The Official AVS Antenna and Related Hardware Topic! - Page 558 - AVS Forum | Home Theater Discussions And Reviews
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post #16711 of 16739 Old 05-12-2017, 06:01 AM
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Originally Posted by SFischer1 View Post
Question about antenna from San Francisco, CA - OTA



To me it does, comments from others?

SHF
That's the HDB91X antenna, which is a clone of the 91XG. Very good antenna, and available for under $40 often on sale. I have two up and running right now, and one in the box waiting...
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post #16712 of 16739 Old 05-12-2017, 11:39 AM
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Quote:
Originally Posted by SFischer1 View Post
Question about antenna from San Francisco, CA - OTA



To me it does, comments from others?

SHF
It looks a lot like a 91XG from Antennas Direct, although at a lower price. Most folks have had excellent results with this antenna, myself included. I bought a 91XG on Amazon for $70, so you don't have to pay list. Still not as cheap as the MCM, but for all the installation trouble and other components involved you probably want a decent product. Is the balun design different? Who knows, can't tell from a picture.

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post #16713 of 16739 Old 05-12-2017, 03:50 PM
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Looks like the 91XG, but it sure is cheaper in price. I wonder how the quality compares. Has anyone compared the two?

My complete SF Bay Area DTV Station Lists: http://www.choisser.com/sfonair.html
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post #16714 of 16739 Old 05-12-2017, 04:09 PM
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Quote:
Originally Posted by Primestar31 View Post
That's the HDB91X antenna, which is a clone of the 91XG. Very good antenna, and available for under $40 often on sale. I have two up and running right now, and one in the box waiting...
How are you configuring them, pointed at separate transmitters? RF combining, switches or separate tuners?

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post #16715 of 16739 Old 05-12-2017, 04:20 PM
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Originally Posted by lifespeed View Post
How are you configuring them, pointed at separate transmitters? RF combining, switches or separate tuners?
In my case, I have a UHF flamethrower station 35 miles away South-East on RF22 (WNEM), that is 1 MEGA-watt, and throws 874kW's my way! It's located about 200 yards away from another tower broadcasting on RF46 (WBSF), that broadcasts a total power of only 70kW's, yet only throws 31kW's my way. I have to use a Jan Jenca Jointenna device for RF46 with a dedicated HDB91x (91xg clone) aimed right at it, to keep it from breaking up. If I don't, RF22 (WNEM) swamps it out.

Then at the opposite farthest end of my local station bearings, there's a station on RF16 (WSMH) pushing only 29.9kW's my way, located right next to a station on RF48 (WAQP) pushing 841kW's!

So, I have one HDB91x dedicated and aimed at RF46 with a Jan Jenca Jointenna, then I have a second HDB91x aimed at the RF16 station (WSMH), which is my "all (UHF) channels EXCEPT channel RF46" antenna on that input of the Jointenna device. The combined output of the Jointenna goes into a Kitztech KT-200-COAX preamp, then into the UHF side of a Radio Shack UVSJ that's power-pass on the UHF side.

So, the two UHF HDB91x antenna's are aimed at the weakest stations in my arc, yet on the "all (UHF) channels EXCEPT RF46" HDB91x, it not only gets full signal on my other weak station in my receivable arc (RF16), BUT, the other stations are still powerful enough that they come in fine with the antenna aimed as it is.

By the way, I also have a third High band VHF only antenna (AC Y10-7-13) aimed at and picking up RF12 (WJRT) which is my only VHF station. That goes into the VHF side of a UVSJ, and is not amplified at all.

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post #16716 of 16739 Old 05-12-2017, 04:21 PM
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Quote:
Originally Posted by Primestar31 View Post
That's the HDB91X antenna, which is a clone of the 91XG. Very good antenna, and available for under $40 often on sale. I have two up and running right now, and one in the box waiting...
How long have you been using it? Just wondering about long-term reliability.
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post #16717 of 16739 Old 05-12-2017, 04:33 PM
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How long have you been using it? Just wondering about long-term reliability.
Using the HDB91x's, or this configuration of them? This configuration is about 1.5 years old, but moved to a new house where it used to have to be much higher up for the same signal levels. It's at 25 feet now, and used to be over 40ft at the previous house.

I've been using the HDB91x's for about 4 or so years and have had no issues with them. I previously had a regular 91XG, but it didn't survive a couple Winters without the plastic getting brittle and breaking.
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post #16718 of 16739 Old 05-12-2017, 04:49 PM
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Originally Posted by Primestar31 View Post
Using the HDB91x's, or this configuration of them?
How long you had the antenna in use. 4 years sounds good. Thanks.
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post #16719 of 16739 Old 05-12-2017, 05:08 PM
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Quote:
Originally Posted by Primestar31 View Post
In my case, I have a UHF flamethrower station 35 miles away South-East on RF22 (WNEM), that is 1 MEGA-watt, and throws 874kW's my way! It's located about 200 yards away from another tower broadcasting on RF46 (WBSF), that broadcasts a total power of only 70kW's, yet only throws 31kW's my way. I have to use a Jan Jenca Jointenna device for RF46 with a dedicated HDB91x (91xg clone) aimed right at it, to keep it from breaking up. If I don't, RF22 (WNEM) swamps it out.
Interesting situation, sounds like you've been able to make it work well with the Jointennas and directional antennae. I ended up going with dedicated network tuners (Silicondust HDHR4-2US) per antenna to combine my signals in the digital domain, no RF interactions and transparent to the user. But this setup presumes you're using a computer DVR front end instead of the tuner in your TV, which may not be so unusual these days.

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post #16720 of 16739 Old 05-12-2017, 05:19 PM
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Originally Posted by lifespeed View Post
Interesting situation, sounds like you've been able to make it work well with the Jointennas and directional antennae. I ended up going with dedicated network tuners (Silicondust HDHR4-2US) per antenna to combine my signals in the digital domain, no RF interactions and transparent to the user. But this setup presumes you're using a computer DVR front end instead of the tuner in your TV, which may not be so unusual these days.
I'm setup this way for using a Tivo Roamio basic, so couldn't go with a coax switch, rotor motor, or network tuners. Luckily the towers I need to aim at are all within about a 47 degree arc from East to South-East. I am dealing with a tree situation also, so that's why I have to also use the Kitztech preamp for uhf reception. The KT-200-Coax brings up the weaker stations a bit (and to compensate for the Jointenna loss), without overloading on the blowtorch stations.
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post #16721 of 16739 Old 05-13-2017, 11:41 AM
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That's a very good price for a fairly good UHF Yagi Antenna.....but it has significant Loss on Lower Channels.
8-Bay Bowtie Antenna (e.g. DB-8e, CM4228+HHH-Mod or HDB-8x) has MUCH more Gain on Lower Channels:
http://www.solidsignal.com/pview.asp?p=hdb8x


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post #16722 of 16739 Old 05-15-2017, 09:04 AM
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.... I previously had a regular 91XG, but it didn't survive a couple Winters without the plastic getting brittle and breaking.
I find that a bit surprising as I'm not aware of any similar concerns or complaints. In my personal experience, I had a "stretched" 91XG up on my previous home for 7 years. The only failure it ever suffered was from getting its tail end swatted by a nearby tree in a windstorm a few years back that required a new rear boom section as a replacement. We do get an occasional warranty call for directors that have been knocked off by hail or an occasional balun enclosure with water ingress, but that's about it. I can't recall a single claim for what you've described in the almost 9 years I've been here so I'd certainly be interested in your situation if you still have your antenna.

Just a reminder to all readers, all Antennas Direct antennas do come with a LIFETIME warranty, so don't overlook that value. We also have customer service personnel working seven days a week to handle inbound customer inquiries.

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post #16723 of 16739 Old 05-15-2017, 09:21 AM
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It was one of the original XG-91's, back at the end of the 1980's. I bought it mail order from an ad in either Popular Electronic's or Radio Electronics. I don't remember the name of the company I got it from anymore. It lasted less than 3 years, (it sagged in the middle also) at the top of a 56' tower.

This one had directors made of aluminum tubing in X's (pretty short ones), not the present stamped type ones.

I no longer have it, or what was left of it.
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post #16724 of 16739 Old 05-15-2017, 09:48 AM
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Antennas Direct has new versions of their Clearstream antennas, including the Clearstream 2MAX now sold at Walmart for $79. It looks like it is easier to assemble, and may now be more omnidirectional without the reflector screen. It also includes the VHF dipole. A 4MAX version is reportedly coming in June.
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post #16725 of 16739 Old 05-15-2017, 01:56 PM
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Originally Posted by Primestar31 View Post
It was one of the original XG-91's, back at the end of the 1980's. I bought it mail order from an ad in either Popular Electronic's or Radio Electronics. I don't remember the name of the company I got it from anymore. It lasted less than 3 years, (it sagged in the middle also) at the top of a 56' tower.

This one had directors made of aluminum tubing in X's (pretty short ones), not the present stamped type ones.

I no longer have it, or what was left of it.
Ah, so that wasn't one of our 91XG antennas after all. Antennas Direct first sold the 91XG around the year 2005 or so.

That explains a lot...

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post #16726 of 16739 Old 05-15-2017, 02:04 PM
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Antennas Direct has new versions of their Clearstream antennas, including the Clearstream 2MAX now sold at Walmart for $79. It looks like it is easier to assemble, and may now be more omnidirectional without the reflector screen. It also includes the VHF dipole. A 4MAX version is reportedly coming in June.
It's simple matter of pulling the antenna out of the box, no antenna assembly is necessary for the C2MAX in order to attach it to a mast. For the C1MAX (on our website) and the C4MAX (available mid June or so), the VHF dipoles need to be attached (pretty easy to do, Philips screwdriver). We re-did those models for our retail customers to make them much easier to install.

Without reflectors, all of the models are bi-directional on both UHF and VHF, not omnidirectional. Reflector kits (add-on option) will be available late summer early fall.

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post #16727 of 16739 Old 05-15-2017, 03:05 PM
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In my personal experience, I had a "stretched" 91XG up on my previous home for 7 years.
Any comments on the specific implementation of stretching, does it involve the higher frequency directors (closer) or lower frequency? What are the benefits, more directivity and gain?

Can we expect to see a scaled version of this antenna for the new 600MHz upper band limit of UHF TV? The 91XG design dates back to an 800MHz upper band edge, now it is 700MHz, soon to be 600MHz. Yes, it works as-is, but there will be a lot of performance left on the table with the much narrower 470 to 608MHz UHF TV band. Match and gain should dramatically improve with a narrower band design.

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post #16728 of 16739 Old 05-15-2017, 03:25 PM
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Any comments on the specific implementation of stretching, does it involve the higher frequency directors (closer) or lower frequency? What are the benefits, more directivity and gain?

Can we expect to see a scaled version of this antenna for the new 600MHz upper band limit of UHF TV? The 91XG design dates back to an 800MHz upper band edge, now it is 700MHz, soon to be 600MHz. Yes, it works as-is, but there will be a lot of performance left on the table with the much narrower 470 to 608MHz UHF TV band. Match and gain should dramatically improve with a narrower band design.
Stretching one is fairly easy, but not worth the trouble. Stacking them is a much better use of your time and money. If you need stacking that is. Raising a single antenna higher (or making sure you have clear line of sight) will usually gain you more.

I also wish they'd redesign for the new spectrum also. I'd buy two to replace my present HDB91x's.
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post #16729 of 16739 Old 05-15-2017, 03:49 PM
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I also wish they'd redesign for the new spectrum also. I'd buy two to replace my present HDB91x's.
I'll probably buy a new antenna once the manufacturers start re-designing their products. The first 100MHz amputation they seemed to ignore, but the band has now shrunk by more than half so lots to gain by a redesign.

As for my interest in stretching the 91XG, it is mostly academic. Stacking side-by-side would help SF bay area multipath via increased directivity, but I can get away with a single antenna currently. We'll see if anything changes after the repack.

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post #16730 of 16739 Old 05-17-2017, 08:17 AM
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The first 100MHz amputation they seemed to ignore, but the band has now shrunk by more than half so lots to gain by a redesign.
Our ClearStream UHF antennas were designed from the ground up for the post-2009 UHF frequencies. Our bowties antennas were also redesigned and relaunched as the "e" series shortly afterward (2011).

Quote:
As for my interest in stretching the 91XG, it is mostly academic.
My "stretched" 91XG was done by adding an additional center section to the stock antenna. It slightly narrowed the beamwidth and helped with a spot more forward gain. Magnitude of any of those changes would be nothing more than a guess at this point.

As for post-2020 UHF frequencies, I did hear that our design engineer was just tasked with the new parameters last week and given instructions on what to do. I do not know any details beyond that. Given that the development pipeline has, in the past, run anywhere from 6-24 months for a new product to emerge on the market, I'd expect 2020 to be the target date as we just spent a BIG truckload of money last year on product re-skins and some new product developments that haven't yet been announced..

As for the 91XG, I have now idea what its future might hold. Anyway, those decisions are above my pay grade, as we used to say when i was in the service years ago.
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post #16731 of 16739 Old 05-18-2017, 05:51 PM
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As for my interest in stretching the 91XG, it is mostly academic. Stacking side-by-side would help SF bay area multipath via increased directivity, but I can get away with a single antenna currently. We'll see if anything changes after the repack.

I made a 41 element 91XG out of two of them. I had it up for awhile and it seemed to work about the same as stacking two of them.
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post #16732 of 16739 Old 06-07-2017, 04:59 PM
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Most if not all of you know a lot more than I do about OTA reception/equipment. So any advise would be much appreciated.


In trying to amp up my signal a couple years ago I tried the RadioShack 15-321 antenna-mounted amp that also comes with an indoor signal booster. It didn't help. In fact. with the booster on, it made things worse. When I first installed antennas on the roof using a chimney mount, I got all new well-insulated RG6 cables. I have a 25' downlead and another 50' after a splitter. I was using a Clearstream 5 along with a DB2e combined with a VHF/UHF diplexer from Antennas Direct. Not the best setup for my situation in south San Jose as it turns out. At the time I got the C5 because I thought it was the only choice available for VHF. And since it receives some UHF, I figured I only needed to augment it with the small DB2e.


Current equipment:


Stellar Labs HDB91x Long Range 91-element UHF yagi (essentially a clone of the A.D. 91XG)
Stellar Labs “Deep Fringe” directional VHF antenna
Same diplexer/combiner as before
Tried a PA-18 preamp from A.D., but it actually results in degraded signal strength across the board on all channels!


With this setup there is still a noticeable db loss after the splitter, but UHF is improved a lot and KNTV RF12 moderately. All stations show up with 100% signal quality EXCEPT RF7, which varies wildly all the time. KGO's wimpy 23.8kw transmitter in SF is still hit or miss and their even weaker (RF35) repeater on Mt Allison is still not reliably consistent.


Any suggestions on amping the signal without spending a lot? I only really need to get KGO working reliably, which I suspect may be out of my control. Everything else may not be perfect, but it's good enough.


What I've considered so far:


Raising the antennas.
Upgrading to RG11 for either the 25' or 50' section or both.
And in case Rf35 ever gets going right, putting the DB2e back up to enhance the UHF from Mt Allison at least (don't know how to combine with the other 2 antennas, though).


Thanks,
Eric
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post #16733 of 16739 Old 06-07-2017, 05:18 PM
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Most if not all of you know a lot more than I do about OTA reception/equipment. So any advise would be much appreciated.
...
Thanks,
Eric
I suggest that you post to:

San Francisco, CA - OTA

Where we have a very knowledgeable group and some of the same experts that are here.

SHF

P.S. The requested method of offering a TVFool report is to include the link like:

http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3de6a49dd34f538 2


Which I extracted from your PDF. That allows some additional information that is only available by clicking.

Please include your ZIP code so we can tell where you are which your TVFool does not include as it usually does.


South San Jose can be hard, one person was way beyond help for KGO. The other comments I will hold until your location is pinned down better.


SHF

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post #16734 of 16739 Old 06-07-2017, 05:30 PM
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I suggest that you post to:

San Francisco, CA - OTA

Where we have a very knowledgeable group and some of the same experts that are here.

SHF
OK. Will do with the proper link.
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post #16735 of 16739 Old 06-07-2017, 05:41 PM
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South San Jose can be hard, one person was way beyond help for KGO. The other comments I will hold until your location is pinned down better.

SHF
Good advice re: how to request help. Not sure if you're referring to my KGO situation in the shadow of a hill with a strong adjacent channel transmitter, but those challenges can be overcome with a good antenna installed with short RG6 to the tuner and no pre-amp. The annoying dropouts were entirely the fault of KGOs repeater setup, which have been stable and resolved for more than a week now.

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post #16736 of 16739 Old 06-07-2017, 06:06 PM
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Originally Posted by lifespeed View Post
Good advice re: how to request help. Not sure if you're referring to my KGO situation in the shadow of a hill with a strong adjacent channel transmitter, but those challenges can be overcome with a good antenna installed with short RG6 to the tuner and no pre-amp. The annoying dropouts were entirely the fault of KGOs repeater setup, which have been stable and resolved for more than a week now.
Not you. That person was blocked from Sutro by two hills I remember and from Mt. Allison by a close hill. And the Mt. Allison transmitter is so much lower power and was blocked. He was South of the hills that Gone Hiking is to the North of according to his zip code.

Almaden Valley can be a big problem the further you go South East.

Yes KGO VC 7 RF 35 is much better these days but I do wonder if Toast0's location has some local problems like airplanes landing or taking off. I think there is a pattern to the large spikes, but I do not have it figured out.

http://ruka.org/~toast/atscdata/chart.php?c=35

Note to those not in the SF Bay area, Toast0 has a 24/7 station monitoring most frequencies.

SHF
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Last edited by SFischer1; 06-07-2017 at 06:17 PM.
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post #16737 of 16739 Old 06-10-2017, 11:57 AM
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Quote:
Originally Posted by ADTech View Post
It's simple matter of pulling the antenna out of the box, no antenna assembly is necessary for the C2MAX in order to attach it to a mast. For the C1MAX (on our website) and the C4MAX (available mid June or so), the VHF dipoles need to be attached (pretty easy to do, Philips screwdriver). We re-did those models for our retail customers to make them much easier to install.

Without reflectors, all of the models are bi-directional on both UHF and VHF, not omnidirectional. Reflector kits (add-on option) will be available late summer early fall.
I currently have a Clearstream 2V mounted in my attic. The specs on the website say - Range: 60 Miles, Gain: 10.2 dBi. However I have removed the reflector to make it bi-directional. With that modification, I don't know how much it changes the gain and range.

I'm considering replacing this antenna with the new Clearstream 4Max. The specs on the website say - Range: 70 Miles, Gain: 11 dBi. However, this model doesn't come with a reflector so it's already bi-directional.

Do you think the 4Max will perform better than the 2V with the reflector removed in a bi-directional application?

I haven't seen a gain plot/map for the new 4Max, so I don't know how symmetrical it is.

The only thing I can find is this image comparing the old Clearstream 2 vs the old Clearstream 4 (both with reflectors)...




One final question regarding the Clearstream JUICE amplifier. I notice that this uses a 12v power source while some competitors products use a 5v power source. Does this make any practical difference in the performance?
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post #16738 of 16739 Old 06-10-2017, 03:09 PM
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I analyzed C2, C2V and C2 w/o Reflector here, note that w/o Reflector it loses 4.1 dB on 470 MHz and 3.3 dB on 698 MHz:
http://imageevent.com/holl_ands/loop...taperedloopc2v

C4 and 4Max appear to be the same...here's the "sell sheet" with specs for the C4:
https://www.antennasdirect.com/cmss_...-sellsheet.pdf
Without reflector, it probably suffers ABOUT the same amount of Loss as C2....

The proof is in the SPECS....if they even bother to tell us what they are....or Calaveras's MEASUREMENTS:
http://photos.imageevent.com/holl_an...028Nov2015.jpg

Perfectly good Preamps can be designed to operate with 5-volts [or LESS], for example see most any CellPhone.....
And I wouldn't rule out that SOME Preamps MIGHT even be using a 5-volt to 12 or 15-volt Voltage Converter Chip, JUST so they can plug the Power Insertion Module into a convenient USB Port on your computer....or DTV.

FWIW: Pete Higgins measured ACTUAL voltages used by a few of his Preamps and also noted that his Winegard Preamps used an Voltage Regulator in the Preamp to ensure a steady 8 VDC was available for the circuitry, irrespective of how much Voltage Drop there might be in the Coax, whereas the RCA Preamp had the Voltage Regulator in the Power Insertion Module and hence was apparently designed to work with considerable Voltage Drop in the Coax:
http://www.digitalhome.ca/forum/81-o...ml#post2195858

Last edited by holl_ands; 06-10-2017 at 03:18 PM.
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post #16739 of 16739 Old 06-10-2017, 03:37 PM
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The problem with the preamps that use 5 V (not the in-line USB amps) is the distance between the preamp at the antenna and the power inserter inside. For the same amount of power (watts) needed by the preamp, the 5 V preamp will draw 2 to 3 times the current of the higher voltage preamps. This means 2 to 3 times the voltage drop in the coax that the preamp might not tolerate without a malfunction.

The general rule with the higher voltage preamps has been RG6 with a copper clad steel center conductor is OK up to 100 feet; RG6 with a solid copper center conductor can be used up to 200 feet. This is because the copper clad steel center conductor has a higher resistance than the solid copper.

I have no idea how long a coax line for a Winegard LNA-200 can be and still function properly, but maybe someday I'll test it.

If you can not measure it, you can not improve it.
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