DX'n Forum

[smdp1]

Originally Posted by alphanguy

You wrote Columbia probably cause I've been blabbering about Columbia, Mo... I've been doing research and calculations tonight, and found that the station I'm aiming for has a transmitter height of 1,876 feet above sea level, while my house is 850 above sea level. At 80 miles away, I don't see why I shouldn't be able to get this. All I have to do now is calculate the curvature of the earth.

Tvfool will tell you if you can hit line of sight or even tropospheric scatter if you run your numbers on it. It will tell you what the signal level in the air should be which you can use to tell if you have chance....and I receive stuff it lists as -127db with no problem and its nowhere near line of sight....its listed as the worst which is tropospheric scatter.....hope this helps....it sure saved me some calculations.

[smdp1]

I saw this in another thread and thought that it had some useful info to people who might be looking around here

Originally Posted by otaota

The biggest challenge for many DX situations is keeping down closer / stronger co-channel and adjacent-channel interference. At those ranges, you are subject to channel re-use problems and need to be smart about antenna pattern tweaking / aiming.

Changing amps might get you an additional dB or two out of a particular setup, but using a carefully thought out antenna array will increase gain and squash local interference sources, resulting in a net improvement of multiple dBs of SNR.

For amps with noise figures below about 3 dB, the price/performance ratio starts to ramp up quickly. You'll have to decide if the increased cost is worth the diminishing returns. You could spend the money on antennas instead. You'll gain almost 3 dB of signal every time you double the number of antennas you gang together, and that's more improvement than you'll ever see out of an amp substitution.

Cheers,

This reminds me of what my mechanic said "you can put all the boost you want to in these little engines, but when it comes down to it there is no replacement for displacement" What I am saying is that a pre-amp is no substitute for a "large" properly made antenna or array of antennas...you have to have a good signal for the amp to pick up or you end up boosting noise.....Hope otaota doesn't mind me reposting this here...

[alphanguy]

I agree with that asessment. Part of my problem could very well be my Radio Shack amp, I've heard everyone and his brother on the net talk about how it has high noise. I've not heard this avalanche of bad comments on their antennas, though....and rightfuly so, theyv'e not been bad performers for me, but I know there is something else out there better. I'm going to change my antenna location as well, which will cut my cable run from 70' to 35', couple that with a low noise UHF only amp , RG-11, and the XG-91, and I should have something a great deal better than what I have now. Your success with that XG-91 has given me hope, and I've read MANY good things about it many other places on the net. This will be the first time I'm using a UHF only, as I've always had combos, an apparently that makes quite a difference according to everyone. And realistically, I don't worry about overloading because at TVfool, I don't come up with LOS on ANY station (Which doesn't surprise me) Now if this setup will pull in digital signal from KMIZ that is 78 miles out, I can completely abandon VHF, and I'll be doing a happy dance.

[Rick0725]

Here is a broadcast quality UHF preamp, 20 DB gain and .5DB noise temp. Model PA-20U-75 $499.

http://www.tonercable.com/Product.aspx?ID=1615

[Midwest Dxer]

Originally Posted by alphanguy

I agree with that asessment. Part of my problem could very well be my Radio Shack amp, I've heard everyone and his brother on the net talk about how it has high noise. I've not heard this avalanche of bad comments on their antennas, though....and rightfuly so, theyv'e not been bad performers for me, but I know there is something else out there better. I'm going to change my antenna location as well, which will cut my cable run from 70' to 35', couple that with a low noise UHF only amp , RG-11, and the XG-91, and I should have something a great deal better than what I have now. Your success with that XG-91 has given me hope, and I've read MANY good things about it many other places on the net. This will be the first time I'm using a UHF only, as I've always had combos, an apparently that makes quite a difference according to everyone. And realistically, I don't worry about overloading because at TVfool, I don't come up with LOS on ANY station (Which doesn't surprise me) Now if this setup will pull in digital signal from KMIZ that is 78 miles out, I can completely abandon VHF, and I'll be doing a happy dance.

KMIZ DT-22 might be a stretch at that distance.They're on a 1000ft stick with a directional favoring the NE.Ya never know though,you might get lucky.A large Band A,or two,or even four like I use would help.Here's a gain chart comparison.

http://alpha.future.ee/triax_unix.png

[smdp1]

Originally Posted by alphanguy

I agree with that asessment. Part of my problem could very well be my Radio Shack amp, I've heard everyone and his brother on the net talk about how it has high noise. I've not heard this avalanche of bad comments on their antennas, though....and rightfuly so, theyv'e not been bad performers for me, but I know there is something else out there better. I'm going to change my antenna location as well, which will cut my cable run from 70' to 35', couple that with a low noise UHF only amp , RG-11, and the XG-91, and I should have something a great deal better than what I have now. Your success with that XG-91 has given me hope, and I've read MANY good things about it many other places on the net. This will be the first time I'm using a UHF only, as I've always had combos, an apparently that makes quite a difference according to everyone. And realistically, I don't worry about overloading because at TVfool, I don't come up with LOS on ANY station (Which doesn't surprise me) Now if this setup will pull in digital signal from KMIZ that is 78 miles out, I can completely abandon VHF, and I'll be doing a happy dance.

I agree with midwest dxer on the maybe 2 or 4 bit...I got to looking at your situation and the KMIZ looks like it is a bit weak on the height side of things and therefore will be harder to get.....you might even consider a 32 bay like the one picture here...it can be constructed out of 4 cm4228's with a little work....either that or stack some xg91s or something similar like midwest dxer showed. I don't really know which one would offer the best chance of success, so if someone else knows please do tell.

here is a 32 bay that someone rigged on two masts....a little engineering and this could easily be adapted to one mast.....I am not sure how the best way to match them up to one piece of coax, but I'm sure someone here could help with the matching on what ever you decided to setup....
http://www.hdtvprimer.com/ANTENNAS/32bay.html

[smdp1]

Originally Posted by Rick0725

Here is a broadcast quality UHF preamp, 20 DB gain and .5DB noise temp. Model PA-20U-75 $499.

http://www.tonercable.com/Product.aspx?ID=1615

when I was considering going uhf only, I looked at a similar amp at a higher price than this, but because some of my stations are going back to vhf for their digital I couldn't go all uhf and therefore couldn't use this amp without introducing split lines down from the antennas and I didn't want to do that so I ended up going with the titan, but if anyone is going uhf only...this amp would be great I believe....very expensive, but great.

[Rick0725]

Use separate amps for uhf and and vhf antennas. You would be able to filter separately and match gain to your needs.

I did that here and performance was better than with just one. use 3 antennas and 3 HDP-269 preamps...43xg, 91xg, 8200p for vhf

That 32 bay is way too friggin heavy...ridiculous.

[alphanguy]

Midwest DX'er I'm still looking over your site, you got an awesome setup there. I'm definately going with the XG-91, but 4 is something I'm not willing to go for. However... I can handle 2, I've done a a little searching on this forum and others, and some people didn't have much luck with stacking the XG-91 vertically, so I guess horizontally would be best? I read somewhere it needs to be 44 inches apart? And the downleads of equal length... right?

[rockstar08]

Tonight, I'm getting snowy analog signals of two stations in Salisbury, MD - over 110 air miles away - WMDT 47 and WBOC 16. No luck with their digitals though.

[smdp1]

Originally Posted by Rick0725

Use separate amps for uhf and and vhf antennas. You would be able to filter separately and match gain to your needs.

I did that here and performance was better than with just one. use 3 antennas and 3 HDP-269 preamps...43xg, 91xg, 8200p for vhf

That 32 bay is way too friggin heavy...ridiculous.

yeah...I imagine a 32 bay would be heavy...lol

I wasn't sure how to hook up separate amps and since I was on somewhat of a fixed budget with the project, I couldn't get the nice amp and a good vhf at the same time....actually the nice amp by itself would have eat up most of my budget.....how much difference does the .5 db noise figure make over the titan 7777s 2 db? I might wish I had waited till after Christmas when I could spare a little more $

[smdp1]

Originally Posted by rockstar08

Tonight, I'm getting snowy analog signals of two stations in Salisbury, MD - over 110 air miles away - WMDT 47 and WBOC 16. No luck with their digitals though.

what kind antenna(s) do you have?....just curious.

[Rick0725]

Originally Posted by smdp1

I wasn't sure how to hook up separate amps

-Use RG11 Coax for added perfomance

-Install separate preamp units for each antenna on the mast. You can select the amps appropriate for your needs for each band. Different gain, different noise temp, etc.

For example. You can install the .5 db amp mentioned above for uhf and use your CM7777 for vhf with the switch set to separate, the vhf antenna to the vhf port and the uhf port terminated and not used. or you can purchase a higher performing amp made specifically for vhf.

-Run separate Coax from each antenna to each Preamp module.

-Run separate coax to each power inserter

-Combine the TV out signal of each amp (separately amplified VHF and UHF) with a UVSJ VHF/UHF combiner.

-Common out of the UVSJ to standard splitters to tuners

[smdp1]

Originally Posted by Rick0725

-Use RG11 Coax for added perfomance

-Install separate preamp units for each antenna on the mast. You can select the amps appropriate for your needs for each band. Different gain, different noise temp, etc.

For example. You can install the .5 db amp mentioned above for uhf and use your CM7777 for vhf with the switch set to separate, the vhf antenna to the vhf port and the uhf port terminated and not used. or you can purchase a higher performing amp made specifically for vhf.

-Run separate Coax from each antenna to each Preamp module.

-Run separate coax to each power inserter

-Combine the TV out signal of each amp (separately amplified VHF and UHF) with a UVSJ VHF/UHF combiner.

-Common out of the UVSJ to standard splitters to tuners

Cool....when I have to climb the tower again I'll consider doing that if money will allow, but until I have a good excuse for going back up there I'll just use what I have ...Thanks.

[Midwest Dxer]

Originally Posted by alphanguy

Midwest DX'er I'm still looking over your site, you got an awesome setup there. I'm definately going with the XG-91, but 4 is something I'm not willing to go for. However... I can handle 2, I've done a a little searching on this forum and others, and some people didn't have much luck with stacking the XG-91 vertically, so I guess horizontally would be best? I read somewhere it needs to be 44 inches apart? And the downleads of equal length... right?

Nothing wrong with a vertical,and it's obviously easier.Anywhere between 3-4ft will work fine with either configuration.A good quality outdoor type splitter/combiner(CM 0538 or equiv) and equal length feed lines and you're set to go.My favorite splitter for a dual UHF stack is the T-shaped cheapies,for the cleanest look on the cables.I normally use Schedule 40 Aluminum pipe,either 1" or 1-1/4" nominal and have it welded up by a local fabricator into a "goalpost" stacking bar.Galvanized pipe/fittings can also be used,or a straight fiberglass tube(1-1/4") run through a large pipe Tee.
Oh,I forgot to mention another setup which will work even better,especially on the lower channels up to 38,is to use a Triax unix 100A and a Wideband coupled by a Triax A/E combiner,then fed to a preamp.I've used this setup and it's killer for complete UHF coverage.The big Band A is King for lower UHF channels..bar none.Costwise,with the lousy conversion rates,is around $258 shipped for all three pieces.