Here is what my (hopefully) final setup looks like once I decided to risk using a 10.5 foot 1.375" diameter electrical conduit instead of the more sturdy 8 foot 1.625 inch diameter fence post, along with a CableGuard CG-500 Coax Demarcation Enclosure for a Channel Plus 2532 combiner.

All coaxial cable is RG-6 quad shielded solid copper.

HDB91X Yagi antenna pointed to 153 degrees magnetic (South Bend), 5 foot coax connection to the 2532 combiner

HDB91X Yagi antenna pointed to 266 degrees magnetic (Chicago), 5 foot coax connection to the 2532 combiner

4 foot coax connection from 2532 combiner to RCA TVPRAMP1R preamplifier, 75 feet coax to a ground block, 50 feet to preamp power inserter and TV.

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To help others planning on installing their own antenna(s), I thought I'd list in no particular order some of the mistakes I made, plus I might mention a few good things I did along the way.

10.5 feet 1.375 inch diameter conduit used to mount two HDB91X antennas (upper South Bend 153 degrees magnetic, lower Chicago 266 degrees magnetic) >> Channel Plus 2532 combiner >> RCA TVPRAMP1R RCA Preamplifier >> 75 ft coax >> Ground Block >> 50 ft coax >> Preamp power supply >> TCL 55R617 Television (no splitters)

1. Measure twice, drill once! Unfortunately, I drilled one hole in my roof that missed the intended rafter by about half an inch. It was preventable by checking the spot that identified by tapping the roof and listening for solid wood was about 16 inches from the hole I had just drilled.

2. Check that a tripod you order has feet that are 32 inches apart when the legs are fully spread, so that when installed on a roof with standard 16 inch rafter separation that the tripod feet can all be positioned over a rafter.

3. Measure accurately how much coaxial cable you really need, and strongly consider ordering exact number of feet of coax you really need. (In my case, my 75 feet of coax from antenna to ground block only needed to be 55 feet and I have 20 feet wasted. Plus my 50 feet coax from ground block to TV only needed to be about 35 feet. So I have extra signal loss due to that extra unneeded coax.

4. A positive - I did use RG-6 quad shielded solid copper for all coaxial cables, including the short ones at the antennas. It is not that much more expensive and ensures proper voltage and current for the preamplifier at the antenna.

5. I have no idea how to obtain a proper meter for checking TV signals, but I should have made an effort to do so to know which part of my roof would get the best signal before installing my tripod. As long as it was not too expensive to do so.

6. At the end of the HDB91X instructions for assembly, you install the mounting bracket. I eventually reversed the direction of that bracket which allows the angle to be adjusted, because using the instructions as written, you can only adjust the angle DOWNWARD. I preferred to adjust tilting slightly UPWARD and therefore needed to reverse that bracket. Also, even if you use the normal "notch", you can push the bolt against one side of that notch to make a few degrees of adjustment.

7. Make sure you use a proper 75 ohm terminator at the end of an unused connection. Also, they can be used to protect the end of a coax cable when used with a female-female connector in the middle of the project.

8. If you can't keep your connections at the bottom of a device, such as with the 2532 combiner, best to put it in a waterproof box that is large enough for the coaxial cable to not bend too much. I also received some good advice from an AT&T technician on how to mount it to the pole, which included needing to drill a few holes in the upper part of the box for a zip-tie and use of silicon caulk to ensure water didn't get into the box.

9. Switching to the 10.5 foot conduit instead of an 8 foot fence post for a mast resulted in better South Bend station reception - but it also resulted in some Chicago station signal reduction. That was something in my case I could live with, but it is something that needs to be considered.

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Thank you for your excellent summary. A well handled learning experience with a successful outcome.

Combining two UHF antennas aimed in different directions with a splitter in reverse can work if you have a suitable location and you do the right things.

Well done, Bud!

VHF-High antenna needed

WBBM real channel 12 (CBS) in Chicago is one of the few extra channels I’d like to receive but the HDB91X never picked it up, even if my second antenna pointing to South Bend was disconnected.

Signal strength - Nm is about 30 dB per TVfool.

Does anyone sell a lower price VHF-high antenna these days? I’d install it below the two Yagi antennas, just above the top of the tripod, about 17 feet above ground, and I can connect to the presently unused VHF input on my RCA TVPRAMP1R preamplifier.

(I did find from the same company this 14 dB maximum gain VHF-High only antenna

https://www.newark.com/stellar-labs/...=VHF%20antenna

and also a lesser 12 dB maximum gain VHF-High model

https://www.newark.com/stellar-labs/...48Y8141?st=VHF

newark has 2 VHF only antennas
30-2475 (little brother)
https://www.newark.com/stellar-labs/...vhf/dp/48Y8141

30-2476 (big brother...which says on backorder but can be ordered)
https://www.newark.com/stellar-labs/...nna/dp/71Y5462

After checking the Hi-VHF gain for about 200 MHz for several antennas, many of them very expensive, none of them had higher VHF gain than the two Stellar Labs antennas. I surely would have bought the larger (30-2476) one with 13-14 dB gain for only $9 more than the smaller one (30-2475)

https://www.newark.com/stellar-labs/...aa00060a24060d

at 11-12 dB. But the larger one was out of stock and I wasn't waiting - and those 2 dB should not matter much with a 30 dB NM signal on my roof for WBBM real channel 12.

It should arrive Saturday or Monday - I'll let you know if this third antenna works great - and without screwing up the 80 UHF channels I'm presently receiving!

(Oh, yeah, I'm going to have to re-scan because I can't manually enter channels - which means I'll need to deal with the 57.1 Daystar channel in Chicago that I hope to avoid, but I surely will need to temporarily point my Chicago antenna significantly off the west direction and scan, hopefully to have WBBM come in and for Daystar to not come in!)

Edit - of course, a day after the 2475 model shipped, I received an email that the 2476 is no longer back ordered and is available for purchase. 2 dBs down the drain which would have cost less than $10 extra. Will have to hope for now the 2475 does the job.

it should. I use a similar antenna (an older winegard VHF only antenna) for a station that is around 27db 2edge for me and it works great.
I also have the 2476 too but that is for something different

I have a VHF-Hi Stellar Labs 30-2475 antenna (https://www.newark.com/stellar-labs/...48Y8141?st=VHF) arriving tomorrow.

This VHF-High antenna will connect directly to the VHF input on an RCA TVPRAMP1R preamplifier, with the UHF/VHF input on that preamp being connected to two HDB91X antennas (via a Channel Plus 2532 combiner).

I am considering mounting this below my two HDB91X antennas and only 6 to 12 inches above the top of the tripod being used. (It would be three feet below the HDB91X Chicago antenna and pointing in the same direction toward Chicago to pick up real channel 12 CBS WBBM.) I know there has been discussion about how far apart a UHF or a VHF antenna needs to be away from an antenna above or below it. Does that criteria also apply to putting an antenna a short distance above the top of the tripod as the lowest of three antennas?

That should be OK according to the Toner spacing chart, dimension D:
https://www.tonercable.com/pdf/antenna.pdf

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But looking at that document for VHF channel 12, 2/3 wavelength = 38 inches so the wavelength is 57 inches and half a wavelength is 28.5 inches.

Then I see in that document that half a wavelength is the minimum vertical separation from the "antennal crossbar" to a nearby mechanical structure.

My personal feeling is that for a 5 foot long antenna, and that only a small part of the antenna will be less than 24 inches from any part of the tripod, I have a gut feeling 12 inches might be enough distance above the top of the tripod.

Looks like this will be another experimentation issue! Temperatures never getting above the high 30s for the next 10 days in southwest Michigan. Not sure when I'll get this VHF antenna installed - hopefully will be next weekend if not too windy.

2/3 wavelength is optimum for vertical stacking of two identical antennas for increased gain. Your UHF and VHF antennas are not identical and are not combined for more gain.


That is true.

As winter begins to show up in Michigan, I plan on getting this third (VHF-High 30-2475) antenna installed before the roof becomes inaccessible.

But come spring, I plan on spending $80 on a Televes 536041 preamplifier (26 dB gain, 10 dB noise) with three inputs (two UHF, plus one "BIII/DAB" 174-254 MHz which encompasses the VHF-High 174-216 MHz channels 7-13) and if it works well, it would replace my Channel Plus 2532 combiner, the waterproof box it is in, and the RCA TVPRAMP1R preamplifier. I'd probably use 10 foot, 7 foot, and 4 foot RG-6 solid copper quad shield connecting the Televes to the South Bend HDB91X, Chicago HDB91X, and Chicago Stellar Lab VHF-High 30-2475, respectively.

At least I already have the tool to strip the coax down to the center conductor, since you connect the center conductor directly and do not use F-connectors on this Televes preamp. (I'll be making some short coaxial cables with an F-connector and female-female adapter on one end and stripped on the other to use for test purposes.)

A quick question about RG-6 and RG-11 coaxial cable. I might run a new cable next spring and I remember having a lot of problem finding solid copper RG-11. Assuming quad shielded RG-6 and quad shield RG-11, is it worth using RG-11 if it is not solid copper but the RG-6 would be? Assume cost of the cable is not a consideration. (In my case, if I ran a new cable it would be about 60 feet from antenna to ground block and 40 feet from ground block to TV.)

There are three factors to consider:

1. The DC resistance of the coax. A copper clad steel center conductor has a higher DC resistance than solid copper, which would cause a greater voltage drop for the preamp power. That might affect the performance of the preamp and would require a calculation.
2. The signal attenuation factor of RG6 is higher than for RG11, but the preamp gain should compensate for that; another calculation.
3. RG11 is hard to work with, requires special connectors, and is not compatible with the new preamp you are considering.

I vote for the solid copper RG6.

A preamp noise figure of 10 dB doesn't impress me, but you would have to try it to see if there is any improvement in your antenna system.

What improvement are you looking for with a new system?

The Televes noise may be close to 3 dB as described in this Solid Signal review:

From https://blog.solidsignal.com/reviews...ed-amplifiers/

“Televes’ mast-mounted amplifiers are a little different from other amplifiers you’ll find on the market. They’re sort of a mix between preamplifier and distribution amplifier — the power levels are extremely high, but then you have the ability to combine multiple signals and, at least according to the manufacturer, there’s a higher noise figure than you normally find in a true preamp.

The company is really addressing the way amplifiers are used in the 21st century. When all TV broadcasting was analog, the preamp itself was more important for pulling in distant signals, and the noise figure was something that was absolutely all-important. After all, it was possible to pull in a very weak signal and amplify it so it would be stronger, but you certainly didn’t want to add a lot of noise as well.

Today, the main reason for amplifying is to overcome long cable runs or distribute the signal to multiple TVs. Televes’ engineers built their amplifiers for that purpose, making them super-powerful, and also adding the ability to power antennas that, themselves, are already amplified.

In real world testing, gain from this amplifier was extraordinarily high, averaging 26dB throughout the usable range. As you can see from the chart, the strongest gain was in the lower end of the UHF spectrum which is perfect for most broadcast applications as the majority of broadcasts are in that range.

Various documents available on the web put the noise figure of these amps between 7.5 and 10 dB. That seemed very high even for a distribution amplifier, which is more of what this amp is. Without a full laboratory to test, our labs tried two different methods to derive the real-world effect of noise on the amplifier.

Using mathematics and analyzing the difference between the signal-to-noise ratios of unamplified and amplified modes, the data suggest that the amplifiers add about 2.75dB of noise when operating, far less than the rated number.

Using a secondary methodology, the antenna’s output was “padded” by 26dB to remove the increase in gain. Therefore, the difference between the signal-to-noise ratio of an unamplified antenna and the signal-to-noise ratio of an amplifed antenna should be the amount of noise inherent in the amplifier. The result, 3.15dB, is very consistent with the mathematical result and the difference between the two numbers could be attributed to minor differences in reception as the tests were taking place.

As a control test, the same measurements and methods were applied to a Winegard LNA100 amplifier, which has a published noise figure of 1dB. The Winegard amp’s number, using those methods, was 1.15dB, which suggests that the calculations are reasonably accurate.

When it comes to Televes’ published specs, they seem largely attributable to extreme honesty and scrutiny in the testing process and real-world results for this amp are far more consistent with other amplifiers with similar power levels.”

Interesting explanation about why the Televes spec sheet noise figure is wrong, but you still haven't said what improvement you are looking for in the Televes system that you don't have now with your present system.

Solid Signal made a similar maneuver when they inflated the gain figures for the HDB91X that is made for them by Qiaohua, which shows a lack of integrity for the sake of marketing.

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If the system works well through the winter and after leaves appear back on the trees in the spring, then there won't be much reason for me to change anything. There isn't any channel in South Bend or Chicago (or in Kalamazoo or Grand Rapids) that at the moment I'm not receiving that I would want to receive.

Interesting that Televes makes other more powerful similar preamplifiers which may not easily be purchased in the USA, Canada, or Mexico. For example, they make a 535840 model (24 volt instead of 12 volt) which is an FM - HiVHF - UHF1 - UHF2 4-input model with nearly 39 dB gain and 9 dB noise for UHF and 32 dB gain / 6 dB noise for VHF-High.



https://www.televes.com/me/downloadf..._001_28811.pdf

Yes, testing at your location is the best way to decide.

Too much preamp gain can cause overload and make it more difficult to receive your weaker signals.

I still remember the first time I connected two preamps in series, thinking "more is better." The overload was so severe, I didn't get any signals at all. Fortunately, my equipment survived.

THREE TYPES OF OVERLOAD

There are three types of preamp or tuner overload, in order of increasing signal strength:

1. The strong signals almost cause enough intermodulation distortion (IMD) to interfere with the reception of weak desired signals, but the spurious signals are at or below the noise floor of the weak signals. This is the point that holl_ands uses in his preamp charts to obtain max SFDR (Spurious Free Dynamic Range). No damage will happen.

As the strongest signals continue to increase in strength, more of the weaker signals are damaged until you reach:

2. The strong signals cause overload to the preamp or tuner that makes it impossible to receive any signals. No damage will happen. The strongest signals are still there, but they can't be decoded because the IMD products have damaged them so that they contain more errors (high BER....bit error ratio/rate) than can be corrected by the FEC (forward error correction).

3. The signals are so strong that the input transistor is toast. You are not likely to encounter OTA signals that strong, unless you live next door to a high power transmitter and you have your high gain antenna aimed at the transmitter's antenna.

As a general rule, tuners can tolerate stronger signals than preamps before overload. The difference in strength is approx. equal to the preamp gain.

RG-11 is not worth considering until the total length is around 200'. You have just 100' which is a typical length for most home installations.

Quad shield is unnecessary in all but the most extreme RF environments. If you have a high powered transmitter next door then quad shield could be useful. Quad shield does not have lower loss. A single foil shield plus a single braid is completely adequate is almost all installations.

I don't know where the idea came from that noise figure isn't as relevant in DTV as it was for analog TV. It's every bit as relevant. OTOH, the method they used to determine the LNA-100 noise figure was 1.15 dB is right in line with the 0.8 db to 1.3 dB noise figure I measured for the LNA-100. They may be entirely correct that the Televes preamp noise figure is around 3 dB. That would be very typical of many current preamps.

A 39 dB gain preamp is unnecessary in almost all cases and will probably do more harm that good if you have any moderately strong stations. There's an optimum amount of gain for preamps.

Optimum Gain to maintain the system noise figure = total loss between preamp and the first amplifier (often the TV tuner) + tuner/amp NF + 8 dB

For 100' of RG-6, a 2-way splitter and a 6dB tuner NF

Gain = 5 dB + 3.5 dB + 6 dB (typical) + 8 dB = 22.5 dB

More gain than that gets you almost nothing and increases the chance of overloading the tuner.

I thought I would show you the tree in the path of my Chicago HDB91X Yagi. It's a 4 or 5 trunk tree and I just measured it to be 20 to 21 feet away from my antenna (closer than I thought it was - I just paced it off).

I set up my tripod away from the west peak edge of the roof partly to back up away from this tree, plus backing up allowed 266 degrees magnetic to be directly through the center of the large gap.

I know the picture shows the antenna not quite horizontal. It presently is a few degrees above horizontal.

I seem to get acceptable signals from Chicago. Would you have expected my reception would be OK aiming through this tree gap only 20 feet away?

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It's never a good idea to put an antenna behind a tree, but if it must be behind that tree and Chicago is centered in the gap, that is the best location for the antenna.



It's certainly better than this:

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I completed 4nec2 Model for Vertically Stacked Stellar-Labs 30-2475 Hi-VHF 9-El FD-Yagi Antennas....Optimum Vertical Stacking Distance across entire Hi-VHF Band was 40-inches, presuming the use of two Equal-Length 300-ohm Twinlead to a common FeedPoint (where Balun is connected)....which has Zero Combiner Loss, cuz eliminates RF Combiner. I'm a bit underwhelmed by the F/B Ratio in this configuration....

I suspect that using 450-ohm Ladder-Line might be a bit better (should know by tomorrow)....and will try to Modify and start running a presumably "Best" alternative using Zero Loss HVH (Holl_ands Vertical Harness), which determines the Optimum Transmission Line Separation (and hence Impedance) and Lengths....so standby a few more days....

================================================== ==========
I analyzed two different combinations of Vertically Stacked UHF and Hi-VHF Antennas. Note that Gain was NOT affected unless they were VERY close together....however, F/B & F/R Ratio degradation was found unless Vertical Separation Distance was at least 4-ft and preferably 8-ft [note that CM4228 vs K6STI 5-El Yagi was Metal-to-Metal, whereas two Yagi's were Center-to-Center]:
https://imageevent.com/holl_ands/stacked/stackuhfhivhf

================================================== ==========
I also added Performance vs Vertical Separation Distance Charts for one of my Optimized UHF 8-El FD-Yagi models:
https://imageevent.com/holl_ands/sta...ck7elfdyagi2rr

PS: Using Narrow-Band "Rules Of Thumb" for Antennas might be good for 144 and 440 MHz Amateur Radio Antennas....but aren't very useful for WIDE BAND TV and FM Bands....where I've seen difficulties trying to provide acceptable performance on BOTH the Lower and Upper Band Edges....hence the need to use an Optimization Program. [Current UHF Bandwidth is 149%, Hi-VHF is 124% and FM is 123%.]

Uh-Oh.
His 30-2475 VHF antenna will also be behind the tree, mounted lower on the mast, and aimed at Chicago for WBBM.


http://www.tvfool.com/?option=com_wr...90380935603672

We'll see how it goes. Although I theoretically could put the HDB91X on the bottom and the 30-2475 VHF-High antenna in the middle, it would be hard to do now because the HDB91X is connected to the 2532 combiner inside the fixed box on the mast. So, until spring, I might be able to get the Chicago UHF antenna a few inches higher, but the VHF-High antenna will almost surely be on the bottom (until spring).

I was wondering with the wavelength of WBBM real channel 12 being between double and triple that of UHF channels, if that tree gap might not be large enough - perhaps the WBBM signal will be significantly affected, more than typical UHF channels.

I suggest you leave it on the bottom as planned and not mess with the UHF antennas that are doing OK.

VHF signals can make it around obstructions better than UHF signals. Try the VHF antenna on the bottom first. Trim the small branches if necessary. If that doesn't work, more drastic measures are required.

With recent snowfall having cleared from the roof today, I installed the VHF-High 30-2475 Yagi so the system looks like this:

* HDB91X Chicago & HDB91X South Bend connected to 2532 combiner
* 2532 combiner connected to UHF input of RCA TVPRAMP1R Preamp
* 30-2475 connected to VHF input of RCA TVPRAMP1R Preamp

TV Fool: http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d9038ce414b4cd c

Despite warnings that the assembly directions would not be helpful for the 30-2475 and that I did have some trouble putting my first HDB91X together, I had very little trouble with the 30-2475. There is MUCH less chance of damaging or bending something accidentally than the HDB91X which you always were concerned how you were going to set it down so none of the fins touched anything.

I didn't realize how small the 30-2475 was compared to the HDB91X. I am really, REALLY regretting not having waited until the 30-2476 larger Yagi was available (which in my case was only a single day when it was no longer backordered and only $9 more in cost).

I am now receiving the hoped for WBBM channel 2 CBS (real channel 12), but it is at a signal level 3 of 5 (minimum acceptable level needed to have a consistently good picture, but I wanted at least 4 out of 5) and there were a few other VHF stations in Chicago I was hoping to receive, but did not.

No problem (I think) sliding the RCA TVPRAMP1R preamplifier separate switch to "separate" - hopefully it stays in position. It is difficult to see exactly what you are sliding on the switch to move it.

I did lose channel 10 WYGN in Berrien Springs MI which I would never watch (very close but East of me, not in line with South Bend antenna) but a few of the UHF channels have slightly better signal strength.

When I re-scanned, unfortunately again the low signal Chicago Daystar virtual 57.1 hijacked the much higher strength signal from WBND ABC 57 from South Bend. As I did previously, I turned the westward Chicago HDB91X to the northwest until Daystar 57.1 lost signal, scanned again, then put it back to 266 degrees magnetic through the tree gap.

That's probably it for the winter. Depending on how things work this winter, the larger 30-2476 VHF-High antenna and the Televes 536041 Three-Input Mast-Mounted Amplifier and Combiner might be considered later, but we'll see how things go this winter.

Thanks to all of you for your encouragement and help - and infecting me with the "OTA bug"! LOL

Bud

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Which stations are those? The only operating high-VHF station I know of in Chicago is WBBM.

- Trip

WRME channel 6 in Chicago
WOCK channel 4 in Chicago
WYGN channel 10 (10 miles east of me)