OTA and Antenna System Gizmos

EscapeVelocity

Moderator, , Webmaster of EV's Antenna Blog
#1
Here is a thread for this and that as regards antenna systems and OTA.


First up.

The Pico Macom LPF-700



Features
Removes channels for insertion of security or other locally originated channels
Passes channels below cutoff frequency
Blocks higher channels allowing clean insertion of channels
Pass-Band Insertion Loss <0.5dB
Stop-Band Rejection >-50dB, SMD High Stability
High EMI Shielded Tube Case
Nickel Plated Precision Brass Threads
Custom design available

Band Pass 5~700MHz (CATV 2-108)
Band Stop 800~1000MHz (CATV 125-158)

Insertion Loss

Band Pass <1.0dB
Band Stop >50dB

Why would you want one?

To cut out possible Cell Tower transmission interference from overloading your amplifier or negatively affecting your system.

700 MHz is just above Channel 51 UHF (US Television).

800 MHz is a common cell tower frequency in use by Cingular and others. Furthermore, the new frequencies that were sold and the resulting squashing of the television UHF band will be put into use, sooner rather than later.

Both legacy television UHF and combo antennas have high gain up past Channel 70 and into the old Channel 80s. Additionally amplifiers current and old amplify signals up into this range. This could result in amplifier overload as the most likely way to negatively affect your TV reception.
 
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Piggie

Super Moderator
#2
Band Pass 5~700MHz (CATV 2-108)
Band Stop 800~1000MHz (CATV 125-158)

Insertion Loss

Band Pass <1.0dB
Band Stop >50dB

The question I have I can't find on the net is how the filter rolls off between 700 and 800 MHz. Assuming their published specs, we know the insertion loss below 700 MHz, and the stop above 800 MHz.

But we don't know how it rolls between them.

The reason I say this is the new 700 MHz band will certainly interfere with digital reception overloading amps if say you live too close to a MediaFlo tower, which is running more power than your average cell site. (assuming the 700 MHz cells will be about the same power as the 800 MHz cells.).

Why would you need one? block cell towers just as you stated yourself.
 

EscapeVelocity

Moderator, , Webmaster of EV's Antenna Blog
#4
Here is the Gizmo of the Day...

75 ohm F Terminator



Here is the Winegard version, model # TT5900 at Solid Signal.

This DC Blocking F-Type terminator helps eliminate interference on open ports. Helps eliminate ghosting and other forms of interference from neaby transmitters.

Are some 75ohm F terminators not DC blocking?

These help reduce standing and reflected waves within the transmission line system.

Get them to terminate wall plates (if your house or apartment is prewired), open unused splitter and distribution amp F connection points.
 

EscapeVelocity

Moderator, , Webmaster of EV's Antenna Blog
#5
Next item up for contemplation...

DC Voltage Blocker

Winegard VB 1000 DC Voltage Block for 75 Ohm F-Connector

Insertion Loss .75 dB Max
Frequency Range 5-1750 MHz
Used to block voltage from in-line power inserters
This is just one example from Winegard. There are many brands available.

What is it used for. Its used to block DC power from going to other televisions or tuners via splits, when using a power injected mast mount amplifier.
 
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EscapeVelocity

Moderator, , Webmaster of EV's Antenna Blog
#6
Gizmo of the Day...

Eagle Aspen FC-300LX Slimline Flexible 8 Inch Flat RG6 Coax Window Cable

Requires no drilling. Use through windows sills and door wall frames for fast and easy installations. Digital ready flat cables allow door or window to close and lock while installed.



Use this for house egress/ingress through a window, instead of slamming a window down on your coax cable and/or putting a towel or weather stripping in the gap at the bottom. This is very useful for renters or those who do not have permission to drill holes through the wall for coax cables to an outdoor antenna. Perhaps this to a nice Clearstream2 or DB2 right outside the window. Ill be picking one of these up to test.

HatTip DonM for turning me onto this product.
 

Fringe Reception

Super Moderator, Chief Content Editor
Staff member
#7
Gizmo of the Day...

Use this for house egress/ingress through a window, instead of slamming a window down on your coax cable and/or putting a towel or weather stripping in the gap at the bottom. This is very useful for renters or those who do not have permission to drill holes through the wall for coax cables to an outdoor antenna. Perhaps this to a nice Clearstream2 or DB2 right outside the window. Ill be picking one of these up to test.

HatTip DonM for turning me onto this product.
------------------------------------------------------------
EV and DonM,

You two just read my mind. :alien: The last time I went to Fry's I purchased a very similar unit. Naturally, I threw away its packaging and the only ID info on it, is the type of shrink tubing. I wonder how lossy they are and how they affect impedence of a coaxial circuit? If you would like a photo of this variation, I can shoot one for you EV.
Jim
 

EscapeVelocity

Moderator, , Webmaster of EV's Antenna Blog
#8
Is it not Eagle Aspen branded? This is the only one Ive seen, although coming from China, Im sure that others slap their brand logos on them.

I also wonder about impedence and loss characteristics. If you have aluminum windows then that could also impact these two measurements.

Id love to see a pic, if its not much trouble.
 

EscapeVelocity

Moderator, , Webmaster of EV's Antenna Blog
#12
Today's Gizmo...

Channel Master Jointenna

These are being closed out or discontinued is the rumor I heard....or maybe just closed out at Amazon.com...where they are on sale for $5.99...nearly half regular price.



These are used to insert a single channel antenna into the same line as another wideband antenna. Perhaps you have one channel that you really want in a different compass heading. That type of thing.

Ive noticed that the odd VHF High channels are more commonly in use than the even....is that just me? You are much more likely to see a channel 7, 9, 11, 13 used up before you see an even numbered VHF High Channel.

Also I think there is a tuneable UHF version of the Channel Master Jointenna, but its more expensive.
 

Piggie

Super Moderator
#13
Here is the Gizmo of the Day...

75 ohm F Terminator

Are some 75ohm F terminators not DC blocking?
A good number of them are just precision resistors, which would pass some of the power through them, if the splitter didn't DC Block.

Since most terminators are used on unused splitter ports, if you were to hook one up that was purely resistive to a port that passed DC on a typical amp, between the amp and the power supply (a rare configuration) then it would get very hot. Fortunately this is a very rare configuration for an antenna install where one antenna is powered and the other not, yet someone used a 3 or 4 way splitter (which would be baffling into itself) to combine the two antennas.

Still this would result using ohms law as Power equals the Voltage squared divided by the resistance. Or about 7 watts.... Probably as much as the power supply can actually output. Even a couple of watts would fry the resistor.

Not sure how the DC blocking ones are made, but probably something like a .01 mfd cap in series with a resistor would be a very low reflected wave and work from about 50 MHz up through UHF.

I am curious is anyone knows what is in one for sure sold for TV installs?

The ones we used in the studio were just 75 ohm resistors, but nothing was powered and we were only dealing with DC to 6 MHz base band analog video.
 

Piggie

Super Moderator
#14
Good catch on the lack of of a slope figure.
I brought that up just to push the esoteric limits of their specs.

But in reality (guessing from other filters), a couple of facts come to bear.

1) It is not cheap to build a brick wall filter. Brick wall means the response curve drops rapidly, over a very small percentage of the bandwidth.

2) Referring to 1) above, they probably can't publish that curve in just text but would require an image that would confuse even a lot of installers. They probably made it as good as they could for $25.

So in conclusion, it is the best thing on the market, and will only get cheaper if suddenly they find a lot of people need them which they probably will as they discover problems.

It's a wonder there hasn't been a sudden burst of problem with FloTV that was poised to operate came on line recently. I am guessing two things. One is FloTV transmitters are often in urban area where most are on cable or the OTA signals are strong and might not be a problem.

And in cases where it has already become a problem, I am betting most installers I have met or know would not even know what FloTV is or the fact of it's frequency or the installation locations that could be their customers problems.
 

Piggie

Super Moderator
#15
Gizmo of the Day...

Eagle Aspen FC-300LX Slimline Flexible 8 Inch Flat RG6 Coax Window Cable

Use this for house egress/ingress through a window, instead of slamming a window down on your coax cable and/or putting a towel or weather stripping in the gap at the bottom. This is very useful for renters or those who do not have permission to drill holes through the wall for coax cables to an outdoor antenna. Perhaps this to a nice Clearstream2 or DB2 right outside the window. Ill be picking one of these up to test.

HatTip DonM for turning me onto this product.
Someone with an analyzer needs to test these. But my guess is it's a trade off as has already been guessed at least in some people's minds.

The impedance of coax is determined by the diameter of the inner conductor, the distance from the outer conductor and the dielectric between them.

So right away, squished a piece of coax one knows it will change the distance between the inner and outer conductors. So it makes those of us that know that cringe.

But as the other devices, what is really inside? They could in fact use a much much thinner center conductor in the flat part. They might have found another dielectric that also helps them maintain or come close to 75 ohms.

Or it might be a squished piece of coax, that is better than trying to close a window on a round piece of coax deforming in unpredictable ways.

Would I recommend it?

Probably for anyone like EV says is a renter and has not choice.

The only thing that would make me change my mind (knowing and stating limitations above) would be if it offered an unacceptable amount of attenuation. Some one needs to at least measure the loss through this device.

It might even work for someone hanging a Winegard FreeVision out the window if they also have VHF but not enough signal inside, which is particularly true on VHF penetrating a building.

As a disclaimer I am waiting on Winegard to ship me a FreeVision to put up out side and play with it. I also have an older HD-1080 I have played with and it will be curious to compare them, though I can only measure signal quality.
 

EscapeVelocity

Moderator, , Webmaster of EV's Antenna Blog
#16
Jim, thanks for the pics. I hope you dont mind I post the pictures you sent me. Did you notice any significant or material decrease in performance with your limited signal meters using this Window PassThru Coax device?



 
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EscapeVelocity

Moderator, , Webmaster of EV's Antenna Blog
#17
Gizmo of the Day

UVSJ = UHF/VHF Signal Joiner

Pico Macom UVSJ UHF-VHF Band Separator-Combiner

Features
Separates and isolates VHF (54~216 MHz) from UHF high (470~809 MHz) signals, providing for clean insertion into headend strip amplifier
Filters and mixes VHF and UHF signals, allowing mixing of multiple antenna onto single cable
Reduces harmonics and out of band interference for improved amplifier performance
Low insertion loss 0.5 dB max
Impedance 75 Ohms
VHF-Band DC Power Passive for remote preamplifier powering
Machined F-Connector Threads
Epoxy Sealed Back Cover
Yellow-Chromate Plated Zinc Diecast Housing


The main reason for these is to joint 2 antennas together into the same coax line. A UHF antenna and a VHF antenna. They can also be used as filters.

Here DTVUSA forum member Piggie explains there use and has other creative ways to use them...

UVSJ vs Combiner/Splitters for Combining Antennas

Combining a UHF and VHF antenna w & w/o amps

The Pico Macom shown, is a favorite for its best of loss insertion spec at .5 dB Max, other similar devices usually spec at .7 dB Typical. Winegard and Channel Master offered several UVSJs or Signal Combiners/Band Seperators that were in larger housings that are worth looking into as well.

PS - The Pico Macoms can be hard to find. MarkerTek is a reputable business.
 

Fringe Reception

Super Moderator, Chief Content Editor
Staff member
#18
re: window passthru coax

EscapeVelocity wrote: Jim, thanks for the pics. I hope you dont mind I post the pictures you sent me. Did you notice any significant or material decrease in performance with your limited signal meters using this Window PassThru Coax device?
----------------------------------------
EV,
I was hoping you would post the photos: I thought you might have a way to add them to your prior post. This is the version Fry's sells and it is can be collapsed to about .100".

I haven't had a chance to try it yet --but I will! My girlfriend will tolerate coax thru our window during summer, but my paper towel and t-p cardboard tube "weather insulators" crammed in the gaps isn't her style! :icon_beat: LOL!
Jim
 

EscapeVelocity

Moderator, , Webmaster of EV's Antenna Blog
#19
Ha! Ha!

Oops! I missed a couple of days...

Gizmo of the Day is...

Variable Anttenuator

Here is one from Solid Signal.



These are used in several capacities. One of the most common is to combat multipath. You dial down the signal until the problematic multipath signal is lowered to the point where the tuner is no longer being affected by it, but still locked onto the primary signal.

You can also get non-variable barrel attenuators with denominations like -1 dB, -3 dB, -6 dB, -10 dB, and -20 dB.

There are other uses for them. They can be used to assess an antenna system when a signal meter or spectrum analyzer is not available. You can also use them to knock down signal enough to where you mast mounted amplifier will not overload (or perhaps your distribution amplifier).
 

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