Elevating my Scantenna

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bep

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With the weather clearing, I have gathered everything I need to elevate my ST2 upwards of 10 feet. Currently receiving Virginia Beach, Va (P25 Phase 1 with a Pro-997) poorly. Sometimes it comes in and sometimes it does not. Thank goodness for feeds.

Several questions/comments:
Raising it is always a good thing, so I have hope (all I got)
Low and High band currently come in very well
Question - is the ST2 somewhat directional? If so I need to point it at the main transmitter site so what is the "front" of the antenna?
Question - What gauge of wire is needed to ground the antenna and can I connect to my Directv ground cable?

Any other suggestions, I am going this alone with only someone on the ground to call 911 should I bounce off the ground.

Thanks
 

bep

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Yes that is it.
But like I said currently is is not doing well on the 800 digital system, which is the one I really want to monitor. The high band Va. State PD system beams in great.
 

SkiBob

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I have found the Scantenna to be very directional. Some will say it's not, but the far outreaching freq's I try to reach just can't be heard if it's not pointing in that direction.

Another thing to consider is this thing is a beast. Make sure you have good guy wires.

I don't have any experience on ground wires.

Have fun and try not to bounce too high. I hear it's the 2nd bounce that hurts the most.
 

AuntEnvy

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I don't believe the ST2 is a good choice for 800.

If that is the primary signal you're attempting to receive, you're better off going with a yagi-specific model, or something akin to.

This antenna is great for VHF lo/hi and I've had great luck with it. Unfortunately, I seem to be in a reception void with the one I'm using now, so it almost seems like a waste to have it up. :(
 

rbm

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The ST2 is very much directional.

I've attached a screen capture of four simultaneous instances of SDRSharp tuned to the very same Satcom frequency.

I have four of my ST2's mounted N, S, E, and W.
(They're offset by about 15 degrees counter clockwise, so North is really pointed at around 345 degrees etc.)

You can see the very different response and if you just look at the narrowband transponders, you'll see more or fewer signals depending on where the antenna is pointing.

Don't use the signal strength between directions as any indication, only look at the relative strength of the transponders.

For example, in the top left image (West) you can see that the transponders to the left of the marked frequency are stronger than those to the right of the marker.

On the other antennas, those same transponders are lower or not even there.

When you get up to 800 MHz, I've found them to be spotty at best.
And that varies from one specific antenna to another. Even when pointed in the very same direction.
Some ST2's work somewhat OK at 800 MHz, others seem not to work well at all.
It may even have something to do with the balun. I don't know enough yet to say what causes it.

One of my projects for this summer is to find out why that's the case.
I want to try several styles/types of baluns and possibly even NO balun.

I also 'suspect' that the mechanical connections of the elements are not always making good contact.
There's just no way that corroded aluminum can make a good reliable, electrical connection.

So, I want to take an ST2 and use very small self tapping screws to make the connections of each element reliable.
That will take some time and experimentation.

Rich

 

Wally46

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OK so here is a stupid question. Do you aim the flat side of the antenna in the direction you want to hear or the skinny narrow end?
 

popnokick

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Wirelessly posted (Mozilla/5.0 (iPhone; CPU iPhone OS 7_0_4 like Mac OS X) AppleWebKit/537.51.1 (KHTML, like Gecko) Version/7.0 Mobile/11B554a Safari/9537.53)

I'm interested in the answer as well since I and others have asked the same question (Which way is the frontal directional lobe?) and gotten no answer from those who document the ST-2 as directional. Nice work proving that it is... But nada from anyone how to aim it.
 

rbm

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OK so here is a stupid question. Do you aim the flat side of the antenna in the direction you want to hear or the skinny narrow end?
At that specific frequency, the mounting boom points in the direction of the desired signal from the mast.

However, depending on the lobes at various frequencies, that may not always work for you.

To test mine, I mount them on a temporary mast about 10' off the ground and watch the results as I rotate the antenna around the mast.
That way, I can do my testing from the ground.

I 'suspect' that the mechanical connections on the antenna make and break over time and things can change.
They depend entirely on the interconnecting elements being held together by mechanical pressure and I don't think that's a good thing.
Especially with corroded aluminum.

Rich
 

SCPD

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You want a kick ---- antenna?get the Comet Gp15,its in a closet in the house and it works great!
i get 4 weather channels from different states,everything around NYC and NJ comes in perfect.
I hear both sides of simplex and aircraft comms.I had it up 20 feet on a chimney mount,was a slice of heaven.

Ground testing isnt gonna show you much,get the dam antenna over the roof!
 

bep

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Thanks all,
Since it is currently on the rood, however low, I believe it will be a quick check to get it up another 10 feet. Since I cannot receive 800 reliably, what do I have to loose. My signal bar suggests great reception, not the case.
I do have a yagi to try, but by ones self I cannot attempt at the is time.
Still confused as to the side of the antenna to "point" to the main transmitter.
 

WA0CBW

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A beam or yagi antenna is directional along the length of the boom. The front being the end with the shorter elements and the back being the end with the longer elements. The ST2 would be directional along the length of the boom but since the front and rear elements are symmetrical either end of the boom is the front. In other words it is bi- directional. Modeling the antenna shows it to be poor as either an omin-directional or directional antenna.
 

LIScanner101

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I've obsessed over what the elements can wreak on all the pressure connections between the fold-out elements on antennas like the ST2 or even the venerable Monitenna. It can't be good over time. My antennas are all in my attic, they all look new. One day I'll mount them outside but I'll probably add dozens of little sheet metal screws like rbm mentioned.
 

davenlr

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My signal bar suggests great reception, not the case.
.
You by any chance listening to a P25 simulcast site? If that is the case, you might be getting two sites at the same "good" strength at the same time on the same frequency. Raising the antenna might make that worse. Rotating the antenna around by 5 degree steps might find a "spot" that nulls out one of the sites allowing good reception on the other.
 

bep

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bep

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Thank you davenir,
I decided to rotate the antenna while a friend watched the "T". It is better than it was, but not great. I am sure raising the antenna is the answer, but with no help topside, it is going to be a challenge and I would rather do it at a warmer time.
However I have a 106 next to the 197 and the "T" on the 106 is definitely displaying much more than the 197. The 197 displays the "T" about once every other second while the 96 of for just a fraction of a second. Both radios have the antenna split so the same source. Additionally the signal bars on the 197 all but disappear for a moment where the 96 stay on all the time.
Do I have a receiver issue?
Thoughts?
 

davenlr

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How do they work when hooked up to the antenna individually? Might be a bad splitter where the two radios are interacting with each other. You also are losing 3db of gain running through a splitter, which if the signal is marginal, will cause even more problems.

If the radio(s) work well individually, then you might consider a amplified splitter (there is another thread on this site on using preamps and amplified splitters).

If you are indeed far out on the edge, and do not have any super close high powered transmitters (or cell sites), you might be able to use a mast mounted preamp. This would boost the signal and overcome your download (coax) losses as well as splitter losses. If going that route, pay attention to the noise figure (lower is better) and frequency range of the preamp (so it covers all the frequencies your scanner does).
 

bep

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Will give that a try. Must leave and do some bunny do lists right now :(

I do have an amplifier just inside the attic for the long run to the scanner. I am hogtied to only one antenna, so I do have it split serving several radios. It is not powered.

BUT the good news, with caution, the signal with the simple rotation is a vast improvement.

Thanks again

Will advise on the advise above later on.
 
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