Date   

10 GHz testing next saturday

bart_ghz <shf2@...>
 

Hello,

Next saturday afternoon I hope to do some testing on 3 cm with my new
setup.
The locator will probably be JO20ss or as an alternative JO20mw.
I'll be using 3W and 70 cm prime focus dish.
I will not have 2m ssb,but i will listening on my car tranceiver on
145.425 MHz.
I'll also be on KST chat.
So any qso (ssb and cw) will be appreciated.

regards on7bv Bart


Re: Smith chart

Michael Scott
 

Nice one Andy, It prints very cleanly from the PDF.
 
73, Mike

----- Original Message -----
Sent: Wednesday, February 20, 2008 4:06 PM
Subject: [ukmicrowaves] Smith chart


In praise of Fruit Flies

Richard Newstead <g3cwi@...>
 

Geneticists like fruit flies. Their short lifespan allows genetic
variation to be studied in relative short time periods. In much the
same way, my microwave system has developed rapidly having been
adapted and improved over the course of over ten outings to the
hills.

On each of these outing I have been interested to note the response
of the people that have called me and I have observed that the
methods use by some people have made my life much easier. In an
effort to bring out these points I have written a short article
which, in my characteristic writing style, has the apparently
meaningless heading "Life in the Zone".

http://www.sotabeams.co.uk/Downloads/Life%20in%20the%20Zone.pdf

I hope that you will find it interesting!

73

Richard
G3CWI


Re: Smith chart

mikeg3pfr@...
 

In a message dated 20/02/2008 19:22:11 GMT Standard Time, g3lyp@... writes:
Nice one Andy, It prints very cleanly from the PDF.
 
Seconded!
 
Regards, Mike, G3PFR


Re: In praise of Fruit Flies

mikeg3pfr@...
 

In a message dated 20/02/2008 19:05:23 GMT Standard Time, g3cwi@... writes:
I hope that you will find it interesting!
 
Thanks, Richard - yes, very interesting, as it changes the face of lightweight microwave operation in a way which was not previously possible. Keep up the good work - you have certainly stirred up some activity and we can all benefit from that!
 
Regards, Mike, G3PFR


Re: Scatterpoint Feb 2008

Andy Talbot <andy.g4jnt@...>
 


Re: Scatterpoint Feb 2008

Peter Day <microwaves@...>
 

Andy Talbot wrote:
No, be fair. After 50 years you'd be getting nostalgic about black spot fets and SOTA operation while marvelling at the beginners building chip-and-bond kits for the 3THz band.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ and pigs might fly :-)

In the immortal words of a certain Orangeman.. "NEVER, NEVER NEVER! :-))

73

Peter, G3PHO


Re: 24GHz

SAM JEWELL
 

Could be....
Thanks for the letter. Arrived today.
Sam


Richard Newstead wrote:

--- In ukmicrowaves@yahoogroups.com, wrote:
>
>
> Hi Sam,
> In order to nail this issue I would (again) recommend everyone
>adopts elevation control

I'm expecting to find depression control of use on shorter paths from
Snowdon on Sunday.

73

Richard
G3CWI



Re: IO73

g4blh <g4blh@...>
 

Hi Ray,

Gerald OGI normally only has low power on 23cms (mW).
I have sent him an Email asking what he will be using, will
post it on here when I get the reply.
With reference to Gerald GW4OIG potential North Wales SOTA
activations this coming weekend, Gerald has Emailed me the following
info.

"At the moment I have been using the beam horizontal, though I will
be making an adaptor plate before the activation so it can be
used vertically polarised. I will be taking a small 3.2m pole with
me and can drop this to change polarisation if needs be. I think
horizontal polarisation will have the best potential for distance
contacts, but realise not everyone has a beam.

The nominal power will be 280mW from the handheld - no power
amplifier as yet and unlikely to get one sorted by the weekend. I
have plans for a Mitsubishi brick to give be 10 watts or more
eventually."

Regards, Mike G4BLH


Re: 24GHz

Richard Newstead <g3cwi@...>
 

--- In ukmicrowaves@yahoogroups.com, <JFELL@...> wrote:


Hi Sam,
In order to nail this issue I would (again) recommend everyone
adopts elevation control
I'm expecting to find depression control of use on shorter paths from
Snowdon on Sunday.

73

Richard
G3CWI


Re: Smith chart

G0ILO
 

some take things a bit too far ;-)

http://my.ece.ucsb.edu/sanabria/tattoo.html

Paul G0ILO.

--- In ukmicrowaves@yahoogroups.com, "Andy Talbot" <andy.g4jnt@...>
wrote:

A good quality PDF

http://www.printfreegraphpaper.com/gp/smith-a4.pdf


--
Andy G4JNT
www.scrbg.org/g4jnt


Smith chart

Andy Talbot <andy.g4jnt@...>
 


Re: 24GHz

JFELL@...
 

Hi Sam,
In order to nail this issue I would (again) recommend everyone adopts elevation control capability and use the facility to empirically deduce if it helps during LOS paths .
What you will gain is at least one very loud additional beacon at some time every 24hrs (don't forget to use smoky glasses ) , which is great to calibrate your system performance whithout the usual "is it them/he/she or mine ...?".
And there are other thingies out there for when your systems evolve into EME ones .
I have recently rediscovered the wheel on 5.7GHz and am very pleased with Rain scatter and aircraft reflections , both of which just love elevation .Near vertical is interesting at times.......
Talking of which I was looking at a waterfall display last Sunday evening at the QTH of Paul M0EYT showing the signals from a Jap Moon orbiting probe .
Paul's antenna consisted of a 1m WLAN mesh dish+dipole feed and the Moon end was apparently 5W to a patch - there is not much in the way though.....


Best 73

John
G0API/W


maplin dishes

geoffrey pike
 

This morning a mail shot from Maplin arrived with details of dishes suitable for 10 GHz i think,anyway they are
65cm order code A10FB at 20 and 90cm order code A11FB at 30 offset angle 24.6 deg
 
regards
Geoff Pike GI0GDP


Support the World Aids Awareness campaign this month with Yahoo! for Good


Re: Frequecy Shift Keying Crystals

Chris Bartram <yahoo@...>
 

Andy

A couple of quick comments on your email.

Firstly, the loaded Q of a crystal in an oscillator is largely a function of
the impedances around the crystal. Changing between a high Q crystal and a
poor one in an oscillator makes surprisingly little difference to QL unless
the oscillator is very good indeed.

If you had a good crystal and good oscillator at 100MHz, you could expect a
loaded Q of perhaps 50 - 60K. In practice, my simulations of various Butler
oscillator designs suggests that most have a loaded Q of between 3K and 20K.
That's borne-out by the way in which people have,in the past, successfully
FMed balloon board derivative oscillators. Don't forget that the original
balloon-board oscillator was designed to generate 50kHz shift FSK at 400MHz!
Before anyone accuses me of anything, I accept that there has been a lot of
development of that oscillator since the 1980s!

A 10s calculation suggests that the time-constant of a crystal in a good
oscillator is likely to be of the order of a couple of ms. Although that
might be worth adding as an extra term in the loop calculations, I don't
think that it's likely to explain your observations.

There's some stuff on my website
<www.christopherbartramrfdesign.com/blaenffos/indexgw4dgu.html> which might
be relevant. I also have the ability to measure oscillators in the modulation
domain, against a Rb reference, if you'd like me to look...

Vy 73

Chris
GW4DGU


Re: 24GHz (and 10G)

Richard Newstead <g3cwi@...>
 

--- In ukmicrowaves@yahoogroups.com, "M Vincent" <ukv@...> wrote:

I would go along with the prognosis that elevation is rarely
helpful,
Reading the comments makes me wonder if, with modern low-noise
systems, there is some subtle compromise between the ratio of ground
to sky within the aperture of the aerial?

73

Richard
G3CWI


Frequecy Shift Keying Crystals

Andy Talbot <andy.g4jnt@...>
 


Re: G3AUS Contact details

SAM JEWELL
 

OK Ray,
No problem.

Sam


Ray wrote:


Thanks...done and dusted.
Ray.

--- In ukmicrowaves@yahoogroups.com, "Ray" wrote:
>
>
> Marek SP4MPB needs G3AUS's contact details in order to confirm the
> contact made on 23cm in December.
> Please reply off-line if you can assist.
> 73 Ray
> GM4CXM at yahoo.co.uk
>



Re: G3AUS Contact details

SAM JEWELL
 

Hi Ray,
I'll try. Bob is somewhat of a recluse, it seems. I think I have his phone number, but that's about all.

Sam


Ray wrote:


Marek SP4MPB needs G3AUS's contact details in order to confirm the
contact made on 23cm in December.
Please reply off-line if you can assist.
73 Ray
GM4CXM at yahoo.co.uk




Re: 24GHz (and 10G)

Martyn G3UKV
 

GM
Very interesting stuff - especially your input Mike about R/H and temperature, and that table from Herstmonceaux.
I would go along with the prognosis that elevation is rarely helpful, if the required direction is clear. Taking the results of hundreds of QSOs on 10GHz, and scores of QSOs on 24GHz, I almost always arrive at the conclusion that I aim for the horizon whilst out portable, from an elevated (ie portable, hilltop) site. I do elevate half a degreee or so on 10G, but I have come to the conclusion this is 'squint' on my dish + feed. For almost all QSOs, except those at S9++, I always optimise azimuth & elevation, but the results are always the same - point to the horizon. The only exception has been when local rain scatter has been involved, and the distant station is locally obstructed, and of course the azimuth is not always a true bearing, due to other factors, such as rainscatter or hill reflections.
On 24G, I can't ever recall a QSO when elevation has improved signals whilst out portable.
 
However, from home, the situation is quite different. I'm surrounded by rising ground in most directions, mostly about 1 to 4 miles distant, and up to 350m higher than my QTH. Elevation of 1 <  3 deg. frequently makes a difference upto ~6 dB or more, and it relates directly to the local topography and/or rainscatter. With the advent of an effective Manchester bcn (GB3XGH), plus KBQ, CCX, SCX, CEM and now LEX,  I'm able to monitor several 10G beacons on a daily basis, in a range of directions and via a range of obstructions. On 24G I have GB3ZME just over the hill - and that has amazing rainscatter properties - I point all over the sky! . So the evidence is quite substantial.
 
In summary, my view is that it all depends where you are, and what surrounds your location.
 
Incidentally, GB3LEX (10G) is usually inaudible down here on the Shropshire plain, but last night  from late afternoon, it came out of the noise, and by about 19:30 it was S9+25 on my system, with only modest QSB. I had about 2 deg. elevation. Not quite sure what that proves HI ! (IO82RR57 to IO92 IQ66).
 
73  Martyn G3UKV
(a pragmatist...)
 

----- Original Message -----
Sent: Tuesday, February 19, 2008 6:17 PM
Subject: RE: [ukmicrowaves] 24GHz

The lower level air was probably condensing out the water vapour because the temperature was dropping. The "wet stuff" is liquid water, not water vapour. Air can hold very little water vapour below freezing temperatures which is how it can be humid yet dry.
 
As you know, signals launched towards the horizon don't go straight into space but tend to follow the curvature of the earth a little because of the refractivity gradient.Being on a hill will put the horizon further away which is good.
 
Elevation will certainly not help, it will send less energy at the horizon which is where you want it. When you transmit horizontally you have to imagine the ground falling away due to the earth curvature and the signals to some extent being bent downwards because the refractive index falls with height.  Elevation will cause more of your transmitted signal to go into space. True it will make the ground noise lower, but at 24GHz front ends are not low enough noise for that to matter very much.
 
Rare exceptions where elevation can help are coupling into elevated ducts, aircraft scatter and satellites - we can forget the ionosphere at 24GHz.
 
Last night we had a duct. Strong refractivity gradients lead to ducts. These can either be caused by anomalous variations in water vapour density, pressure or temperature. We all know all about these already (see http://www.mike-willis.com/Tutorial/PF6.htm ) . The difference at 24 GHz is the effect of the water vapour gas losses. Not only do you need a strong refractivity gradient to trap the energy but to avoid losing too much signal to gaseous losses you also need the air to be dry in the duct - which in our maritime climate needs for it to be cold.
 
Here are the observations for Herstmonceaux at 00 Z on 19th Feb - if Yahoo does not reformat them. Obviously a temperature inversion close to the ground but look at the line for 469m. Temperature drops suddenly and the water vapour concentration does unusual things too getting high then suddenly dropping. We have air of low refractive index near the ground, then higher then very sharply lower again. The effect is trapping the radio signals between the bottom of the temperature inversion and the  point were the humidity suddenly drops. 
------------------------------------------
   PRES   HGHT   TEMP   DWPT   RELH   MIXR 
   hPa     m      C      C      %    g/kg
------------------------------------------
 1024.0     52    1.4   -0.5     87   3.62
 1022.0     68    2.4    1.0     90   4.04
 1012.0    148    4.8    2.3     84   4.48
 1010.0    164    5.0    1.2     76   4.16
 1002.0    229    6.0   -3.0     52   3.07
 1000.0    245    6.2   -4.8     45   2.69
  998.0    261    6.2   -6.1     41   2.43
  997.0    270    6.2   -6.8     39   2.31
  988.0    344    6.0   -7.0     39   2.30  
  973.0    469    5.6   -3.4     52   3.07
  960.0    578    6.4  -14.6     21   1.29
  951.0    655    6.0  -15.0     21   1.26
  925.0    881    4.8  -16.2     20   1.17   
 
The humidity is around 50% and the temperature 6C. That gives a loss of around 0.1 dB per km at 24.048. Had this happened in the summer at 20C the loss would be 0.2 dB per km. Over a 150km path, we are looking at 15 dB vs 30 dB.
 
Mike


From: ukmicrowaves@yahoogroups.com [mailto:ukmicrowaves@yahoogroups.com] On Behalf Of SAM JEWELL
Sent: 19 February 2008 09:42
To: ukmicrowaves@yahoogroups.com
Subject: RE: [ukmicrowaves] 24GHz

Thanks Mike,
understand about relative humidity and temperature. The point I was trying to make is that at low level the air seemed to be very moist as evidenced by the wet on everything. Surely that is an indication of lots of water vapour in the lower levels? For stations like John G4BAO, and (maybe) myself, low elevations are a disadvantage in these conditions because we are beaming at the horizon and the signal has to travel through a considerable distance of this wet stuff before the earth curvature allows the signal out of it into dryer air? Or is a my reasoning wrong?
It would appear to me that a hill top home location will win out in these conditions.
It may also be a really good reason to have elevation on the dish as well, especially if you live in a low lying area.
I wonder what your thoughts are on this, Mike?
 
73 de Sam


"Willis, MJ (Michael! )" ac.uk> wrote:
Congratulations. Relative humidity is a function of temperature so even though the RH appeared high the water vapour concentration would not be. Gaseous loss on a 180km path at 24.048 would be about 17 dB at 70% RH and 1C. At 70% RH and 20C the loss would be nearer 50 dB.
 
That is why it works when cold.
 
Mike


From: ukmicrowaves@yahoogroups.com [mailto:ukmicrowaves@yahoogroups.com] On Behalf Of SAM JEWELL
Sent: 19 February 2008 09:09
To: ukmicrowaves@yahoogroups.com
Subject: [ukmicrowaves] 24GHz

Folks,
if ever there was any question about the effectiveness (or otherwise) of home to home on 24GHz, last night's burst of activity on the band should have put any doubts to rest.
Humidity levels were higher (in this area anyway) than the previous evening, with wet dripping off the trees and a damp feeling in the air. My RH meter showed ~60 - 70% RH.
I heard GB3FNM/B on 24048.906MHz for the first time (147km) at levels increasing to 57. G8KQW (179km) and I tried several times during the evening but apart from a few brief bursts of signal, no QSO. This path will go at some stage.
Signals over the 79km path to G4BAO in Cambridge produced only a weak, but workable, signal. G0EWN was a huge signal at 247km with an easy SSB at up to 58 - 59 at times from Gordon's 500mW!
G8APZ also worked Gordon for his ODX and Robin reported my signals as strong
 when trying with Ian and when workin! g Gordon. The path offset was over 30 degrees at this time. When beaming at each other the signals were also colossal.
I can only assume that although the lower levels of the atmosphere were nearly saturated, once the signal cleared those levels the air was much drier above and propagated the signals extremely well. At least in some directions.
Ducting on 24GHz seems to be confined a great deal more than on 10GHz, leading to very selective opens in certain directions.
I know there were a number of other contacts on 24GHz last night, but I'll let the participants comment for themselves.
A great evening on 24GHz!
 
73 de Sam