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Discussion Starter · #1 ·
Ok, here's an odd one. I have a Channel Master 4228 (is that the right number?), the UHF only bow tie (the 8-bay one). With that antenna alone I was able to receive ABC, CBS, and both WB channels (24,29,19, and 12) here in Palo Alto. I tacked on a 7775 UHF only amp and there is no improvement whatsoever on any channels and I think it might have made my signal numbers a little worse. Anyone have any thoughts?


The reason I ask is because NBC and FOX are at 56 and 57, I can't even get a signal from them on my DTC 100. This also begs another question, if NBC is coming off Mt. Sutro with ABC and CBS shouldn't I be able to at least get something?

Is it possible for one frequency band to have such a large drop off?


thanks in advance

Tim
 

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Tim.


56/57 is a high on the UHF freqency band and it is harder

to pick up. I had the same problem in San Jose until I

readjusted the antenna to be a better signal lock. In

fact I have just the CM3017 with a RS indoor cable amp.


What signal are you getting for 19/24/29?

Are you able to pick up 30 (KQED) and 45 (UPN) as well?


Use channel 29 to see if you can improve the signal lock.

Channel is best of the three to test with because it is

slightly higher in the frequency band. If you can see

30/45, then use the highest UHF channel possible. Keep pivoting the antenna until you get the best signal lock. Now try to see if you can get 56/57....


As KC as indicated, you might be overloading the signal.

The CM 4228 is big enough to not require the amplification

of the signal. Remember when you amplify a signal, you are

going to amplify some noise as well.


Hope this helps.
 

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Your NBC problem is going to go away in another 3 months, when NBC switches from KRON to Ch 11 in San Jose. Ch 11 broadcasts digital on 12-1 from a transmitter somewhere down there. (Good news for you. bad news for me)
 

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Discussion Starter · #4 ·
Well, I went back out and double checked all my connections and everything is set properly. Here is what really bugs me....


If I pull the amp off and tune in the stations I can receive from Mt. Sutro (19,24,29,30) -- they all max out around 60 signal strength at the same antenna position. In this spot I get 56 at about 20 signal strength and nothing on 45 or 57 (44 is ok though). When I put the amp on, none of these numbers change. What the heck??


[This message has been edited by thollida (edited 10-09-2001).]


[This message has been edited by thollida (edited 10-09-2001).]
 

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Quote:
Originally posted by thollida:
When I put the amp on, none of these numbers change. What the heck??

That is consistent with my findings. The meter is measuring quality, not quantity.




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-Glenn
 

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Its weird, from where I'm at in Mountain View, I can see all the channels pretty well, except 12 in San Jose. Hopefully 19 continues to multicast 12 on its auxilliary bandwith, when the NBC switchover occurs.


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Tho!
 

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Yeah, but unfortunately I think that means no HD on that transmitter. Not a big loss right now, but when NBC finally gets its act together with HD, I'd like to have access to it. Unfortunately, I'm in the shadow of the hills right under the channel 12 transmitter, so I don't get the primary signal. Oh well.


>>Hopefully 19 continues to multicast 12 on its auxilliary bandwith, when

>>the NBC switchover occurs.
 

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Of course, part of the reason for the bad reception of KNTV-12 might also be that their supposedly only putting out ~9kw of power? http://www.metronet.com/~chipk/tv/SFO.html


I'm guessing that would change when they have actually something of worth to show on their network....


Its actually really amusing to see KICU, a full-time independent, outpower KNTV by a huge margin.


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Tho!


[This message has been edited by junkman (edited 10-09-2001).]
 

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I've had two Channelmaster antenna mounted preamps and found that both made things worse. I've concluded that they aren't of much use when you are relatively close to other TV transmitters. In my case, I'm about 11 miles from the Dayton analog transmitters and about 50 miles from the Cincinnati digital transmitters I'm trying to receive. I even called Channelmaster tech support and they told me I was way too close to the Dayton transmitters to be able to use a preamp.


Dean
 

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Make sure your connections are correct. It is easy to reverse cables with that two-piece preamp combo and not even notice it.


Assuming your connections are correct, there may be a problem with your DT tuner being overloaded by the signal from the preamp. That can cause spurious signal generation within the receiver's front end and cause signal detection and demodulation problems.


The CM 7775 is designed to be mast-mounted and CM expects a fair amount of cable to be run from the mast-mounted preamp to the power supply. The preamp has 24 to 26 dB of gain depending on frequency. It's possible that overload is occuring, but it's not too likely.


Another possibility is a strong local out-of-band signal close enough to the UHF TV spectrum is also being amplified by your preamp, and that in turn is causing problems for the receiver. Have you tried reception with another STB? The RCA DTC-100 is an old design, and there are more sensitive models out there.


KC
 

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Discussion Starter · #12 ·
Really? Channel Master said you were too close? Hmmm, methinks I have a phone call to make tomorrow. Thanks for the heads up!


Tim
 

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i live in hd antenna hell. i also get a worse signal with the preamps so i gave up. i use a rotor because i get reflected signals and the rotor gets me all los angeles hd channels except ktla which doesn't even come up with a channel scan.
 
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