WXSat proof of concept

[Archive-8]

@Analoguesat @Terryl do these figures look right for 137.500



If they our I have cut my wire to the wrong length

 

[Analoguesat]

The antenna isnt performing very well but Ive managed to get a partial picture. I dont think this is too bad for a first proper attempt

 

[Terryl]

@Analoguesat @Terryl do these figures look right for 137.500

View attachment 115932

If they our I have cut my wire to the wrong length

NO, the 1/4 wavelength for 137.5 MHz (center of the band we need to use) is 54.545 CM or 545.45 MM

http://www.onlineconversion.com/frequency_wavelength.htm

 

[Terryl]

The antenna isnt performing very well but Ive managed to get a partial picture. I dont think this is too bad for a first proper attempt

View attachment 115933

Not bad, the drop outs to the North and South are due to the directionality of the antenna, the "V" type antenna is directional, not much in the way as to an omni directional antenna for right hand or left hand circular polarized signals has been found to work right. (home brew stuff that is)

I'm looking at a design that looks like a barbers pole, (twisted dipole) will post results when it gets built.

 

[Terryl]

For your next pass try the antenna orientated 45 degrees diagonal to the ground and not horizontal.

 

[Analoguesat]

Not bad, the drop outs to the North and South are due to the directionality of the antenna, the "V" type antenna is directional, not much in the way as to an omni directional antenna for right hand or left hand circular polarized signals has been found to work right. (home brew stuff that is)

I'm looking at a design that looks like a barbers pole, (twisted dipole) will post results when it gets built.

The house is in the way to the north - the antenna is hard up against our south facing living room wall.

 

[Terryl]

Ahhh man, looks like your going to have to move the house.....Now I see why the dropouts to the N/S, can you raise it higher to clear the house??

 

[Terryl]

I have found out how to adjust my RF bandwidth on one of my hand held radios, but have to wait for an SMA to SO-239 cable to arrive, the antenna connection on my VX-5R is an SMA and the cable I had for it to connect to the mobile antenna on the car is fubar, so I will be awaiting on the post again.

This may take out some of the sparkles in the photos as some have a note at the bottom saying "IF bandwidth too narrow".

 

[Archive-8]

I have changed the coat hanger to twin and earth, I am still getting a dirty signal.

Listening to the wav file I can now hear the transmission, then it gets swamped with other “stuff”

 

[Analoguesat]

If you want the pretty coloured pics Chris change the wxtoimg settings so you are making extra formats during the processing phase.

Options - Auto processing options - tick create images - image settings - add in some of the enhancements.

You want the hvc ones highlighted. Some of them arent produced when illumination levels are low - so you only get the pretty "BBC Weather" type maps during the day. Then you find them in the saved images tab.

 

[Terryl]

What type/brand of coax are you using and how long???

You may need a pre-amp or a band pass filter or a combo of both, here is some info on that.

http://lna4all.blogspot.hr/2015/11/diy-137-mhz-wx-sat-bp-filter.html

 

[Terryl]

I'm lucky as I live out in the boonies, the only transmitters around here that can affect the WRX receivers are mine.

I have a 2 meter pre-amp that will cover the 132 MHz band, I may try it.

 

[Analoguesat]

Cable length is 2-3m of some unbranded sat coax stuff I found in the junk box. It came off the dish farm at the old place

There is some intermittent local interference - probably pager transmissions at a guess. I shall try to decode it at some point. Fortunately nothing has popped up on top of the 3 prime noaa frequencies yet.

 

[Archive-8]

I can’t join in, as I have discovered water poring in to my garage.

It’s dripping down the wall over a power socket. So for safety I have shut the garage power off.

Called a roofer for tomorrow morning.

So hopefully I can get it sorted quick.

I just don’t want to think about the bill coming my way

 

[Terryl]

Hummm that may be a problem as the normal receiver antenna impedance is about 50 ohms,(some can use 75) your loosing some signal strenght due to a mismatch, can you try some 50 ohm stuff, like RG-58 or what I used RG-8x.(RG-8 mini in your area)

https://www.radioworld.co.uk/rg8_mini_coax_100m_drum_of_mini-8_50_ohm_coaxial_cable?query=coax&page=3

 

[Analoguesat]

Mk 2 antenna built.

1 6ft broom handle type thing found in the back of the shed
1 chocbloc connector,
2 pieces of thickish garden wire for the antenna elements,
a longer piece of coax so I can just get it clear of the house. West passes are still going to have the house in the way on the northern part of the pass but east should be better.

This is completely experimental and will only be possible during reasonable weather as the elements will never survive a good Scottish gale - that improvement will come with a future mk 3. So now awaiting a couple of good passes to see what the improvement is

Once Ive found a reasonable design I shall relocate the antenna over onto the top of the dish supports well clear of the house

 

[Analoguesat]

Performing better already - this on a not particularly favourable pass - Max Elevation just 26 degrees, / 17E

Some interference blips by the looks of it but not bad. Not bad at all.

 

[Lazarus]

So, are we still due some snow tomorrow.

 

[Analoguesat]

Who do you think I am?? Michael Fish???

 

[Archive-8]