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Old 9-Mar-2014, 7:22 PM   #1
joshg0207
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channelmaster 7777 not working

So I bought a what is supposed to be new channelmaster 7777 preamp...I went to hook it up and it is not getting good signal on some channels...i know there is good signal in the air cause I had a electroline drop amp hooked up prior to this and it was performing alot better than the channelmaster...I guess my question is do I have the channelmaster hooked up right or what could be going on...I would certainly think the channelmaster would out perform the electroline any day...any thoughts on my situation...
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Old 9-Mar-2014, 7:38 PM   #2
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Please post your TV Fool report.

What channels (Call Sign / Real Channel Number) are having trouble?

What make and model antenna are you using?

Where is the antenna mounted? (Above the roof, in the clear, In the attic...)?

FWIW, The CM-7777 is a deep fringe amplifier and not appropriate for use when one or more strong signals are present. Bigger is not always better
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Old 10-Mar-2014, 2:17 AM   #3
joshg0207
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**http://www.tvfool.com/?option=com_wr...5b94e62254e8fa

I have two setups right now a temporary one and a permanent one...I cant use the permanent one cause the rotator dont work...but its a channelmaster 3020 antenna on a 40ft tower with a channelmaster 7777 preamp and a rotator...the one im testing right now is ge attic antenna on a pole with a rotator on the outside of the house about 30 ft in the air...I first used a electroline drop amp and was able to pick up wtaj with 50% signal strength and watm with about 30% signal strength but it had drop outs...so I got a channelmaster 7777 pre amp and hooked it up and thought I could fix the dropouts on watm but the signal strength was worse with the channelmaster preamp about 30% on wtaj and no signal on watm...was just wondering why the channelmaster isnt performing better than the electroline drop amp any idieas...
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Old 10-Mar-2014, 2:35 AM   #4
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Because with 30 dB of gain and moderately strong signals, either the 7777 is overloading internally or it's causing an over load in the tuner.

The Electroline amp has only about 15 dB internal gain (minus any splitting loss, if applicable) and is capable of handling very strong signals without going into either IMD or blocking.


In other words, the 7777 is precisely the wrong tool for your situation.
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Old 10-Mar-2014, 3:01 AM   #5
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Add in the nearby FM stations & that amp is most certainly overloading.

I would consider a different antenna as well to address the strong FM. The 3020 is a good FM antenna & unfortunately not a good fit for your situation.
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Old 10-Mar-2014, 3:41 AM   #6
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What antenna do you guys recommend...would a antenna direct 91xg be all right to use...im trying to pull in distant stations 70 miles away
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Old 10-Mar-2014, 7:51 AM   #7
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It's not clear which signal(s) you're after... A call sign and real CH-# would remove any doubt.

The 91XG would be the antenna of choice for UHF signals with single digit NM values... particularly if they are in the upper end of the band (real CH-30 and up). If you are after a weak UHF signal in the lower end of the band (real CH-14 to CH-30ish) then the DB8E would be my choice. If you've got a mix of weak UHF channels at both end of the band, then the DB8E is the antenna I'd use.

If you are after weak H-VHF (real CH-7 through CH-13) then use the Antennacraft Y10713.


If you're in need of an amplifier that is quite tolerant of strong local signals, the RCA TVPRAMP1R is my choice.

(I own a 91XG, Y10713 and a TVPRAMP1R. I also have a DB4E, which is a great UHF antenna... that beats my old Winegard HD8800 hands down.)
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Last edited by GroundUrMast; 10-Mar-2014 at 7:58 AM.
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Old 10-Mar-2014, 10:21 PM   #8
joshg0207
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**http://www.tvfool.com/?option=com_wr...5b9409cb14b836
this is the tv fool report for my setup on a 40 ft tower...I was thinking about putting an antenna direct 91xg with a channelmaster 7777 and a rotator on the tower...im going to try to pick up the following channels...whsv...wtaj...watm...wjac and also would like to get wvir but thats probably out of the question...do you guys think this setup is good and do think I may be able to get these channels...
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Old 22-Mar-2014, 7:56 PM   #9
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Signals with predicted NM (noise margin) values of -10 dB and lower are going to be quite difficult to receive reliably.

WTAJ & WVIR are using the same real channel, CH-32. the other signals are also beset by adjacent and co-channel interference issues.

I won't tell you 'not to try', but rather, 'have realistic expectations'. If you get reception of any of the call signs you've listed, it will likely be dependent on atmospheric conditions occasionally providing favorable DX propagation conditions.

If I were to try this, I'd either use a DB8E & TVPRAMP1R or a custom built array... perhaps a quad-stacked 5 or 6 wavelength Rhombic.

http://forum.tvfool.com/showthread.php?t=2865
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Last edited by GroundUrMast; 22-Mar-2014 at 8:51 PM. Reason: link to DIY rhombic designs.
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Old 22-Mar-2014, 11:42 PM   #10
teleview
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A 4 antenna stack of cut to channel antennas.

WTAJ is Real UHF 32.

And a Single channel preamplifier.

Might get reliable reception of UHF channel 32.

----------------

The single channel , 4 antenna stacks and single channel amplifiers are available for other channels.

-----------

The prices of the quad stacks of antennas and the preamplifiers , will make you back up.

The Sitco division of Simplicity Tool.

www.simplicitytool.com

Last edited by teleview; 23-Mar-2014 at 5:07 AM. Reason: Clarify information and typos.
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