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Mistakes were made: SH289 help in Columbus, OH

5K views 21 replies 6 participants last post by  nikiml 
#1 ·
Hi all.

I need some assistance. I read a bunch and tried to go it alone but failed to cut the cord smoothly. Now I've got a house of people rooting for me but slowly becoming discouraged after a week with no television and an unusable living room full of cables and empty boxes and tools.


TL;DR: I need a UHF only antenna with good-excellent <20km and good-excellent 10-50km range that can pick up everything <50km facing SSW and one station 16km to the NNE, nearly 180degrees from the other stations.

I have a fairly decent looking tvfool map. @8ft (just above my TV set) & @25ft (just above my gutters)

I practically live under the antennae of abc, cbs, fox and nbc and could probably pick them up with my pants unzipped. There are also a number of local, local stations; various religion and foreign language focused as well as an indie or two which fall into the same category.

According to my tvfool report, my local pbs station (wosu/ch. 38) and cw affiliate (wwho ch.46), though more distant, are fairly powerful stations to which I have LOS.

I forgot to add that all of my local stations are UHF.

So, armed with the information above, I figured I'd only need a store bought cheapo antenna. I bought an RCA rabbit ear and loop combo and hooked it up to my recently acquired tivo hdxl.

Magic! Many stations came in with near 100% signal with the antenna set on a small shelf just above the tv. Except for wosu(38) and wwho(46). With a little movement of the small loop and with the rabbit ears fully extended, each nearly 45 degrees from vertical, don't know why the Vhf antenna played a role, but they did, I was able to pick up wwho(46) at about 75% and wosu(38) at about 60-65%. This was all done at night BTW.

The following day, wosu(38) was unwatchable, wavering between 0 and 75% often enough but hanging around 40-70% most of the time. The image was pixelated and full of drop outs along with the sound. The programs I had recorded for my kids were all unwatchable.

I scoured the internet for pay and diy solutions, came upon this forum, read a ton, studied the antenna decision chart and decided that my situation required the SH289 because of the bi-directional nature of my tvfool report as PBS, wosu(38) {an absolutely necessary station for familial harmony} was pretty near 180degrees from all the rest of my desired channels.

I built the SH289, or the close variant mentioned in this youtube vid and referenced by ota-canuk, out of 4 gauge copper grounding wire.

I built it for indoor use, hoping to mount it in my attic if it worked at ground level but found that it performed worse than the cheapo, but still not useful, rca rabbit/loop i bought.

Here are pictures of my build in an album with notations.

What did I do wrong that the rabbit/loop works better than the SH289 even when randomly placed anywhere in the room to compare performance?

Did I choose the wrong antenna to build?

Should I have chosen the SBGA instead?

I have an average of comparison numbers for each station with the two antennae at random points 8ft above ground level (excluding the position above the TV) if you think it would help. There were a lot more seesawing between a greater range of %'s with the SH289 [ie: 30-40 %age points with corresponding no picture at any point of the fluctuation]


The three most important averages are:


Strong major (avg.%) abc/cbs,etc.- El Cheapo Ant-96% || My SH289 87%

WOSU(38) PBS- El Cheapo Ant- 61 to 67% w/ constant dropouts || My SH289 0-40,50&60% seesawing w/ constant dropouts


WWHO(46) CW- El Cheapo Ant- 18% no pic || My SH289 0-20% seesawing, no pic

Thanks in advance,
Failhawk
 
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#4 ·
I built it for indoor use, hoping to mount it in my attic if it worked at ground level but found that it performed worse than the cheapo, but still not useful, rca rabbit/loop i bought
Good reason. At a 70 NM, youre just plain overloading. Just take a large paper clip and unbend it and stick it in your F connector on the back of the TV. It should work better than any of the antennas you tried so far.

A reflectorless SBGH could help if you have multipath problems, which is likely with very strong signals, but youre going to have to buy an attenuator to use with it.
 
#6 ·
At a 70 NM, youre just plain overloading. Just take a large paper clip and unbend it and stick it in your F connector on the back of the TV.
Assuming that you were not joking, I unbent a large paperclip and stuck it in the back of my TiVo.

It did nothing to solve the issues with the Specific channels I am having issues with. I also stripped an 8" piece of coax down to a single copper strand and stuck that in the back. That didn't work either.

I receive all of the 70 Nm channels without issue.

It is the 65NM channel WOSU (38) at 28degrees, situated 162degrees away from the 70NM channels, with which I am having issues.

I would also like to be able to receive WWHO (46) at 55NM but 25 miles further distant than my 70NM channels at 190degrees.
 
#7 ·
I receive all of the 70 Nm channels without issue.
Nope, I really wasn't kidding. But now I have an idea of the quality of your tuner, which looks to be pretty good.

I unbent a large paperclip and stuck it in the back of my TiVo.
Wait a minute, you were bypassing the TV tuner in that case ?


It is the 65NM channel WOSU (38) at 28degrees, situated 162degrees away from the 70NM channels, with which I am having issues.

I would also like to be able to receive WWHO (46) at 55NM but 25 miles further distant than my 70NM channels at 190degrees.
Heh, 25 miles LOS is really, really close in my world.

For simplicity, just build the original reflector less SBGH and aim it 38 or 46 and you should get both fine along with the strong 70NM channels, but I would strongly recommend getting a variable attenuator to fine tune the stronger channels.

The plans are here:
http://www.digitalhome.ca/ota/superantenna/design.htm

OMIT the reflectors on that plan.
 
#9 ·
Nope, I really wasn't kidding. But now I have an idea of the quality of your tuner, which looks to be pretty good.
I bought an older model Tivo. series 3 HD XL. mainly for the fact that it is supposed to have a rockin' OTA tuner.

Wait a minute, you were bypassing the TV tuner in that case ?
My TV is a Pro model :rolleyes: (meaning no TV tuner/No Speaker) panasonic plasma monitor. So, yes. All OTA goes through the TiVo.

Heh, 25 miles LOS is really, really close in my world.
Kinda why I thought this would be a piece of cake. That is why I am failhawk.

variable attenuator
This I will need to put in my learning cue. I understand from a quick wikipedia search that this is an anti-amp though I haven't the slightest idea how to use one or what type to purchase for this application.

Time to search this forum for answers... or, someone could point me in the right direction perhaps ;)
 
#8 ·
Failhawk,
You could make the Hourglass Antenna (called an Urban Commando on this site I think, see Holl_ands page athttp://imageevent.com/holl_ands/loops;jsessionid=oo8p3yxy71.goose_s and scroll down for Hourglass, or search my older posts) in less time than the SSH, and get better reception I think? It works well for me! Its small & DCb gain is better that the SSH (I do have an amp on it with a reflector, but with you in a strong signal environment with a need for 180 reception, so just get rid of the reflector, no amp.)
Try it! You could have great TV in 2 hours! Stick it in a second story window or attic.

Schoolbus
(ps I live in Oshawa and get stations from Buffalo and Toronto.)



Antenna Research & Development 2013-10-01, 12:35 AM
Replies: 368 Super Stealth Hawk (two Stealth Hawk#289 antennas combined)
Views: 99,921 Posted By schoolbus
Hello, Arent the numbers for the UHF hourglass...

Hello,
Arent the numbers for the UHF hourglass equal or better than the DCB gain for the SuperStealth Hawk? It had difficulty getting over 10 Dcb but the UHF hourglass is over 10.
 
#10 ·
Failhawk,
You could make the Hourglass Antenna (called an Urban Commando on this site I think, see Holl_ands page athttp://imageevent.com/holl_ands/loops;jsessionid=oo8p3yxy71.goose_s and scroll down for Hourglass, or search my older posts) in less time than the SSH, and get better reception I think? It works well for me! Its small & DCb gain is better that the SSH (I do have an amp on it with a reflector, but with you in a strong signal environment with a need for 180 reception, so just get rid of the reflector, no amp.)
Try it! You could have great TV in 2 hours! Stick it in a second story window or attic.
Am going to read your posts now.

It would be sad-funny if all I ever needed was a upended bow tie (this is what I am assuming the hourglass looks like).

I'm off to discover what it is.

Thanks
 
#11 ·
Time to search this forum for answers... or, someone could point me in the right direction perhaps
Also known as a Gain Adjuster etc.

http://www.solidsignal.com/pview.as...F-HD-Off-Air-Reception-1296F&sku=853748001293

Radio Shack has overpriced ones, but your best bet in OTA supplies is major supplier like Solid Signal or Summit Source. For extremely specialized stuff call Tinn Lee.

You could also go with a set of fixed attenuators, and then trial and error.

I understand from a quick wikipedia search that this is an anti-amp
What ??? All it does is knock the signal down, usually by way of a simple cheap resistor. An amp amplifies signals via a vacuum tube or transistor and power. Since an attenuator requires no power, it cant be considered an amp or an anti-amp. (except by unscrupulous marketing people, heh.)
 
#13 ·
it does the opposite of an amp. reduces a signal vs amplifying one
OK in that context, heh.

For an assortment of fixed attenuators, I would say 10 db, 20db and 30db with a 5db mixed in for a series attenuation. :)

Also, the reason Im suggesting the reflector less SBGH is not for gain, but for directivity. In other words, signals from the back and the front. The side signals should be powerful enough to come in on their own.
 
#14 ·
Im suggesting the reflector less SBGH is not for gain, but for directivity. In other words, signals from the back and the front. The side signals should be powerful enough to come in on their own.
There is basically nothing from the side or nothing I care about from the side.

Everything is about 6 miles from me at 190-199degrees and one at 30 miles at 190degrees. The outlier (and important to acquire) is 10 miles at 28degrees.

I can run rg6 coax from the tuner to the attic to get everything out of the way, about 25-30 ft run. Would that help attenuate the signal enough to render moot the need for a physical attenuator (the variable attenuator you linked is discontinued unfortunately)?

What about the hourglass design suggested by user 'schoolbus'? I don't know enough about signal reception to make sense of anything on the antenna design page he linked.
 
#15 ·
I can run rg6 coax from the tuner to the attic to get everything out of the way, about 25-30 ft run. Would that help attenuate the signal enough to render moot the need for a physical attenuator (the variable attenuator you linked is discontinued unfortunately)?
With RG-6 coax, you lose about 1 db every 18 feet at uhf frequencies. Do the math and do you have enough coax, heh ?

Umm, just search solid signal.

What about the hourglass design suggested by user 'schoolbus'? I don't know enough about signal reception to make sense of anything on the antenna design page he linked.
Today 10:36 PM
Yeah, he kind of messed up posting this time. We may all do that time to time, heh. (I have a tendency to screw up a lot)

But its a decent design, 3X more gain than you need.

With your strong signals, the main points are the reduction of signal and directivity to avoid multipath. Multipath in the old days was called "ghosting". Basically what it is is, is the signal coming in from two different directions at nearly the same time. Nearly the same time isn't good enough for TV tuners. For Sci-Fi fans, its a distortion in the time field, as your tuner sees it, heh. To minimize multipath, one treatment is directivity.

Please ask more questions if I used terminology you don't get. I realize I and others on this forum may be talking over the heads of some, but we certainly don't mean to.
 
#16 ·
With RG-6 coax, you loose about 1 db every 18 feet at uhf frequencies. Do the math and do you have enough coax, heh ?
I have a ton, but perhaps not nearly enough at 18:1. :)

Just how many db do I need to dump?

I'm assuming, again, that the attenuator is dumping dB across the entire spectrum of MHz not by, or adjustable to 6MHz chunks/per station.

How do I benefit from dumping dB to get a good signal from the 30 mile away tower when it is already too weak to tune in at 55NM of power and can't compete with the nearer 70NM stations?

Sorry if I'm being obtuse, RF stuff isn't my bailiwick. I'm just trying to turn my TV back on and get the channels in my city.
 
#17 ·
Just how many db do I need to dump?
That is determined by experimentation. That's why a variable attenuator is useful. One you know the attenuation, you can throw in a fixed attenuator.

have a ton, but perhaps not nearly enough at 18:1.
Give it a try, you never know until you do. :p

How do I benefit from dumping dB to get a good signal from the 30 mile away tower when it is already too weak to tune in at 55NM of power and can't compete with the nearer 70NM stations?
Its going to be a balance, hence experimentation.

Basically, like I said, you need to reduce gain and increase directivity towards the channels you want. There might be a fine balance there. I think its going to more of an art than a science.
 
#18 · (Edited)
failhawk: Try this low gain antenna 1/2 hentenna .

CM Experimental Antenna Design
CE 1/2Hentenna
GW 1 1 0 -0.25 0 0 0.25 0 0.025
GW 2 3 0 -0.25 0 0 -3.375 0 0.04
GW 3 3 0 0.25 0 0 3.375 0 0.04
GW 4 3 0 -3.375 0 0 -3.375 2.375 0.04

GW 6 3 0 3.375 0 0 3.375 2.375 0.04
GW 7 2 0 3.375 0 0 3.375 -1.25 0.04
GW 8 8 0 3.375 -1.25 0 -3.375 -1.25 0.04
GW 9 2 0 -3.375 -1.25 0 -3.375 0 0.04

GS 0 0 0.0254
GE 0
EK
LD 5 0 0 0 5.8e7 0
EX 0 1 1 0 1 0
GN -1
FR 0 1 0 0 584 0
XQ
EN

It is a U shape with the feed points 1.25" off the base. It is a 300 ohm design (needs balun) made from 12 gauge wire. The side is 3.625" and the base is 6.75".

Just tested this antenna. Look's like it should work for you. I have NM in the high 60's and
have a tall build to give me reflection. You should put 3 coils in the coax before the tuner.
This helps to stop the coax from becoming the antenna.
 
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