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Discussion Starter · #1 ·
In an effort to pull in WENH HD PBS station from my home in Boston, I have recently added a second antenna with a pre-amp and a jointenna to my roof.


I have my original 3021 antenna feeding into the B port of the jointenna, and my new 3023 feeding into a Channelmaster 7775 pre-amp which then feeds into the A port of the jointenna which has the DC pass.


The cable then travels from the jointenna into my home and through the pre-amp power supply to my Dish6000 receiver with OTA module.


I am able to pull in the OTA signals I have always been able to get through my original antenna *until* I plug in the pre-amp at which time the channels seem to pulse from around 50% to 0% and are unable to lock(where without the preamp plugged in, they come in very strongly -- over 90%)


With the pre-amp plugged in, I am able to get one channel I was not able to get before, but the channel I am aiming for pulses in a way similar to the channels above (no lock), only in this case there is no signal when the pre-amp is unplugged.


Any ideas?


Could the fact that the two antennas are on the same mast and very close together be playing into this?


Any thoughts at all are appreciated.




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Todd

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Did/can you try the preamp on the other side of the Jointenna? That is where mine is on my analog gear and it works great. My digital gear is a single antenna so I can't help much there.



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What do you mean by "preamp plugged in"? The preamp itself, or its power supply, or both? If you have both antennas, the jointenna, and the power supply installed, does the original antenna work?


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Todd,


Sounds like you are almost in business.


You should daisy chain from qantenna to pre-amp-powersupply BEFORE the jointenna. Jointenna should have "All channels" not from the pre-amp antenna and the 57 inserted from the new antenna powersuppy.


You will overamp the current good channels otherwise. I tried to pre-amp Needham from here (farther than Allston to Needham and had horrible effects. (I actually just put a UHF in parallel and everythiong worked fine).


I actually don't know if the ChannelMaster Pre-Amy comes in the two pieces as I have described. You can easily move the Jointenna inside (near power) with a longer run to the pre-amp (close to the antenna).


Tim

 

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Discussion Starter · #5 ·
Thanks for the great responses!


Barry, by "preamp plugged in" I mean the power supply. When the power supply is plugged in, I get pulses on the channels received by the original antenna. When the power supply is unplugged, it comes in as it did before the new antenna assembly et al.


Man E and Tim, Your suggestion seems to me to be a good next step. The Titan pre-amp does come in two parts and I think I can put the pre amp power supply on the other side of the jointenna pretty easily (fortunately, I have a spare length of coax running from the antennas inside!)


It makes sense to me that that would eliminate the pulses on the channels from the original antenna. I only hope that it somehow results in a strong steady signal from the WENH tower... I'll find out for sure tomorrow hopefully, but out of curiosity, is there any reason to expect this? How would the current arrangement result in pulsing signal on 57 WENH?



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[This message has been edited by tdemelle (edited 08-23-2001).]
 

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If you have the spre length of coax, that would be the best thing to do. That way, you only have the pre-amp on the weak channels, and the preamp DC supply is completely separated from the jointenna.


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Discussion Starter · #7 ·
Today's update:


This morning, I brought the jointenna inside and chained it between the power supply and the Dish6000 receiver. The setup goes like this now:


3023 antenna pointed at WENH tower-> pre-amp -> coax run into house -> power supply -> trunk A (dc pass) on 0538 jointenna -> OTA module in Dish6000 receiver


3021 antenna pointed at Needham tower -> coax run into house -> trunk B on 0538 jointenna -> OTA module in Dish6000 receiver


Unfortunately, when I plugged in the preamp, I had the same pulsing problems with the channels I get flawlessly from the Needham tower with the preamp unplugged.


I then called Stark Electronics who referred me to Channelmaster Tech Support. The gentleman at Channelmaster asked me what kind of joiner I had. I checked the case and saw that it is a 0538. He said those aren't very reliable for joining two UHF antennas and that I should get an 0585 tuned to channel 57. At that point I checked my notes which I used to place my order and saw that the joiner listed was the 0585. Somehow in the process of ordering from Stark, that must have gotten confused.


At any rate, before I order the 0585 tuned to 57, I'm going to see if I can get 57 without the jointenna in the mix. That will be tonight's project.


Thanks again for all the feedback!


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Todd

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Quote:
Originally posted by tdemelle:

At any rate, before I order the 0585 tuned to 57, I'm going to see if I can get 57 without the jointenna in the mix. That will be tonight's project.
Good idea. That way, you'll know if you can get away with using an A/B switch if the jointenna doesn't work.




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Concur.


Best way to troubleshoot is reduce variables. Only 57 pointing antenna plus pre-amp to receiver.


Note the signal has to be strong enough to "Add Digital" on Dish 6000 for it to even "take."


If it doesn't get added the signals not strong enough. Unfortunately there's a 57 analog out west which sometimes confuses STBs.


Tim
 

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Discussion Starter · #10 ·
With just the 3023 and the preamp, I am able to get a signal lock on 57, although this requires pointing the antenna several degrees west of where the tower should be in order to miss the tree which grows directly north of my roof.


Despite a signal lock with the signal in the 60% to 80% strength, I was only able to get 57-1 through 57-4 to add to the channel list one of several attempts and after failing to tune in (got the first vestiges of a high def image of the interior of a museum!) it removed itself. http://www.avsforum.com/ubb/frown.gif


In the Dishnetwork add DTV channel screen, when I'm tuning in and the signal is locked, the channel number at the bottom of the screen flashes intermittently between a bright green 57 and a dim 80. Any idea what this indicates?


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Todd

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Todd,


It means you are there, but here's adish specific oddity.


The signal (PBS National HD feed) is trying to map itself to 80, specifically 80-03 PBS1D. Here's the problem, the "Antenna" setting for the OTA module does not go to Channel 80 and the unit gets "confused."


Go into Menu/Systems Settings/Installation/HDTV Setup and change "Off-Air" to "Cable" and then add the station.


You'll be good to go and can add to Favorites.


Sounds like good progress.


Tim
 

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Quote:
Originally posted by rudolpht:
Todd,


It means you are there, but here's adish specific oddity.


The signal (PBS National HD feed) is trying to map itself to 80, specifically 80-03 PBS1D. Here's the problem, the "Antenna" setting for the OTA module does not go to Channel 80 and the unit gets "confused."


Go into Menu/Systems Settings/Installation/HDTV Setup and change "Off-Air" to "Cable" and then add the station.


Tim
Note that you can get all the digitals with the "Cable" settings, but you'll have to go back to "Off Air" to pick up the UHF analog channels.


This oddity was introduced by the recent update to the 6000, and they know about the problem. I've also emailed

the channel 11 engineer asking that they replace the virtual channel 80-xx (in this case with 11-xx) as several other PBS-stations have.


 

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Discussion Starter · #13 ·
Thanks for the felicitous insights! How this would be possible without your help I can not imagine. The AVSForum strikes again!


Hopefully at 7pm tonight I will be able to tune in PBS-HD... and then it's just a matter of working out the small matter of the joiner.


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Todd

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Discussion Starter · #14 ·
Welp, despite my best efforts last night and so far today, I have been unable to repeat my original signal lock on 57. I find it odd and a bit frustrating since it is a clear, windless day. Some other atmospheric conditions perhaps?


The signal I do get is an intermitent pulsing that hits a signal strength in the 50s and then back to 0 about every half second.


Seems to me that I'm *almost* there. Is there anything I can do to give me that little extra push over the edge? Aside from wait for the leaves to fall off the tree to the north of my home http://www.avsforum.com/ubb/smile.gif or for WENH to turn up the juice (any time frame on that?) or for GBH to enter the 21st century with the rest of us?


Also, can anyone elaborate on what causes that pulsing effect in the signal? That seems to me to be at the center of what I will need to resolve to finally get PBS-HD.


One nice thing that's come from all this is that I've readjusted my Dish satellites and improved their signal strength.


Any further help is as always, much appreciated!


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Todd

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Todd,


Was hoping you would have better news.


Have you tried adjusting azimuth as well as compass direction?


It took me 3 tries and a lot of walkie talkie @#$% with my wife at the STB to get a solid lock.


Tim
 

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Discussion Starter · #16 ·
Hi Tim,

I was hoping for better results too! (My g/f and I were on opposite ends of cordless phones after the off the hook tone subsided.)


I was pretty thorough in moving the antenna around. I fully expected to get a lock after getting one the other night. I rotated the antenna on its pole over a wide range, cutting out a big piece of pie in the direction of the WENH tower. (Aren't compass direction and azimuth the same thing?) At the strongest point and in the general direction in which I had initially achieved a lock, I got nothing but pulsing.


I figure at this point I can do 4 things:


1. try again

2. go get a map and a compass and be scientific about it

3. call Channelmaster and see if they have any voodoo they can apply

4. wait


I'll probably end up doing all four. http://www.avsforum.com/ubb/smile.gif


I'll keep y'all updated.




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Todd

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Todd,


I may be using the wrong term. Assume you have the antenna mounted horizontally level. I would play with elevating angle (I'm about 10 degrees up, but I believe in voodoo so it may be at best coincidental.


BTW I get 0 signal when they are not broadcasting.


Tim
 

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Todd,


Seems like you're trying to do all the right things here to try and get a little PBS HD.I've also went to great lengths to pick up an out of market PBS HD station.


I done some research on your location prior to responding,so correct me if I miscalculated anything.


The zip code for Allston is 02134.That would put you around 6mi.from some very high power stations.One of which is WLVI(CH-56) running an ERP of 2240Kw.The estimated field strength is almost 115dbu.WENH is around 57mi.at a FS of 47dbu.


Even though the signals are 125deg.off axis,WLVI could be overloading WENH,especially if you're using a pre-amp(adjacent-channel interference).This may be more of a factor than the tree.When you swing your antenna to the west it might be (nulling) out 56 as it would be closer to a 90deg.angle from it.


It would be interesting to hook up an analog tv, without the blue screen feature, to your antenna and see what's going on.


If this scenario is a possibility,there is one thing you might try.WENH is tansmitting circular polarization and WLVI is horizontal,which means you could turn the 3023 to a vertical axis,and possibly kill two birds with one stone.I may be "reaching here",but who knows.



Just some thoughts.I've certainly been wrong before!


Good Luck!


[This message has been edited by MAX HD (edited 08-26-2001).]
 

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Discussion Starter · #19 ·
Tim,


Went another round on the roof armed with your ideas. I had done a little playing with the elevation in my first attempts and unfortunately it doesn't seem to get me beyond the pulsing signal... how on earth I got a lock the other night, I do not know!


Max, thanks for going out of your way with your research. I actually moved from Allston to Brighton recently, but they're only about a mile apart so your issues would probably still apply. I don't know a lot about the physics of transmissions, and really enjoyed getting a little glimpse about the science of the situation from your post.


Anyway, I drilled a couple holes in the 3023 so I could u-bolt it vertically to the mast. Once it was up there however there was no signal at all. http://www.avsforum.com/ubb/frown.gif Great idea anyway. http://www.avsforum.com/ubb/smile.gif


If the pulsing is coming from adjacent channel interference, would a filter maybe help? Something which only allows channel 57 to pass down to the receiver? My sense is that that is what the jointenna is ideally supposed to do. I'm going to call Channelmaster tomorrow and see if they can make any suggestions.


Thanks again for helping me out. I'm actually having fun and learning a little something working on this problem.




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Todd

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Todd,


Had no idea you'd run right out and try that! I would probably have done the same.


The proper way to mount a vertical is to attach it to a non-metallic mast.Maybe3-4ft away from any vertical metal object that can re-radiate the RF signals.This may be something to try after consulting with a Tech at Channel Master.


RF signals propagate much better at night(usually).Sometimes to the the extent of interfering or completely wiping out nearby locals.


You've got the right antenna and pre-amp to reach the station you're after,as long as you have a decent line of sight and the antenna height is ~30ft,give or take a few feet.


Filtering adjacent channels is not easy and the Jointennas are not designed to do that.Special antenna arrays that naturally "null out" unwanted signals are normally used for that purpose.That's assuming,of course,your problem is Adjacent channel interference.


If you have an analog tv without blue-screen mute,look at the DT stations.The "snow" should be very similar on all the DT channels,including 57. If there's any lines or dark bands jumping around,you can bet there's an analog channel interfering.


Please post back after you talk to CM and let us know how things are going.


[This message has been edited by MAX HD (edited 08-26-2001).]
 
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