Date   

Re: Passive Relay's

Nick Gregory G0HIK
 

Thanks for the PDF's, no time today, but I'll print them off and read later.

All sounds good though.

I'll have to dig some aerials out and see what I have and can throw up for a quick and dirt test.

Nick G0HIK


Re: Chris & Andy please......

Neil Smith G4DBN
 

Back in "normal" times, the GB3MCB beacon on 144 MHz looked like this in late afternoon.  Path is 430 km. There are very few times when there wasn't at least *some* aircraft reflection and signal enhancement.  Time runs downwards, total of 6.5 minutes.  It is probably fair to say that the majority of the received signal was enhanced via plane reflections.

Neil G4DBN

On 19/05/2020 11:10, alwyn.seeds1 wrote:
Dear Alan,

Totally agree with you.

The original aircraft reflections papers in the RSGB were even earlier- the 1960s- “A little flutter on VHF” Douai School. 

They are great papers- all done with analytical geometry- I apologise that I have forgotten the author’s name.

This leads me to some questions for the microwavers: At my site in IO92FA GB3VHF and GB3UHF are received over an obstructed 154km path.

Under flat conditions the penalty relative to free space used to be 30 dB relative to free space on 2m and 33 dB relative to free space on 70cm.

Re-checking in our little aircraft scatter world the GB3VHF signal strength is little altered, except that QSB is greater (was 1 dB with period around 5s) now fades of 6 dB plus common.

GB3UHF, however is much weaker- seems to be about 15 dB down and the pervasive aircraft doppler now missing, fades also much deeper (was 2 dB with period around 1 s) now 6db to 10 dB.

My questions are:

1. Have others noticed this?

2. Can someone who is LOS of these beacons confirm whether the GB3UHF signal strength is normal?

3. What do people receiving at greater distances observe?

Regards, and thanks, as ever, to Chris and everyone who made these and our other beacons possible.

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.
_____________________________________________________

-- 
Neil
http://g4dbn.uk


Re: Stacking frames

ian hope (2E0IJH)
 

Watch your antennas, not every make requires one inverted, for example our comet cya 16's all have to be the same way up
 
Ian
2E0IJH

 
 
Sent: Tuesday, May 19, 2020 at 9:47 AM
From: "Pete - GM4BYF via groups.io" <gm4byf@...>
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Stacking frames

Important at those frequencies to ensure that any conducting frame does not intrude on the line of the elements.

For a stack of four, this is easy to do provided you invert one antenna and then get the phasing correct. Been there and got it wrong !!

73
Pete GM4BYF
On 18/05/20 20:39, Robin Szemeti wrote:
Aluminium every time.
 
 
On Mon, 18 May 2020 at 19:51, chris ruddy via groups.io <mm0kos=yahoo.co.uk@groups.io> wrote:
Hi All

just a quick question, would you build your stacking frames from Aluminium of Carbon Fibre for 23 and 13cm

Thanks Chris


--
Best regards,

Robin Szemeti

Redpoint Consulting Limited

E: robin@...
T: +44 (0) 1299 405028
M: +44 (0) 7971 883371

CONFIDENTIALITY NOTICE
The information contained in this e-mail is intended only for the
confidential use of the above named recipient. If you are not the
intended recipient or person responsible for delivering it to the
intended recipient, you have received this communication in error
and must not distribute or copy it.
Please accept the sender's apologies, notify the sender immediately
by return e-mail and delete this communication.

Thank you. 

--
vry 73
Pete GM4BYF


Re: RF getting into cheap LED meters?

Andy G4JNT
 

Oh dear, if the meters are what I think they are then look to see where teh current shunt is.  Commonly in the negative lead.   Since there's every chance the negative lead (ground) goes via several roundabout routes, all bets are off as to what current you're actually measuring

For decent I measurement, you can beat proper high-side current monitoring chips (covered in an episode of DNotes a while back)
 


On Tue, 19 May 2020 at 11:23, Andy GD1MIP <gd1mip@...> wrote:
I have just finished putting together a 23cm amplifier based on a PE1RKI 150w amp.
In my case I now have switch mode PSU's for 28v DC (amplifier)  and 12v DC (relays, sequencer and fans).

All works well as an amplifier.  Except I fitted some cheap LED dual A / V meters from a rally. These meters work fine out of the confines of the case but in the case their display on Amps only  reduces (rather than rises) as the amplifiers output wattage increases. At levels beyond 50watts the meters effectively start going 'backwards' until by 100watts they read zero. (volts readings remain stable / true).

I assume RF is getting where it shouldn't,  the meters are not screened, the PCB's are held in a plastic frame. I tried decoupling caps at the meters with some effect, but not enough.  A mixture of clip on ferrites on the LED meter leads seems to have tamed this issue and today I will fabricate some screening boxes for the meters.

Is there anything else I should look at (other than buying better meters).

Thanks Andy GD1MIP 

PS a link to my meters.... https://drive.google.com/folderview?id=1YBujeGcEnsWeOeAZxSjfBZWJMp00yydh


Re: Passive Relay's

Andy G4JNT
 

I feel a spreadsheet coming on ..
Seem to recall doing this calculation back in the dim and distant past for work, and IIRC the mid point gave furthest range extension.   But that would have been for a naval scenario and no hills !



On Tue, 19 May 2020 at 10:58, Iain Young <g7iii@...> wrote:
Hi Nick,

On 19/05/20 10:24, Nick Gregory G0HIK via groups.io wrote:

> I have been told that you cant have the passive repeater anywhere near
> the middle of the link and has to be right at one end of it. Not sure
> how the logic works, as several of the communities fed by these are not
> that close to them, say up to 2 to 5 miles away.

I beg to differ. While this was done on 144MHz, and 433MHz, last time I
checked the rules of physics don't change at 1.2GHz and up,so here are
a couple of links tto a presentation that I did based on an experiment a
couple of years ago:

http://hal.g7iii.net/ppt/Passive_Repeater_Experiment.pdf
http://hal.g7iii.net/ppt/Passive_Repeater.pdf

Personally, I think it's all about overcoming the extra path loss, so
you need gain in the antennas. I must try it on 23cms and up sometime...


73s

Iain




Re: Tactics in microwave contest with very few planes.

Nick Peckett G4KUX
 

I have actually used commercial passive reflectors to get links into awkward locations before, where it’s just not feasible to build an active repeater. They need very accurate foundation engineering but work very well. Information here.

https://az276019.vo.msecnd.net/valmontstaging/vsna-resources/microflect-passive-repeater-catalog.pdf?sfvrsn=6

 

Regards & 73s

 

Nick G4KUX/YA4F

Sent from Mail for Windows 10

 

From: Murray Niman
Sent: 18 May 2020 12:55
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Tactics in microwave contest with very few planes.

 


So thinking laterally for a contest/QSO-aid (and a loophole in the rules) - you could deliberately fly a a fairly static drone or metallised balloon as a medium altitude passive reflector....
and not just a random scatterer either - there are surface designs that can help refocus the scattered beam

73

 Murray G6JYB  :)

 


RF getting into cheap LED meters?

Andy GD1MIP
 

I have just finished putting together a 23cm amplifier based on a PE1RKI 150w amp.
In my case I now have switch mode PSU's for 28v DC (amplifier)  and 12v DC (relays, sequencer and fans).

All works well as an amplifier.  Except I fitted some cheap LED dual A / V meters from a rally. These meters work fine out of the confines of the case but in the case their display on Amps only  reduces (rather than rises) as the amplifiers output wattage increases. At levels beyond 50watts the meters effectively start going 'backwards' until by 100watts they read zero. (volts readings remain stable / true).

I assume RF is getting where it shouldn't,  the meters are not screened, the PCB's are held in a plastic frame. I tried decoupling caps at the meters with some effect, but not enough.  A mixture of clip on ferrites on the LED meter leads seems to have tamed this issue and today I will fabricate some screening boxes for the meters.

Is there anything else I should look at (other than buying better meters).

Thanks Andy GD1MIP 

PS a link to my meters.... https://drive.google.com/folderview?id=1YBujeGcEnsWeOeAZxSjfBZWJMp00yydh


Re: Chris & Andy please......

alwyn.seeds1
 

Dear Alan,

Totally agree with you.

The original aircraft reflections papers in the RSGB were even earlier- the 1960s- “A little flutter on VHF” Douai School. 

They are great papers- all done with analytical geometry- I apologise that I have forgotten the author’s name.

This leads me to some questions for the microwavers: At my site in IO92FA GB3VHF and GB3UHF are received over an obstructed 154km path.

Under flat conditions the penalty relative to free space used to be 30 dB relative to free space on 2m and 33 dB relative to free space on 70cm.

Re-checking in our little aircraft scatter world the GB3VHF signal strength is little altered, except that QSB is greater (was 1 dB with period around 5s) now fades of 6 dB plus common.

GB3UHF, however is much weaker- seems to be about 15 dB down and the pervasive aircraft doppler now missing, fades also much deeper (was 2 dB with period around 1 s) now 6db to 10 dB.

My questions are:

1. Have others noticed this?

2. Can someone who is LOS of these beacons confirm whether the GB3UHF signal strength is normal?

3. What do people receiving at greater distances observe?

Regards, and thanks, as ever, to Chris and everyone who made these and our other beacons possible.

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.
_____________________________________________________


23 m UKAC 19th May 2020

Andy GD1MIP
 

Tonight I plan to unleash my new 100 watt amplifier on the unsuspecting UKAC folk. After feeder loss I probably have 55w masthead (30m LDF450) ,  so hopefully a healthy increase over the 5w last month. 

I will be on KST. Hope to get a few of you (and looking at my 2m UBNS hope to accurately log 🤯).

Andy GD1MIP 
45 ele Q loop from NE GD.


Re: N-type (5/8" 24tpi UNEF) die?

Neil Smith G4DBN
 

5/8" UNS normally comes in 14tpi or 27tpi, but as the "S" means "Special", I guess it could be anything.  Threadform is the same for UNEF/UNS/UNF/UNC/UNM

Neil G4DBN

https://www.gewinde-normen.de/en/unified-special-thread.html

On 19/05/2020 10:12, John Lemay wrote:

Neil

 

This thread (awful pun) has raised a question in my mind; I have a die marked “ 5/8 24 UNS”. It fits an N type thread, but is it the same ? Googling has not provided much clarity.

 

John G4ZTR

 



Re: Passive Relay's

Iain Young
 

Hi Nick,

On 19/05/20 10:24, Nick Gregory G0HIK via groups.io wrote:

I have been told that you cant have the passive repeater anywhere near the middle of the link and has to be right at one end of it. Not sure how the logic works, as several of the communities fed by these are not that close to them, say up to 2 to 5 miles away.
I beg to differ. While this was done on 144MHz, and 433MHz, last time I
checked the rules of physics don't change at 1.2GHz and up,so here are
a couple of links tto a presentation that I did based on an experiment a
couple of years ago:

http://hal.g7iii.net/ppt/Passive_Repeater_Experiment.pdf
http://hal.g7iii.net/ppt/Passive_Repeater.pdf

Personally, I think it's all about overcoming the extra path loss, so
you need gain in the antennas. I must try it on 23cms and up sometime...


73s

Iain


Re: Tactics in microwave contest with very few planes.

Neil Smith G4DBN
 

I send a KST meep to request a try with a specific plane 5 minutes or so in advance. For long-range contacts where the reflection will be brief and weak, as the plane approaches the reflection line, I call for 5 seconds, then listen for 5 seconds until the plane is well past the reflection line or I hear the other station. Absolute minimal exchange, spoken clearly and repeated until I hear rogers. Don't say "roger" unless you have received *everything*. Probably best to say "55023 55023 IO93NR" to fill the 5s slot.  If you are disciplined enough, you can time it so you TX in the even numbers 5s slots and the other station sends in the off 5s slots. If you get part of the exchange, but some is missing, just send "serial serial serial serial" or "report report report" or "locator...". If using CW, if you send "NR" or "SER" or "RPT", the "R" can get confused with a roger, so it is best to come up with an agreed protocol with folks you nhave regular A/S contact with.

For shorter-range contacts, where off-axis will work, you can follow the plane and have a much less structured contact over a slightly longer period, but the rule should always be that you only send what is relevant and expected, as you might only have 12-18 seconds to complete the QSO

Neil G4DBN

On 19/05/2020 09:50, Nick Gregory G0HIK via groups.io wrote:
I've not had an A/S QSO yet and I'm still going to be on the drive in the van this evening with limited computing power.

Do you need a waterfall to be able to use a this mode?

Does it just give you more time, i.e. you can see it before you can hear it ?

I'm still not sure of the mechanics of setting this up in a contest. If anyone is going to try this tonight and want IO84 please let me know, I'll be on KST and 07955635646.

10w and 1.2mtr dish

Nick G0HIK


Re: Tactics in microwave contest with very few planes.

Phil Guttridge G3TCU
 

OK Nick,

I'll meep you well ahead of expected plane times (assuming there are some!)

If it's clear, I expect to be calling CQ on 1296.245

73, Phil.

On 19/05/2020 10:42, Nick Gregory G0HIK via groups.io wrote:
Hi Phil,

Thanks that would be good if we could try, with Pete North of me and you south, these will be great tests :)

My locator is IO84JE65WK.

I dont use KST2me, I'll  take a look at it for next time. But I will keep a close eye on KST for meeps, it's so easy to miss them.

Ring or mail me if you want to disscuss further.

Nick G0HIK 

Virus-free. www.avg.com


Re: Tactics in microwave contest with very few planes.

Nick Gregory G0HIK
 

Hi Phil,

Thanks that would be good if we could try, with Pete North of me and you south, these will be great tests :)

My locator is IO84JE65WK.

I dont use KST2me, I'll  take a look at it for next time. But I will keep a close eye on KST for meeps, it's so easy to miss them.

Ring or mail me if you want to disscuss further.

Nick G0HIK 


Re: Tactics in microwave contest with very few planes.

Nick Gregory G0HIK
 

Thanks very much Pete,

I also have the central Lake district fells in that direction, but they are in the distance so could be a good direction for me to try.

The 9700 is pretty much on frequency. 

My little notepad has not got the speed to handle Airscout unfortunately, so I'll be reliant on you although I can watch Flight Radar 24 on my phone app.

Do you want to message me on KST, I'll keep a close watch on it for "Meeps".

My email in nickg0hik@..., if you want to talk further.

Nick G0HIK

  

That is great, my locator is IO84JE65WK.


Passive Relay's

Nick Gregory G0HIK
 

Living in a valley, I've been interested in using a passive relay and have talked about them several times over the years with local amateurs.

When I was working, on one of the sites we had tanks that were refurbished WWII fuel dumps with chambers underground. To enable the UHF radios to work we had a folded dipole in the chamber with LDF4-50 feeding and 18 ele jaybeam. This gave comms back to the control room (Less than a mile).

While working on the rigs, we had a blind spot, I installed a system with two folded dipoles back to back. This was not perfect, but was a great improvement.

As I walk on the Fells around here there, I often come across community TV repeaters. They are always been powered, not sure if they are simply a pre-amplifier or they frequency shift.

I have been told that you cant have the passive repeater anywhere near the middle of the link and has to be right at one end of it. Not sure how the logic works, as several of the communities fed by these are not that close to them, say up to 2 to 5 miles away.

Finding a site locally that I could use that is on a hill and secure was a problem. But recently a radio friend who lives the other side of the valley, around 5 miles away said I could install one on the roof of his shack for me to try out. I was thinking of 144MHz because I was talking about this with another chap in the club whom I would like to communicate with who has Two metres. But it could be any band, maybe 23cm's might be a good one to try out.

Nick G0HIK

 


Re: N-type (5/8" 24tpi UNEF) die?

John Lemay
 

Neil

 

This thread (awful pun) has raised a question in my mind; I have a die marked “ 5/8 24 UNS”. It fits an N type thread, but is it the same ? Googling has not provided much clarity.

 

John G4ZTR

 

 

From: UKMicrowaves@groups.io [mailto:UKMicrowaves@groups.io] On Behalf Of Neil Smith G4DBN
Sent: 19 May 2020 09:45
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] N-type (5/8" 24tpi UNEF) die?

 

I have one Ian, email me your address and I'll get it in the post

Neil G4DBN

On 19/05/2020 09:35, Ian White wrote:

Does anyone have an N-type die (5/8in x 24tpi UNEF) that I could borrow by post, please, for literally 5 minutes?

 


Re: Tactics in microwave contest with very few planes.

Phil Guttridge G3TCU
 

Hi Nick,
 
Can you give me an 8 (or 10) character LOC and I'll set up an Airscout alarm path to you tonight. I don't find the waterfall much help with AS QSOs as the path mostly opens and closes quickly.
As most large planes are cargo flights heading roughly E-W these days, they cross the path, rather than flying along it, so the 'opening' can be very short, so overs need to be extremely brief.

Do you use KST2me? 'Raw' KST usually has too much latency for arranging AS skeds. And I find a display dedicated to KST2me is useful, otherwise I can easily miss meeps.
Having said that, I'm just as guilty as everyone else at not responding to meeps sometimes. If I'm trying to complete a 'good Dx' QSO at very weak signal levels, I can't type a reply at the same time.

My home QTH system on 23cm is 250W to a 44 ele

73, Phil G3TCU

IO91QE43DL



On 19/05/2020 09:50, Nick Gregory G0HIK via groups.io wrote:
I've not had an A/S QSO yet and I'm still going to be on the drive in the van this evening with limited computing power.

Do you need a waterfall to be able to use a this mode?

Does it just give you more time, i.e. you can see it before you can hear it ?

I'm still not sure of the mechanics of setting this up in a contest. If anyone is going to try this tonight and want IO84 please let me know, I'll be on KST and 07955635646.

10w and 1.2mtr dish

Nick G0HIK

Virus-free. www.avg.com


Re: N-type (5/8" 24tpi UNEF) die?

Ian White
 

Thanks, Neil.

73 from Ian GM3SEK

On 19/05/2020 09:44, Neil Smith G4DBN wrote:

I have one Ian, email me your address and I'll get it in the post

Neil G4DBN

On 19/05/2020 09:35, Ian White wrote:

Does anyone have an N-type die (5/8in x 24tpi UNEF) that I could borrow by post, please, for literally 5 minutes?



Re: Scatterpoint Activity column

Paul Randall G3NJV
 

Hi, I intend to mix down to 2m and bought a  TOKO 5HW-73050A-735 filter off eBay for 3 quid to give the mixer a better chance.

What mixers are you guys planning to use? 


Paul


Sent from my Samsung Galaxy smartphone.



-------- Original message --------
From: "John E. Beech" <john@...>
Date: 18/05/2020 22:26 (GMT+00:00)
To: UKMicrowaves@groups.io
Subject: Re: [UKMicrowaves] Scatterpoint Activity column

Tnx fer that Andy. In that case I might try a very simple Schottky diode mixer for starters. I've got a series of 3dB, 6 dB & 10 dB BNC attenuators I can clag in to see how much I need & then build a dedicated attenuator.

de John G8SEQ

>  -------Original Message-------
>  From: Andy G4JNT <andy.g4jnt@...>
>  To: UK Microwaves groups.io <UKMicrowaves@groups.io>
>  Subject: Re: [UKMicrowaves] Scatterpoint Activity column
>  Sent: May 18 '20 18:46

>  The output of any LNB is so high you'll need attenuation rather than
>  gain
>  The broadband noise output over the complete IF band from 600MHz to
>  2GHz or so is so high, it can run into compression in some mixers.
>  DBMs shpuld be OK, but the I/Q downconverter I used to get to 28MHz
>  required at least 10dB attenuation of the 739MHz input to stay
>  comfortably in the linear region.

>  Don't forget image filtering if you use a simple mixer - otherwise you
>  throw away 3dB S/N on every signal you hear

>  Andy
www.g4jnt.com

>  On Mon, 18 May 2020 at 17:57, John E. Beech <john@...> wrote:

>  > Hi John,
>  > I don't know if this is of any interest, but while I have been
>  > trying to revive my SSB electronics L 23 S TVTR, my brain went into
>  > overdrive. Having recently bought a NanoVNA, I now have an easily
>  > programmable LO with which to make a simpler SDR for QO-100. My LNB
>  > puts out 739 MHz. By injecting 739 MHz into a suitable mixer ( ie a
>  > copy of the Rx mixer in the L 23 S, I down convert the 739 MHz to
>  > baseband to use with some existing software I have.
>  > But there are more questions than answers. Will I need any
>  > amplification/filtering at 739 MHz before the mixer or will it have
>  > sufficient gain? Should I put an audio buffer amplifier between the
>  > mixer and the sound card input. Has anyone already done this or am I
>  > barking up the wrong tree?
>  >
>  > de John G8SEQ
>  >
>  >> -------Original Message-------
>  >> From: John Worsnop <johnworsnop@...>
>  >> To: UKMicrowaves@groups.io <UKMicrowaves@groups.io>
>  >> Subject: [UKMicrowaves] Scatterpoint Activity column
>  >> Sent: May 18 '20 17:45
>  >>
>  >> GE All,
>  >> I've had no contributions for the Scatterpoint activity news this
>  >> month so far, so it'll be "The G4BAO report" unless I get
>  > something
>  >> before lunchtime Wednesday.
>  >>
>  >> Doing anything interesting? made any out of the ordinary QSOs?
>  >> switched the rig on instead of checking the web for activity? had
>  > a
>  >> QSO that didn't involve exchanging "59007 IO92WI" ?
>  >>
>  >> ;-)
>  >>
>  >> Send it to me at the above address before Wednesday Lunchtime and
>  > the
>  >> UKuG will put your name in lights............
>  >>
>  >> 73
>  >> John
>  >>
>  >>





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