[NLRS] VHF low pass filters?

S. Earl Jarosh earl at jarosh.org
Wed Jan 2 11:37:05 EST 2013 

The whole digital thing was a cluster from the get go, here is the current
twin cities channel matrix with the exception that the full HD 45 is now
dark.  All was suppose to go to UHF then things in the gov happened and
upper VHF was included.  9 and 11 where allowed to keep their original
channels at the cutover.  There was suppose to be No low VHF in the Digital
plan and I did not know Des Moines was allow to keep their old analog
channel 5 for DTV.  Kind of defeats the purpose of the entire digital
cluster fix.

Analog Station Network Temp Perm 	Apo 		Dpo
Tower Loc
2 	KTCA 		PBS 	34 	34 	100KW 	924KW 	Shoreview
East
4 	WCCO 		CBS 	32 	32 	100KW 	1000KW 	Shoreview
West
5 	KSTP 		ABC 	50 	35 	100KW 	1000KW 	Shoreview
West
9 	KMSP 		FOX 	26 	9 	316KW 	691KW 	Shoreview
East
11 	KARE 		NBC 	35 	11 	316KW 	774KW 	Shoreview
West
17 	KTCI 		PBS 	16 	26 	141KW 	50KW
Shoreview East
23 	WUCW 		CW 	22 	22 	4570KW 	1000KW 	Shoreview
West
29 	WFTC 		UPN 	21 	29 	5000KW 	1000KW 	Shoreview
East
41 	KPXM 		ION 	40 	40 	2770KW 	1000KW 	Big Lake MN
45 	KSTC 		Ind 	44 	45 	5000KW 	82KW  	Shoreview
West


S. Earl Jarosh, N0HZ
Cell:  612.868.1313
Off:   763.545.3275
Home:  763.546.7897
Fax:   763.546.7897
earl at moneycenters.com

 
-----Original Message-----
From: nlrs-bounces at mailman.qth.net [mailto:nlrs-bounces at mailman.qth.net] On
Behalf Of Barry Malowanchuk
Sent: Wednesday, January 02, 2013 9:55 AM
To: Ed WB0VHF
Cc: nlrs at mailman.qth.net
Subject: Re: [NLRS] VHF low pass filters?



Good Morning,

This is a good topic.  I am concerned here in AZ with my own TV antenna and
burning out the amplified splitter .....it seems to handle 2, 432 & 1296 but
have not pointed the antenna at it :-).   6m always has been bad for getting
into stuff.  For my QTH I would look at inserting one of the Minicircuits
BHP-600 High pass filters on the TV antenna line which would be OK if you
can accept the insertion loss.  I would not want to be playing around with
some one elses antenna system...but if you can do it indoors, connectorized
and ..then ok if you have to do it

Barry VE4MA/W7

----- Original Message -----
From: "Ed WB0VHF" <wb0vhf at gmail.com>
To: nlrs at mailman.qth.net
Sent: Wednesday, January 2, 2013 7:40:17 AM
Subject: Re: [NLRS] VHF low pass filters?



Kirk,

Another thought would be to check with the League (either or both the web
and call) to see what tvi resources they have.

GL & 73,
Ed
WB0VHF


Sent from my HTC

----- Reply message -----
From: w0zq at aol.com
Date: Wed, Jan 2, 2013 08:29
Subject: [NLRS] VHF low pass filters?
To: <nlrs at mailman.qth.net>




Tough one Kirk.  Here are my thoughts.

If you can arrange it, have him watch his TV while your transmit.  

Questions to ask are:

Does the interference happen on all channels or just some?   
If its some, which ones and are these channels still the over-the-air VHF
channels .... UHF channels are OK?   This means figuring out where each
channel is actually transmitting (freq wise that is)
If all channels are affected then check to see if his over-the-air UHF
antenna has a preamp .... it may be built into the antenna or perhaps he is
using an (additional?) external preamp downstream.  You are most likely
swamping (blocking) the preamp.  Some of these preamps have adjustable gain
.... try turning the gain down if its adjustable.  I have not done this
myself, but it may be possible to put a high pass filter between the antenna
and the preamp, or the UHF antenna manufacturer may have such an option.
Again, I don't recall where all the over-the-air TV stations are
transmitting (in terms of freq) these days.  

I doubt the problem is on your end so there is not much that you can do
other than to try dropping your transmit power to see if there is a
threshold that is reasonable ..... for example maybe 400 watts doesn't cause
a problem, etc.   

If the problem is that his antenna preamp is being overloaded, you can point
this out to him and suggest that he switches to cable .... more of a sales
job here than a technical one.  Again, it most likely not your fault that
his powered UHF antenna preamp is of such a design that its easiely
overloaded (if that is what it is).

73, Jon
W0ZQ

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