HFU HF Underground

Loggings => 10/11 meters => Topic started by: ChrisSmolinski on November 14, 2013, 1550 UTC

Title: SSTV 27700 USB 1500 UTC 14 Nov 2013
Post by: ChrisSmolinski on November 14, 2013, 1550 UTC
Starting to roll in. I'll try to post some of the better pics later.
Title: Re: SSTV 27700 USB 1500 UTC 14 Nov 2013
Post by: Sealord on November 14, 2013, 1604 UTC
(http://i761.photobucket.com/albums/xx256/Sealord40m/201311141600_zpsdacfe9df.jpg)
(http://i761.photobucket.com/albums/xx256/Sealord40m/201311141606_zps71b10c77.jpg)
(http://i761.photobucket.com/albums/xx256/Sealord40m/201311141646_zps10e9cd90.jpg)
Title: Re: SSTV 27700 USB 1500 UTC 14 Nov 2013
Post by: Capt. Radio on November 14, 2013, 1853 UTC

Sealord,

In reference to your images, it's interesting to see the difference in signal levels at any given time between two localities. Here's the view from Indiana on two of the pics you have posted. As you will notice, one of my images is clearer than yours, the other is poorer.

Title: Re: SSTV 27700 USB 1500 UTC 14 Nov 2013
Post by: Sealord on November 14, 2013, 2136 UTC
Hi Capt. Radio - I don't see any images in your post?
Title: Re: SSTV 27700 USB 1500 UTC 14 Nov 2013
Post by: ChrisSmolinski on November 14, 2013, 2147 UTC
I copied the same pictures here, but worse quality. The 670 ft sky loop isn't great on 11 meters, where it is 19 wavelengths long.
Title: Re: SSTV 27700 USB 1500 UTC 14 Nov 2013
Post by: Capt. Radio on November 15, 2013, 0000 UTC

Sealord,

I can't explain why you don't see images from my post. I assume Chris sees them, as he didn't mention he couldn't.

Chris... It's entirely possible and likely that the skyloop is much too directional at the higher HF freqs. The gain must be tremendous at 11 meters (at some compass point), but the penalty for that gain is extreme directivity of the pattern. Unless the 11 meter signal you wish to copy is exactly in line with the pattern lobe(s) of the loop, little signal will be delivered to the receiver. (IMHO). 
Title: Re: SSTV 27700 USB 1500 UTC 14 Nov 2013
Post by: Sealord on November 15, 2013, 0007 UTC
Ah, it's Firefox - I opened the thread with IE and can see them that way.  Yep, nice capture on the Azteca SSTV CR :)
Title: Re: SSTV 27700 USB 1500 UTC 14 Nov 2013
Post by: Capt. Radio on November 15, 2013, 0111 UTC

Yea, some browsers have peculiarities that have to be addressed with careful checks of settings.

BTW, I caught that Scotland pic also, but it wasn't nearly as good as yours. In fact, I couldn't clearly make out the call enough to know it was indeed Scotland.

I seem to have a pretty good path to Mexico, here in Indiana. I seem to get some pretty nice scans from there. This morning there was a good number of them, but I didn't post them because they were "so-so".

It seems that everyday the band is open, mornings bring the French stations to me. Most of them have noise in the image unless the band is exceptional.

On another note, do you have any idea why my posted scans seem to be smaller in size than yours or Chris's? I'm not an expert at posting pics on forums.
Title: Re: SSTV 27700 USB 1500 UTC 14 Nov 2013
Post by: Sealord on November 15, 2013, 0155 UTC
On another note, do you have any idea why my posted scans seem to be smaller in size than yours or Chris's? I'm not an expert at posting pics on forums.

I use an image hosting site like Photobucket for my SSTV images & whatnot, then add the links along with my info in my posts using SMF Bulletin Board Code here (http://www.hfunderground.com/board/index.php?action=help;page=post/) (listed under the posting section) - the images are probably bigger since the hosting site displays the full SSTV 320x256 size.
Title: Re: SSTV 27700 USB 1500 UTC 14 Nov 2013
Post by: Capt. Radio on November 15, 2013, 0206 UTC

Thanks for the info on posting the pics Sealord. I though that I was doing something wrong when setting up my posts.
Title: Re: SSTV 27700 USB 1500 UTC 14 Nov 2013
Post by: ChrisSmolinski on November 15, 2013, 1417 UTC

Thanks for the info on posting the pics Sealord. I though that I was doing something wrong when setting up my posts.

I'm not exactly sure why, but you seem to be posting them as attachments? I upload them to a website and then provide the URL in the message. That could be the difference.

Title: Re: SSTV 27700 USB 1500 UTC 14 Nov 2013
Post by: Capt. Radio on November 15, 2013, 1444 UTC

Chris,

I took Sealord's example and have created a photobucket account for a future postings of images.

Thanks for looking into the problem.
Title: Re: SSTV 27700 USB 1500 UTC 14 Nov 2013
Post by: ChrisSmolinski on November 15, 2013, 1716 UTC
Chris... It's entirely possible and likely that the skyloop is much too directional at the higher HF freqs. The gain must be tremendous at 11 meters (at some compass point), but the penalty for that gain is extreme directivity of the pattern. Unless the 11 meter signal you wish to copy is exactly in line with the pattern lobe(s) of the loop, little signal will be delivered to the receiver. (IMHO). 

Yes, from some modeling I've done, the loop has lots of peaks and nulls in various directions. Fiddling with the geometry (making small changes to the dimensions and locations of the wires) causes use differences in these, telling me that there's no way to accurately model how the antenna is actually behaving (since I can't measure the wire geometry accurately enough, and it probably changes enough with the wind to cause significant errors in the model output). So I don't think I can really adjust it for any desired characteristics. That said, it generally works well over all of HF and the upper half of MW. So it's a keeper.

For fun I just tried my Radio Shack VHF scanner antenna at 27700, and wasn't hearing anything.