[NLRS] VHF low pass filters?

[S. Earl Jarosh]

Radio Shack produces several High VHF/UHF passive antennas for local and
fringe work


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 w0zq at aol.com
Sent: Wednesday, January 02, 2013 11:24 AM
To: nlrs at mailman.qth.net
Subject: Re: [NLRS] VHF low pass filters?




Darn, I meant to add one more important thing.  If the plan is to go with a
new antenna, do not buy a "HD" or "Digital" antenna as these may only cover
the UHF TV band.  Because CH 9 and CH 11 are VHF, the TV antenna needs to be
a VHF/UHF style, not just UHF.  Lots of marketing hype/claims in these TV
antennas.   

In summary, a "local coverage" (ie, small) VHF/UHF TV antenna, maybe in the
$50 price range, should do the trick.  As someone else said use good coax
too.

73, Jon
W0ZQ



-----Original Message-----
From: w0zq <w0zq at aol.com>
To: nlrs <nlrs at mailman.qth.net>
Sent: Wed, Jan 2, 2013 11:12 am
Subject: Re: [NLRS] VHF low pass filters?




 just checked the FCC database and I agree with Chris .... Channel 9 at 186
-
92 MHz and Channel 11 at 198 - 204 MHz are still being used here in the
greater 
win Cities area.  My money is that the problem is preamp overload.
Solutions 
ay be
1)  If the preamp can be turned off (probably not), turn it off.  If the
gain an be turned down, try that.
)  Buy a new antenna.  Switch to an non-active antenna using good coax.  No 
reamp.   RadioShack and Menards have "passive" TV antennas.  See what the 
icture looks like with this set-up.  Chances are it should be fine.  
)  If a preamp is needed, use an external preamp and look to find a HP
filter hat has a cut off above 50 MHz but still passes Channel 9 (186 MHz).
As others ave said, place it between the antenna and the preamp, not after
the preamp.
One short story to tell.  About 12 years ago my immediate neigbor calls me
with  2m TVI complaint.  While he was on the phone I reduce my power more
and more 
ntil I was down to 2 watts and still the problem existed !    Since I had
not 
hanged anything I asked him if he had made any changes to his "stuff" .... a
ew TV, move to a new room, etc, etc.  Turns out that he had visited Radio
Shack nd the sales man sold him a very nice 25 dB gain switchable preamp.  I
asked im to turn the preamp off and bingo, problem fixed.  Why he installed
a 25 dB ain preamp when we live in Bloomington with P5 picture quality was
beyond me, ut my advice to him was to return the preamp as its not needed
and it only 
reates problems (for HIM).   PS:  We still talk and the preamp is gone.
73, Jon
0ZQ

-----Original Message-----
rom: Chris Elmquist <chrise at pobox.com>
o: Northern Lights Radio Society <nlrs at mailman.qth.net>
ent: Wed, Jan 2, 2013 10:44 am
ubject: Re: [NLRS] VHF low pass filters?

I think Kirk is in New Hope, so we're talking about the DTV channels re in
the Twin Cities right?
his means that the only VHF carriers in play are 9 (186-192 MHz) and 11
98-204 MHz).  I don't think his 6m signal is having an in-band affect
rather, he's not stomping on a channel that is close to 6m.
eems more like fundamental overload/blocking due to either a preamp being
turated or the TV front-end not rejecting off-channel stuff well enough.
hris N0JCF

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