TV Fool - Not getting all the channels

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Not getting all the channels

I recently put up a RCA TV antenna (model number ANT3036WR) but I couldn’t get all the stations I wanted. All stations are approximately 30 miles away. I live in a wooded area. The antenna is about 30 feet off the ground.

The antenna is pointing north towards the stations. At first I would only pick up the weak power stations. The following I don’t understand, the weak stations 12.6 and 30kW, come in great. The more powerful ones 90, 813, and 1000kW will not come in.

I then installed a channel master 7777 pre-amp. When I auto program, my tv finds the other higher power stations but they barely come in.

Help please.

Please post a link to your TVFool report.

You can create it with the following directions: http://forum.tvfool.com/showthread.php?t=14508

What stations did you get, by callsign, without the 7777 preamp and what ones did you get with the 7777?

Quote:

Originally Posted by rabbit73 (Post 54417)

What stations did you get, by callsign, without the 7777 preamp and what ones did you get with the 7777?

Before; WJLA, WUSA, WNVT. (these stations except WNVT, came in great. WNVT is pixilated)

After; WRC, WFDC, WHUT. (these stations have no signal or very pixilated or rarely come in at all)

Sounds like amplifier overload (excessive amplification).

Return the 7777, exchange it for a 7778.

Quote:

Originally Posted by ADTech (Post 54432)

Sounds like amplifier overload (excessive amplification).

Return the 7777, exchange it for a 7778.

How can I tell if the signal are being over amplified? I would like to know before I send the the unit back and get the other one.

You don't know for sure if you have no way to measure the signal strength, and neither do we because RCA doesn't give the antenna gain figures.

There is a simple test you can do. Insert a variable attenuator between the antenna and the preamp input to see if the system behaves any better.
https://www.antennasdirect.com/store...ttenuator.html
http://www.3starinc.com/drop_in-line_attenuator.html
http://mjsales.net/collections/atten...ant=1083705673
•Attenuation values 1, 3, 6, 8, 10, 12, 16, 20dB (FAM)
click on 1 dB for other values; the up and down arrows are faint

You are going to have to do some experiments if you want any improvement.

There is no way we can give you a guarantee.

If you want some numbers:
Channel Master says the 7777 is only for weak signal areas.
http://www.channelmaster.com/TV_Ante..._p/cm-7777.htm

Quote:

This antenna amplifier is a high gain, low noise preamplifier used to allow weaker signals at the antenna to be amplified to a viewable strength, and is ideal for installations in which all broadcast towers are located at a distance of more than 80 miles......Due to the high gain output of this product, it can result in over amplification if not used in the appropriate scenario. Over amplification can cause issues with the television tuner’s ability to receive and display some or all channels.

Gain 30dB
Max input level 15 dBmV = -34 dBm
WHUT signal power is -45 dBm
-45 dBm + 12 dB antenna gain = -33 dBm, which is more than -34 dBm max input

-33 dBm at input + 30 dB preamp gain = -3 dBm preamp output to tuner input

tuners are not designed to handle signals stronger than -8 dBm with multiple high-level signals, which means a 5 dB overload

ATSC Recommended Practice:
Receiver Performance Guidelines
Document A/74:2010, 7 April 2010

RECEIVER PERFORMANCE GUIDELINES

5.1 Sensitivity

Quote:

A DTV receiver should achieve a bit error rate in the transport stream of no worse than 3x10E-6 (i.e., the FCC Advisory Committee on Advanced Television Service, ACATS, Threshold of Visibility, TOV) for input RF signal levels directly to the tuner from –83 dBm to –5 dBm for both the VHF and UHF bands.

5.2 Multi-Signal Overload

Quote:

The DTV receiver should accommodate more than one undesired, high-level, NSTC or DTV signal at its input, received from transmission facilities that are in close proximity to one another. For purposes of this guideline, it should be assumed that multiple signals, each approaching –8 dBm, will exist at the input of the receiver.

I've test all the popular amps and my recommendation is based on staying with your amplifier same company (if you wish, I didn;t try pushing you into our amp) and getting you an amp that won't overload as easily as the one you self-selected.

Quote:

Originally Posted by ADTech (Post 54481)

No worries, I never felt that you were trying to push. Thanks for the advice.

[QUOTE=rabbit73;54478]You don't know for sure if you have no way to measure the signal strength, and neither do we because RCA doesn't give the antenna gain figures.

There is a simple test you can do. Insert a variable attenuator between the antenna and the preamp input to see if the system behaves any better.

Where do I place the attenuator, before or after the power input of pre amplifier?

antenna > attenuator > preamp > coax > power inserter > TV

Quote:

Originally Posted by rabbit73 (Post 54512)

antenna > attenuator > preamp > coax > power inserter > TV

My preamp is mounted on the mast. Do you know if the attenuator can be used outdoors?

It can be outdoors if it is one of the fixed value attenuators, but it doesn't matter because it is only a temporary test to see if the 7777 is being overloaded. If it is, you will be more confident about switching to the 7778.