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post #91 of 99 Old 04-02-2012, 02:37 PM - Thread Starter
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Yes, just click on the blue box with the white arrow > next to kenglish & holl_ands in my last post.

Or click below:
Holland:

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post #92 of 99 Old 04-03-2012, 11:52 AM
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I just checked and Warren Electronics no longer has the old design 7777 preamps. And to add insult to injury, the price has increased by $10.

Another good product cheapened and ruined by a shortsighted company.
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post #93 of 99 Old 04-03-2012, 02:05 PM
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I ordered a spare 7777 and 7778 from them when I heard the original models were being replaced.
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post #94 of 99 Old 04-06-2012, 09:27 AM - Thread Starter
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Quote:
Originally Posted by tylerSC View Post

Is there a link to a post where they recommend these devices? I am not an electrician nor engineer, so hopefully there is a somewhat simple, nontechnical solution. What is the best way to ground an attic antenna and protect the preamp?

Tyler, check out the following:
Quote:
Originally Posted by kenglish View Post

A nearby lightning strike can still induce a surge in to the attic antenna. Your best bet is to ground the cable, along with a surge-limiting lightning-arrestor.

Quote:
Originally Posted by holl_ands View Post

There are three general types of coax surge protectors (aka Grounding Block):

1) Air Gap--relies on a spark jumping across an air gap:
Which SHOULD be inside a protective enclosure to keep out dirt & dust (most are not).
They also act as a high current conductor when overwhelmed by a high voltage event:
https://www.tselectronic.com/pico/grb_hrl.html
I've yet to see any specs on breakdown voltage (probably quite high), reaction time
(probably quite slow) and current capability vs time to destruct....
but for house entry points for OTA Antenna, SAT & Cable, they "meet NEC code"....

2) Gas Tube (e.g Holland GRB-AR) with internal spark gap:
Very careful construction means the breakdown characteristics can be controlled
inside the gas filled tube. Holland even provides detailed specs:
http://www.hollandelectronics.com/ca...Protection.pdf
http://www.l-com.com/item.aspx?id=20928
But, since they still rely on an "air" gap, the breakdown voltage is fairly high
(90 volts for GRB-AR), so don't expect them to provide very much protection to attached
electronics equipment. Also note the higher current ratings for the Toner Cable devices.

3) Solid State devices (e.g. MOV & Silicon Avalanche, such as Holland SA-1F SiDACtor):
http://www.hollandelectronics.com/ca...Protection.pdf
have a much lower breakdown voltage (25 volts for the SA-1F) and hence will leak off
static electricity build-up and thereby prevents excessive voltages being applied
to sensitive electronics equipment. But when the solid state device is overstressed,
it will blow, meaning the only protection is whatever air gap was (hopefully???)
intentionally designed into the device.
I've seen many coax MOV type devices listed, but very few quote specs....

If you check the current specs for the Holland devices, note that neither device
will sustain high current conditions for more than a handful of microseconds---
whereas a lightning strike will typically last for many milliseconds.....so don't think that any
of these devices will provide much protection against a direct lightning spike:
http://www.atlanticscientific.com/lightning.html

MOV (& Si avalanche) type devices, such as are found in most "Power Surge Protectors",
are usually combined in parallel to increase the overall energy absorbion rating (joules).
As power spikes are absorbed, individual "crystals" within each device are sacrificed,
eventually making each device inoperative....hence the need to parallel individual devices:
http://www.extremetech.com/article2/...1155237,00.asp
Unfortunately, this can also slowly degrade RF signals going through Coax Surge Protectors,
which can result in significant signal attenuation that increases over time...so test frequently....

=========================================
The best approach is to use a combination of either #1 or #2 for protection
against large (but very rare) surge voltage events and and a solid state devices
to drain off static electricity on a daily basis.


PS: If you have reception problems, carefully check to make sure that these devices
are not contributing excessive loss--esp if the device has undergone one too many spikes...

For more info:
http://www.arcelect.com/lightnin.htm NOTE THE USE OF THREE DEVICES!!!
http://www.panamax.com/PDF/IEEE_Guide.pdf
http://en.wikipedia.org/wiki/Surge_protector

Explains Static Electricity Buildup:
http://www.renewwisconsin.org/wind/T.../Lightning.pdf
http://www.nottltd.com/article.html
http://www.atlanticscientific.com/lightning.html

==============================================
OTA TV Antenna Grounding info contained in C-M Installation Guide:
http://www.channelmasterstore.com/v/...l%20master.pdf

SAT Dish Grounding References (also apply to OTA TV Antennas):
http://www.mikeholt.com/mojonewsarch...s~20020303.htm
http://www.sadoun.com/Sat/Installation/Grounding.htm


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post #95 of 99 Old 04-10-2012, 01:08 PM
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Picture and sound started breaking up on certain channels, mainly a weak VHF13 and a low power UHF30, as well as a moderate strength UHF22. Real RF channels. Unplugged the control box for the outside irrigation system, in the adjacent garage, and all is back to normal. Good reception, no breakups. Went to Radioshack and got 2 ferrite cores, placed them on the power cord for the irrigation box, plugged back in, and no problem. Stable reception again. Problem solved. But amazing how one small, seemingly insignificant thing can wreak havoc on DTV reception.
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post #96 of 99 Old 04-16-2012, 06:21 PM
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Had a blown fuse controlling electrical outlet in room adjacent to TV. Neighbor came over and "shocked" the fuse back into use with some sort of electrical device. But now I am getting noise and interference on 2 of my weaker DTV channels. Is the bad fuse creating electrical noise that is interfering with my reception? Preamp is plugged into outlet that must be on same electrical circuit. Should I replace the fuse in the master control panel?
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post #97 of 99 Old 04-17-2012, 08:23 AM
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Quote:


Had a blown fuse controlling electrical outlet in room adjacent to TV. Neighbor came over and "shocked" the fuse back into use with some sort of electrical device.

Hmmmm....

Tech support for Antennas Direct
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post #98 of 99 Old 04-17-2012, 01:57 PM
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Last week a friend of a friend installed a 4221HD antenna and a "new" 7777 preamp at a location with this TVFool:

Result: no signal
I replaced the "new" 7777 with an old 7777. Both channels were receivable at 4 out of 5 bars on their Sanyo HDTV signal meter.

So, the new 7777 was either defective, or just not as good as the old 7777. The old style 7777 worked great. This is purely anectdotal experience and of course, YMMV. That being said, based on this experience, I am through with knockoffs of what were formerly great ChannelMaster preamp products.

BTW, this TVFool location is for a house built directly up against the bottom of a tall hill that is blocking the stations. Other hills are between the house and the transmitters, too. The best hot spot for reception of these two UHF channels was about 4' off the ground and we had to do a lot of walking to find the hot spot. I suspect the TVFool signal strength prediction is not very accurate, either.
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post #99 of 99 Old 04-17-2012, 06:23 PM
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I am aggravated as well that the new Channel Master antennas are now Chinese made knockoffs of their formerly great American made TV reception products. Their original antennas were widely acclaimed, but now , for the most part, are no longer available.
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