[Blowfly]

Hi,
Well, I have my new APT-06 up and running, and my antenna is in a temporary position as we speak.
I'll try to post a jpeg of today's exercise, and would love to get your opinions.
I have had a couple of failures, but this image is my 4th attempt, and it looks fairly reasonable. Having listened to the download, I've noticed a bit of 'static' and I lose some signal. It reflects in the completed image as a black, almost-solid line across the image.
This recording was from a NOAA which passed almost overhead.
I was using WXtoIMG with standard settings, except for colour and 'crop telemetry'.
Volume was set at 60 in the calibration.
Antenna was home-made to Darren's plans.
Antenna situated about 10 metres from RXer, using 15 metres of RG6 main lead to RX.
Antenna height is only about 3 metres from the ground, as I don't want it installed on the roof. At present, it's stuck in the pool fence held aloft with predominately 40mm pvc pipe.

[Spectre]

Good work... there'd be a little bit of movement on that pvc pipe mast but it turned out okay, did you incorporate an RX amp into your installation?

[Blowfly]

Good work... there'd be a little bit of movement on that pvc pipe mast but it turned out okay, did you incorporate an RX amp into your installation?

Hi, Spectre,
Thanks for your reply.
You're quite correct, the pipe was initially 25mm, but I've tried to beef it up with 40mm. Seems a fair bit more stable now, although in a bit of a breeze it still gets the wobbles up. Does movement of the antenna reflect in the quality of the image received? If so, and as soon as I can get a stable image, I'll change over to a metal mast.
Can you tell me what caused that black 'bar' across the image? On a couple of earlier recordings, the lines are even more frequent.
I don't have an amp or booster attached, either.
Thanks again
Blowfly

[VK4LHD]

That's not bad going at all in fact your about as close to perfect as you will get with the antenna down so low. Getting the antenna above the roof line will make all the difference but no matter how hard you try you will still get a bit of doppler drift (noise & signal loss) if you live in a built up or city area. Keep at it and the more you play with antenna position the better the image will get. If that was done without a pre amp you are doing very well. I could never get the images that good without the use of a pre amp.

[bodyguardnz]

thats pretty damn good, very well done
nothing there to worry about

[Blowfly]

Hi, guys,
Thank you for those kind words of encouragement, and I appreciate your advice.
I'll try to get a couple more images today and see if the last one wasn't a fluke.
Have a good weekend
Blowfly

[OldMarty]

Awesome effort, you've now inspired me to get into it too....

On another note, does antenna height off the ground really matter? as the satellite is above us, or at least at some sideward angle, for example living in perth and tracking a satellite over the east coast/NZ etc etc...

How narrow is the beamspread from the satellite anyway? i wouldn't expect the antenna would need to "track" the satellite unless it's a very narrow beamwidth????


Don't shoot me, i'm simply asking coz i don't know (at least i admit it lol) ;-)

[VK4LHD]

On another note, does antenna height off the ground really matter? as the satellite is above us, or at least at some sideward angle, for example living in perth and tracking a satellite over the east coast/NZ etc etc...

The height above the ground all depends on your surroundings. If you got a lot of buildings or trees around you then the higher the better but with height there is signal loss with long cable runs. You have to compromise a little with depending on your QTH and if you have a lot of high building around you then you only have the over head passes that will work well and not an eastern or western low angle pass.

With my QTH I have a lot of trees to the west of me and clear to the east so the only passes that work well for me are east and overhead passes. West passes work but are noisey. Using a Turnstyle antenna you don't need to track the satellite as it RX's on a 360 deg radius much like a vertical or a scanner discone. If you use a yagi then yes you have to track the satellite.

You don't need much to get started just a simple scanner and discone antenna will work but don't expect high quality images but. I was playing with one of those USB TV dongle things and using SDR sharp as the RXer and was getting some nice images with that. Simple $20 usb stick off flea bay and a Turnstyle antenna and you off and running. The good bit about using SDR is you can change the RX band width to offset the doppler effect.

[Blowfly]

Hi, guys,
Once again, I need your advice.
Since my first 'success', it's gone a fair bit downhill, particularly after today's modifications.
I've raised the antenna to about 4.5 metres AGL, still using PVC pipe which is affected a little by the wind...but not too much. Could this be a problem, and should the antenna be totally rigid?
I'm still using about 15 mtrs of RG6, but this time I have TWO joins in it. One is a small 6" flylead to connect the main cable to the BNC input on my receiver. Someone told me it was a good idea,,,save damaging the RX when hooking-up and removing cable frequently.
The other join is midway along the main cable. Do I have too many joins? And how do I waterproof any exposed joins?
I am using F-Connectors, screw-on type. Are these satisfactory, or could they be causing my problem? Also, is it ok to re-use these screw-on F-Connectors?
Sorry for all my questions, but I must confess it's starting to bug me a bit.
Thanks in advance,
Blowfly

[Blowfly]

Hi, guys,
Well, I'm going to buy a masthead amp to see if I can remove some of those black lines that are annoying me.
Question is, do I go for Darren's Poltec MH32, or one of the many Kingrays on offer?
Any recommendations appreciated.
Thanks
Blowfly

[VK4LHD]

Well you really got a couple of options. The tv mast head amp is really not built for the purpose of 137 mhz WX sat imaging but having said that Darren is having good success with his so I would use the exact same as he is using.
The other option and I think it would be the better choice is to get one of those Mini Kits pre amps. That way you have a pre amp that is purpose built for what your doing. I think Darren is only using a scanner as his RXer (corrrect me if I'm wrong here) so how the TV pre amp would work on your APT 06 I don't know. My pre amp is now over 20 year old and is a purpose build for the job by SCI SAT Products all that time ago. If your not good at building (soldering) kits then ask if they could build it for you. Might cost a few extra dollars but I think the mini kits pre amp is cheaper than a tv pre amp anyway.

[Blowfly]

Hi, VK4LHD,
Thanks for your reply.
I thought of the mini-kit preamp dedicated to 137MHz, but decided it would be too difficult to build. I believe they can be bought fully assembled, but another poster said he had difficulty in fitting the finished product. So that seemed all a bit too hard.
I note that the Poltec that Darren uses has a frequency range of 47-862 MHz. Some of the Kingray models have a VHF range of 44-230MHz, and my thoughts are that the Kingray may be more suitable for the 137MHz. This, of course, is based on the fact that I know absolutely nothing when it comes to frequencies, or indeed, anything in this field...LOL.
I really appreciate your advice, and I'll give it some more thought.
Cheers
Blowfly