[MAMS] 24/47 GHz

[Lloyd Ellsworth]

Dave, Zack,

Don WW8M and I ran a pile of contacts, QSO's on 47 GHz. Various
distances, and paths. Wind effects on signals, were very noticable.
Especially on paths of say >10 miles. Many times, acting as a variable
attenuator to signals, as the wind changed. To a lesser extent, we saw
this on 24 GHz. Set up, was set up a fixed beacon, for a few hours,
and let it run. Watch, record the changes. Kind of fun to watch. More
watchable than most TV.

So yes. Have seen it, and would agree that it is more prominent on 47
GHz than 24 GHz. I would add, 47 GHz the signals seem to find more
things to reflect off of. To bounce off of than 24 GHz. 5/10 GHz I
would characteurize as being more forgiving with paths. Fringing,
refracting, vegatation and so forth. As well as finding all sorts of
things to reflect off of. 24 GHz, is not forgiving. Any vegetation,
forget it. 47 GHz, in between. We found sort of a what I would
describe as a wall at 45 miles, that took quite a bit to get past.
More power was the answer.

The SBMS mixer diode set up. About the best DX we have seen with
stations using that. About 2 KM. PS, that is a really good, quick way
to get on. Or make a beacon, for testing.

We noted a pile of observations, that we are still mulling over, and
trying to figure out.

In general, I would agree with the theory that if conditions, signals
are really good on 10 GHz, 24 GHz stands a good chance. Then the same
between 24 GHz and 47 GHz. However, not always. Don and I found times
and conditions, where 24 GHz was better than 10 GHz. And 47 GHz better
than 24 or 10 GHz. One of those situations, involved fog. Took a pile
of understanding and working with all this, to make our 2 VUCC's on 47
GHz happen.

Currently, working with Bob K2YAZ, to get him on 47 GHz. Currently has
a SBMS mixer diode.

On LO stability. What Don and I played around with, suggests that 47
GHz, you can still use a basic xtal with heater oscillator technology.
Yes, it will drift for 20 minutes or something, but will settle down
enough to be useable. Our best guess is that 78 GHz +, you will want
something better. More stable. 24 GHz. Max DX, has been about 120
miles. 47 GHz, Max DX has been about 70 miles. Over water. And yes it
was beyond LOS. On Lake Michigan.

Another observation. 24 GHz, using a 2 ft dish, is about the maximum
size dish you can practically aim. Bigger becomes just too difficult.
EG 3 ft. On 47 GHz, about 1 ft is it. Bigger is just too difficult to
aim. Even with a good solid telescope mechanical (Az El) mount.

73, Lloyd NE8I/r
EN74 etc

On Tue, May 10, 2011 at 2:35 PM, Dave Calvert <kb0pe at yahoo.com> wrote:
> Hi Zack,
> I was wondering how your 24 Gig project is coming along?  Also I am very
> interested in knowing if you had built up the W1GHZ 10 Gig beacon and re-tuned
> it for 12 Gig for a 24 Gig L.O.?  I wanted to know before I built up my boards
> for this project....  Kinda waiting to hear how the output level and stability
> compare to you first L.O.
>
> One question for the group is that although my 24 Gig operating time has been
> very limited, I did notice that when the wind would pick up out in front of the
> Dish, it almost sound like the wind would push the signal.  Especially when
> there was a lot of dust in the wind.  I am now thinking that the dust and wind
> was acting like a floating attenuator that would move in front of the Dish.  Has
> anyone experienced this to?  Is this more predominate on 47 Gig's?
>
>
> I was told that if 10 Gig's is good, so will 24 Gig's.  Also, if you can work
> each other on 10 Gig with the same amount of RF power and Dish gain on 24 gig's
> you will work the same distance?  If this is true Zack, we should be able to
> catch another 10 Gig opening and then try 24........  I do not have 10 Gig's at
> the moment but with the DEMI
> 3 watt amp, I was putting out a little under 2.5 watts with the 17 mW of drive
> from my old DEMI transverter.  My 24 Gig system is 2 watts but I have
> considerable more gain in the Dish than 10 Gig's.   What are some of the
> distances that have been achieved on 24 Gig's?
>
> 73,
> Dave
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