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Discussion Starter · #1 ·
I am having a problem keeping a signal in for CBS which I get from MT. Wilson. I was watching CBS last night and after about 1/2 hour the signal went from a steady 55 to 60% down to below 40% and then gone. I switched to NBC, ABC and other stations and they all came in at about 59 to 67%. This seems to happen no matter what time of day or night. I have tried adjusting my RatShack amp. which is connected inside the house from no connection to full gain with no success. I live in Moreno Valley which is about 1,300 ft above sea level and I have a pretty good look at MT. Wilson. There is a small MT. in part of my path that has some antennas on it but if I can get the other stations in steady why not CBS??.


My setup is as follows:


CM 3679 mounted on the peak of my two story house with a 15ft cable run to my E* sw64 with the signal split there and then into the house.


A RatShack cheap amp.


E* 6000 with 8VSB.


I don't know what to do and could use any advice you can give me. Thanks
 

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Based on some reception tests in the Hollywood - Bel Air - Malibu - Brentwood area, it appears that if you have a pretty good shot towards Mt. Wilson, all you will probably need is the Channel Master #3021 (also sold in two packs as the #4221) 4-bay UHF screen antenna. It sells for less than $30.


You may or may not need the accessory preamp (Model #7775 Ttan 2, $69.95 MSRP), but if you do, the combo should solve your problems. The Radio Shack preamps are unstable and often oscillate, causing more harm than good.


Since all of the Los Angeles DTV channel allocations are UHF at present, it makes no sense to use a VHF or combo VHF/UHF antenna for reception. Maximize your gain and stick with a UHF design. The 3021 is a good choice because it has more gain above channel 60 than any other CM antenna, and you have channels 59, 60, 65, and 66 on-air out there.


For more info on UHF antennas and DTV reception, go to www.projectorexpert.com - there are several articles posted on the subject there.


KC
 

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Howdy, neighbor! I'm in Rialto, and usually have been having similar problems lately between 5:30 p.m. and 7:00 p.m. with an RCA DTC100. I've suspected setting sun atmospherics and evening on-shore moisture, but I don't really know. I've found RatShack's antennas are ok if you don't take the company's grossly inflated "range" advertising seriously, but their amps and pre-amps tend to be noisier than CM's or Weingard's. The model 7775 from CM (I think that's the manufacturer - someone correct me if I'm wrong.) is very well regarded and has a noise figure of just ~2 dB. Many of RatShack's amps approach twice that figure with the result that they often hurt more than they help. I was unable to access the CM site, so tell me a bit about your 3679 if you can. Which L.A. digital channels are you able to lock? I'm unable to lock KCOP, KTLA, and KWHY with my current antenna (RatShack 80" UHF yagi).
 

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Discussion Starter · #4 ·
I can't tell you much about my antenna because this is so new to me, but I do know it is a long range directional unit. As far as the channels you listed I can lock onto all of them. When I installed the antenna I leveled it horizontally but not vertically, would this make a differences???
 

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I am using the channel master 4221 bowie and also using a cm

7775 preamp. I live in Carson, CA. The antenna is on my roof and I installed a rotator. And I am very happy with the antenna. I'm about 3 hours away from San Diego and I am getting all the stations from San Diego. I have noticed that some Los Angeles sations such as Pbs 59.1 have been having " searching digital signal" problems during the day time. What I have heard is the broadcasting stations sometimes turn off the broadcasting due to power saving.And also KWHY 42.1 go off line like on Sundays. I went to the Titantv programming guide and it sais 42.1 off broadcasting. I am getting pretty much all the channels except Kttv-dt 11.1. Now I have noticed this channel always sais "searching for digital signal", before I was getting this channel. I also noticed that 11.1 and 65.1 are the same channels. I was wondering what might cause one channel to dissapear from a signal search? Any help would be appreciated.


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PeterDz
 

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Quote:
Originally posted by Peter Diaz:
I also noticed that 11.1 and 65.1 are the same channels. I was wondering what might cause one channel to dissapear from a signal search? Any help would be appreciated.
Peter, KTTV's digital channel is UHF 65. Your receiver remaps the channel number to the customery "11" for convenience if "Acquire Off-Air Guides" is activated. The same holds true for KABC (53 to "7"), KTLA (31 to "5"), KCBS (60 to "2"), KNBC (36 to "4"), KCAL (43 to "9"), and KCOP (66 to "13"). During the morning and afternoon hours, PBS (59) blanks out because they're in a budget squeeze. Previously they were multicasting 59-2 (simulcasting KCET's regular fare), 59-3 ("PBS Kids" national feed) and 59-4 ("PBS You" telecourses). KCAL typically doesn't go on air with their digital broadcasts (43-1 and 43-2) until 7:00 to 8:00 p.m. unless there's an Angels, Lakers, Kings, or Ducks game they're going to carry earlier. So, if you're doing a signal search when a channel is off air, it'll be missed. It's not your receiver.

 

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Using a 102" RadioShack UHF-only rig, picking up all Lost Angeles channels no problemo 42 miles south east of Mt. Wilson. The $30 RS variable-gain preamp is working fine (no sign of oscillation or drop outs).


Regards,

Don
 

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Have you tried getting the signal with the Radio Shack amp totally taken out (amp and power supply) ?


I think you will do better with a lower gain 10db radio shack model than with the poor adjustable ones.

 

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Discussion Starter · #9 ·
I have tried bypassing the amp completely and again it will still come up 00% on CBS but then when I change to NBC or ABC they come in strong. At times I have had all of the major stations register 00% then when I switch away to another channel that is a regular channel on the Dishnetwork and then back again they all come in and sometimes all but CBS. HELP.


I live near the intersection of Sunnymead and Perris.
 

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If you know lat/long of your location and of the CBS tower, you can get a topographical profile between the two locations by using a software package called "terrain navigator" from www.maptech.com
 

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Discussion Starter · #11 ·
I can see the Box Springs Mt. is just in my line of sight at about 3 miles. Should I try buying the antenna that Kelvin suggested or maybe tilt my antenna??? I don't know if I'm stuck with the inconsistent signal or what I should try. Could someone tell me if trying to get San Diego stations may be an option and where to turn my antenna to.
 

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Almost due south. First tune a good FM radio to KFMB-FM at 100.7 and see if you can hear them ... they are a class B transmitting at 30,000 watts from the KFMB-TV tower.


If you are planning to seek San Diego regularly you should invest in a rotor. They are at about 190 degrees true to you.


From what I have seen in this forum, XETV/Fox (Tijuana), KFMB/CBS and KGTV/ABC are all you should expect from the south, as KNSD/NBC is transmitting at very low power. KPBS/PBS is about to fire up.


But these stations transmit from 3 different places: Mt Soledad (La Jolla), Tijuana and Mt San Miguel (La Mesa). All three are to the south from you in the same general area but you will surely want to "fine tune" these.


As for your problem with Mt Wilson, I doubt you have a line-of-sight. You are possibly benefitting from "knife-edge reflection" and other electronics voodoo that some expiramenting with antenna tilt and poiting will doubtlessly help. Elevate your antenna, as always, as high as you can.




[This message has been edited by zuma hans (edited 05-26-2001).]
 

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Discussion Starter · #13 ·
Based on some reception tests in the Hollywood - Bel Air - Malibu - Brentwood area, it appears that if you have a pretty good shot towards Mt. Wilson, all you will probably need is the Channel Master #3021 (also sold in two packs as the #4221) 4-bay UHF screen antenna. It sells for less than $30.

You may or may not need the accessory preamp (Model #7775 Ttan 2, $69.95 MSRP), but if you do, the combo should solve your problems. The Radio Shack preamps are unstable and often oscillate, causing more harm than good.


Since all of the Los Angeles DTV channel allocations are UHF at present, it makes no sense to use a VHF or combo VHF/UHF antenna for reception. Maximize your gain and stick with a UHF design. The 3021 is a good choice because it has more gain above channel 60 than any other CM antenna, and you have channels 59, 60, 65, and 66 on-air out there.


For more info on UHF antennas and DTV reception, go to www.projectorexpert.com - there are several articles posted on the subject there.


KC


Can anyone tell me what Kelvin is suggesting would work if I do have a Mt. out about 5 miles in the line of sight the the TV tower
 

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I would recommend ditching the RS antenna in favor of the Winegard or Channel Master. I also tried their biggest yagi first and got spotty performance at best. Switching to the Winegard bowtie completely eliminated all my problems.


BTW, I also got a separate CM VHF antenna and diplexed it with the WG bowtie. Not only do I now receive the VHF stations clearly, my FM reception (in Chino Hills, which tends to be RF Dark Territory) is dead on for just about all local radio stations. (Of course, having just connected a PC to my Mits 73907 and routing the sound card to my receiver, who needs commercial-ridden OTA radio when you've got sonicnet.com streaming great music to the entire home?)


Good luck!


[This message has been edited by RSongco (edited 05-31-2001).]
 

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Go to www.projectorexpert.com and you will find an article titled "Long Strange Trip" under the DTV section. It details a modification to a Channel Master 3023 / 4308 suburban UHF yagi that helps performance in the high end of the UHF band. This antenna solved an even more difficult DTV reception problem than yours in a canyon in Beverly Hills. It was coupled to the Channel Master 7775 UHF preamp.


KC
 

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WOW! I corrected all my problems regarding stations that are missing and that were dropping out. I have a CHANNEL MASTER 4221 bow tie ant on a straight up position before. I was getting all channels and also getting San Diego channels but some stations where having drop out problems specially Fox channel 11.1. I followed Tom Pffar's suggestion. I also made a "T" out of an antenna mast that I purchased from HOME DEPOT. I went ahead and tilted the bowie ant at about 45 degrees. And now all channels are coming in very strong. Fox channel is fixed. Wow again !

Now I know that the CM 4221 bowie style ant works best if tilted.


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PeterDz
 

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KBoucher -


I am also in Moreno Valley (Kitching & Cottonwood area) but am currently only analog capable. I have found that with my RS antenna/amp setup channel 24 (located on Box Springs - that mountain with all the antennas on it) is so strong that it causes herringbone lines on almost every channel. From other posts I have learned that this can be especially frustrating while trying to tune DTV channels because you can't see what is causing you to not get a signal lock.


Try one of these and I am sure it will fix the problem for you. First, try taking the amp out altogether. I know it will cause a drop in picture quality on analog stations but digital only requires that the proper signal to noise ratio (S/N) be present. Second, if that doesn't help, try putting the amp back in but put an attenuator on the OUTPUT. I tried putting one on the input to my amp and it didn't help much. When I put it on the output most of the interference from KVCR went away. Third, try tilting the antenna as suggested by others in this thread. Not a practical solution in my setup but it might help you.


There could also be an atmospheric component to the problem. I have noticed that analog ch. 30 tends to drop out severely from time to time and get overwhelmed by digital ch.31. It seems to correspond to good propagation to the south from San Diego. If you are interested in SD digital stations you could try using this as a "beacon".
 

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Bernie -


Here in Moreno Valley (just east of Riverside) we do get at least some signal from San Diego all of the time. We are only about 75 mi as the crow flies (ATCF) and changing the bearing seems to affect the signal on the different channels only slightly. The hills at the south end of our valley (Lake Perris area) add quite a bit of multipath on 6, 8, 10, 12, and 15. 39, 51, and 45 (when it comes in) are usually pretty good, especially 51. When propagation is favorable they can all come in as strong as LA with no ghosting. 69 (at least with my current setup) is unusable. 21, 27, and 33 sometimes come in very strong even off the side of the beam when my antenna is pointed to LA. Too bad I don't speak Spanish! Even channel 3 in Tijuana comes in well enough that we could watch regularly if so inclined.


[This message has been edited by dlsnyder (edited 06-03-2001).]
 

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But these stations transmit from 3 different places: Mt Soledad (La Jolla), Tijuana and Mt San Miguel (La Mesa). All three are to the south from you in the same general area but you will surely want to "fine tune" these.


.....

not to be too nit picky Zuma but Mt. San Miguel is not in La Mesa, CA but is in the south eastern area of greater San Diego just to the north of Otay Lake.


BTW I live near La Mesa and pick up ALL of the LA stations -- over 115 miles away using a large roof top antenna and DTC-100 !!!!!

Bernie

 
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