Date   

locked the ridiculous three stage licensing

Dave Cawley G4IUG
 


I totally agree.  Many likely candidates are also not going to attend Radio Club meetings.  I and others I know, simply read the syllabus and took the RAE, no faffing around with resistor colour codes or group hugs.  If in my day it was like it is now, I would not have bothered.
 
Regards
 
Dave
 
G4IUG   Ex G8EAO


Re: Cardiff Round Table

Neil Smith G4DBN
 

I raised this last year and offered to assist with any necessary adaption work on the syllabus and was thanked for my input and heard nothing more, so I hope that indicates the proposal is being pursued actively and does not require additional resource.

Neil G4DBN


On 18/03/2019 10:31, Richard wrote:
You can Never have too much "junk", as as for rain we were lucky it wasn't in Barry
the locals call that place "the p*** pot of Wales" My xyls family are from there.
4 generations of them.
At last a RT on the west side of the UK , it's been a long time .
It really needs some hard lobbying from the UK uWave group to get the ridiculous three stage
licensing changed for students doing RF courses at Uni's, exempt from having to buy a packet of cornflakes and the intermediate
levels, so they can just do the full licence test and get full access to the microwave bands.
Maybe something for the AGM ???

Richard g8jvm



On Mon, 2019-03-18 at 05:10 +0000, PAUL NICKALLS via Groups.Io wrote:
Thanks Derek for organising the event.

Excellent event despite the clashes.  For us it was number one priority.

Fears of the traffic and road closures meant arriving an hour early but it was good to find other people waiting to chat to.  There was no problem with the traffic at all.  Pity about the rain after the event but it was Wales!

Good venue with plenty of parking.  Excellent buffet lunch. Good lectures. Plenty of people to chat to. Too much junk to buy. Good venue. Please repeat.

Very good to hear how you are getting on with the University radio club.  Brings back memories of my misspent youth at Swansea. Too much time in the shack and not enough in lectures.

73
Paul G8AQA



On 17/03/2019 17:17, Peter GW4JQP wrote:
I'll agree with all the above and thank Derek and his colleagues for a very interesting and enjoyable day.   It was well supported and both the venue and the lunch were excellent.  

It was also particularly useful to be able to pick so many brains in one place.   Unfortunately I had to slip off before the end, but the bonus was I missed the traffic.

A very good start to the Roundtable season, and let's hope it becomes an annual event.

Thanks again and 73

Peter GW4JQP


Virus-free. www.avg.com


GM4JJJ SK

Ian White
 

RSGB have posted an obituary at:

https://rsgb.org/main/blog/news/silent-keys/2019/03/18/david-anderson-gm4jjj-14th-march-2019/

along with a superb image of his 2m array during a big aurora.

The early microwave references are here: https://www.lothiansradiosociety.com/lrs-archive/51-silent-keys/752-silent-key-george-burt-gm3oxx-20-september-2017

-- 
73 from Ian GM3SEK


Re: Cardiff Round Table

Richard <richard@...>
 

You can Never have too much "junk", as as for rain we were lucky it wasn't in Barry
the locals call that place "the p*** pot of Wales" My xyls family are from there.
4 generations of them.
At last a RT on the west side of the UK , it's been a long time .
It really needs some hard lobbying from the UK uWave group to get the ridiculous three stage
licensing changed for students doing RF courses at Uni's, exempt from having to buy a packet of cornflakes and the intermediate
levels, so they can just do the full licence test and get full access to the microwave bands.
Maybe something for the AGM ???

Richard g8jvm



On Mon, 2019-03-18 at 05:10 +0000, PAUL NICKALLS via Groups.Io wrote:
Thanks Derek for organising the event.

Excellent event despite the clashes.  For us it was number one priority.

Fears of the traffic and road closures meant arriving an hour early but it was good to find other people waiting to chat to.  There was no problem with the traffic at all.  Pity about the rain after the event but it was Wales!

Good venue with plenty of parking.  Excellent buffet lunch. Good lectures. Plenty of people to chat to. Too much junk to buy. Good venue. Please repeat.

Very good to hear how you are getting on with the University radio club.  Brings back memories of my misspent youth at Swansea. Too much time in the shack and not enough in lectures.

73
Paul G8AQA



On 17/03/2019 17:17, Peter GW4JQP wrote:
I'll agree with all the above and thank Derek and his colleagues for a very interesting and enjoyable day.   It was well supported and both the venue and the lunch were excellent.  

It was also particularly useful to be able to pick so many brains in one place.   Unfortunately I had to slip off before the end, but the bonus was I missed the traffic.

A very good start to the Roundtable season, and let's hope it becomes an annual event.

Thanks again and 73

Peter GW4JQP


Virus-free. www.avg.com


Re: Ecoflex 15 Plus at 2,400Mhz

Dave Cawley G4IUG
 


OK, so this brings this to a conclusion.
 
I'm not the only one; from http://www.df9ic.de/tech/station/station.htm   "I found out that the ECOFLEX-15 cables I have installed are widely out of specification, and show attenuation values on 1296 MHz which are not better than ECOFLEX-10. They were bought new! I cannot replace them easily as they are installed in a protective tube so it will need some time to improve the situation. Very bad!" 
 
Others here that I trust have measure OK, so I think it's a quality control issue.  I could never sleep at night if I thought my cable was not what I thought, or about to deteriorate.
 
A very good friend has some new LDF4-50A with Andrews connectors sealed in boxes for me.
 
This whole saga has been a great disappointment to me after retuning to amateur radio after 20+ years.
 
However,  I am a very strong SSB signal though Es’hail 2 / QO-100, but that is another story !
 
Regards
 
Dave  G4IUG  Ex G8EAO


Re: Cardiff Round Table

Paul G8AQA
 

Thanks Derek for organising the event.

Excellent event despite the clashes.  For us it was number one priority.

Fears of the traffic and road closures meant arriving an hour early but it was good to find other people waiting to chat to.  There was no problem with the traffic at all.  Pity about the rain after the event but it was Wales!

Good venue with plenty of parking.  Excellent buffet lunch. Good lectures. Plenty of people to chat to. Too much junk to buy. Good venue. Please repeat.

Very good to hear how you are getting on with the University radio club.  Brings back memories of my misspent youth at Swansea. Too much time in the shack and not enough in lectures.

73
Paul G8AQA



On 17/03/2019 17:17, Peter GW4JQP wrote:
I'll agree with all the above and thank Derek and his colleagues for a very interesting and enjoyable day.   It was well supported and both the venue and the lunch were excellent.  

It was also particularly useful to be able to pick so many brains in one place.   Unfortunately I had to slip off before the end, but the bonus was I missed the traffic.

A very good start to the Roundtable season, and let's hope it becomes an annual event.

Thanks again and 73

Peter GW4JQP


Virus-free. www.avg.com


Re: EsHailsat QRP Operation

Ole OZ2OE
 

Andy,

Thank you for the explanations. I fully agree that with many different parameters in play - and some not really known - the analysis is not simple.

But I was only trying to comment a statement you've written in an earlier posting that: "provided any ground station has sufficient antenna gain to see the transponder noise floor, S/N will be constant".

While this is true for ground stations seeing high (ie 10 dB or more) transponder noise, it is not the case for ordinary 60 to 70 cm RX antennas, where noise level after latest transponder gain adjustments are more like 3 dB. Here there is a degradation from the ultimate S/N level otherwise possible with bigger antennas, because one noise source - from the transponder - is not dominating the other - from the LNB.

In the "simple" case of a +3 dB raise in noise level, the two contributions - within the transponder bandwith - are equal and because they are unrelated, they add up. At this level the ultimate S/N ratio is reduced by 3 dB. Improvements can be made by selecting good LNB's. Not all "0.1 dB" LNB's are equal - although all are not 0.1 dB!

Bigger RX antennas are essential for QRP operation. Those with "recommended size" antennas will have to use Goonhilly WebSDR or similar for detection of the really weak ones.

73 Ole OZ2OE




Den 17. marts 2019 kl. 13.37.37 +01.00, skrev Andy G4JNT <andy.g4jnt@...>:

Warning - this rambles on for quite a bit, and I've changed the subject line.

No, it's not as simple as you state, although LNA noise figure does matter, it's only significant when you have a small antenna.  First of all, when considering any space link  budget, we must stop talking about Noise Figure in the overall system.  When antenna temperature is anything other than a warm terrestrial 290K it becomes meaningless.   A decent antenna looking up at cold sky may have an antenna temperature of 10 - 30K,   call it 20K for now.   And now LNA noise figure becomes a lot more significant.  Eg a 1dB NF LNA, has a noise temperature of 290 * (10^(1/10) - 1) =  75K.   Assuming this dominates the complete receive chain, that means a system noise temperature of 75+20 = 95K.

Which all goes to show that LNA performance becomes a lot more critical when receiving WEAK signals from space.

But now consider a situation where a satellite transponder has enough gain that it is radiating a significant amount of it's own receiver noise but no other signals.   Lets say it's radiating sufficient noise such that our ground station is seeing that transmitted noise at a level of 5dB above the ground station's own noise level.  BUt it is a radiated signal now, and as such cannot be directly added in to the ground stations own noise in any meaningful way.   Here, for example, that 5dB increase in our 95K system defined above, 3.16 in linear terms, could be said to correspond to a new receiver noise temperature of 3.16 * 95k = 300K,  of which 95K is our own, the rest from the satellite
But if we used a bigger antenna on the ground, and saw a transponder noise level 10dB above Rx noise, that could be said to be 950K by the same argument.   Which is absurd - increasing antenna gain does NOT change system noise temperature.

So ... yes, LNA performance does contribute to overall system performance, and more than in dB for dB terms, but ONLY WHEN receiving weak signals from space.    A satellite downlink from a linear transponder IS NOT A WEAK SIGNAL if you are using a 'normal' downlink receive antenna, so LNA / LNB performance is not that critical.

I believe, although can't yet prove for myself as I have a slightly blocked view of the satellite, is that a 60cm dish and good LNA results in transponder received noise floor appearing about 5dB above receiver noise.   Goonhilly uses a larger dish

What actually IS the weak signal when operating QRP into the satellite is defined by the satellite's antenna gain and noise temperature.   Now, a satellite antenna global beam looking at the earth will be seeing warm terrestrial noise, and have a much higher noise temperature - something like 200K used to be taken in my old days working on Inmarsat as there is some attenuation of hot earth and spillover into cold sky - sort of sidelobes working in reverse!

Assume a low power uplink results in a received S/N of 10dB (using a noise bandwidth appropriate to the signal of interest).  That S/N will be radiated by the transmitter and can never be bettered, whatever you do to the ground Rx system.    Only if you have a very small antenna or poor LNA wil there be significant further degradation.  

There are so many interdependent variables in a satellite up and downlink using a bent-pipe transponder that it is only really possible to get exact contributions from any particular part by putting together a spreadsheet containing every single parameter.  And unfortunately, for this system, we don't have all the satellite parameters to hand to do this properly.  We don't know transponder gain and we can only estimate Rx noise figure / temperature and the Rx and Tx antenna gains.
 
What makes life even more complicated is when receiving LARGE signals via the satellite.  If you have a very small ground station antenna (or poor noise figure) and can't see transponder noise  you'd still get them - but now your own Rx performance really is the limiting factor - which is actually my situation at the moment.
I did say it wasn't straightforward !
 
Goonhilly, with it's 1.3m dish is seeing a transponder noise floor something like 10dB above thermal, so any QRP operation via that is entirely dependent on uplink EIRP and coding efficiency.   SO the WebSDR there is an excellent receiver goto when testing QRP uplink operations.

I've rambled on a bit here, but hope you can see that for any typical ground station, unless the operators reduce the transponder gain significantly,  anyone with a recommended system of 60cm dish or more with good LNA should be seeing transponder noise.   Ground station LNA noise figure does matter, but certainly not in a one-for-one dB related way. 



On Sun, 17 Mar 2019 at 10:19, Ole OZ2OE <ole@...> wrote:
Hi Andy

I enjoy reading technical comments on this group. But I think you have missed the effect of background LNB noise?

Just "seeing" the transponder noise floor is not enough to ensure S/N will be constant. In (the simple) case of a 3 dB transponder noise floor, what you see is actually the LNB noise floor plus an identical amount of transponder noise - adding up to a 3 dB increase. Increasing transponder noise floor from here will reduce influence of LNB noise - to a a point where LNB noise is really in the "background".

But at a low values of transponder noise floor there is some degadation in S/N. And LNB noise figure becomes important.

- or is it me missing something - hi.

73 Ole OZ2OE





moderated Re: AxisNT TDD 2,3 - 2,4 Ghz amplifier

Richard <richard@...>
 

Arduino €6, loads of profit !

In the UK we call this a scam

Also there is no device that can not be manually biased, so not dead , just requires a little engineering

WE in this little island have ways of reviving the dead SSPAs


73 Richard g8jvm

On Sun, 2019-03-17 at 22:44 +0100, Stanislaw Ziemczonek wrote:
 Mike,
PA need programming  quiescent current 4 transistors in each PA and switch on ,
without this PA is completely dead.
I installing little Arduino module  programmed by SQ6QV and I start PA.
Each PA must be programmed individually ,  so you must send PA to me.
It costs 100E + shipping costs (20-30E, depending on whether you send the whole PA or PCB with shilding only).

73's de Staszek SP6GWB
I am interested but I have been otherwise engaged for the past couple of weeks so put it to one side. Unfortunately I am not due to visit Poland in the near term. What does the modification do?

Mike G0MJW



moderated Re: AxisNT TDD 2,3 - 2,4 Ghz amplifier

Stanislaw Ziemczonek
 

 Mike,
PA need programming  quiescent current 4 transistors in each PA and switch on ,
without this PA is completely dead.
I installing little Arduino module  programmed by SQ6QV and I start PA.
Each PA must be programmed individually ,  so you must send PA to me.
It costs 100E + shipping costs (20-30E, depending on whether you send the whole PA or PCB with shilding only).

73's de Staszek SP6GWB

I am interested but I have been otherwise engaged for the past couple of weeks so put it to one side. Unfortunately I am not due to visit Poland in the near term. What does the modification do?

Mike G0MJW



moderated Re: AxisNT TDD 2,3 - 2,4 Ghz amplifier

Mike Willis
 

I am interested but I have been otherwise engaged for the past couple of weeks so put it to one side. Unfortunately I am not due to visit Poland in the near term. What does the modification do?

Mike G0MJW


Re: Cardiff Round Table

Peter GW4JQP
 

I'll agree with all the above and thank Derek and his colleagues for a very interesting and enjoyable day.   It was well supported and both the venue and the lunch were excellent.  

It was also particularly useful to be able to pick so many brains in one place.   Unfortunately I had to slip off before the end, but the bonus was I missed the traffic.

A very good start to the Roundtable season, and let's hope it becomes an annual event.

Thanks again and 73

Peter GW4JQP


a Gotcha to watch out for

Richard <richard@...>
 

PCBs in tin plate boxes.

Don't always assume you have good ground bonding if you haven't seam
soldered all the way around if using double sided pcb with one plane as
a continuous ground plane.
A few years down the line when surfaces oxidise good contact gets
lost, Sods law will strike

--
Best wishes /73
Richard Bown

Email : richard@g8jvm.com

HTTP : http://www.g8jvm.com

######################################################################

Ham Call: G8JVM . QRV: 50-432 MHz + Microwave
Maidenhead QRA: IO82SP38, LAT. 52 39.720' N LONG. 2 28.171 W
QRV 6mtrs 200W, 4mtrs 150W, 2mtrs 300W, 70cms 200W,
Microwave 1296MHz 140W, 2320MHz 100W & 10368MHz 5W
OS: Linux Mint 19.1 x86_64 Tessa, on a Dell Inspiron N5030 laptop
######################################################################


Re: Does 27MHz have to be 27.000000MHz for LNB LO?

Andy G4JNT
 

No, not exactly.   The LNB - at least the one I tested - http://g4jnt.com/PLL_LNB_Tests.pdf and http://g4jnt.com/OctagonExtLo.pdf  suggest a frequency in the  range 26 to 28MHz, and a bit beyond, will lock up.

However, in  the interests of sanity best not stray too far.
The PLL multiples the 27MHz ref by  by 361.111111   (325 / 9) and ideally any shifted reference ought to at least maintain integer MHz.

Andy G4JNT


On Sun, 17 Mar 2019 at 10:54, Leo Bodnar <leo@...> wrote:
I have been looking into spectrum purity on GPS clocks.
While I can find settings for 25MHz and 26MHz output with no spurs within 1MHz from the fundamental, 27MHz is not that lucky.  There are few -100dBc to -110dBc spurs between 10kHz and 100kHz offset that I can't get rid of.

Firstly, is this level a problem?

And, secondly, does LO for LNB has to be 27.000MHz precisely or it can be offset slightly while remaining stable?
If it can be slightly off what is the acceptable range?  I will then look something up around this area which has no spurs.

Phase noise is not affected by settings, but the spurs are, and short of testing all combinations I don't know of a reliable way of weeding them out in a digital system.

If you have a choice, I'd use  25MHz or 26MHz for now when using GPS clocks.

Cheers
Leo / M0XER


EsHailsat QRP Operation

Andy G4JNT
 

Warning - this rambles on for quite a bit, and I've changed the subject line.

No, it's not as simple as you state, although LNA noise figure does matter, it's only significant when you have a small antenna.  First of all, when considering any space link  budget, we must stop talking about Noise Figure in the overall system.  When antenna temperature is anything other than a warm terrestrial 290K it becomes meaningless.   A decent antenna looking up at cold sky may have an antenna temperature of 10 - 30K,   call it 20K for now.   And now LNA noise figure becomes a lot more significant.  Eg a 1dB NF LNA, has a noise temperature of 290 * (10^(1/10) - 1) =  75K.   Assuming this dominates the complete receive chain, that means a system noise temperature of 75+20 = 95K.

Which all goes to show that LNA performance becomes a lot more critical when receiving WEAK signals from space.

But now consider a situation where a satellite transponder has enough gain that it is radiating a significant amount of it's own receiver noise but no other signals.   Lets say it's radiating sufficient noise such that our ground station is seeing that transmitted noise at a level of 5dB above the ground station's own noise level.  BUt it is a radiated signal now, and as such cannot be directly added in to the ground stations own noise in any meaningful way.   Here, for example, that 5dB increase in our 95K system defined above, 3.16 in linear terms, could be said to correspond to a new receiver noise temperature of 3.16 * 95k = 300K,  of which 95K is our own, the rest from the satellite
But if we used a bigger antenna on the ground, and saw a transponder noise level 10dB above Rx noise, that could be said to be 950K by the same argument.   Which is absurd - increasing antenna gain does NOT change system noise temperature.

So ... yes, LNA performance does contribute to overall system performance, and more than in dB for dB terms, but ONLY WHEN receiving weak signals from space.    A satellite downlink from a linear transponder IS NOT A WEAK SIGNAL if you are using a 'normal' downlink receive antenna, so LNA / LNB performance is not that critical.

I believe, although can't yet prove for myself as I have a slightly blocked view of the satellite, is that a 60cm dish and good LNA results in transponder received noise floor appearing about 5dB above receiver noise.   Goonhilly uses a larger dish

What actually IS the weak signal when operating QRP into the satellite is defined by the satellite's antenna gain and noise temperature.   Now, a satellite antenna global beam looking at the earth will be seeing warm terrestrial noise, and have a much higher noise temperature - something like 200K used to be taken in my old days working on Inmarsat as there is some attenuation of hot earth and spillover into cold sky - sort of sidelobes working in reverse!

Assume a low power uplink results in a received S/N of 10dB (using a noise bandwidth appropriate to the signal of interest).  That S/N will be radiated by the transmitter and can never be bettered, whatever you do to the ground Rx system.    Only if you have a very small antenna or poor LNA wil there be significant further degradation.  

There are so many interdependent variables in a satellite up and downlink using a bent-pipe transponder that it is only really possible to get exact contributions from any particular part by putting together a spreadsheet containing every single parameter.  And unfortunately, for this system, we don't have all the satellite parameters to hand to do this properly.  We don't know transponder gain and we can only estimate Rx noise figure / temperature and the Rx and Tx antenna gains.
 
What makes life even more complicated is when receiving LARGE signals via the satellite.  If you have a very small ground station antenna (or poor noise figure) and can't see transponder noise  you'd still get them - but now your own Rx performance really is the limiting factor - which is actually my situation at the moment.
I did say it wasn't straightforward !
 
Goonhilly, with it's 1.3m dish is seeing a transponder noise floor something like 10dB above thermal, so any QRP operation via that is entirely dependent on uplink EIRP and coding efficiency.   SO the WebSDR there is an excellent receiver goto when testing QRP uplink operations.

I've rambled on a bit here, but hope you can see that for any typical ground station, unless the operators reduce the transponder gain significantly,  anyone with a recommended system of 60cm dish or more with good LNA should be seeing transponder noise.   Ground station LNA noise figure does matter, but certainly not in a one-for-one dB related way. 



On Sun, 17 Mar 2019 at 10:19, Ole OZ2OE <ole@...> wrote:
Hi Andy

I enjoy reading technical comments on this group. But I think you have missed the effect of background LNB noise?

Just "seeing" the transponder noise floor is not enough to ensure S/N will be constant. In (the simple) case of a 3 dB transponder noise floor, what you see is actually the LNB noise floor plus an identical amount of transponder noise - adding up to a 3 dB increase. Increasing transponder noise floor from here will reduce influence of LNB noise - to a a point where LNB noise is really in the "background".

But at a low values of transponder noise floor there is some degadation in S/N. And LNB noise figure becomes important.

- or is it me missing something - hi.

73 Ole OZ2OE


Cardiff Round Table

Dave G8KHU
 

Can we also add our thanks to all for hosting a thoroughly enjoyable day.
Dave G8KHU / Dave G1TVL


Does 27MHz have to be 27.000000MHz for LNB LO?

Leo Bodnar
 

I have been looking into spectrum purity on GPS clocks.
While I can find settings for 25MHz and 26MHz output with no spurs within 1MHz from the fundamental, 27MHz is not that lucky.  There are few -100dBc to -110dBc spurs between 10kHz and 100kHz offset that I can't get rid of.

Firstly, is this level a problem?

And, secondly, does LO for LNB has to be 27.000MHz precisely or it can be offset slightly while remaining stable?
If it can be slightly off what is the acceptable range?  I will then look something up around this area which has no spurs.

Phase noise is not affected by settings, but the spurs are, and short of testing all combinations I don't know of a reliable way of weeding them out in a digital system.

If you have a choice, I'd use  25MHz or 26MHz for now when using GPS clocks.

Cheers
Leo / M0XER


Re: Cardiff Round Table

G3PHO - Peter
 

Many thanks indeed to Derek and his team for a very interesting day. It was well worth the 200 mile trip from IO93 square! It was also great to meet up with microwave pals from the "Old Days" .... M0GHZ, G4ASR, G4UVZ, G8JVM, G4LDR, etc. 

Barry, G8AGN, who came down with me for the weekend, passes his thanks to you all.

73

Peter, G3PHO


On 17 Mar 2019, at 09:36, Denis Stanton G0OLX via Groups.Io <denis.stanton@...> wrote:

Derek
Also many thanks from myself 
Had no trouble with traffic at all both ways 
An excellent venue as well
Thanks to all your team
Best 73’s
Denis
G0OLX


On 16 Mar 2019, at 20:16, DAVID G4ASR via Groups.Io <g4asr@...> wrote:

Derek, 

You and your team did an excellent job putting on the smooth running microwave event.
Thank you very much for the hospititalty and to be honest I didnt see any rugby fans. 
It was great to meet you and all the old timers, me included. 

73 David G4ASR 




Re: EsHailsat Location Beacon running

Ole OZ2OE
 

Hi Andy

I enjoy reading technical comments on this group. But I think you have missed the effect of background LNB noise?

Just "seeing" the transponder noise floor is not enough to ensure S/N will be constant. In (the simple) case of a 3 dB transponder noise floor, what you see is actually the LNB noise floor plus an identical amount of transponder noise - adding up to a 3 dB increase. Increasing transponder noise floor from here will reduce influence of LNB noise - to a a point where LNB noise is really in the "background".

But at a low values of transponder noise floor there is some degadation in S/N. And LNB noise figure becomes important.

- or is it me missing something - hi.

73 Ole OZ2OE

Den 16. marts 2019 kl. 19.29.20 +01.00, skrev Andy G4JNT <andy.g4jnt@...>:

The critical factor for QRP operation is S/N into the satellite receiver.  Then, provided any ground station has sufficient antenna gain to see the transponder noise floor, S/N will be constant, and a function of uplink  EIRP only.    Changing transponder gain will move the downlink received signal up or down, and the noise floor will go with it, maintaining downlink S/N.

Things only hurt when you have a low gain downlink antenna or poor noise figure (*).  If transponder gain is dropped too much, the received signal could fall below the ground station's own noise floor and that would degrade S/N

(*) There is a figure of merit used in spacecraft link terminology for the receiver performance, called G/T; gain of the antenna divided by system noise temperature in Kelvin.  It is usually expressed in dB, a fact that confuses many who meet the term for the first time (like me when I first met it !).  G/T expressed in dB is either 10.LOG(linear antenna gain / temperature)    or    Antenna gain in dB - 10.LOG(temp) 

Andy


On Sat, 16 Mar 2019 at 17:39, Martin - G8JNJ via Groups.Io <martin_ehrenfried=yahoo.com@groups.io> wrote:
On Sat, Mar 16, 2019 at 05:35 PM, Martin - G8JNJ wrote:

Yes that's another problem, as the Goonhilly dish may also have moved with the wind (as mine did too) so it's difficult to find a common reference point.
I think Phil may also have adjusted the Goonhilly SDR gain too, so that's another factor.

Regards,

Martin - G8JNJ





Re: Cardiff Round Table

Richard <richard@...>
 

I'll add to that.
Well organised, the traffic wasn't as bad as expected, and I noticed
when driving home laybys nears railway stations full .
So it looks like most used public transport to get to the rugby match.
Didn't think much of the amount and size of the potholes on the A48M,
probably why so many used public transport.
I guess there is a lot of hangovers in Wales today though.

Richard g8jvm

On Sat, 2019-03-16 at 22:11 +0000, R Hopkins via Groups.Io wrote:
I'll second that David. I had a thoroughly enjoyable day.

Well done to all concerned in organizing the event.

Roger GW4NOS (rugby fan)


On Sat, 16 Mar 2019 13:16:57 -0700, you wrote:

Derek,

You and your team did an excellent job putting on the smooth
running microwave event.
Thank you very much for the hospititalty and to be honest I didnt
see any rugby fans.
It was great to meet you and all the old timers, me included.

73 David G4ASR





Re: Cardiff Round Table

Denis Stanton G0OLX
 

Derek
Also many thanks from myself 
Had no trouble with traffic at all both ways 
An excellent venue as well
Thanks to all your team
Best 73’s
Denis
G0OLX


On 16 Mar 2019, at 20:16, DAVID G4ASR via Groups.Io <g4asr@...> wrote:

Derek, 

You and your team did an excellent job putting on the smooth running microwave event.
Thank you very much for the hospititalty and to be honest I didnt see any rugby fans. 
It was great to meet you and all the old timers, me included. 

73 David G4ASR 



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