Date   

Re: 9 & 3 the other night

Kjeld, OZ1FF
 

Hi John

The reason for the much shorter reflection time on 10 GHz is the smaller opening angle of the antenna. I have made a lot of 10 GHz QSOs with DL6NAA over 650 km. If the aircraft is on the path one AC is mostly sufficient. If AC crosses the path up to 5 ACs can be needed to complete a QSO. It is like working ES on 144 MHz.

Good tools for monitoring ACs is AirScout/ and/or the Tucnak logprogram.




The triangles are ACs. Pointing on the AC shows data in the upper right corner. The yellow box is the Fressnell zone to SM1HOW showing a suitable AC for an easy QSO.

Vy 73 de OZ1FF, Kjeld
CU on AR.


Re: Battery

Colin Ranson
 

Gordon,  forgot to mention these were 3.7v (x 3) flat profile phone batteries.

 

Certainly takes the biscuit !

 

 

Colin.

 

Sent from Mail for Windows 10

 

From: Gordon REASON via groups.io
Sent: 28 November 2020 23:56
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Battery

 

I'm pretty sure I have some "5000 mA" 18650? cells that have a smaller cell inside ........

have'nt had he guts to open one yet !

On 28 November 2020 at 23:43 Colin Ranson <g8lbs@...> wrote:

uW’ers et al,

 

12V Rechargeable 3000mAh Li-ion Battery Storage AC/DC for CCTV Camera Battery

 

A year or so ago I bought the above off the bay with the intention of supplying a noise free 12v to small projects on the workbench.

 

DON’T !     It turned out pretty useless, soon dropped volts/and would not hold charge.

 

Just took it apart for curiosity.

 

Contents – three Huawei 1500mAh connected in series.  Batteries dated 2010.

 

Caveat Emptor !

 

Stay safe all,

 

 

Colin de G8LBS.

 

 

 

 

Sent from Mail for Windows 10

 


 


 

 


variable vane attenuator 0 to 60 db

Barry VE4MA
 

HI Paul,

I wonder how you are measuring that ? Spectrum Analyzer or Power meter/ diode detector system?  ..enough dynamic range in test system?

Best 73
Barry VE4MA


Re: variable vane attenuator 0 to 60 db

Gordon REASON <gordonj.reason@...>
 

get a B  pencil , and refresh the attenuator coating ........... ?

On 28 November 2020 at 19:41 Paul G8KFW <paul@...> wrote:

 

Hi all

just bean testing a commercial variable vane attenuator  0 to 60 db but  although the vane rotates the attenuation dues not increase after 35 dB

 

Has any one come across this before the wave guide is WG 23  / WR 22   33 to 50 Ghz  and testing was at 37 Ghz

also looking for a few short lengths of wave guide in WR 22  and WR 19   ( 33-50 Ghz  and 40 to 60 Ghz )

 

Best Regards Paul


 


--
Paul Bicknell G8KFW   South Coast UK


 


Re: Battery

Gordon REASON <gordonj.reason@...>
 

I'm pretty sure I have some "5000 mA" 18650? cells that have a smaller cell inside ........

have'nt had he guts to open one yet !

On 28 November 2020 at 23:43 Colin Ranson <g8lbs@...> wrote:

uW’ers et al,

 

12V Rechargeable 3000mAh Li-ion Battery Storage AC/DC for CCTV Camera Battery

 

A year or so ago I bought the above off the bay with the intention of supplying a noise free 12v to small projects on the workbench.

 

DON’T !     It turned out pretty useless, soon dropped volts/and would not hold charge.

 

Just took it apart for curiosity.

 

Contents – three Huawei 1500mAh connected in series.  Batteries dated 2010.

 

Caveat Emptor !

 

Stay safe all,

 

 

Colin de G8LBS.

 

 

 

 

Sent from Mail for Windows 10

 


 


 


Battery

Colin Ranson
 

uW’ers et al,

 

12V Rechargeable 3000mAh Li-ion Battery Storage AC/DC for CCTV Camera Battery

 

A year or so ago I bought the above off the bay with the intention of supplying a noise free 12v to small projects on the workbench.

 

DON’T !     It turned out pretty useless, soon dropped volts/and would not hold charge.

 

Just took it apart for curiosity.

 

Contents – three Huawei 1500mAh connected in series.  Batteries dated 2010.

 

Caveat Emptor !

 

Stay safe all,

 

 

Colin de G8LBS.

 

 

 

Sent from Mail for Windows 10

 


Re: Boost converter magic smoke caveat

Brian Flynn GM8BJF
 

I have used these Chinese SMPS boards widely in different projects.  All of the buck types supposedly based on the LM 2596 IC that I have come across used what I took to be a re-marked (not fake) LM2576 chip. This is a cheaper part. The telltale sign is the frequency that they operate at. The real 2596 runs at 150kHz wheras the 2576 runs at 50kHz. Also the markings often wash off with IPA.;-) .It is just a creative way of adding value to the product.  My solution has been to source some LM2596s from a trusted supplier (RS) and just replace the IC. Some simple soldering! While I am at it I usually replace the caps as the ones supplied normally have poor ESR ratings and run hot under a decent load. If the boards are sourced with this in mind it is still cheap for the PCB! I never pay more than 90p for one.
The boost converters using the XL6009 I have found excellent. That (chinese) chip is much more efficient than the NS/TI equivalents as it uses MOS devices as the main switching element with a lower on resistanbce than the aforementioned bipolar parts. That assumes the PCBs are properly soldered, but that is up to "goods inwards" to accertain!

73s
Brian GM8BJF


Re: Low Band Cumulatives

John Quarmby
 

Thanks for pointing that out Andy - the results were published in Scatterpoint, and are now visible on the web site as well.

73

John G3XDY

On 28/11/2020 14:13, Andy G4JNT wrote:
Looking at the results for the Low Band Cumulatives, just published.
They don't appear to include June's event ?
The claimed scores are there, along with the other four events, but not in the final listings.


Virus-free. www.avg.com


variable vane attenuator 0 to 60 db

Paul G8KFW
 

 

Hi all

just bean testing a commercial variable vane attenuator  0 to 60 db but  although the vane rotates the attenuation dues not increase after 35 dB

 

Has any one come across this before the wave guide is WG 23  / WR 22   33 to 50 Ghz  and testing was at 37 Ghz

also looking for a few short lengths of wave guide in WR 22  and WR 19   ( 33-50 Ghz  and 40 to 60 Ghz )

 

Best Regards Paul


--
Paul Bicknell G8KFW   South Coast UK


Re: Digital was:9 & 3

John Fell
 

Agreed .
"Visual modes are entirely human-operated " - Hellshriber is perhaps machine generated but Human readout exception - looks FB on QO100 Waterfall - dreadful waste of bandwidth - LOL.

John
G0API 

(Looking at 5 instances of WSJT-X v 2.3.0-rc2 on 137kHz as I type and only WSPR 2 and FST4W1800 yielding any decodes )

On Sat, 28 Nov 2020 at 18:20, Neil Smith G4DBN <neil@...> wrote:

It depends if you want to make microwave contacts which are impossible by CW or voice. Using long FFTs to pull out signals from way below the noise using visual modes like DFCW and QQRS works well on LF, and would also work well on SHF troposcatter, where a 20 second carrier might be detectable by eye on a high-contrast waterfall with all the stops pulled out.

It is now routine to pull out VLF signals around 60dB under noise, but with troposcatter spreading and SHF stability, you can't get down much lower than about 26dB below noise in 2.5 kHz on 3cm.  Compared with slow CW, readable at about 4dB over noise in 200 Hz (or around 7dB below noise in 2.5 kHz) that is the difference between 5 watts TX on 3cm and 400 watts.

Visual modes are entirely human-operated, and even at 3cm, QRSS or DFCW with a 100Hz shift and 10 to 30 second dots would work well. It has certainly been used in the past: http://www.g4jnt.com/DFCW.htm

The alternative is not to have a contact. Nobody (unless they are daft) is going to use digi on SHF except for long-duration semi-automated propagation tests, or for extreme weak signals, or to make aircraft-scatter possible with very short reflections.  If there is enough signal for SSB, then that's the mode of choice. If FM will work during rainscatter, then that's the "right" mode.  When propagation is too poor for SSB, then CW will work for a few more dB.  Then there is a zone where "ordinary" digimodes like JT4G or QRA64 will work, but once they stop working, you can often still see the traces, and in that region of extreme weakness, slow visual modes work.  Once you drop below the threshold of visibility even for 90 second dots, we are probably stuffed, as things like EbNaut need phase-stable signals and micro-Hertz bandwidths.

Of course, this isn't applicable to 2m or HF, where there are psychological and social factors at play about why amateurs prefer not to speak or send Morse to each other. 

The TL:DR version: For me, digi on SHF is something to be used as an extension of the capabilities of voice/morse modes, not an end in itself.

Neil G4DBN


On 28/11/2020 17:02, Clive Elliott GW4MBS via groups.io wrote:
On Sat, Nov 28, 2020 at 04:20 PM, militaryoperator wrote:
I for one would not have the slightest interest in using digital modes, either now or in a contest. I'm probably in the minority though, seems more and more are happy to make these computer-aided contacts. (excluding KST of course)
 
If it requires my computer to talk to another computer then frankly the hobby is dead.
Ben my feelings as well. I still get the same thrill of just hearing a signal on 3cm as I did 50 years. The novelty has not worn off, although the equipment has rather changed and yes I am so old fashioned that I still use a paper log and have a straight Morse key.
 
--
Clive GW4MBS (ex-G8ADP)
Pottering on 6m - 3cm in a valley in IO71XW where any QSO is a triumph of optimism over geography!


Re: Digital was:9 & 3

Neil Smith G4DBN
 

It depends if you want to make microwave contacts which are impossible by CW or voice. Using long FFTs to pull out signals from way below the noise using visual modes like DFCW and QQRS works well on LF, and would also work well on SHF troposcatter, where a 20 second carrier might be detectable by eye on a high-contrast waterfall with all the stops pulled out.

It is now routine to pull out VLF signals around 60dB under noise, but with troposcatter spreading and SHF stability, you can't get down much lower than about 26dB below noise in 2.5 kHz on 3cm.  Compared with slow CW, readable at about 4dB over noise in 200 Hz (or around 7dB below noise in 2.5 kHz) that is the difference between 5 watts TX on 3cm and 400 watts.

Visual modes are entirely human-operated, and even at 3cm, QRSS or DFCW with a 100Hz shift and 10 to 30 second dots would work well. It has certainly been used in the past: http://www.g4jnt.com/DFCW.htm

The alternative is not to have a contact. Nobody (unless they are daft) is going to use digi on SHF except for long-duration semi-automated propagation tests, or for extreme weak signals, or to make aircraft-scatter possible with very short reflections.  If there is enough signal for SSB, then that's the mode of choice. If FM will work during rainscatter, then that's the "right" mode.  When propagation is too poor for SSB, then CW will work for a few more dB.  Then there is a zone where "ordinary" digimodes like JT4G or QRA64 will work, but once they stop working, you can often still see the traces, and in that region of extreme weakness, slow visual modes work.  Once you drop below the threshold of visibility even for 90 second dots, we are probably stuffed, as things like EbNaut need phase-stable signals and micro-Hertz bandwidths.

Of course, this isn't applicable to 2m or HF, where there are psychological and social factors at play about why amateurs prefer not to speak or send Morse to each other. 

The TL:DR version: For me, digi on SHF is something to be used as an extension of the capabilities of voice/morse modes, not an end in itself.

Neil G4DBN


On 28/11/2020 17:02, Clive Elliott GW4MBS via groups.io wrote:
On Sat, Nov 28, 2020 at 04:20 PM, militaryoperator wrote:
I for one would not have the slightest interest in using digital modes, either now or in a contest. I'm probably in the minority though, seems more and more are happy to make these computer-aided contacts. (excluding KST of course)
 
If it requires my computer to talk to another computer then frankly the hobby is dead.
Ben my feelings as well. I still get the same thrill of just hearing a signal on 3cm as I did 50 years. The novelty has not worn off, although the equipment has rather changed and yes I am so old fashioned that I still use a paper log and have a straight Morse key.
 
--
Clive GW4MBS (ex-G8ADP)
Pottering on 6m - 3cm in a valley in IO71XW where any QSO is a triumph of optimism over geography!
_._,_._,_



Re: Digital was:9 & 3

Clive Elliott GW4MBS
 

On Sat, Nov 28, 2020 at 04:20 PM, militaryoperator wrote:
I for one would not have the slightest interest in using digital modes, either now or in a contest. I'm probably in the minority though, seems more and more are happy to make these computer-aided contacts. (excluding KST of course)
 
If it requires my computer to talk to another computer then frankly the hobby is dead.
Ben my feelings as well. I still get the same thrill of just hearing a signal on 3cm as I did 50 years. The novelty has not worn off, although the equipment has rather changed and yes I am so old fashioned that I still use a paper log and have a straight Morse key.
 
--
Clive GW4MBS (ex-G8ADP)
Pottering on 6m - 3cm in a valley in IO71XW where any QSO is a triumph of optimism over geography!


Re: Digital was:9 & 3

militaryoperator
 

Then isn't it about time the rules were brought into the 21st century
Why so backward and stuck in the dark ages?


The autocorrecting digimodes aren't permitted in most contests, so we are stuck with ISCAT for aircraft scatter, but it does work if you can ignore the false decodes. 



I for one would not have the slightest interest in using digital modes, either now or in a contest. I'm probably in the minority though, seems more and more are happy to make these computer-aided contacts. (excluding KST of course)

If it requires my computer to talk to another computer then frankly the hobby is dead. Use an email or phone the person. 

I agree the rules should be changed. One band contests, like the 23Cm UKAC, make it the same on the other bands. 
And level the playing field a bit, power and antenna wise. Hardly a "contest" at the moment just an evening/day to test one's equipment. 

Ben G4BXD


Re: 9 & 3 the other night

Neil Smith G4DBN
 

I've managed a few aircraft scatter contacts into Germany on 3cm, but you do need multiple planes as most reflections last under 10s.  The fast rate of doppler also messes up reception if you are using a narrow filter, so do get this to work really well, you'd need a digimode that has a fast-ish symbol rate, short tx/rx period, gear than can switch REALLY fast, and adaptive receive which can handle doppler of 50 Hz/sec or more.  Human brains work fairly well, but it would be good to have a mode which was synchronous and GPS timed, so no need to extract sync from the data, fixed length frames and capable of decoding when there are multiple tones at different fast doppler rates.

Error correction isn't all that important if you have enough redundancy.  Perhaps that's perhaps why FSK441, ISCAT and RTTY are perceptually much nicer than MSK144, JT9 and FT8, despite the latter modes being all mathematical and clever (and cold and robotic and often densely stupid when they fail to decode signals loud enough to hear, dammit). Also with very short reflections on microwaves, the protocol needs to be able to work with a 5 second fast-dopplered peak, so frame lengths have to be short, but symbol rates need to be low enough to deal with scintillation eating your symbols.

You can see why the WSJT-X team are concentrating on "easy" things like EME, HF F&H and VHF meteor scatter.

Having the ability to track planes in az/el based on predicted paths does help to extend the reflection period, certainly when one end is an omni beacon.  If both ends had plane tracking based on real-time ADS-B reception, then there is a possibility of some much longer reflections.

Also, what about electrical steering of massive patch arrays as being done by Starlink User Terminals: Vid starts in the middle. The whole thing is interesting but is long and not done by an RF/Microwave specialist https://youtu.be/iOmdQnIlnRo?t=1992

That would make fast tracking easier if anyone can work out how to do it on transmit as well as receive on a big panel array (or separate tx/rx panels?)

Because I'm a mechanicals nerd, I'll stick with mech tracking, but just imagine a non-adjustable patch array driven by multiple small PA devices on 10 GHz.  That might be an amusing way to get high TX power with relatively cheap devices.

Neil G4DBN

On 28/11/2020 14:46, John Lemay wrote:

My experience with aircraft assisted contacts on 70 and 23cms has been encouraging. But it seems that as one goes up in frequency, the useful period of reflection gets progressively shorter. For example, listening to 10GHz beacons that are marginal on tropo, the aircraft reflection seems limited to just a few seconds. Much too short to be useful. Maybe there’s an explanation of this somewhere ?

 

Presumably it works better with high gain dishes at both ends of the path, but at present it looks really difficult.

 

John G4ZTR

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Andy G4JNT
Sent: 28 November 2020 14:28
To: UK Microwaves groups.io
Subject: Re: [UKMicrowaves] 9 & 3 the other night

 

Then isn't it about time the rules were brought into the 21st century

Why so backward and stuck in the dark ages?

 

Andy

 

 

 

On Sat, 28 Nov 2020 at 14:24, Neil Smith G4DBN <neil@...> wrote:

 

The autocorrecting digimodes aren't permitted in most contests, so we are stuck with ISCAT for aircraft scatter, but it does work if you can ignore the false decodes. 

 

 



Re: 9 & 3 the other night

John Lemay
 

My experience with aircraft assisted contacts on 70 and 23cms has been encouraging. But it seems that as one goes up in frequency, the useful period of reflection gets progressively shorter. For example, listening to 10GHz beacons that are marginal on tropo, the aircraft reflection seems limited to just a few seconds. Much too short to be useful. Maybe there’s an explanation of this somewhere ?

 

Presumably it works better with high gain dishes at both ends of the path, but at present it looks really difficult.

 

John G4ZTR

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Andy G4JNT
Sent: 28 November 2020 14:28
To: UK Microwaves groups.io
Subject: Re: [UKMicrowaves] 9 & 3 the other night

 

Then isn't it about time the rules were brought into the 21st century

Why so backward and stuck in the dark ages?

 

 

 

On Sat, 28 Nov 2020 at 14:24, Neil Smith G4DBN <neil@...> wrote:

 

The autocorrecting digimodes aren't permitted in most contests, so we are stuck with ISCAT for aircraft scatter, but it does work if you can ignore the false decodes. 

 

 

Virus-free. www.avg.com


Re: 9 & 3 the other night

Andy G4JNT
 

Then isn't it about time the rules were brought into the 21st century
Why so backward and stuck in the dark ages?



On Sat, 28 Nov 2020 at 14:24, Neil Smith G4DBN <neil@...> wrote:


The autocorrecting digimodes aren't permitted in most contests, so we are stuck with ISCAT for aircraft scatter, but it does work if you can ignore the false decodes. 



Virus-free. www.avg.com


Re: 9 & 3 the other night

Neil Smith G4DBN
 

30s cycles for voice of CW scatter contacts mean you need multiple planes, and these days that is very rare except on the glide slopes of major airports, so it puts a crimp on the paths that are feasible.

The autocorrecting digimodes aren't permitted in most contests, so we are stuck with ISCAT for aircraft scatter, but it does work if you can ignore the false decodes. 

Timed SSB overs with a parrot work OK for plane scatter, just yell the exchange at the parrot, then push the button and watch the clock to give 30s tx and 30s rx (or if you have a fancy time-triggered thing, then just hit GO).  I've tried 5s tx/5s rx cycles on voice, trying to get a QSO in a single reflection, but it is hard to do that at 10 GHz.  Works on 23/13 cm.

We did a load of tests with very short periods on 23cm JT9F, as low as 5 second overs, and managed complete A/S contacts in 25 seconds during a single reflection, but that mode isn't allowed in contests.  Also it is a relay-wrecker.

Off-axis scatter and back-scatter work really well off the Heathrow stack for medium distances.

Record and playback of the received SSB or CW is permitted during the contest, but it is naughty to review recordings after the contest, so if you record the received signal during the QSO and can do simultaneous record/play, you can play it back slower with a pitch shift, or play it a character at a time.

All huge fun.

Neil G4DBN

On 28/11/2020 14:04, Robin Szemeti - G1YFG wrote:
The chances of my brain decoding that funny intermittent carrier are minimal ... I may have to put some effort into it this year.  Many years ago I could just about manage 8wpm but, the skill has left me.

On Sat, 28 Nov 2020 at 12:43, Nick Peckett G4KUX <nick@...> wrote:

No not like FT8, brain involved in decoding not CPU........KUX

 



Low Band Cumulatives

Andy G4JNT
 

Looking at the results for the Low Band Cumulatives, just published.
They don't appear to include June's event ?
The claimed scores are there, along with the other four events, but not in the final listings.


Virus-free. www.avg.com


Re: 9 & 3 the other night

Ian White
 

On 28/11/2020 12:18, Robin Szemeti - G1YFG wrote:
>Beginning to sound a little like FT8!

Where do you think JT&Co got their ideas from?

73 from Ian GM3SEK



On Sat, 28 Nov 2020 at 12:04, Nick Peckett G4KUX <nick@...> wrote:

A technique I sometimes use for really long haul QSOs on 3Cms and other bands is to set up who transmits and when. I’ve had several contacts with Maurice F6DKW at over 700klm using this tequnique. When setting up the contact on KST we decide who is going to TX first and second, usually 30sec periods. CW speed is usually around 20wpm. As the mid point of the path is over London we frequently get aircraft reflections from the Heathrow Stack and this enables us to receive various parts of the QSO info almost like MS, generally we can complete in around 10mins, Worth trying if both can run reasonable power.

 

Nick G4KUX

 

Sent from Mail for Windows 10

 

From: militaryoperator via groups.io
Sent: 27 November 2020 19:32
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] 9 & 3 the other night

 

If the QSO is marginal,  with multiple requests to send again, repeating back what you think you have copied, does allow the sender to confirm what you have is correct.. If the contact is solid then I agree there is little point. I feel a "pip" sender is essential for setting up on the higher bands, I'm surprised how few people use them.. I built mine, from the "Morse code and tone generator" design of David Wrigley G6GXK that uses a PIC.. sends a minute of pips then your callsign in CW if you set it up.

 

Mike G6TRM

 

 

 

ebay 143013099879

 

This might be handy, long set of dots or dash's then callsign. 

 

Cheaper than buy the bits and building. 

 

Ben

 


--
Robin Szemeti - G1YFG


Re: 9 & 3 the other night

Robin Szemeti - G1YFG
 

The chances of my brain decoding that funny intermittent carrier are minimal ... I may have to put some effort into it this year.  Many years ago I could just about manage 8wpm but, the skill has left me.

On Sat, 28 Nov 2020 at 12:43, Nick Peckett G4KUX <nick@...> wrote:

No not like FT8, brain involved in decoding not CPU........KUX

 

Sent from Mail for Windows 10

 

From: Robin Szemeti - G1YFG
Sent: 28 November 2020 12:19
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] 9 & 3 the other night

 

Beginning to sound a little like FT8!

 

 

On Sat, 28 Nov 2020 at 12:04, Nick Peckett G4KUX <nick@...> wrote:

A technique I sometimes use for really long haul QSOs on 3Cms and other bands is to set up who transmits and when. I’ve had several contacts with Maurice F6DKW at over 700klm using this tequnique. When setting up the contact on KST we decide who is going to TX first and second, usually 30sec periods. CW speed is usually around 20wpm. As the mid point of the path is over London we frequently get aircraft reflections from the Heathrow Stack and this enables us to receive various parts of the QSO info almost like MS, generally we can complete in around 10mins, Worth trying if both can run reasonable power.

 

Nick G4KUX

 

Sent from Mail for Windows 10

 

From: militaryoperator via groups.io
Sent: 27 November 2020 19:32
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] 9 & 3 the other night

 

If the QSO is marginal,  with multiple requests to send again, repeating back what you think you have copied, does allow the sender to confirm what you have is correct.. If the contact is solid then I agree there is little point. I feel a "pip" sender is essential for setting up on the higher bands, I'm surprised how few people use them.. I built mine, from the "Morse code and tone generator" design of David Wrigley G6GXK that uses a PIC.. sends a minute of pips then your callsign in CW if you set it up.

 

Mike G6TRM

 

 

 

ebay 143013099879

 

This might be handy, long set of dots or dash's then callsign. 

 

Cheaper than buy the bits and building. 

 

Ben

 


--
Robin Szemeti - G1YFG

 


--
Robin Szemeti - G1YFG

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