths.

de John G8SEQ

>  -------Original Message-------
>  From: Andy G4JNT <andy.g4jnt@...>
>  To: UK Microwaves groups.io <UKMicrowaves@groups.io>
>  Subject: Re: [UKMicrowaves] Are LEDs a noise source
>  Sent: Jan 23 '21 20:36

>  LEDs do not generate noise. Being forward-biassed, there is no noise
>  generation mechanism.
>  Gordon. you are referring to regulators, aren't you. They suffer from
>  instability if not decou[led.

>  Specs call-up minimum of 0.22uf on the output and a few uF on the
>  input if more than a few cm away from the supply.
>  The Question was about LEDs

>  Andy
www.g4jnt.com

>  On Sat, 23 Jan 2021 at 20:27, Gordon REASON via groups.io
>  <gordonj.reason=virgin.net@groups.io> wrote:

>  > Yes , Rick , should be decoupled with a 10 or 22 nF and a 4.7 uF .
>  >
>  >> On 23 January 2021 at 19:27 "G8ZHA via groups.io"
>  >> <g8zha-1=blueyonder.co.uk@groups.io> wrote:
>  >>
>  >> I have just built a G4DDK PGA-103 preamp to use for ADSB receive
>  >> on 1090MHz. The preamp will be mounted up on a pole, directly
>  >> underneath a PCB antenna, in a plastic tube. I feed 12V up to the
>  >> preamp and have 5V regulator next to the preamp. I usually include
>  >> a LED on the 5V shining down at the ground, so I can confirm that
>  >> the preamp is powered.
>  >>
>  >> Do LEDs generate any noise?
>  >>
>  >> Rich G8ZHA
>  >
>  >>








--
Robin Szemeti - G1YFG


Re: cling film?

militaryoperator
 

Hi Ben,
Polystyrene boxes and cling film are OK for temp /P .
Keep up the good work .
73
John
G0API


Thanks John. 

Should do a little better this year, didn't start in this field until April last year so should get 3 months of extra points, hi.
Thinking on keeping rain off the radiator, a balloon would be good, blown up to cover but not touch the elements but can't get it on, hi. 

Need like a sphere, in two halves, bottom has coax though it first, connected, then bottom and top halves joined together to keep the rain off the radiator, hi. 

All good fun!

Ben 


Re: Are LEDs a noise source

Andy G4JNT
 

No, It WAS done yonks ago in Oz, using WSPR just after it first came out

They used 60W of red LEDs, WSPR on a subcarrier and got 200km plus on cloud scatter.

I keep thinking I really ought to have a go at this, get some really big high power RED LEDs and find some suitable optics.    It's difficult getting a non point source into a narrow beam though, needs physically big and thick lenses.



On Sun, 24 Jan 2021 at 16:22, John Fell <john.g0api@...> wrote:
-45dB would probably relate to the developmental WSJT-X software yet to be released .(Done in VK ?)

I have had Transatlantic decodes at -44dB/noise , using JST4W-1800 on 137kHz  - that seems to be the limit but up in the realtime nano metre wavelengths , with massive path scattering a 65 tone or more system would need to be used .
Andy JNT knows more about the Shannon theory ....but all the LEDs in his right side are aching again .I blame the Snow .

It's Bloody clever stuf .

73
John
G0API

On Sun, 24 Jan 2021 at 16:09, Robin Szemeti - G1YFG <robin@...> wrote:
Speaking of which ... there was a rather excellent article in DUBUS a while ago about some chaps resurrecting a 90's LED optical transceiver and adding JT65 or similar to it and getting phenomenal performance ... hundreds of kilometres over non-line-of-sight paths, just relying on atmospheric scattering and recovering signals at -45 dB S/N

On Sun, 24 Jan 2021 at 14:53, Andy G4JNT <andy.g4jnt@...> wrote:
Especially white ones.



On Sun, 24 Jan 2021 at 14:34, John E. Beech <john@...> wrote:
It could be argued that LEDs produce noise at nanometer wavelengths.

de John G8SEQ

>  -------Original Message-------
>  From: Andy G4JNT <andy.g4jnt@...>
>  To: UK Microwaves groups.io <UKMicrowaves@groups.io>
>  Subject: Re: [UKMicrowaves] Are LEDs a noise source
>  Sent: Jan 23 '21 20:36

>  LEDs do not generate noise. Being forward-biassed, there is no noise
>  generation mechanism.
>  Gordon. you are referring to regulators, aren't you. They suffer from
>  instability if not decou[led.

>  Specs call-up minimum of 0.22uf on the output and a few uF on the
>  input if more than a few cm away from the supply.
>  The Question was about LEDs

>  Andy
www.g4jnt.com

>  On Sat, 23 Jan 2021 at 20:27, Gordon REASON via groups.io
>  <gordonj.reason=virgin.net@groups.io> wrote:

>  > Yes , Rick , should be decoupled with a 10 or 22 nF and a 4.7 uF .
>  >
>  >> On 23 January 2021 at 19:27 "G8ZHA via groups.io"
>  >> <g8zha-1=blueyonder.co.uk@groups.io> wrote:
>  >>
>  >> I have just built a G4DDK PGA-103 preamp to use for ADSB receive
>  >> on 1090MHz. The preamp will be mounted up on a pole, directly
>  >> underneath a PCB antenna, in a plastic tube. I feed 12V up to the
>  >> preamp and have 5V regulator next to the preamp. I usually include
>  >> a LED on the 5V shining down at the ground, so I can confirm that
>  >> the preamp is powered.
>  >>
>  >> Do LEDs generate any noise?
>  >>
>  >> Rich G8ZHA
>  >
>  >>








--
Robin Szemeti - G1YFG


Re: Are LEDs a noise source

John Fell
 

-45dB would probably relate to the developmental WSJT-X software yet to be released .(Done in VK ?)

I have had Transatlantic decodes at -44dB/noise , using JST4W-1800 on 137kHz  - that seems to be the limit but up in the realtime nano metre wavelengths , with massive path scattering a 65 tone or more system would need to be used .
Andy JNT knows more about the Shannon theory ....but all the LEDs in his right side are aching again .I blame the Snow .

It's Bloody clever stuf .

73
John
G0API


On Sun, 24 Jan 2021 at 16:09, Robin Szemeti - G1YFG <robin@...> wrote:
Speaking of which ... there was a rather excellent article in DUBUS a while ago about some chaps resurrecting a 90's LED optical transceiver and adding JT65 or similar to it and getting phenomenal performance ... hundreds of kilometres over non-line-of-sight paths, just relying on atmospheric scattering and recovering signals at -45 dB S/N

On Sun, 24 Jan 2021 at 14:53, Andy G4JNT <andy.g4jnt@...> wrote:
Especially white ones.



On Sun, 24 Jan 2021 at 14:34, John E. Beech <john@...> wrote:
It could be argued that LEDs produce noise at nanometer wavelengths.

de John G8SEQ

>  -------Original Message-------
>  From: Andy G4JNT <andy.g4jnt@...>
>  To: UK Microwaves groups.io <UKMicrowaves@groups.io>
>  Subject: Re: [UKMicrowaves] Are LEDs a noise source
>  Sent: Jan 23 '21 20:36

>  LEDs do not generate noise. Being forward-biassed, there is no noise
>  generation mechanism.
>  Gordon. you are referring to regulators, aren't you. They suffer from
>  instability if not decou[led.

>  Specs call-up minimum of 0.22uf on the output and a few uF on the
>  input if more than a few cm away from the supply.
>  The Question was about LEDs

>  Andy
www.g4jnt.com

>  On Sat, 23 Jan 2021 at 20:27, Gordon REASON via groups.io
>  <gordonj.reason=virgin.net@groups.io> wrote:

>  > Yes , Rick , should be decoupled with a 10 or 22 nF and a 4.7 uF .
>  >
>  >> On 23 January 2021 at 19:27 "G8ZHA via groups.io"
>  >> <g8zha-1=blueyonder.co.uk@groups.io> wrote:
>  >>
>  >> I have just built a G4DDK PGA-103 preamp to use for ADSB receive
>  >> on 1090MHz. The preamp will be mounted up on a pole, directly
>  >> underneath a PCB antenna, in a plastic tube. I feed 12V up to the
>  >> preamp and have 5V regulator next to the preamp. I usually include
>  >> a LED on the 5V shining down at the ground, so I can confirm that
>  >> the preamp is powered.
>  >>
>  >> Do LEDs generate any noise?
>  >>
>  >> Rich G8ZHA
>  >
>  >>








--
Robin Szemeti - G1YFG


Re: Snow Scatter

Neil Smith G4DBN
 

I couldn't hear myself on it, which is very unusual.

After sending my note about not hearing CAM, I checked Bspot and then saw the red splodge. That explains matters...

Neil G4DBN

On 24/01/2021 15:45, Robin Szemeti - G1YFG wrote:
I do check the Mow Cop SDR from time to time, it has been remarkably barren of late ...

On Sun, 24 Jan 2021 at 15:26, John Fell <john.g0api@...> wrote:
Thanks for the heads up on CAM John.
Spent some mins looking for it earlier - should have looked at BS first .
Did encourage me to put the mast up a bit and was pleased to find GB3MCB on 10GHz.Not heard for some time here and it turns out my Pine tree is not helping - tree surgeon needed .
73
John
G0API 

On Sun, 24 Jan 2021 at 14:36, John Lemay <john@...> wrote:
Neil

I believe 'CAM on 10GHz is off air. I spent some time listening for it on Friday, before finding the relevant info on Beaconspot.

John G4ZTR

-----Original Message-----
From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Neil Smith G4DBN
Sent: 24 January 2021 14:25
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Snow Scatter

All this 475 kHz is microwave compared with *proper* LF at 8270 Hz. Heh heh.

No sign of scatter on 10 GHz here at the moment, but there is a blanket
of drizzle to the south which is very absorbent. I can't even hear
GB3CAM, never mind KBQ/PKT/OSW.

I'm going back to the machine shop to bash some metal until the
troposphere bucks up its ideas.

Neil G4DBN





Re: Are LEDs a noise source

Robin Szemeti - G1YFG
 

Speaking of which ... there was a rather excellent article in DUBUS a while ago about some chaps resurrecting a 90's LED optical transceiver and adding JT65 or similar to it and getting phenomenal performance ... hundreds of kilometres over non-line-of-sight paths, just relying on atmospheric scattering and recovering signals at -45 dB S/N

On Sun, 24 Jan 2021 at 14:53, Andy G4JNT <andy.g4jnt@...> wrote:
Especially white ones.



On Sun, 24 Jan 2021 at 14:34, John E. Beech <john@...> wrote:
It could be argued that LEDs produce noise at nanometer wavelengths.

de John G8SEQ

>  -------Original Message-------
>  From: Andy G4JNT <andy.g4jnt@...>
>  To: UK Microwaves groups.io <UKMicrowaves@groups.io>
>  Subject: Re: [UKMicrowaves] Are LEDs a noise source
>  Sent: Jan 23 '21 20:36

>  LEDs do not generate noise. Being forward-biassed, there is no noise
>  generation mechanism.
>  Gordon. you are referring to regulators, aren't you. They suffer from
>  instability if not decou[led.

>  Specs call-up minimum of 0.22uf on the output and a few uF on the
>  input if more than a few cm away from the supply.
>  The Question was about LEDs

>  Andy
www.g4jnt.com

>  On Sat, 23 Jan 2021 at 20:27, Gordon REASON via groups.io
>  <gordonj.reason=virgin.net@groups.io> wrote:

>  > Yes , Rick , should be decoupled with a 10 or 22 nF and a 4.7 uF .
>  >
>  >> On 23 January 2021 at 19:27 "G8ZHA via groups.io"
>  >> <g8zha-1=blueyonder.co.uk@groups.io> wrote:
>  >>
>  >> I have just built a G4DDK PGA-103 preamp to use for ADSB receive
>  >> on 1090MHz. The preamp will be mounted up on a pole, directly
>  >> underneath a PCB antenna, in a plastic tube. I feed 12V up to the
>  >> preamp and have 5V regulator next to the preamp. I usually include
>  >> a LED on the 5V shining down at the ground, so I can confirm that
>  >> the preamp is powered.
>  >>
>  >> Do LEDs generate any noise?
>  >>
>  >> Rich G8ZHA
>  >
>  >>








--
Robin Szemeti - G1YFG


Re: Snow Scatter

Brian Howie GM4DIJ
 

In message <CAHLi5mU8tLPqY+PtquoNvoYQtPK9WqzUMnFqRLTC_6R1sgXQZA@mail.gmail.com>, John Fell <john.g0api@gmail.com> writes
A large band of snow cloud heading East from this QTH is producing SS
from SEE and PKT .
73
John
G0API
Not snow scatter, but I recently worked out why the GB3CSB microwave beacons sounded fuzzy on a particular heading.

This is 23cm, 9cm and 13cm are much broader at times. I get a reflection on 3cm, but I've not looked at it on Spectran.

The GB3CSB site is line of sight to the huge Whitelees Wind farm on high ground to the south of Glasgow IO75TR81 . The turbines are very tall , the rotor hub is 65m agl, the rotor 9m diameter and there are 215 of them.

I'm not LOS to them but the path is not too bad.

The Spectrogram was Tuesday afternoon. By the time the contest started and the snow came on, both the 23cm and 9cm beacons, ( and everyone else) had vanished.

Maybe someone in a suitable location might like to try a turbine scatter QSO.

Brian GM4DIJ


--
Brian Howie


Re: Snow Scatter

Robin Szemeti - G1YFG
 

I do check the Mow Cop SDR from time to time, it has been remarkably barren of late ...

On Sun, 24 Jan 2021 at 15:26, John Fell <john.g0api@...> wrote:
Thanks for the heads up on CAM John.
Spent some mins looking for it earlier - should have looked at BS first .
Did encourage me to put the mast up a bit and was pleased to find GB3MCB on 10GHz.Not heard for some time here and it turns out my Pine tree is not helping - tree surgeon needed .
73
John
G0API 

On Sun, 24 Jan 2021 at 14:36, John Lemay <john@...> wrote:
Neil

I believe 'CAM on 10GHz is off air. I spent some time listening for it on Friday, before finding the relevant info on Beaconspot.

John G4ZTR

-----Original Message-----
From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Neil Smith G4DBN
Sent: 24 January 2021 14:25
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Snow Scatter

All this 475 kHz is microwave compared with *proper* LF at 8270 Hz. Heh heh.

No sign of scatter on 10 GHz here at the moment, but there is a blanket
of drizzle to the south which is very absorbent. I can't even hear
GB3CAM, never mind KBQ/PKT/OSW.

I'm going back to the machine shop to bash some metal until the
troposphere bucks up its ideas.

Neil G4DBN








--
This email has been checked for viruses by AVG.
https://www.avg.com







--
Robin Szemeti - G1YFG


Re: Snow Scatter

John Fell
 

Thanks for the heads up on CAM John.
Spent some mins looking for it earlier - should have looked at BS first .
Did encourage me to put the mast up a bit and was pleased to find GB3MCB on 10GHz.Not heard for some time here and it turns out my Pine tree is not helping - tree surgeon needed .
73
John
G0API 

On Sun, 24 Jan 2021 at 14:36, John Lemay <john@...> wrote:
Neil

I believe 'CAM on 10GHz is off air. I spent some time listening for it on Friday, before finding the relevant info on Beaconspot.

John G4ZTR

-----Original Message-----
From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Neil Smith G4DBN
Sent: 24 January 2021 14:25
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Snow Scatter

All this 475 kHz is microwave compared with *proper* LF at 8270 Hz. Heh heh.

No sign of scatter on 10 GHz here at the moment, but there is a blanket
of drizzle to the south which is very absorbent. I can't even hear
GB3CAM, never mind KBQ/PKT/OSW.

I'm going back to the machine shop to bash some metal until the
troposphere bucks up its ideas.

Neil G4DBN








--
This email has been checked for viruses by AVG.
https://www.avg.com







Gap Waveguides

Chris Bartram G4DGU
 

I don't believe gap WGs will have much application in amateur microwaves unless low-cost micromachining becomes available.

What is attractive and not currently used in any amateur designs AFAIK is 'Substrate Integrated Waveguide'. I played with this for my own nefarious purposes just before I left GW, and it isn't difficult to make work.

Essentially, it's relatively easy to design TM-mode dielectric loaded waveguide structures which can fit within double sided PCBs. These can be transmission-lines,  filters, couplers, and resonators and basically anything which you can do with conventional microstrip or waveguide. The losses are dependent on the conducting materials and the substrate. Calculation of the size of structures, unlike microstrip, isn't complicated by the consequence of the differing simultaneous propagation characteristics air and the substrate which you get with microstrip.

There is even a variant of the SIW technique called 'empty SIW' where the substrate within the structures is removed completely, and the dielectric losses are completely eliminated. That even makes it possible to make low-loss structures using FR4 as a substrate ...

Once my current unpaid employment as a house builder is completed, and I've got myself back on the air, I'll try to sit down and write something for 'Scatterpoint'.

73

Chris G4DGU


Re: Are LEDs a noise source

Andy G4JNT
 

Especially white ones.



On Sun, 24 Jan 2021 at 14:34, John E. Beech <john@...> wrote:
It could be argued that LEDs produce noise at nanometer wavelengths.

de John G8SEQ

>  -------Original Message-------
>  From: Andy G4JNT <andy.g4jnt@...>
>  To: UK Microwaves groups.io <UKMicrowaves@groups.io>
>  Subject: Re: [UKMicrowaves] Are LEDs a noise source
>  Sent: Jan 23 '21 20:36

>  LEDs do not generate noise. Being forward-biassed, there is no noise
>  generation mechanism.
>  Gordon. you are referring to regulators, aren't you. They suffer from
>  instability if not decou[led.

>  Specs call-up minimum of 0.22uf on the output and a few uF on the
>  input if more than a few cm away from the supply.
>  The Question was about LEDs

>  Andy
www.g4jnt.com

>  On Sat, 23 Jan 2021 at 20:27, Gordon REASON via groups.io
>  <gordonj.reason=virgin.net@groups.io> wrote:

>  > Yes , Rick , should be decoupled with a 10 or 22 nF and a 4.7 uF .
>  >
>  >> On 23 January 2021 at 19:27 "G8ZHA via groups.io"
>  >> <g8zha-1=blueyonder.co.uk@groups.io> wrote:
>  >>
>  >> I have just built a G4DDK PGA-103 preamp to use for ADSB receive
>  >> on 1090MHz. The preamp will be mounted up on a pole, directly
>  >> underneath a PCB antenna, in a plastic tube. I feed 12V up to the
>  >> preamp and have 5V regulator next to the preamp. I usually include
>  >> a LED on the 5V shining down at the ground, so I can confirm that
>  >> the preamp is powered.
>  >>
>  >> Do LEDs generate any noise?
>  >>
>  >> Rich G8ZHA
>  >
>  >>








Re: Snow Scatter

John Lemay
 

Neil

I believe 'CAM on 10GHz is off air. I spent some time listening for it on Friday, before finding the relevant info on Beaconspot.

John G4ZTR

-----Original Message-----
From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Neil Smith G4DBN
Sent: 24 January 2021 14:25
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Snow Scatter

All this 475 kHz is microwave compared with *proper* LF at 8270 Hz. Heh heh.

No sign of scatter on 10 GHz here at the moment, but there is a blanket
of drizzle to the south which is very absorbent. I can't even hear
GB3CAM, never mind KBQ/PKT/OSW.

I'm going back to the machine shop to bash some metal until the
troposphere bucks up its ideas.

Neil G4DBN








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Re: Are LEDs a noise source

John E. Beech
 

It could be argued that LEDs produce noise at nanometer wavelengths.

de John G8SEQ

-------Original Message-------
From: Andy G4JNT <andy.g4jnt@gmail.com>
To: UK Microwaves groups.io <UKMicrowaves@groups.io>
Subject: Re: [UKMicrowaves] Are LEDs a noise source
Sent: Jan 23 '21 20:36

LEDs do not generate noise. Being forward-biassed, there is no noise
generation mechanism.
Gordon. you are referring to regulators, aren't you. They suffer from
instability if not decou[led.

Specs call-up minimum of 0.22uf on the output and a few uF on the
input if more than a few cm away from the supply.
The Question was about LEDs

Andy
www.g4jnt.com

On Sat, 23 Jan 2021 at 20:27, Gordon REASON via groups.io
<gordonj.reason=virgin.net@groups.io> wrote:

> Yes , Rick , should be decoupled with a 10 or 22 nF and a 4.7 uF .
>
>> On 23 January 2021 at 19:27 "G8ZHA via groups.io"
>> <g8zha-1=blueyonder.co.uk@groups.io> wrote:
>>
>> I have just built a G4DDK PGA-103 preamp to use for ADSB receive
>> on 1090MHz. The preamp will be mounted up on a pole, directly
>> underneath a PCB antenna, in a plastic tube. I feed 12V up to the
>> preamp and have 5V regulator next to the preamp. I usually include
>> a LED on the 5V shining down at the ground, so I can confirm that
>> the preamp is powered.
>>
>> Do LEDs generate any noise?
>>
>> Rich G8ZHA
>
>>


Re: Snow Scatter

Neil Smith G4DBN
 

All this 475 kHz is microwave compared with *proper* LF at 8270 Hz. Heh heh.

No sign of scatter on 10 GHz here at the moment, but there is a blanket of drizzle to the south which is very absorbent. I can't even hear GB3CAM, never mind KBQ/PKT/OSW.

I'm going back to the machine shop to bash some metal until the troposphere bucks up its ideas.

Neil G4DBN


Re: cling film?

ian hope (2E0IJH)
 

Totally off topic, but I burst into laughter when saw cling film as title, as had been watching the re-runs of London's Burning on drama, If anyone remembers  Cling Film was one of fire fighters
 
Ian
M5IJH

 
 
Sent: Sunday, January 24, 2021 at 11:16 AM
From: "Andy G4JNT" <andy.g4jnt@...>
To: "UK Microwaves groups.io" <UKMicrowaves@groups.io>
Subject: Re: [UKMicrowaves] cling film?
A different sort of use, but I used to use cling film and silicone grease along with a tie wrap to hold it in place,  to protect the end of a run of EW90 guide when the dish wasn't connected to it.
 
Andy
 
 
On Sun, 24 Jan 2021 at 11:14, militaryoperator via groups.io <Military1944=aol.com@groups.io> wrote:
As my uw antennas are all temporary, ie I put then up and down only when needed, akin to portable op's but from the home qth, I noticed after the last 23cm use which was in the rain here, got soaked inside but that's another problem, that there was water shorting or very nearly shorting the folded dipole to the boom. 
 
I guess those with permanent setups way up high have other techniques for wx or such.
 
Has anyone with portable experience, non so far here, tried say cling film over the radiator or a plastic bag etc? 
 
My 23 and 13 are standard Yagi folded dipole type, I'm ok on 9, its a flat panel in an outside protective cover and my 10Ghz ex mil dipole on wg feed did have a plastic cover over it, presumably to stop the ingress of water to the wg but it was cracked so I removed it. A small piece of cling film over the end would stop any ingress I'm guessing. 
 
Anyway, thoughts?
 
Ben.G4BXD
 

 

 


Re: cling film?

alwyn.seeds1
 

Dear Ben,

My stacked 23 cm Wimos detune significantly in the rain- return loss falls from 15dB to 11dB (corrected for feeder loss). Have known this to trip the PA in torrential rain, before I added a circulator.

I have some professional shrouded Yagis that I might replace the Wimos with; these use heavy plastic shrouds and and are massively constructed, but gain at 23cm is lower.

That said, you’re not losing a lot of signal with a 10dB return loss at the feedpoint.

Regards,

Alwyn G8DOH
  
_____________________________________________________

Alwyn Seeds, Director
SynOptika Ltd.,
114 Beaufort Street,
London,
SW3 6BU,
England.


SynOptika Ltd., Registered in England and Wales: No. 04606737
Registered Office: 114 Beaufort Street, London, SW3 6BU, United Kingdom.
_____________________________________________________


Re: Snow Scatter

John Fell
 

No decodes from Dave last night but a few GMs on 475kHz WSPering at upto 800km .

I am a newcomer to LF , having been NDB banging for some years the recent beta releases on WSJT-X have made things interesting for the older people on the band .Some of these stations were built up to work DX using Marconi T antennas and several hundred W of PA output .100Ft tall masts and inverted Ls are in use .

Amazingly I manage to hang on to a few shirt tails using an E Probe antenna for RX , in a Pine Tree @ 5m agl above "rubbish" ground .
The probe + either my SDR-IQ or ELAD FDM Duo are good from 10kHz to  10MHz .

For a pcb and components at around £10 the probe is beyond compare for low noise floor performance in terms of £/km .

I could never much hear 160m traffic on a 1/4 wave sloper but with that as a TX antenna and the E-probe on RX several thousand km are available at times .

73
John
G0API

No signs of LEX on 10GHz or CAM , so wrong kind of Snow from here .....


On Sun, 24 Jan 2021 at 13:34, Robin Szemeti - G1YFG <robin@...> wrote:
I chat with GM3YXM on 160m every morning (another LF regular),  normally he is a couple of dB above the noise, today a good S9 +20 ... another regular in Portsmouth gave hime a similar report, everyone was up at least 20dB, quite remarkable.

On Sun, 24 Jan 2021 at 12:51, John Fell <john.g0api@...> wrote:
Hi Robin,
Blue Sky and Sunshine now - Topband (1.8MHz) is normal level here but on the real "Topbands " at 137kHz and 475kHz it was quite lively overnight .
Plenty of TA  WSPR-2 and FST4W modes .

WSPRSpot site says I decoded 20 spots on 137kHz ( poor by recent times, but it was crunchy at times from lightening out of Snow clouds etc ) and 1038 spots on 475kHz .

Several G stations have had 2 way QSOs with the States and JA on 475kHz

Quite a few uwavers are active on LF/MF .....

73
John
G0API


On Sun, 24 Jan 2021 at 10:43, Robin Szemeti - G1YFG <robin@...> wrote:
At the other end of the spectrum, top band is unbelievably good at the moment .. never heard anything like it.

On Sun, 24 Jan 2021 at 09:53, John Fell <john.g0api@...> wrote:
A large band of snow cloud heading East from this QTH is producing SS from SEE and PKT .
73
John
G0API


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Robin Szemeti - G1YFG


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Robin Szemeti - G1YFG

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