My own construction, 23dB gain, motorized aerial

hairybadger · Nov 5, 2013

mouse3 said:
Intresting antenna,jbx21 but very expensive there,one hundred pounds.
Here with post and package atx 91 its little over 40 euros,made in Poland.Hurricane and strong wind are not available in Transilvania.
It s the last think i want, replace each year antenna after storm season.Better i replace wife,it s free.

Transylvania must be the only part of the world where divorce doesn't cost an arm and a leg

Sounds like a gap in the market to me....

mikeisyou · Nov 5, 2013

hairybadger said:
Transylvania must be the only part of the world where divorce doesn't cost an arm and a leg Sounds like a gap in the market to me....

Too many vampires

battenfan · Dec 12, 2013

Does anybody know any clever tricks for making a practical wide band balun for UHF? Etching a pcb? I assume there's no suitable ferrite cores for this range. I have an old, fairly long yagi-ish antenna with unknown characteristics. The driving element looks something like: O_ _O Not quite a folded dipole. Maybe it's easier to buy an amp. Suggestions?

hairybadger said:
Hi - I understand how you calculate the length of the driven element, but how about the directors and reflectors? Idem for their shape. Is it a matter of educated guess and trial and error?

You might enjoy playing around with 4nec2 _http://www.qsl.net/4nec2/

battenfan · Dec 15, 2013

I'm guessing my antenna is closer to 75 than 300 ohm so I went for a simple 1:1 choke balun. I've tried an ugly coax coil in the past but I wasn't happy with how it behaved. The bifilar is from a flat-cable off a scraped computer. From the top of my head, the distance between the leads and the dielectric constant of the insulation makes its characteristic impedance close to 75 ohm. The coil's impedance at the lowest frequency should be >5 times higher than the antenna's. An one-layered air coil has its highest inductance when the length is 2-2.5 times larger the diameter.

I've probably overdone the number of wraps. I could have spaced them further apart. Nevertheless, at less than 2 meters off the ground pointing into trees in the rain, it has great reception at least up to channel 48, maybe 50 km from the transmitter of unknown power. Maybe I was just lucky. So many unknowns.

(Oh btw, 13MB pdf, but great read: _http://www.nonstopsystems.com/radio/balun-sevick.pdf )

battenfan · Dec 15, 2013

iggy said:
I am using LNA-177 30dB amplifier, mounted directly on dipole

Damn, they are cheap but the place I found them have a minimum order of €500. Does anybody know where else one can buy them or anything similar?

Tony1A · Jan 3, 2014

Cool thread!

battenfan · Jul 17, 2014

Why hasn't anybody told me about http://www.dvbtmap.eu/ ? It's basically "dishpointer" for terrestrial. The site might need some polish, I liked the android app more. Feature requests would include choosing closest transmitter farther than 30km as people in this thread have shown possible, and more detailed database informing on t/t2, mpeg2/mpeg4, scrambled/fta und so weiter.

timo_w2s · Jul 18, 2014

battenfan said:
Why hasn't anybody told me about http://www.dvbtmap.eu/ ? It's basically "dishpointer" for terrestrial. The site might need some polish, I liked the android app more. Feature requests would include choosing closest transmitter farther than 30km as people in this thread have shown possible, and more detailed database informing on t/t2, mpeg2/mpeg4, scrambled/fta und so weiter.

Thanks, useful site!

Archived-1 · Nov 15, 2014

Interesting thread, i need to install a TV aerial at home and have a brand new antenna rotator doing nothing, so I will put it to use,

I am quite high up at my location it will be interesting to see what I can get.

Channel Hopper · Nov 16, 2014

martin-f said:
Interesting thread, i need to install a TV aerial at home and have a brand new antenna rotator doing nothing, so I will put it to use,

I am quite high up at my location it will be interesting to see what I can get.

View attachment 69886

Grease everything in the rotor before installing with something that sticks, the cogs on those rot within a couple of years once the moisture sets in.

Archived-1 · Nov 16, 2014

Channel Hopper said:
Grease everything in the rotor before installing with something that sticks, the cogs on those rot within a couple of years once the moisture sets in.

Many thanks for the tip CH

.

Archived-1 · Dec 10, 2014

Advise please,

I don't want to go to the extreme of putting two aerials up H/V, would I be correct in saying i would be best putting the aerial up horizontal ?,

Also what would you advise me to buy with a good chance of some distant DX, I get a good discount from Blake aerials Sheffield if you could point me to one from there please,

I was thinking of getting the one below, i know there are some with bigger gain but a bigger price.
http://www.blake-uk.com/dmx-high-gain/175-dmx10-a-b-t-w.html

rolfw · Dec 11, 2014

Not a bad aerial, about par on gain and performance, used to use quite a lot of them.

Archived-1 · Dec 11, 2014

rolfw said:
Not a bad aerial, about par on gain and performance, used to use quite a lot of them.

Thank you Rolf, I will pop down and get one this morning.

rolfw · Dec 11, 2014

May also be worth buying yourself a filter against 4G whilst there if there are transmitter masts near you, can overwhelm digital signals at the top of the spectrum.

Here's an example from a couple of days ago, the mast was quite close though. The first picture shows spectrum with masthead still inline, second with masthead amp removed and third with no masthead and an LTE filter installed.

Archived-1 · Dec 11, 2014

Many thanks Rolf, I will pick one up whilst I am there, there is a few transmitters around Sheffield with all the hills, and its going on a motor so would be wise to fit one.

Archived-1 · Dec 11, 2014

Will any do please Rolf, also does it fit at the antenna end or indoors please.
http://www.blake-uk.com/110-lte-gsm-and-overlap-filters

Edit I can see it fits indoors

rolfw · Dec 11, 2014

Yes, in fact there are both masthead and internal types, masthead only required if fitting in front of an existing masthead amplifier. Most new mastheads have LTE filters built in.

Archived-1 · Dec 11, 2014

I've popped down and picked the bits up, i was so tempted to get JBX21A what a beast it is, but i ended up with the one in the link above, i also bought a wall/patio mount for the 1.2 dish, i need to keep away from these shops

,

I presume this filter will be ok for the job.

Captain Jack · Dec 11, 2014

martin-f said:
i also bought a wall/patio mount for the 1.2 dish

You're keeping your 1.2m in service?

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