11m sstv

[vlf2hf]

It's been awhile, but I thought I'd give 11m sstv a listen. I've recently revamped my rx antenna and wanted to see how it worked at the upper range of HF. So far, I've been pleased with its 10m performance. At 11:00 PM local time last night, I was seeing VK's decoding at -2db in the FT8 mode. That was a surprise at such a late hour.

Just a few hours ago, I set up the airspy HF+ D to listen on 27.700 mhz for sstv dx. I could hear faint sstv tones, most likely from the EU. I was pleasantly surprised to hear a couple stronger signals that decoded to these pics:

https://www.dropbox.com/s/xbk947o3ouv7sv0/9tc.jpg?dl=0

https://www.dropbox.com/s/3ddxkl88t0doqwd/birds.jpg?dl=0

Canada and Venezuela. The band is only in so-so condition, so I'm encouraged that the rx hardware seems to be up to the task of upper HF. It'll be nice to see what the sigs look like with a good band opening.

Ray... Texas



 

[RobRich]

Welcome to the HFU community. A 20' vertical is slightly longer than a halfwave vertical on 11m/10m, so it should do nicely for low-angle DX signal work.

Even better if you are using a transformer or similar to mitigate the huge impedance mismatch between the antenna and (assumed coaxial) feedline. A 49:1 or 64:1 would be "ideal" for around a halfwave, but even a 9:1 or 4:1 should suffice for receiving IMO, plus offer a much larger usable working range than a higher ratio.

I feed my 31' vertical over a radial field with a basic 4:1 unun, and it suffices for most reception from MW through HF. The angle of radiation is a little high at upper HF, but it still works decently enough that I rarely even bother swapping feedlines over to one of my 18' end-fed verticals.

[vlf2hf]

Thanks for the welcome RobRich. Sounds like you also have a good working vertical with the radial field under it. That's seems to be the way to go to get the most you can out of it. If you're not seeing enough difference to warrant the switch over to the shorter verticals, than it's doing just fine.

I have to do a bit of compromising as the location of the vertical is not conducive to putting in a radial system. I'm using a horizontally run counterpoise (#14  copper awg) that runs for approx.100 ft. ... about a foot off the ground. It's supported by a ranch type wire fence along the back yard. It's not electrically tied to earth ground or the fence wires.

I'm using a broadband transformer made up of two BN-73-202's glued end to end. I don't remember the turns ratio but it works out to be roughly a 49:1 impedance ratio. The transformer primary connects to 75 ohm cable to the shack.

It seems to do well from LF through 10m.

[ChrisSmolinski]

I received a few images yesterday as well, 11 mb half wave folded dipole up about 50 ft:

[vlf2hf]

Looking good Chris. I'd love to get a (rotatable) dipole up about 50 ft. or this vertical away from the powerline interference. My "monkey" decode of 9TC508 shows what the noise does to the pic. The noise blankers in the hdsdr software do the best they can, but sometimes they just get overwhelmed with the intensity. I suppose I could put up a loop to cancel the noise but at my age I find myself running out of patience and energy to deal with this. :-)

Still nice to see the sstv coming in on my first try in quite a while. Thanks for your comment to the post.