AVS Forum banner

Status
Not open for further replies.
1 - 20 of 24 Posts

·
Registered
Joined
·
1,897 Posts
Discussion Starter · #1 ·
Schad electronics on 1st street in San Jose has a large stock of Winegard CC3613 antennas for KNTV Channel 12. Priced at $19.95 they are a bargain. This is a Channel 11-13 only VHF antenna with 6 elements. They are currently backordered on the 10 element version. They also have the couplers for coupling UHF and VHF antennas but they indicated that the nice Channel Master trap couplers have been discontinued the builtin traps are to reject channel 12 from the UHF antenna and bandpass it on the VHF side. A 6 element Yagi ought to have around 10 db of gain.


..Doyle
 

·
Registered
Joined
·
189 Posts
Good information Doyle,


There are a lot of folks having the NBC DTV problem in the Bay Area. I'm glad that Schad is on top of the problem. I'm sorry to hear that the band pass/reject filters have been discontinued. Given that we have digital broadcasting from three different directions I expect Schad will be selling a few rotators too. I finally bit the bullet and put up a rotator. I can actually reveive NBC off the back of my VHF antenna when pointed at 333 degrees in Palo Alto so do not move the antenna much for all but ch36.


Don Cone
 

·
Registered
Joined
·
1,897 Posts
Discussion Starter · #3 ·
I went home Friday night and installed the 6 element Channel 11-13 antenna along with the UHF/VHF combiner on the roof of my 2 story Sunnyvale house. Unfortunately, it made no difference in my signal from KNTV 12. I still get an instantaneous freeze and catchup which I call a judder or stutter in the video. Previous reports of this seemed to indicate that most people are not seeing this with Channel 12. All of the Sutro tower stations come in perfectly. I am convinced that there is something different about the KNTV signal. I am using a Unity Motion receiver HD1000A which has worked faultlessly for years.


I have tried deleting the channel and reinstalling it but that didn't make a difference. I thought it was a signal strength problem and that is why I added the VHF antenna. Previously I was receiving the signal off of the back of the UHF antenna and the signal had no pixelization or dropouts, only the judder every 3-5 seconds.


Does anyone have any ideas as to what could be causing this or is anyone else seeing a problem with KNTV 11?


..Doyle
 

·
Registered
Joined
·
1,100 Posts
Doyle,


Have you tired just the channel 11-13 antenna by itself - without the joiner or main antenna? Make sure you are pointing the small end at Loma Preita. Also, what STB are you using? Have you tried any other STB?
 

·
Registered
Joined
·
1,897 Posts
Discussion Starter · #5 ·
The antenna is pointed in the right direction. Interesting that I saw no difference between using the UHF antenna only or using the combination of UHF and VHF. I haven't tried the VHF alone without the combiner. I will give that a try but I have a feeling it is something with respect to my stb and what they are transmitting. I am using a Unity Motion HD1000A which has worked faultlessly for a couple years. My only complaint is that it does not give a signal strength indication so I don't have a relative measure of the various antennas, only the image to view on the set. I will try a few more experiments tonight. Not sure what to make of it.

I have not tried other stbs. I haven't been able to talk my neighbor into buying one yet.


Thanks for the suggestions,


Doyle
 

·
Registered
Joined
·
189 Posts
Doyle,


I have had no trouble with NBC with several combinations of antennas. I have received it solid off the back of an UHF bowtie. I am now receiving it off the back of my VHF/UHF antenna when pointed at 333 degrees from Palo Alto. Of course it is also solid when I rotate the antenna to 11-1. There are never any drop outs. I would also suggest you test with the VHF antenna only. Your problem maybe in combining the two antennas. It is not always easy.


Don Cone
 

·
Registered
Joined
·
121 Posts
Doyle,


When you do the solo test on the VHF antenna, try it with an attenuator also.


I have the same antenna hooked up to a CM7777 pre-amp. However, if I connect my HDTV directly to the pre-amp, the signal-strength meter shows about 20% less than if I put a 4-way splitter in between. This splitter cuts the signal by 7.4db, and my HDTV likes it better.


BTW, I live 55+ miles away from the KNTV-12 transmitter and have over 100' of cable run.
 

·
Registered
Joined
·
1,034 Posts
I guess I went for, maybe, unnecessarily expensive antenna, but this was my first experience with a outdoor antenna, and what did I know without much research...


Anyway, what I've just installed (this morning, in fact) is Terk HDTV60 on a 10' poll on a single-story house roof. I live in San Jose, so maybe that's why, but I had it point to Sutro since all but one digital signals (KNTV) come from there. However, it also worked extremely well (maybe the best) for KNTV (both analog and digital) so much so that even my antenna installer was surprised. The reception on other analog channels were sub-par though.


BTW, is KBHK-DT (UPN) off during the day? I noticed that it was the only one that didn't have any signal (or one that the antenna didn't pick up).


Hong.
 

·
Registered
Joined
·
1,897 Posts
Discussion Starter · #9 ·
Well, with the last 3 posts, I am even more convinced that it is not a signal strength problem. The antenna is aimed right at Loma Prieta. Antennas are kind of my thing having been a ham for over 30 years. I put up the VHF antenna to eliminate that as a possible problem although I was pretty well convinced there is something different about KNTVs signal. I will try taking out the combiner just to be thorough in my analysis. I was hoping to hear from someone who had a Unity Motion receiver to see if they have a similiar problem.


..Doyle
 

·
Registered
Joined
·
189 Posts
Hang in there Doyle!


There is nothing wrong with the NBC proadcast. Get down to basics. One narrow band VHF antenna and your STB. If there is still a problem add attenuation and try again.


If that fails, it is time to scrounge another STB to try.


Don Cone
 

·
Registered
Joined
·
1,034 Posts
I guess I spoke too soon.


Last evening when I went home, the signal strength was very weak for most from the Sutro. KNTV-DT is consistently strong though. Only KGO-DT and KTVU-DT had enough signal strength, and KPIX-DT and KQED-DT were very inconsistent...


Oh, well...


Hong.
 

·
Registered
Joined
·
69 Posts
What do you think MY chances are of pulling in KNTV-12 with a similar antenna in combination with my existing?


I'm located in Hayes Valley in San Francisco. Fortunately I have direct line-of-sight to Sutro Tower and I'm receiving all the DTV signals from there using a Radio Shack 15-2160 UHF antenna up on the roof of a 4-story building with nothing taller in the area.


Currently I get a signal strenghth of 40 (no lock) on channel 12. I'd like to believe it's possible.....


Any recommendations?
 

·
Registered
Joined
·
189 Posts
For the price of the small VHF antenna for ch12 I would sure give it a try. If you are getting something on your UHF antenna you shouod do better with a ch12 Yagi. Since you only have a UHF antenna now you should be able to get a Channel Master UHF/VHF combiner that would get the job done. RS has them too, but not sure how good they are at seperating the bands.


Don Cone
 

·
Registered
Joined
·
69 Posts
Great, thanks for the information.


How much separation (vertically on the mast) do you think I need if both antennas are mounted on the same mast pointing in different directions, or is this a non-issue in my situation?


(This little project has gotten WAY outta hand!)
 

·
Registered
Joined
·
189 Posts
I would put the VHF antenna on the top of the mast and a 3-4ft separation should be adequate. I may get a bit tricky pointing the antennas, but since you already know where to point the UHF, you could work with just the VHF and then put the UHF back up and combine them.


Don Cone
 

·
Registered
Joined
·
6 Posts
I live in the Oakland hills and wonder if anyone in the area is able to receive KNTV's HD signal. If so, what sort of antenna are you using?
 

·
Registered
Joined
·
1,897 Posts
Discussion Starter · #18 ·
Well, here is the latest update on my KNTV studdering problem. I disconnected the UHF antenna and ran the VHF antenna directly into the receiver. I tweeked the aiming of the antenna based on my discussions with the KNTV engineer that gave me a call yesterday. The result was no difference. Still the same minifreezes. The KNTV engineer said the only time he saw that sort of problem was when signal strength was low. It is a bit baffling as I can receive about 2/3 of the Sutro stations using the VHF antenna pointed in the opposite direction. I didn't have time to do a lot of testing last night. I haven't tried moving the VHF antenna to the top of the mast but both antennas are pretty much in the clear and the angle of incidence from station to antenna is pretty low so I don't think there is a problem there. I have just over 3 feet of separation. The new VHF antenna has a double driven element with 1 reflector and 3 directors and the director end is pointed at KNTV. At this point my conclusion is that there is something different about this signal that my old Unity Motion receiver doesn't like.


I went into the Terrestial setup menu and looked to see what could be changed on each channel. The variables are Frequency which is set at 204 MHz, Vertical RC or Horizontal RC. Currently all of my stations are set at Vertical. I tried Horizontal but no difference. Lastly there is a number that is 19393 Kbs which can be changed in increments of 10. I don't know what that is or if that is the right number. All of my other stations have that number set in. I think this weekend I will try deleting the station again and rescanning to see if that fixes the problem. I haven't done that since I put the new antenna up. I will also borrow a friends UM receiver this weekend to see if his does the same. Unfortunately I don't have access to any other receivers. My system needs RGBHV output and I cannot take Component into my projector. The only good news is that it is summer rerun time and I have until the fall to figure all of this out.


..Doyle
 

·
Registered
Joined
·
72 Posts
You have probably thought of this already but the problem I had with 12.1 was multi-path. The symptoms were exactly the same as yours. The receiver was unable to seperate the two signals it was getting and so loked on one, lost that one (the lockup of the picture) and then locked onto the same signal or the other one.


By adjusting the antenna to all possible angles I found a point where it is reliable. It isn't pointing at Loma Prieta. Adding an attenuator may produce similar results if one signal is weaker than the other.


michael
 

·
Registered
Joined
·
133 Posts
I live in Cupertino and get signal level of 40 for channel 12-1 with my RS antenna pointing at Suttro. When I turn it to point at Loma Prieta the best I get is 28. Neiter is good enough to watch. My antenna is the largest log periodic RS sells and I have RS preamp at antenna. Does anybody have any suggestions
 
1 - 20 of 24 Posts
Status
Not open for further replies.
Top