[Cialug] [OT] Digital TV

[murraymckee at wellsfargo.com]

It is 100' of line across the attic, down to the basement, across the basement ceiling, and back up to the living room.

I've heard of amplified antennas but not of amps in the line from a standard antenna.  Where does one look for them?  I've talked to both Best Buy and Radio Shack about the problem and they suggested the amplified antenna, but putting it in the living room, not in the attic.  It would seem to me to make more sense to put it in the attic. 

There is a lightening arrester cable coming down the gable of the roof a few feet from where I anticipate bringing the coax cable into the attic.  I could jumper from the block over to that.  I'll have to recheck where it goes into the ground.  I haven't looked at it intentionally in years.  

I have a cell phone tower not too far from the house and I expect it will attract the vast majority of the lightening in the area so I expect my house will be pretty safe, but I don't want to loose all my electrical equipment just to prove a point.

Murray McKee 
Operating Systems Engineer
WFFIS - Wells Fargo Financial Information Systems 
800 Walnut Street
MAC F4030-037
Des Moines, IA 50309-3605
WORK (515)557-6127 Cell (NEW) (515) 343-6630  FAX (515) 557-6046
MurrayMcKee at WellsFargo.com 
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-----Original Message-----
From: cialug-bounces at cialug.org [mailto:cialug-bounces at cialug.org] On Behalf Of Zachary Kotlarek
Sent: Monday, May 04, 2009 2:15 PM
To: Central Iowa Linux Users Group
Subject: Re: [Cialug] [OT] Digital TV


On May 4, 2009, at 12:33 PM, <murraymckee at wellsfargo.com> <murraymckee at wellsfargo.com 
 > wrote:

> There is a 4 way splitter in the living room with one line going to  
> each of the two DTV boxes, one to the VCR, and one to the TV.


I am not a radio engineer, but my (non-DTV) experience fighting with a  
roof-mounted rotary UHF mast suggests that 4 legs without an amp is  
probably optimistic -- RG-6 has a loss of about 1 dB per 20 feet, and  
a 4-way splitter likely has a loss of 7-8 dB. You might consider  
replacing the splitter with a distribution amp or adding a pre-amp to  
the antenna feed.


> How does one ground the antenna so that lightening doesn't get  
> transferred to the DTV box / VCR / TV etc.?


Start with a grounding block between the antenna and the entrance to  
your house -- a grounding block is essentially a female-female coax  
gender-changer where the shield is tied to a screw:
	http://www.sadoun.com/Sat/Products/Accessories/RECDSV70.jpg

Attach that screw to a standard ground rod (or other suitable  
grounding device) as close to the antenna as is practicable using a  
heavy gauge wire with no small-radius turns -- essentially the same  
procedure you'd use for a lightning rod. I believe the NEC always says  
you should connect the new ground rod to your breaker box, and I'm  
sure there are other rules about wire and antenna placement that you  
should follow if you want to do things right.

	Zach