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HDTV Antennas

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May 19, 2005 10:07:28 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

OK Still new to HD.. Went to the local radio shop. Really these guys have
always done a good job with help/info for me for many years.
On recommendation I bought their 'local' special antenna.

Had problems with my old antenna getting the NBC station HD, which is the
closest station on SD. CBS station SD is at the same tower.
CBS HD is out of reach for anybody that isn't in the valley there
transmitter is in, have got this info from more than one source.

Now I can get all of the available stations 'sometimes' They are all spotty
at best. The antenna must be tweaked for each station and never seems to be
in the same spot from day to day.

Last night I got p o'd and went and got out a REAL old UHF bow tie that came
with a portable TV that I think got tossed five years ago..
Sitting in my chair holding this antique wire, I could get all of the
stations with NO dropouts HAAAAAAAAAAAAAA.....

Is it possible to overdrive the antenna inputs on a HD receiver?

Years ago I had to put an amp inline to boost the signal to get the PBS
station local...

jb..

More about : hdtv antennas

May 20, 2005 4:07:43 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

I get the one over-the-air HD station here with a cheapo "amlified" pair of
rabbit ears I got at Walmart.
Anonymous
May 20, 2005 5:16:38 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

Perhaps the feed line (coax) to your "special" antenna is not in too
good a shape and that might be the problem ?
Related resources
Anonymous
May 20, 2005 8:15:16 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

"jb" <st1@cpsv.com> wrote in news:D 6j67l$oek$1@news.netins.net:

> OK Still new to HD.. Went to the local radio shop. Really these guys
> have always done a good job with help/info for me for many years.
> On recommendation I bought their 'local' special antenna.
>
> Had problems with my old antenna getting the NBC station HD, which is
> the closest station on SD. CBS station SD is at the same tower.
> CBS HD is out of reach for anybody that isn't in the valley there
> transmitter is in, have got this info from more than one source.
>
> Now I can get all of the available stations 'sometimes' They are all
> spotty at best. The antenna must be tweaked for each station and never
> seems to be in the same spot from day to day.
>
> Last night I got p o'd and went and got out a REAL old UHF bow tie
> that came with a portable TV that I think got tossed five years ago..
> Sitting in my chair holding this antique wire, I could get all of the
> stations with NO dropouts HAAAAAAAAAAAAAA.....
>
> Is it possible to overdrive the antenna inputs on a HD receiver?

Yes, it is possible, depending on the receiver. And overdriving can
introduce intermod products that may interfere with reception. Of
course, if they would make receivers with decent GaAsFET front ends in
the first place, they would be a lot better at digging into the noise,
probably would not need a preamp unless at the end of a long transmission
line and would be difficult to overload. In fact, it may be that your
preamp is what's being overloaded if you're in an area with a lot of
strong UHF channels (analog or digital doesn't matter).

A good receiver front end should not need a preamp for short feedline
runs. It should have sufficient gain to pull in any signals that are
readable and it should have a good enough signal-to-noise ratio as well.
But not all receivers are equal. If your signals are weak and mixed with
a lot of string local stuff, you MAY get better mileage out of a
directional outdoor antenna with a mast-mounted preamp of good quality.
If the signals are then too strong for the receiver, you can introduce an
attenuator (the cheapest is a coil of RG-59 inserted into the coax line).

You can learn a lot by watching any analog signals that are on UHF. If
the signals are smeared and ghosty, then a directional antenna may help
you considerably by removing some of the reflections. If they are messed
up with stuff from off-channel transmitters, then you have intermod. Try
attenuating the signal. At this end of the Fraser Valley, there is
really only one UHF signal of any quality that I can get. It's the
analog French-language CBC feed on channel 14 and the best quality on it
comes from the tuner in my DVD recorder.


--
Dave Oldridge+
ICQ 1800667

A false witness is worse than no witness at all.
God is an evolutionist.
Anonymous
May 20, 2005 6:54:57 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

jb wrote:
> OK Still new to HD.. Went to the local radio shop. Really these guys have
> always done a good job with help/info for me for many years.
> On recommendation I bought their 'local' special antenna.
>
> Had problems with my old antenna getting the NBC station HD, which is the
> closest station on SD. CBS station SD is at the same tower.
> CBS HD is out of reach for anybody that isn't in the valley there
> transmitter is in, have got this info from more than one source.
>
> Now I can get all of the available stations 'sometimes' They are all spotty
> at best. The antenna must be tweaked for each station and never seems to be
> in the same spot from day to day.
>
> Last night I got p o'd and went and got out a REAL old UHF bow tie that came
> with a portable TV that I think got tossed five years ago..
> Sitting in my chair holding this antique wire, I could get all of the
> stations with NO dropouts HAAAAAAAAAAAAAA.....
>
> Is it possible to overdrive the antenna inputs on a HD receiver?
>
> Years ago I had to put an amp inline to boost the signal to get the PBS
> station local...
>
> jb..
>
>

It is possible that your antenna booster is doing more harm then good.
The fact that your indoor bow tie antenna out performed the RS antenna
strongly suggests that something is wrong with the RS antenna system.
Not necessarily the RS antenna itself, but maybe the feed line or your
antenna booster. Possibly, your booster might be VHF only. If your feed
line is twin lead or old cable (possibly weathered), replace it with a
new coaxial line. Although twin lead does provide lower loss then coax
cable, it is susceptible to installation anomalies which may induce
reflections along the line. Also it may pick up unwanted noise. If you
use coax make sure that the cable is connected to the antenna with a 75
ohm to 300 ohm transformer, as most TV antennas are designed for 300 ohms.
A good pre-amp (booster) can make the difference between reception and
no reception, especially is situations where the signal is weak. A good
preamp is the Channel Master 7777. It provides a separate pre-amp for
VHF and one for UHF, combined in the same housing. It provides
respectable noise, gain and overload capability.
However, as pointed out by another poster, if your coaxial line length
is short (maybe less then 25 feet) no pre-amp might provide the best
results. In my case with a 100 foot cable length a pre-amp does improve
reception. Install the pre-amp at the antenna if you decide to use one.
Anonymous
May 21, 2005 12:07:07 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

Hi. Can I use a preamp with an indoor Zenith silver sensor with a 50 foot
coax run until I get a roof top antenna?
"numeric" <numeric@att.net> wrote in message
news:5Tmje.232637$cg1.94476@bgtnsc04-news.ops.worldnet.att.net...
>
>
> jb wrote:
> > OK Still new to HD.. Went to the local radio shop. Really these guys
have
> > always done a good job with help/info for me for many years.
> > On recommendation I bought their 'local' special antenna.
> >
> > Had problems with my old antenna getting the NBC station HD, which is
the
> > closest station on SD. CBS station SD is at the same tower.
> > CBS HD is out of reach for anybody that isn't in the valley there
> > transmitter is in, have got this info from more than one source.
> >
> > Now I can get all of the available stations 'sometimes' They are all
spotty
> > at best. The antenna must be tweaked for each station and never seems to
be
> > in the same spot from day to day.
> >
> > Last night I got p o'd and went and got out a REAL old UHF bow tie that
came
> > with a portable TV that I think got tossed five years ago..
> > Sitting in my chair holding this antique wire, I could get all of the
> > stations with NO dropouts HAAAAAAAAAAAAAA.....
> >
> > Is it possible to overdrive the antenna inputs on a HD receiver?
> >
> > Years ago I had to put an amp inline to boost the signal to get the PBS
> > station local...
> >
> > jb..
> >
> >
>
> It is possible that your antenna booster is doing more harm then good.
> The fact that your indoor bow tie antenna out performed the RS antenna
> strongly suggests that something is wrong with the RS antenna system.
> Not necessarily the RS antenna itself, but maybe the feed line or your
> antenna booster. Possibly, your booster might be VHF only. If your feed
> line is twin lead or old cable (possibly weathered), replace it with a
> new coaxial line. Although twin lead does provide lower loss then coax
> cable, it is susceptible to installation anomalies which may induce
> reflections along the line. Also it may pick up unwanted noise. If you
> use coax make sure that the cable is connected to the antenna with a 75
> ohm to 300 ohm transformer, as most TV antennas are designed for 300 ohms.
> A good pre-amp (booster) can make the difference between reception and
> no reception, especially is situations where the signal is weak. A good
> preamp is the Channel Master 7777. It provides a separate pre-amp for
> VHF and one for UHF, combined in the same housing. It provides
> respectable noise, gain and overload capability.
> However, as pointed out by another poster, if your coaxial line length
> is short (maybe less then 25 feet) no pre-amp might provide the best
> results. In my case with a 100 foot cable length a pre-amp does improve
> reception. Install the pre-amp at the antenna if you decide to use one.
>
Anonymous
May 21, 2005 6:02:49 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

rppb wrote:
> Hi. Can I use a preamp with an indoor Zenith silver sensor with a 50 foot
> coax run until I get a roof top antenna?

A good pre-amp and a 50 foot coaxial line length may help; but try the
antenna first without a pre-amp. If you get satisfactory results, your
done. Recently, I tried a 50 foot length of coaxial cable connected to
an attic antenna with no real noticeable difference between the pre-amp
and no pre-amp. Either way I got good results; but not as good as when
I had the antenna mounted on the roof.
Anonymous
May 21, 2005 4:28:05 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

"numeric" <numeric@att.net> wrote in message
news:5Tmje.232637$cg1.94476@bgtnsc04-news.ops.worldnet.att.net...
>
>
> jb wrote:
> > OK Still new to HD.. Went to the local radio shop. Really these guys
have
> > always done a good job with help/info for me for many years.
> > On recommendation I bought their 'local' special antenna.
> >
> > Had problems with my old antenna getting the NBC station HD, which is
the
> > closest station on SD. CBS station SD is at the same tower.
> > CBS HD is out of reach for anybody that isn't in the valley there
> > transmitter is in, have got this info from more than one source.
> >
> > Now I can get all of the available stations 'sometimes' They are all
spotty
> > at best. The antenna must be tweaked for each station and never seems to
be
> > in the same spot from day to day.
> >
> > Last night I got p o'd and went and got out a REAL old UHF bow tie that
came
> > with a portable TV that I think got tossed five years ago..
> > Sitting in my chair holding this antique wire, I could get all of the
> > stations with NO dropouts HAAAAAAAAAAAAAA.....
> >
> > Is it possible to overdrive the antenna inputs on a HD receiver?
> >
> > Years ago I had to put an amp inline to boost the signal to get the PBS
> > station local...
> >
> > jb..
> >
> >
>
> It is possible that your antenna booster is doing more harm then good.
> The fact that your indoor bow tie antenna out performed the RS antenna
> strongly suggests that something is wrong with the RS antenna system.
> Not necessarily the RS antenna itself, but maybe the feed line or your
> antenna booster. Possibly, your booster might be VHF only. If your feed
> line is twin lead or old cable (possibly weathered), replace it with a
> new coaxial line. Although twin lead does provide lower loss then coax
> cable, it is susceptible to installation anomalies which may induce
> reflections along the line. Also it may pick up unwanted noise. If you
> use coax make sure that the cable is connected to the antenna with a 75
> ohm to 300 ohm transformer, as most TV antennas are designed for 300 ohms.
> A good pre-amp (booster) can make the difference between reception and
> no reception, especially is situations where the signal is weak. A good
> preamp is the Channel Master 7777. It provides a separate pre-amp for
> VHF and one for UHF, combined in the same housing. It provides
> respectable noise, gain and overload capability.
> However, as pointed out by another poster, if your coaxial line length
> is short (maybe less then 25 feet) no pre-amp might provide the best
> results. In my case with a 100 foot cable length a pre-amp does improve
> reception. Install the pre-amp at the antenna if you decide to use one.
>

He never said it was a Radio Shack (RS) antenna, just a "Special" antenna
from a local radio shop. RS antennas work quite well in Albuquerque, NM
And they don't cost all that much.
--
Bearman
If it's got tits, tires, tubes, or transistors, it's trouble.
Anonymous
May 22, 2005 9:00:42 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

bearman wrote:

> He never said it was a Radio Shack (RS) antenna, just a "Special" antenna
> from a local radio shop. RS antennas work quite well in Albuquerque, NM
> And they don't cost all that much.

Your right, I missed that. I could however cover up and say that RS is
an abbreviation for "radio shop" ;) . Do not think I would have changed
my reply though.
May 22, 2005 6:51:07 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

"jb" <st1@cpsv.com> wrote in message news:D 6j67l$oek$1@news.netins.net...
> OK Still new to HD.. Went to the local radio shop. Really these guys have
> always done a good job with help/info for me for many years.
> On recommendation I bought their 'local' special antenna.
>
> Had problems with my old antenna getting the NBC station HD, which is the
> closest station on SD. CBS station SD is at the same tower.
> CBS HD is out of reach for anybody that isn't in the valley there
> transmitter is in, have got this info from more than one source.
>
> Now I can get all of the available stations 'sometimes' They are all
> spotty at best. The antenna must be tweaked for each station and never
> seems to be in the same spot from day to day.
>
> Last night I got p o'd and went and got out a REAL old UHF bow tie that
> came with a portable TV that I think got tossed five years ago..
> Sitting in my chair holding this antique wire, I could get all of the
> stations with NO dropouts HAAAAAAAAAAAAAA.....
>
> Is it possible to overdrive the antenna inputs on a HD receiver?
>
> Years ago I had to put an amp inline to boost the signal to get the PBS
> station local...
>
> jb..
>
>

I use a 4 bay bow tie from channel master in the attic with no pre amp and
70 ft of RG6. The antenna is on a channel master rotator. I get great
results with one of the stations 40 miles away and through city clutter. I
tried pre amps and they actully introduced to much resistance and my
channels dropped out. I tried 2 antennae with a joiner and that did the same
thing. Added about 7 db of noise per antenna channel. The rotator is the
best. The 4 bay bowtie has a wide acceptance angle and I only have to
rotate for the one 40 nile disatant channel.

BC
May 23, 2005 12:31:52 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

Thanks guys for the input.
Some lingering answers.. No it's not from Radio Shack. The old antenna was
and gave great reception for the 20 years it was up. Just didn't seem to be
able to do the UHF for the local NBC station. The antenna new one was build
in a town not to far from here. I think they might also do RCA antenna
because the box it came in was a backward wrap of an RCA model... ? Strange
at first but wft..

Coax run is about 50ft or so and was put in when the house was built in the
seventies.. Don't know for sure what the exact numbers are on it but
guessing it's the lowest grade possible. Will attempt to replace with some
new coax.

Booster is spec'd for VHF UHF but who can say.. Going to remove it from the
HD line and try that for awhile..

Receiver is a USD from our friendly Wally World..

jb..


"BC" <bcphoto@core.com> wrote in message
news:v%0ke.31$rk.0@newssvr17.news.prodigy.com...
>
> "jb" <st1@cpsv.com> wrote in message news:D 6j67l$oek$1@news.netins.net...
>> OK Still new to HD.. Went to the local radio shop. Really these guys have
>> always done a good job with help/info for me for many years.
>> On recommendation I bought their 'local' special antenna.
>>
>> Had problems with my old antenna getting the NBC station HD, which is the
>> closest station on SD. CBS station SD is at the same tower.
>> CBS HD is out of reach for anybody that isn't in the valley there
>> transmitter is in, have got this info from more than one source.
>>
>> Now I can get all of the available stations 'sometimes' They are all
>> spotty at best. The antenna must be tweaked for each station and never
>> seems to be in the same spot from day to day.
>>
>> Last night I got p o'd and went and got out a REAL old UHF bow tie that
>> came with a portable TV that I think got tossed five years ago..
>> Sitting in my chair holding this antique wire, I could get all of the
>> stations with NO dropouts HAAAAAAAAAAAAAA.....
>>
>> Is it possible to overdrive the antenna inputs on a HD receiver?
>>
>> Years ago I had to put an amp inline to boost the signal to get the PBS
>> station local...
>>
>> jb..
>>
>>
>
> I use a 4 bay bow tie from channel master in the attic with no pre amp and
> 70 ft of RG6. The antenna is on a channel master rotator. I get great
> results with one of the stations 40 miles away and through city clutter.
> I tried pre amps and they actully introduced to much resistance and my
> channels dropped out. I tried 2 antennae with a joiner and that did the
> same thing. Added about 7 db of noise per antenna channel. The rotator
> is the best. The 4 bay bowtie has a wide acceptance angle and I only have
> to rotate for the one 40 nile disatant channel.
>
> BC
>
>
>
May 23, 2005 4:53:06 PM

Archived from groups: alt.tv.tech.hdtv (More info?)

Many stations are not up to full power on their HD yet but are working it in
stages I understand so what may be a marginal signal today may be strong in
the future. I don't think signal boosters are any good for weak signals.
They work ok to distribute a strong signal to a number of sets. I tried
Radio Shack's best antenna (stealth like) and got nothing and with the nuch
less expensive Channel Master 4 bay bow tie I get 7 HD channels with an
attic installation.

BC




"jb" <st1@cpsv.com> wrote in message news:D 6rbqg$g7b$1@news.netins.net...
> Thanks guys for the input.
> Some lingering answers.. No it's not from Radio Shack. The old antenna was
> and gave great reception for the 20 years it was up. Just didn't seem to
> be able to do the UHF for the local NBC station. The antenna new one was
> build in a town not to far from here. I think they might also do RCA
> antenna because the box it came in was a backward wrap of an RCA model...
> ? Strange at first but wft..
>
> Coax run is about 50ft or so and was put in when the house was built in
> the seventies.. Don't know for sure what the exact numbers are on it but
> guessing it's the lowest grade possible. Will attempt to replace with some
> new coax.
>
> Booster is spec'd for VHF UHF but who can say.. Going to remove it from
> the HD line and try that for awhile..
>
> Receiver is a USD from our friendly Wally World..
>
> jb..
>
>
> "BC" <bcphoto@core.com> wrote in message
> news:v%0ke.31$rk.0@newssvr17.news.prodigy.com...
>>
>> "jb" <st1@cpsv.com> wrote in message news:D 6j67l$oek$1@news.netins.net...
>>> OK Still new to HD.. Went to the local radio shop. Really these guys
>>> have always done a good job with help/info for me for many years.
>>> On recommendation I bought their 'local' special antenna.
>>>
>>> Had problems with my old antenna getting the NBC station HD, which is
>>> the closest station on SD. CBS station SD is at the same tower.
>>> CBS HD is out of reach for anybody that isn't in the valley there
>>> transmitter is in, have got this info from more than one source.
>>>
>>> Now I can get all of the available stations 'sometimes' They are all
>>> spotty at best. The antenna must be tweaked for each station and never
>>> seems to be in the same spot from day to day.
>>>
>>> Last night I got p o'd and went and got out a REAL old UHF bow tie that
>>> came with a portable TV that I think got tossed five years ago..
>>> Sitting in my chair holding this antique wire, I could get all of the
>>> stations with NO dropouts HAAAAAAAAAAAAAA.....
>>>
>>> Is it possible to overdrive the antenna inputs on a HD receiver?
>>>
>>> Years ago I had to put an amp inline to boost the signal to get the PBS
>>> station local...
>>>
>>> jb..
>>>
>>>
>>
>> I use a 4 bay bow tie from channel master in the attic with no pre amp
>> and 70 ft of RG6. The antenna is on a channel master rotator. I get
>> great results with one of the stations 40 miles away and through city
>> clutter. I tried pre amps and they actully introduced to much resistance
>> and my channels dropped out. I tried 2 antennae with a joiner and that
>> did the same thing. Added about 7 db of noise per antenna channel. The
>> rotator is the best. The 4 bay bowtie has a wide acceptance angle and I
>> only have to rotate for the one 40 nile disatant channel.
>>
>> BC
>>
>>
>>
>
>
Anonymous
May 24, 2005 3:16:36 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

In article <Smkke.462$2u1.225@newssvr19.news.prodigy.com>,
"BC" <bcphoto@core.com> writes:
> Many stations are not up to full power on their HD yet but are working it in
> stages I understand so what may be a marginal signal today may be strong in
> the future. I don't think signal boosters are any good for weak signals.
> They work ok to distribute a strong signal to a number of sets.
>
I think that you are kind-of close about your understanding of the
benefits of 'boosters' or more appropriately VHF/UHF preamps -- they
are not a panacea. However, they can be very helpful for purposes
beyond their 'gain' alone.

For example, if you have a long run of coax, then putting the preamp
immediately after then antenna can help to mitigate many of the negative
effects of the coax attenuation.

Another purpose is to help to mitigate some of the problems due to
the sometimes extreme mismatch between the antenna/coax/TV-frontend.

In some cases, a preamp can help to improve indoor reception, but the
gain isn't always the primary benefit.

For a preamp to be 'rock solid' and not have significant negative effects
in practically all circumstances, it would have to have a fairly specific
set of behaviors:

Limited gain (approx 10-15dB at most.)
High power output capability (on the order of 10-100mw -- 10-20dBm)
High 3rd order intermod intercept (30dBm or greater.)
Reasonably low noise over a wide impedance range (<1.5-2dB NF over a wide
range around 75ohms.)
Reasonably good input/output isolation to help buffer the mismatches.
Of course, appropriate bandwidth, etc.

You'll find that few CHEAPO preamps will meet these criteria, especially
the power handling capabilities. This will mean that the preamps will
create more damage than they'll help.

I happen to have some preamps that are 'marginal', but do help my
reception: approx 15dB gain, 10dbm power output, 3dBNF. I doubt
that most junk from consumer manufacturers will meet even those
'weak' specs.

A good preamp could be built for $5 parts cost (or even less.) A super
good preamp could be built for $10 parts cost. A reasonably good preamp
(like mine) could probably be built for less than $2-3.

A preamp with performance that is worse than mine (above) is more likely
to cause problems than to be helpful (except in limited circumstances.)

John
!