Date   

Re: QO-100

Andy G4JNT
 

It only works if you have a receive system that is transponder noise limited.  Mine isn't.   I think local trees degrade the signal a bit as my 0.6m dish is 10dB below the Goonhilly websdr.    I could use that as the measurement , but so far haven't tried a decent calibrated measurement with it.   Furthermore, need to make a standard gain horn for 2.4GHz, (simple enough with tinplate from an old engine oil can :-)

A reasonable estimate of G/T can't be too far off.    Assume 1dB noise figure for the satellite receive - pretty typical of LNAs with a bit of preceding loss.   That's seeing mostly Earth's surface with a substantial amount of ocean reflection from cold space, so the antenna temperature will be perhaps 150 - 200K.  On -L-Band in my MSS days, IIRC we used 200K.      So a total Noise Temp, call it 250K
A global coverage antenna from GEO will have to have 18 degree coverage, so if made efficiently should be managing 19.5 - 20dBi

Thus the G/T can't be too far away from -4dB/K.   The transponder gain is of rather more interest, and there are too many variables to get an accurate estimate of that, not least really accurate RMS noise measurement in a precisely know bandwidth
Few SDRs, or more to the point FFT software, give an accurate noise bandwidth/effective bin size.    Some don't even declare what window type they use, so absolute S/N measurement can't really be much better than perhaps 2- 3dB accurate

But your comment has reinspired a bit of interest, so I'll see if I've got the materials to make a SGH for 2.4GHz

 


On Sat, 5 Jun 2021 at 08:11, Mike Willis <willis.mj@...> wrote:
I thought you had measured it? Don't you believe yourself?

Transmitting a known EIRP from a standard horn and measuring the signal above the noise floor of the NB transponder gives you the answer once you calibrate for your receive G/T. With the transponder noise floor 10 dB or so above the noise that correction is already fairly minor. Make a few assumptions about the noise temperature of the earth and atmosphere. We can work out the compensation for our own RX G/T or or less accurately from solar transits. About 24 dB in my case. That should be able to get the figures within a dB or so. It will vary by more than that over the coverage area.
 
--
Mike G0MJW


Re: QO-100

Mike Willis
 

I thought you had measured it? Don't you believe yourself?

Transmitting a known EIRP from a standard horn and measuring the signal above the noise floor of the NB transponder gives you the answer once you calibrate for your receive G/T. With the transponder noise floor 10 dB or so above the noise that correction is already fairly minor. Make a few assumptions about the noise temperature of the earth and atmosphere. We can work out the compensation for our own RX G/T or or less accurately from solar transits. About 24 dB in my case. That should be able to get the figures within a dB or so. It will vary by more than that over the coverage area.
 
--
Mike G0MJW


Re: Activity List for the UK Microwave Group Low Band Contest - Sunday 6th June

Peter GW4JQP
 

Hello John et al

I aim to be on.

Callsign: GW4JQP 
Locator: IO71KR
Band: 1.3 GHz 12W 35 element
Talkback: CQ on 23cm and KST.   Using an iPad so regret can’t hear meeps.
Times: On and off throughout.

73

Peter GW4JQP 


Big Dishes

Chris Bartram G4DGU
 

I can't disagree at all with John.

I'm just staggering back onto 10GHz EME after a very long absence.

My personal philosophy involves the design and making of most of my own equipment. I draw the line at designing my own transceivers, simply because if I did that, I'd never get on the air! I also feel that the march of consumerism into our hobby is a very negative factor. For me, amateur radio is not about a 'mine's bigger/more expensive that yours' contest, but rather a means of continuing self-education. It has taught me a lot.

Having had a reasonably sized (2.4m offset) dish on 10GHz, I didn't feel that was was necessary or desirable when getting get back on the band from a QTH with a conventionally sized garden, and neighbours, rather than rolling Welsh acres and relative isolation as was the case before.

As John says, optimising a small antenna for good results on the EME path is a heck of a lot more satisfying than using an antenna which which I could detect significant Moon noise straight into the transverter, and was able to make my initial QSOs with just a few watts!

I wrote a note for 'Scatterpoint' back in the late 2010s suggesting that a QSO might be possible (using JT4) between 10W/1m dish stations. I was rather optimistic in my assumptions regarding the performance of JT4 at 10GHz (which was quite new at the time I was writing) but the latest WSJT mode, Q65, does seem to be approaching the required performance in practice. Certainly, as John will tell you, 20W to 1.1m is enough to work a 1.6m dish with a bit to spare - but it does require that 1.1m dish and its associated systems to be working very well.

73

Chris

G4DGU

Any fool can make EME QSOs with a big dish, the challenge with EME for anyone with half an interest in pushing technology is making QSOs with what you can build and fit in your garden and get past your neighbours.
My experience is that there are some REALLY badly set up big dishes out there, especially on 10GHz but if you REALLY work on the Engineering, an optimised small dish station will outperform bigger dishes run by those who just chuck a feed in to a big dish and don't even try to optimise it. There are plenty of those in the EME community. They do this quite innocently because they just find they can make QSOs without bothering to optimise. With a big dish, you have to do the mechanical Engineering really well but some don't bother with the radio part.

That said there are some extremely well set up big dishes as well, and you know when they're on!
Peter G3LTF (see my June GHz column) is a case in point.

If all you want is a lot of QSOs with little effort or to make more QSOs than everyone else take up HF contesting, not EME, unless you have a VERY big garden, no neighbours and shedloads of money.

Me, I prefer a few quality QSOs not just ANY QSOs


Re: WFVIEW IC705

Adrian G4UVZ
 

OK Chaps ..thanks for the info ...at least this backs up my first law of communications ..that the fault was at the other end of the link!!


Re: WFVIEW IC705

Paul Evans W4/VP9KF
 

There is no build for this under iOS. Delete and wait to see if they port the code.

--
73, Paul Evans G4BKI [VP9KF]


Re: WFVIEW IC705

Colin G4EML
 

You can’t run programs designed for a laptop on an Iphone, so the file is of no use to you.

 

In fact you can’t run any program on an Iphone unless it has been approved by Apple and downloaded from the app store. (excluding hacked Iphones!)  The only exception to this are what are called ‘Web Apps’ but they are quite limited in what they can do and I don’t think WFVIEW is one of those.

 

Colin G4EML

 

 

 

 

From: Adrian G4UVZ via groups.io
Sent: 03 June 2021 15:04
To: UKMicrowaves@groups.io
Subject: [UKMicrowaves] WFVIEW IC705

 

Having had great success with this program on my laptop  I wanted to use it on my Iphone..I downloaded a Zip file to the phone and subsequently unzipped it ..I think. I now have a 60.4 MB file on the Iphone but my IT skills have now run out !!! The file is residing in Recents along with the Zip file ...Any idea how I activate this file?

Thanks

Adrian

 


WFVIEW IC705

Adrian G4UVZ
 

Having had great success with this program on my laptop  I wanted to use it on my Iphone..I downloaded a Zip file to the phone and subsequently unzipped it ..I think. I now have a 60.4 MB file on the Iphone but my IT skills have now run out !!! The file is residing in Recents along with the Zip file ...Any idea how I activate this file?

Thanks

Adrian


Re: Dubus..arrggghh

Barry VE4MA
 

There is a good discussion of the antenna decoupling and lower dispersion experienced by large antennas on the PA0EHG web site at   http://www.pa0ehg.com/what47ghz.htm

Best 73
Barry VE4MA


From: "ve4ma" <ve4ma@...>
To: "UKMicrowaves" <UKMicrowaves@groups.io>
Sent: Wednesday, June 2, 2021 5:04:23 PM
Subject: [UKMicrowaves] Dubus..arrggghh

My philosophy has always been to make a smaller dish work to the max....as you say John there  has always been lots of big underperforming dishes on EME.  Although I think there are fewer of those around now than 30 years ago !
Best 73
Barry VE4MA


Re: Dubus..arrggghh

KENT BRITAIN
 

Hi John

I was one of the stations on 3 cm EME when they put VE3ONT on the air using that big dish.
And yes, they were not the strongest signal on the band.  Cleanest perhaps, but not the strongest.

Imagine the Radar Range Equation, but instead to the Radar beam hitting the aircraft, the beam is so narrow it it only hitting part of the aircraft.    Now instead of 100 sq Meters Radar cross section, you only have 10.    So signals are 10 dB less than you might think.

The other way to look at it.   For 3 cm, a dish in the 5 to 6 Meter class now has all the TX energy hitting the moon.  Having the same energy hitting just a small area of the moon does not increase the amount of energy reflected back to the earth.   (Yes, using just the very center of the moon is a tiny bit closer to the earth, and you have reduced Doppler smear, but signal improvements are no longer linear as antenna gain increases when communicating with a smaller dish.)

On the receive side,the smaller dish is illuminating the entire surface of the moon.  The field strength per area is fairly constant.   Looking at only pieces of that field strength always sees the same signal level.    Again the improvement with a big dish is slight.      Now big dish to big dish is a different matter.    VE3ONT was only using about 1% of the surface of the moon.   Signals from a 2nd very large dish would have been very strong, but only if both dishes were pointing at the same 1% of the moon.    Radar studies of the moon suggest the crater Tyco would make a good common aim point.    Eleven US and Soviet Radar studies of the moon can be downloaded at:  http://www.wa5vjb.com/moon.html     73 Kent WA5VJB


On Thursday, June 3, 2021, 04:09:00 AM CDT, John Fell <john.g0api@...> wrote:


There are advantages on the Moon circuit from the use of narrow beamwidth .

I remember listening to some tests from a group who had access to the Canadian equivalent of Jodrell Bank , back in 1994 era ,
Prior to the event much was made of the potential "mega" signal , but for some reason the signal strength during the tests I heard were of average strength for the era - certainly not the levels of WA7CJO or SM4DHN ., who both put in SSB echoes .
However the thing that stood out was the much reduced multipath signal spreading , which was the result of their smaller reflection area , near T9 CW rather than Ar .

Anyone doing EME on the upper Microwave bands should go through the craft learning route of a "small" dish and build/optimise for best performance .Then use the skills with the largest dish form that is practical .

If you get to SSB echoes at any phase of the Moon the fun really starts .....1000Hrs of work per QSO is probably not too far off the mark .

73
John
G0API

On Wed, 2 Jun 2021 at 23:04, Barry VE4MA <ve4ma@...> wrote:
My philosophy has always been to make a smaller dish work to the max....as you say John there  has always been lots of big underperforming dishes on EME.  Although I think there are fewer of those around now than 30 years ago !

Best 73
Barry VE4MA


Re: Dubus..arrggghh

John Fell
 

There are advantages on the Moon circuit from the use of narrow beamwidth .

I remember listening to some tests from a group who had access to the Canadian equivalent of Jodrell Bank , back in 1994 era ,
Prior to the event much was made of the potential "mega" signal , but for some reason the signal strength during the tests I heard were of average strength for the era - certainly not the levels of WA7CJO or SM4DHN ., who both put in SSB echoes .
However the thing that stood out was the much reduced multipath signal spreading , which was the result of their smaller reflection area , near T9 CW rather than Ar .

Anyone doing EME on the upper Microwave bands should go through the craft learning route of a "small" dish and build/optimise for best performance .Then use the skills with the largest dish form that is practical .

If you get to SSB echoes at any phase of the Moon the fun really starts .....1000Hrs of work per QSO is probably not too far off the mark .

73
John
G0API

On Wed, 2 Jun 2021 at 23:04, Barry VE4MA <ve4ma@...> wrote:
My philosophy has always been to make a smaller dish work to the max....as you say John there  has always been lots of big underperforming dishes on EME.  Although I think there are fewer of those around now than 30 years ago !

Best 73
Barry VE4MA


Dubus..arrggghh

Barry VE4MA
 

My philosophy has always been to make a smaller dish work to the max....as you say John there  has always been lots of big underperforming dishes on EME.  Although I think there are fewer of those around now than 30 years ago !

Best 73
Barry VE4MA


Re: Dubus..arrggghh

Lou Blasco
 

I find I'm happier counting my blessings and successes rather than worrying about what others have done. 

Regards

Lou
VK3ALB


On Thu, Jun 3, 2021 at 12:28 AM g4bao <john@...> wrote:
Really Ben? Just what is the matter with you!?

Any fool can make EME QSOs with a big dish, the challenge with EME for anyone with half an interest in pushing technology is making QSOs with what you can build and fit in your garden and get past your neighbours.
My experience is that there are some REALLY badly set up big dishes out there, especially on 10GHz but if you REALLY work on the Engineering, an optimised small dish station will outperform bigger dishes run by those who just chuck a feed in to a big dish and don't even try to optimise it. There are plenty of those in the EME community. They do this quite innocently because they just find they can make QSOs without bothering to optimise. With a big dish, you have to do the mechanical Engineering really well but some don't bother with the radio part.

That said there are some extremely well set up big dishes as well, and you know when they're on!
Peter G3LTF (see my June GHz column) is a case in point.
 
If all you want is a lot of QSOs with little effort or to make more QSOs than everyone else take up HF contesting, not EME, unless you have a VERY big garden, no neighbours and shedloads of money.

Me, I prefer a few quality QSOs not just ANY QSOs

;-) 
BREEEATHE JOHN!
:-)
73
John

 


13cm

steve G1PPA
 

Hi all

Before purchasing a new 13cm Khune txvtre , does anyone have one for sale

Cheers steve

G1PPA

 

Sent from Mail for Windows 10

 


[camb-hams] For Sale 23cm Quad Loop Yagi

John Worsnop
 



---------- Forwarded message ---------
From: g6ohm@... via groups.io <g6ohm=talktalk.net@groups.io>
Date: Wed, 2 Jun 2021 at 15:16
Subject: [camb-hams] For Sale 23cm Quad Loop Yagi
To: camb-hams@groups io <camb-hams@groups.io>


23cm Quad loop Yagi

48 element. 3.75 m long !

Breaks down into 1.8 m aprox sections

N type Socket.

60 pounds

Tel: 01354695186 have caller id. Just give your callsign.


 73 Andy G6OHM. Sent by Amazon Fire Tablet.





Re: QO-100

DD1US
 

Hi Andy,

 

I am afraid they are still secret and will remain secret.

 

Kind regards

 

Matthias

 

www.dd1us.de

 

 

Von: UKMicrowaves@groups.io <UKMicrowaves@groups.io> Im Auftrag von Andy G4JNT
Gesendet: Mittwoch, 2. Juni 2021 16:08
An: UK Microwaves groups.io <ukmicrowaves@groups.io>
Betreff: [UKMicrowaves] QO-100

 

Are the value for G/T and transponder gain for the QO-100 narrowband transponder still Tippy-Toppy-Secret?

Or perhaps could someone be persuaded to release the figures?

 

Andy

 


Re: Dubus..arrggghh

g4bao
 

Really Ben? Just what is the matter with you!?

Any fool can make EME QSOs with a big dish, the challenge with EME for anyone with half an interest in pushing technology is making QSOs with what you can build and fit in your garden and get past your neighbours.
My experience is that there are some REALLY badly set up big dishes out there, especially on 10GHz but if you REALLY work on the Engineering, an optimised small dish station will outperform bigger dishes run by those who just chuck a feed in to a big dish and don't even try to optimise it. There are plenty of those in the EME community. They do this quite innocently because they just find they can make QSOs without bothering to optimise. With a big dish, you have to do the mechanical Engineering really well but some don't bother with the radio part.

That said there are some extremely well set up big dishes as well, and you know when they're on!
Peter G3LTF (see my June GHz column) is a case in point.
 
If all you want is a lot of QSOs with little effort or to make more QSOs than everyone else take up HF contesting, not EME, unless you have a VERY big garden, no neighbours and shedloads of money.

Me, I prefer a few quality QSOs not just ANY QSOs

;-) 
BREEEATHE JOHN!
:-)
73
John

 


QO-100

Andy G4JNT
 

Are the value for G/T and transponder gain for the QO-100 narrowband transponder still Tippy-Toppy-Secret?
Or perhaps could someone be persuaded to release the figures?


Re: Activity List for the UK Microwave Group Low Band Contest - Sunday 6th June

Phil Guttridge G3TCU
 

Callsign: M0HNA/P
Locator: IO91GI44
Bands: 1.3GHz 400W 67ele
2.30GHz 60W 0.9m dish
2.32GHz 60W 0.9m dish
3.4GHz 15W 1.1m o/s dish
Talkback: ON4KST, (23cm M0HNA-1, 9&13cm M0HNA-2), direct CQ on 23cm.
Times: Throughout the event

73, Barry G4SJH, Dave G1EHF, Graham G3TCT, Phil G3TCU



On 01/06/2021 12:24, John Quarmby via groups.io wrote:
Another UKuG contest takes place this coming weekend - the June edition of the Low Band events on 1296MHz, 2300MHz, 2320MHz, and 3400MHz.

Times are 1000 - 1600GMT (1100 - 1700 BST) on Sunday 6th June.

The weather forecast looks set fair for Sunday, and as this contest coincides with a microwave contest in many European countries there should be some good DX available.

As usual I will compile an activity list, which will probably be published Saturday evening, so please post your plans before noon Saturday. Usual format please:

Callsign: G3XDY
Locator: JO02OB
Bands: 1296MHz 400W 4 x 23el
             2300/2320MHz 200W 0.8m dish
             3400MHz still QRT (replacement transverter awaited)
Talkback: ON4KST & direct CQ on 1296MHz
Times: Various throughout

73

John G3XDY

UKuG Contest Manager




Re: Dubus..arrggghh

Andy G4JNT
 

It's just this minute arrived.   Oh yes, see what you mean.

Mind you...   it is probably perfectly genuine, but the picture does have a certain 'Photoshop feel' about it.   There's something 'odd' about the lighting.




On Wed, 2 Jun 2021 at 13:20, militaryoperator via groups.io <Military1944=aol.com@groups.io> wrote:
Well!. Already feeling disillusioned and frustrated this months Dubus cover takes the Michael.

I can see no point in me messing with my paltry 60cm or even my pathetic 1.4Mtr looking at the cover. 
I might as well give up now. 

Does anyone want to buy some radio bits? might even repurpose them as birdbaths, hi. 

Ben (down in the dumps after mixer and 3 ADF boards u/s)

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