Dubus..arrggghh


militaryoperator
 

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)


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)


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

 


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

 


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


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


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


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