The Official AVS Antenna and Related Hardware Topic! - Page 94

AntAltMike, thanks for those posts. I'm on my way to the dentist so I don't have time to digest them them yet but I can give you a bit more info. The "signal meter" I'm using is the one in a Dish 942 sat receiver so no doubt it's not entirely accurate for what I need to do. What it tells me is that when tuned to 22.1 or 22.2 the graph style meter is pegged at 100%. I can get a couple of Sutro stations at around 50-65%. The station is KCRB with analog 22 and digital 22.1 and 22.2. And you're right about 47 and 68, they are also strong as well but not as strong as 22.

My actual location is,

Lat 38.4473457
Lon 122.6992493

I don't recall what Sutro Tower or San Bruno Mt transmitters are at but those are the 2 I'm mainly concerned with.

Attached is a PDF map of the transmitter locations in the SF bay area.

 

Towers_All2.pdf 286.109375k . file

My house still has an ancient (1970's) era TV antenna attached to the chimmney; I still use it for SD PIP occasionally. It picks up the stronger VHF (analog) channels pretty clearly, and several of the UHF channels with varying amounts of fuzz and/or static. It doesn't have a rotation motor, but according to the HD maps, I need a "Red" antenna for all the stations in my metro area (Atlanta), which are fortunately clustered in a fairly small wedge southeast of my house.

N00b time: any chance this old clunker would work with an HD tuner, perhaps along with an added preamp? Sure would be nice, particularly from a cost/hassle perspective...

Digital receiver graphs don't really show signal strength so you can't tell if KRCB's signal is too strong or not. Some ways to reduce overload are to use a lower gain more overload resistant pre-amp like the Winegard AP-8700 (as long as the receiver doesn't overload) or to use antenna directivity to reduce the interferor. You have 30 degrees between KRCB and the SF towers, with a horizontal stack you could adjust their spacing until KRCB is notched while pointing towards the SF towers. I think that spacing would be at 300/524*(0.5)/sin(30) meters or about 22.5 inches center to center (it's OK if the reflectors overlap a bit). KRCB is at 22 analog and 23 digital (which re-maps to 22.1 & 22.2). So to reduce its power a filter would need to notch both channel's 22 and 23. A Join-Tenna for channel 23 would work and probably only affect channels 19 and 27 slightly if at all. Here is a list of the digital channels near you, note that the reciever will re-map the channel number to the old analog number with -1 or -2 appended etc:
http://www.fcc.gov/fcc-bin/tvq?state...lon2=57&size=9

It's not that I wasn't interested, I'm just trying trying to absorb all the info presented. I freely admit that a lot of this is over my head. I know see that you gave that info because the towers were close. When I originally read it, I saw the reference to 20 miles and since my desired stations are at 50-60 miles I did not give it the attention it deserved.

I really do appreciate all the info all of you have presented and I'm just trying to consolidate everything down into an approach I should take. My antenna is 70' in the air on top of a tree so trips ups and down need to be at a minimum.

I haven't purchased anything yet so what I do is still on the table. It may very well be that the channel in question is not harming reception of the further located stations and I guess my original query was if steps could be taken to insure that it doesn't.

I think at this point, I will go with dual 91XGs stacked horizontally and spaced as deconvolver suggests, and I'm probably leaning toward the JoinTenna for ch 23.

Would the ability to adjust the horizontal plane remotely be of value? The cost to do such would be around $350. Money is not an issue if the functionality increases at least somewhat. Of course it's impossible to say would it be worth it, I suppose I'm asking simply is it a worthy modification?

I have no line of sight whatsoever to the SF towers, and probably not to the CH 22 tower either, so everything I get is bounced from somewhere.

please help me figure this out, I have a channel master 3018 and a hd tivo, I get fox and wavy in the 90% range,but cbs and ch 13 wvec,keep going from 60 % to back to 0 % constantly over and over,Its odd that at night time it seems to level out,Ive tried moving the ant from 263 deg to 259,it doesnt help. this ant is about the same range as the 4228.

I was going to try and just get a 4228 from domes but they want 100 bucks for it and it retails for 59 bucks,whats the deal with that?

As far as Keenan and his Cheshire channel 22.1 are concerned, I have good news and better news. The good news is, according to Antennaweb, channel 23 DTV/22.1 doesn't exist. Even when I punched in Cotati's, California's zip code.

The better news is, the FCC says it does exist but is only transmitting at 67 KW, so there is no way that it is overloading his preamplifier or tuner and should be of no concern to him.

Twenty miles isn't close when a transmitter is 40 degrees off target and transmitting at 67 KW. You should only be thinking about mitigating channels 47 and 68, regardless of what your signal meter scale says. You don't know how strong 68 is because it is analog, and your signal strength indicator saying that 47 is "weaker" than 22.1 is not measuring actual strength, such that it might adversely affect a preamplifier or tuner.

The people here who have installed tilters have enjoyed playing with them, but I don't think anyone vouches for them.

What aren't you getting reliably from San Francisco?

Back to the drawing board guys....there are over FIVE nearby UHF transmitters with significant levels...

By checking ALL four boxes on the right side of the fol site, you can find ALL of the local transmitters:
http://www.2150.com/broadcast/default.asp
Suggest you limit the search radius to about 30 miles, otherwise it times out.

There are two analog UHF transmitters listed only a few miles away (repeater and a so-called "low power"):
UHF CH25: K30DO (aka K25HI), 25.8 deg, 4.7 miles, 17 kW ERP, 17 kW Max, 547 m AMSL.
UHF CH36: KTVJ-LP (Fiori Media), 25.8 deg, 4.7 miles, 21.3 kW ERP, 50 kW Max, 547 m AMSL.

Note that there is an antenna tilt mod for KTVJ-LP listed, reducing ERP (towards horizon) to 21.3 kW,
but the maximum power in all H and V directions is still 50 kW....no doubt directed downwards towards Keenan.

Note KRCB-DT (and KRCB-TV) filed Construction Permits to relocate with different antenna patterns and beam tilt:
UHF CH23, KRCB-DT (Rural), 135/136 deg, 9.5/9.6 miles, 4.7+ kW ERP, 110 kW Max, 800m AMSL.

The downward antenna tilt situation also applies for fol. nearby station:
UHF CH28: KDTV-CA (Sta Rosa), 17.5 deg, 15.1 miles, 8.2 kW ERP, 109 kW Max, 1219 m AMSL.

If you really want to know how high the receive signal levels are, I suggest you look at the below spread sheet.
Note that I did not calculate the "Add'l Loss" for those towers that are not Line-Of-Sight,
nor the XG-91 antenna pattern as you point towards different stations.
So there is still work for the interested student....

 

SF DTV_Overload_Calc_RevB.zip 10.2138671875k . file

Given that Keenan already has a tall mast, has already tried one of the best 8 bay bowties and one of the best "yagi(s) with corner reflectors", has a nice, high gain, high powered preamp with little liklihood of amplifier or receiver overload, yet he is generally dissatisfied, across the board, with his distant, San Francisco reception, which, he believes, does not enjoy line-of site predictability, there just isn't any reliable way to improve his reception. He might be better off "borrowing" different receivers and seeing which one seems to most reliably lock onto the signals that he now has.

He can cheaply rule out preamp overload with the trial insertion of 22/47/68 Jointennas. I think I pay $24 each for them. I don't know what retail is, but they will definitively settle the issue of whether he is suffereing from preamp overload fairly cheaply.

He can also buy an analog FSM on eBay for twenty bucks to take out the guesswork regarding the signal strength of undesired signals.

The hi-gain CM-7777 is definitely OVERLOADED, and the antenna sidelobes aren't enough to cure the problem,
esp given that signals will also bounce back off nearby hills.

Recommend using a lower gain Preamp, such as the Winegard HDP-269 which has 3 dB Noise Figure,
12 dB Gain (just enough to overcome the coax downlead and HDTV Noise Figure)
and has 11.5 dB HIGHER overload specs that the already excellent W-G AP-4700 (or equal) Preamps.

=======================================================
I did quick Line-Of-Sight check using Google-Earth.
All the nearby stations, except perhaps KTLN are LOS to Keenan's location.
I would guess a moderate amount of "Add'l Loss" due to diffraction from KTLN (under 10 dB?) and Sutro Towers (under 20 dB?).
But if you really want to know, I suggest RADIO MOBILE (for Windows) or SPLAT! (for Linux):
http://hdtv.forsandiego.com/messages...tml?1126050076

Using the exact lat/long from FCC database, you can actually see the towers
or in some cases the ground preparation work since some of the photos are fairly old.
Google-Earth can be off by several minutes from the posted lat/long due to coordinate "datum" differences (FCC's NAD 27 vs WGS84):
http://www.keyhole.com/GoogleEarthHelp/GoogleEarth.htm
[So Keenan is probably not living in a tree house.]

Which transmitter(s) are you saying are overloading it?

I wasn't able to use the linked transmitter locator because I don't have Keenan's map coordinates, but I Googled the Santa Rosa, California zip code and determined, via Antenna web, that the Sutro Tower is at a bearing of 145 degrees and the channel 22/23 transmitter is at 108 degrees. The channel 22(23) tower is therefore 37 degrees off targetline. The reception antenna gain of 22/23 will be down by somewhere between 10 and 20dB, most likely, 15dB down or more.

The two local, low-power transmitters that holl_ands has indentifed, at around 25 degrees, are about 120 degrees off-targetline to the rear, meaning the gain of them is down over 20 dB using either the 4228 or the screen-reflected Yagi.

The 7777 has a maximum output of 51dBmV for a two channel load, 47 for four channels and 42 for eight channels. But that refers to equal strength channels. This antenna receives the equivalent of a two or three channel load, maximum. Does anyone remember what a "block tilt" was and is? Blonder Tongue and others used to advise that you could increase your VHF highband channels by 2dB if you also lowered all your low band channels by 4dB. But you only got to do that once. If you instead eliminated the VHF lowband channels all together, you would only raise the highband maximum output by 3dB. But if you then eliminated half the VHF upper channels (not that doing so would ever be beneficial), the maximum output went up by another 3dB

The San Francisco signals are insignificant to the loading estimate. Therefore, this preamp doesn't even begin to excessively intermodulate until the one "pig" carrier output goes somewhere over 50dBmV, which means that its input is over 24dBmV. And even then, that is the level at which an analog picture might begin to show imperfections that initially can only be seen by those who know a TASO Grade 1 picture. The overloading input would have to be several dB higher than that to start breaking up the digital signals.

A low power transmitter five miles away hitting the rear oblique of a screen-reflected antenna will not develop 20dBmv. The only potential threat is the channel 68 that is on line but twenty miles away, and even then, it is not really powerful for that high a frequency, having an output of only 1,000KW.

Lat 38.4473457
Lon 122.6992493

BTW, all this attention is making me feel like a very important person so I'll say again, I do appreciate all the input, very much. I look at this as a challenge to try and get the best that is possible.

I'll need to read the last several posts later as I'm off to dinner, but if any additional info from my end is needed, please ask.

Thanks

P.S. If you all feel my particular situation would be better served in another thread and not pollute the focus of this one, please say so.

Nah, just a bunch of bored guys .

Attached is the Digital & Analog stations out to 70 miles Added: for keenan.
.

 

Broadcast Television Station.pdf 417.228515625k . file

The transmit and receive beampatterns and diffraction losses are important for the low power stations. KTVJ is transmitting in a different direction and all the low power stations are in a completely different receive direction from San Fran so the receive beampattern will be low towards them. The low power stations are also not mounted on high towers so diffraction losses could be significant. All together I don't think the low power stations are a likely overload problem. That leaves KRCB and KTLN as the main overload possibilities. Strong reflected paths from very different angles than the direct path are possible but unlikely so direct path directions are the main threat. The current configuration probably doesn't have severe overload because his performance now for the distance is pretty good- but a slight overload is a possibility. If overload does exist then I would expect any one of the following remedies would likely eliminate it: A horizontal stack with a null towards KRCB plus a Join-Tenna for KTLN if needed, channel 23 and/or channel 68 Join-Tenna's with the unneeded input's terminated, replacing the CM 7777 with a WG 8700 or 4700 or 2870. Note that the horizontal stacking distance is not super critical to eliminate KRCB (ex. 24 inches instead of 22.5 inches should be OK but my original math needs to be checked), just steer to place the null for minimum interference and the main-lobe should be close enough to San Fran. The horizontal stack has the advantage of additional gain as long as a low loss coupler is used. The Winegard pre-amps have the disadvantage of slightly poorer performance than the 7777 in the absence of overload and the Join-Tenna is not well shielded and will add some loss for channels near the "null". One thing that could be tried with the WG pre-amp and Join-Tenna's is to put the Join-Tenna's in the house between the Pre-amp output and a low noise low gain distribution amp. That may help overcome lead-in losses which is especially useful if the receiver has a poor noise figure. I agree though with AntAltMike that once overloading is ruled out there is probably no reasonable way to get a big improvement from the current performance. (edited to add KTLN as an interference possibility)

It might work OK especially if you replace the lead-in cable with a new balen and good RG-6 coax. I would recomend the Winegard 4700 if you want to try a pre-amp because it has a low noise figure and overload will be less of a worry for it than for a higher gain pre-amp.

I bought a house that has a mast with two stacked Yagi antennas (with no reflectors) designed to pick up a signle VHF channel (9). One antenna is 4-5 feet above the other.

I have no use for the above antenna and instead mounted a CM 4228 between them to pick up the digital UHF channels. Since the gap between the two Yagis was more than the hight of CM 4228, I now have one about a foot higher than the CM 4228 and the other a few inches below. Would either one of these elements (which are not hooked up to anything) have any effect on the performance of the CM 4228? My RF knowledge is failing me here .

Thanks,
Amir

Yes, and probably negative.

Good Idea. I deleted all my post in this thread that did not contain "DIY Info, How 2's or Links"

OK kennan, from the top, you have:

Lat 38.45 North
Lon 122.70 West or -122.70

91XG Antenna at 70 ft.
Antenna Rotor
Channel Master 7775 Pre-Amp
Dish DVR-942

Problem? Objective?

I just saw your antenna mounting. If you have very much antenna movement with wind there will be a high probability of picture problems on the DTV stations.

Also have an ATSC tuner in my Mits WS73615 and one in a DirecTv HD-TiVo unit although the Dish unit seems to be the best of the bunch.

Yes, the tree mount is not ideal but I don't really have any alternative as I'm surrounded by them and a metal tower would probably prove to be to much effort and expense.

Essentially my goal here is to maximize reception of digital channel 45.1 KBHK from Sutro Tower-SF as it's the only channel I desire that is not provided any other way(sat-cable), and secondarily, I enjoy trying to get OTA signals, not really a hobby, but it's fun and interesting to try.

The signal I get now is around 60-70% on the Dish meter. Usually at the lower end of that range and there are complete drop-outs as well at times. If I could improve that signal say another 5-10% I would have a solid reliable signal. The complete dropouts are a nuisance but I doubt there is much I can do about that as I'm guessing the cause of those are out of my control.

DETAILED OVERLOAD CALCULATIONS FOR KEENAN'S LOCATION:

The below spread sheet shows that the CM-7777 will be overloaded if antenna is
pointed to any of the local stations. The HDTV Tuner may also be overloaded.

When pointed towards Sutro Towers with one of the sidelobe notches pointed towards
A-KRCB and KRCB-DT (9.5 miles away), the CM-7777 will be overloaded by KRCB-DT.
Also overloaded by A-KTLN and KTLN-DT, that are directly on the line to Sutro Towers.
The HDTV Tuner may also be overloaded, but can be avoided by inserting attenuation
on the Tuner input (e.g. RF Splitters or R-S Variable RF Attenuator).

Note that the sidelobe notch is much deeper for A-KRCB on CH51 (I assumed 20 dB)
than it is for KRCB-DT on CH23 (I assumed 10 dB).
Since I have not seen antenna pattern measurements or NEC simulations for the
XG-91 type antenna, I assumed that it was similiar to the high-gain CM-4228 antenna,
using NEC Sim results found in www.hdtvprimer.com/ANTENNAS/comparing.html.

When the specs for the new Winegard HDP-269 were entered, all of the Preamp
overload problems were not only cured, but the input signal was 15-20 dB below
the specified overload point, which maximizes the Spurious Free Dynamic Range
so that intermods are pushed down towards the noise floor. This facilitates
reception of the weakest signals from remote locations.

With only 12 dB of gain in the HDT-269, the input level to the HDTV Tuner was still
uncomfortably close to what I have seen specified for maximum input levels.
This can be avoided by inserting a small amount of attenuation prior to the Tuner,
e.g. RF Splitter(s) and/or a R-S Variable RF Attenuator.

I didn't take the time to tailor RADIO MOBILE for the S.F. area, so some of the path loss
numbers are "best guesses" based on performing similiar runs in LA and San Diego area.
So there is still a useful exercise left for the interested student....

Let me know if you find any errors in the spread sheets....no really...

ERRATA:
================================================
1. Found a small error in the Off-Beam Rcv Ant Gain when pointed towards
Sutro Tower and using W-G HDP-269 Preamp.
Now it's the same as for CM-7777, which was correct to begin with.

===============================================
2. deconvolver found an error: A-KRCB should be CH22 (vice my KUSI on CH51).
This also changes the Antenna Gain and Off-Beam notch depth, resulting in
a stronger overload contribution. A-KRCB is the second strongest overload source
and KRCB-DT is still the strongest overload signal when pointed toward Sutro Towers.

3. The KTLN-DT and A-KTLN broadcast antenna gain corrections (voltage not power) were incorrect.
This results in reduction in the overload contribution from these stations by several dB,
but they remain lurking just below the CM-7777 spec overload level.

4. In double checking, I found that KDTV-DT should be A-KDTV, which deletes
the 8 dB Average to Peak Power conversion.
This wasn't the principal problem before and is even less so now.

==============================================
I also added calculations for the W-G AP-4700 (or equal) Preamp:
RevC spread sheet has been replaced by RevD:

 

SF DTV_Overload_Calc_RevD.zip 12.677734375k . file

anyone care to comment on this statement from our local OTA forum:

"...a Multidirectional antenna might give you problems, like the DB4, but the 4221 is really more one direction, but with a wide reception angle, and far more gain."

Aren't these two identical in design and performance?

I know DB-8 and 4228 work differently because in one case the screens are connected together and in the other not. I have not looked at DB-4 but the same might be true there.

Amir

They are very similar really and should give similar results with the main difference being the DB4 costs more. The DB4 is certainly not a multidirectional antenna.

I would agree with "..a multidirectional antenna might give you problems", though.

The screening difference between the DB8 and the 4228 mainly effects the high band vhf performance, improving it on the 4228 over the DB8.

I keep getting "Internet Explorer Can't Open...", and, "... Cant Find..." messages when I try to open the spread sheet.

I can't find any overload specs for the HDT-269. What are they?

Winegard's specs chart for their other amplifiers doesn't specify the channel loading. It seems to me that the channel loading figure used to be on that chart. Does anyone know what it is?

Holl_ands analysis assumes that Keenan's antenna performed like a 4228, which is an 8-bay bowtie, but it looks more like a 4248, which is even less favorable for his situation, since the off axis rejection of a corner reflector Yagi is not as great as the 8-bay bowtie.

I had assumed that the channel 22 transmitter was 15 miles away, the channel 68 was 22 miles away, and that the angle between them was about 40 degrees. But from the map coordinates, channel 22 is just 9.5 miles away, and the angle between the desired and undesired transmissions is just 30 degrees.

Let's assume that his antenna has a net gain over isotropic of 12dB at channel 22 and 16dB at channel 68. In order to violate the input threshold in a two channel analysis, either both of those channels would have to develop 25dBmV coming off the antenna, or perhaps one could be 27dBmV with the other about 21dBmV

Roughly figuring, channel 22 is 10 miles away and 30 to 40 degrees off axis, and has a transmitter power of, I believe, 65Kw. If the 30-40 degree off-axis antenna gain "discount" at channel 22 is 10-15dB, rather than 15-20dB as I had speculated in my estimate, then the antenna is going to net somewhere in the range of -3dB to +2dB relative to isotropic. Will a 65Kw signal develop twenty-something dBmV of signal power at that distance with effectively negative antenna gain?

Now, Telemundo channel 68 analog, 47 digital is another matter. 16dB of antenna gain on channel 68, 21 miles of dissipation and 1,100Kw analog. That's the one I expressed concern about in my earlier posts. That's the one that is getting Keenan's system in trouble.

Channel Vision or Channel Plus has a lowpass filter that rolls off somewhere around 750Mz, with an insertion loss of no more than 1dB. That should scrape off channel 68 nicely.

The Telemundo channel 47 digital is transmitting at 220Kw at present, but it will get increased to 1000Kw. Assuming that Keenan doesn't habla espanole, the WT-2700 should neatly mitigate that one without touching his precious 45 UPN from San Francisco.

What is Holl_ands using for receiver minimum and maximum input levels? I'm going to be working on top of a nice tall building, just three or four miles from some DTV towers this weekend (Ritz Carleton, corner of 23rd and M St, NW, 20037, if anyone wants to develop a spreadsheet that I can take with me). I'm going to have an early Samsung tuner and one of those receivers that Radio Shack just closed out on (Accurian?) and will feed some strong and weak filtered signals into them to see how far I can exceed the input thresholds on both the low and high ends.

(note: edited to incorporate distances and angles from the FCC page linked in deconolver's post #101)

Is it likely that the 91XG from Antennas Direct would offer better performance than a bowtie type?

I just got the same error clicking on above zip file. Always worked in the past....
Sometimes I get a "Cannot find file" error when clicking on pdf files.
In both cases, I can Right Click and use "Save target as...." selection to save file.

=======================================================
I couldn't find HDP-269 on Winegard Website, but is for sale from usual sources:
http://www.warrenelectronics.com/antennas/hdp269.htm
http://www.solidsignal.com/prod_disp...PROD=ANWHDP269
http://www.summitsource.com/product_...oducts_id=5577
http://www.summittvantenna.com/category66.html

========================================================
If you look at hdtvprimer.com NEC plots, you'll see that the +/- 30 deg side-lobe depths aren't
all that much different for all of the listed high gain antennas: CM4228, CM4248, DAT-75.
What will change a little bit is the exact angle of the notch for mid to high frequencies,
with narrower beamwidth antennas having a corresponding smaller angle to the notch.
For all of the listed antennas, the notch was very shallow for the low frequencies.
Since I haven't seen anything published on the XG-91 type antennas from over half
a dozen different vendors, we're left with doing the best we can with what we have.
The angle of the sidelobe notches for the XG-91 type antenna is probably a few degrees
less than the CM4228, due to the slightly higher gain and hence narrower beamwidth.

For Keenan, small changes in direction are needed in order to "aim" the notch
towards A-KRCB and KRCB-DT. You might try both the Analog and Digital
station to see which one demonstrates the "worst" signal indicator.
The antenna beamwidth towards Sutro Towers is specified to be 36 degrees for low frequencies
and 22 degree for the high frequencies, so there is a moderate amount of wiggle room.

I used 20-26 dB F/B specs found on the Dipol website for their ATX-91 antenna.
Note their Gain is in dBi (subtract 2.15 for dBd):
http://www.dipol.com.pl/esklep/a3710.htm
They also have the best picture for the generic 2.22 meter, 91 "element" antenna
that is sold worldwide under many different names from many different sources.

So do you have anything better than Dipol and Funke websites for XG-91???

I would be very wary of any F/B or sidelobe notch claims in excess of about 20 dB.
[I saw some F/B specs as high as 32 dB for the XG-91 type antenna!!!]
[Can't be average. Maybe the absolute best value for an extremely narrow rear angle???]
You might see > 20 dB in a NEC sim run or even in an idealized plot from the manufacturer,
but real world systems mounted in the vicinity of nearby objects will tend to fill in the nulls.

========================================================
I searched...and I searched....and I searched for specs on ATSC Tuner Modules.
Such as it is, the ATSC_NTSC TUNER MODULE SPECS spread sheet is posted
(along with everything else of interest on this subject) at:
http://hdtv.forsandiego.com/messages...tml?1126050076

In all of my searching for DTV Receiver performance tests, I have yet to find any
meaningful overload and intermod tests on Preamps and HDTV Receivers.

For what's it's worth, Charles Rhodes reverse engineered the intermod characteristics
for the 1st Generation Zenith Receiver, concluding that the double conversion tuner
has an Output Third Order Intermod Intercept of OIP3 = +14 dBm:
http://www.tvtechnology.com/features...gital_tv.shtml
Hardly anyone makes double conversion ATSC Tuners. Only one in list is by Samsung.
If you check the available "state of the art" in my PREAMP SPECS spreadsheet,
you'll see that the OIP3 was pretty mediocre.

====================================================
Wouldn't it be great if the AV rags would conduct meaningful equipment tests on DTV equipment????
It would also be very retro if the manufacturers would actually publish meaningful specs.

You show A-KRCB as channel 51 but it should be channel 22 so one notch covers both the analog and digital stations. Also the distances and angles to all Keenan's stations can be found here:
http://www.fcc.gov/fcc-bin/tvq?state...lon2=57&size=9

Thank you for information

Different antennas work better in different situations. Outdoors, the yagis (like the 91XG) seem to have a leg up. In an attic, the bowties seem to be a little better. You also have to consider which frequencies you're after. If you need something above channel 51, the 91XG is probably the better choice. Which is better in your particular situation? Hard to tell. But if a yagi isn't working, trying a bowtie is better than trying another yagi, and vice-versa.

All four of those linked sites selling the HDP-269 copied the same consumer data sheet, which says that the "Maximum total input" is 350,000 microvolts. Correct me if I'm wrong, but I don't think that maximum input levels can be usefully denominated in unreferenced, cumulative microvolts. We've got to work some "squares" or "square roots" into the tallied inputs to reflect the fact that, if you halve the voltage, you reduce the power consumption by 75%.


Winegard's channel loading standard, which HDTVPrimer has inadvertently excised from the table it copied, can be found in Winegard's own 1996 catalog #215 on page 14. They claim that their UHF preamps don't exceed 0.5% Cross Modulation with FIVE CHANNEL UHF INPUTS of 30,000 microvolts for the high gain (28dB) models and 93,000 microvolts for the low gain (19dB) models.

Hmmmm... Using Winegard's own conversion chart from page 26 of the same catalog, that means that their low noise preamps can output about 57dBmV with a FIVE CHANNEL LOAD without developing excessive cross modulation. Does anyone believe that? That's four times the maximum attainable power output per channel of a Channel Master 7775 or 7777, at two and a half times the channel load. Cripes, the Holland Electronics (no relation?) "high powered" rack-mounted UHF strip amplifiers, which I think are now discontinued, could barely develop that kind of output of a single channel.

The HDP-269's 350,000 microvolt maximum input is 51dBmV. With 11 to 12 dB gain, its amplifier output would be 62 or 63 dBmV. My trusty, workhorse Blonder Tongue BIDAs, which regrettably have noise figures of around 8 or 9dB, can develop an output level of just 46dBmV with 60 channel loads. To simply the arithmetic, I'll fudge a little and call that the 64 channel rating: 46dB at 64 channels, 49dBmV @ 32 channels, 52dBmV @ 16 channels, 55dBmV @ 8 channels, 58dBmV @ 4 channels, 61dBmV @ 2 channels, and 64 dBmV @ 1 channel. So why am I paying $400 per amplifier for behemoths with 8-9dB noise figures? In fact, if Winegard is using the same loading assumption for the HDP as it does for its AP's, I might start using them to light Christmas trees.


We should all live so long. But I'm even more concerned about the relevance of the methodology we are using to arbitrarily arrive at useful parameters for estimating amplifier power sufficiency when loaded with digital signals, rather than analog ones.

Thanks! Are the Yagi's more directional than the combination UHF/VHF I have now, or about the same? I have a CM 3678.