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post #17851 of 17921 Old 08-20-2019, 08:19 PM
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Originally Posted by EF9500 View Post
Sorry guys
http://www.tvfool.com/?option=com_wr...9038e801023797

Trying to get 7, 11, and 13. For some reason 13 wnet is not on that list. Strange
Thank you for the report.

TVFool is using a defective database to generate reports.

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Originally Posted by EF9500 View Post
The vhf dipole didn't do very good. I might try taking the front section off the 2476...basically making it the shorter 2475, then maybe take the back reflector off, and try it on the mast with my cs4. Maybe that will cure all my el noise interference, and give me enough gain. I will also try using a ground block on the coax.
I suggest you leave at least one reflector element on the rear end of the boom like on the 2475; you have some very strong local channels at the rear that might overload your preamp.



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post #17852 of 17921 Old 08-21-2019, 02:38 AM
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Originally Posted by rabbit73 View Post
Thank you for the report.

TVFool is using a defective database to generate reports.


I suggest you leave at least one reflector element on the rear end of the boom like on the 2475; you have some very strong local channels at the rear that might overload your preamp.



Here's a better list. Thanks again
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post #17853 of 17921 Old 08-21-2019, 08:14 AM
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Originally Posted by EF9500 View Post
Here's a better list. Thanks again
Thank you for the better list; excellent! I see two very strong ones from the East, so I think you need the reflector.

This is the link to your report. Trip, who runs the rabbitears.info site, has designed the link so that it doesn't show your location as the previous reports did. It truncates the coordinates to two places after the decimal point in the report as TVFool does, unless you specify otherwise.
https://www.rabbitears.info/searchma...&study_id=5456

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post #17854 of 17921 Old 08-21-2019, 08:25 AM
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Originally Posted by rabbit73 View Post
...
I suggest you leave at least one reflector element on the rear end of the boom like on the 2475; you have some very strong local channels at the rear that might overload your preamp.
I test one reflector bar on the back and it worked ok. Better signal quality with one reflector over none. Just need drill 3/16" hole through the beam. Non destructive modification-- if they need to go back to the big reflector they can.

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post #17855 of 17921 Old 08-21-2019, 09:21 AM
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Thank you for the better list; excellent! I see two very strong ones from the East, so I think you need the reflector.

This is the link to your report. Trip, who runs the rabbitears.info site, has designed the link so that it doesn't show your location as the previous reports did. It truncates the coordinates to two places after the decimal point in the report as TVFool does, unless you specify otherwise.
https://www.rabbitears.info/searchma...&study_id=5456

I know for a fact wlny "behind me from the East" has been off due to the repack. I might try no reflector on back. Does that reduce gain on front? Or not really. Thanks for all the help.

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post #17856 of 17921 Old 08-21-2019, 10:59 AM
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Originally Posted by EF9500 View Post
I know for a fact wlny "behind me from the East" has been off due to the repack. I might try no reflector on back. Does that reduce gain on front? Or not really. Thanks for all the help.
Removing the reflector WILL reduce the forward gain by about 3 dB and increase the probability of interference from multipath reflections. I think you need that extra gain for your weakest desired VHF channels. Try it both ways to satisfy our curiosity.

If you do leave it off, what will happen when WLNY comes back up with its 1000 kW ERP transmitter?
https://www.rabbitears.info/tvq.php?...ms&facid=73206

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post #17857 of 17921 Old 08-21-2019, 11:33 AM
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Originally Posted by rabbit73 View Post
Removing the reflector WILL reduce the forward gain by about 3 dB and increase the probability of interference from multipath reflections. I think you need that extra gain for your weakest desired VHF channels. Try it both ways to satisfy our curiosity.

If you do leave it off, what will happen when WLNY comes back up with its 1000 kW ERP transmitter?
https://www.rabbitears.info/tvq.php?...ms&facid=73206
On, it will go 😀

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post #17858 of 17921 Old 08-21-2019, 03:39 PM
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Stellar Labs 30-2475 Analysis already explored various mods:
https://imageevent.com/holl_ands/yag...agistellarlabs
So, only remove the 2 Reflectors above & below the plane of the Yagi.
Even better, re-purpose those 2 Reflectors as an additional Pair of Directors [shorter, with Boom Extension].

a) As built, per measurements by Mike Bear:

HiVHF Raw Gain = 8.7 to 10.8 dBi, F/B & F/R Ratio = 10.3 to 21.0 to 19.2 to 19.8 dB
[Poor on Low Channels] and SWR (300-ohms) is Under 2.2 (EXCELLENT).

b) Analyzed Upper/Lower Reflector Rods Repurposed as Two Additional Directors:
[Requires a Front Boom Extension.]

HiVHF Raw Gain = 8.6 to 12.0 dBi, F/B Ratio = 14.1 dB and SWR (300-ohms) Under 2.2.
Improves Ch13 Gain and F/R Ratio on Lower Channels. SWR is Excellent.
New Boom Length = 95.7-in + Ends

c) Upper/Lower Reflector Rods were removed to investigate degradation to F/R Ratio
(at expense of Raw Gain). See below Charts for results.

d) ALL three Reflector Rods were removed to investigate degradation to F/R Ratio
(at expense of Raw Gain). See below Charts for results.

e) Location of Upper/Lower Reflector Rods relative to Middle Reflector was Re-Optimized,
but there was NO overall improvement when Constrained to be BEHIND the Folded Dipole.





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post #17859 of 17921 Old 08-21-2019, 04:06 PM
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Originally Posted by holl_ands View Post
Stellar Labs 30-2475 Analysis already explored various mods:
https://imageevent.com/holl_ands/yag...agistellarlabs
So, only remove the 2 Reflectors above & below the plane of the Yagi.
Even better, re-purpose those 2 Reflectors as an additional Pair of Directors [shorter, with Boom Extension].

a) As built, per measurements by Mike Bear:

HiVHF Raw Gain = 8.7 to 10.8 dBi, F/B & F/R Ratio = 10.3 to 21.0 to 19.2 to 19.8 dB
[Poor on Low Channels] and SWR (300-ohms) is Under 2.2 (EXCELLENT).

b) Analyzed Upper/Lower Reflector Rods Repurposed as Two Additional Directors:
[Requires a Front Boom Extension.]

HiVHF Raw Gain = 8.6 to 12.0 dBi, F/B Ratio = 14.1 dB and SWR (300-ohms) Under 2.2.
Improves Ch13 Gain and F/R Ratio on Lower Channels. SWR is Excellent.
New Boom Length = 95.7-in + Ends

c) Upper/Lower Reflector Rods were removed to investigate degradation to F/R Ratio
(at expense of Raw Gain). See below Charts for results.

d) ALL three Reflector Rods were removed to investigate degradation to F/R Ratio
(at expense of Raw Gain). See below Charts for results.

e) Location of Upper/Lower Reflector Rods relative to Middle Reflector was Re-Optimized,
but there was NO overall improvement when Constrained to be BEHIND the Folded Dipole.
Should note 30-2475 and 30-2476 have different reflector design. 30-2476 does not have reflector rod on plane as from factory. Overall, I think these antennas are tolerant of modifications.
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post #17860 of 17921 Old 08-21-2019, 04:39 PM
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Originally Posted by johnny antenna View Post
Should note 30-2475 and 30-2476 have different reflector design. 30-2476 does not have reflector rod on plane as from factory. Overall, I think these antennas are tolerant of modifications.
Yeah, I have the 2476. When I remove the front section, it will actually be shorter than the 2475. Hoping for good results.
Also, quick question. Gonna be using a kt-200 amp. I'm using an ad combiner. Amp is going to be inside attic, so just have the amp feed the combiner, then the antennas?

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post #17861 of 17921 Old 08-22-2019, 12:25 PM
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Just wasted 3 hours of my life putting the 30-2476 out on the roof. Signal was no better, possibly worse on channel 13. I tried every area on the roof. So back up in the attic it went. I moved it one bay over, signal seems good, a/c not interfering. Strange that one bay over fixed it. Wondering if my kt-200 will give me slightly better signal. That's coming tomorrow.

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post #17862 of 17921 Old 08-22-2019, 12:55 PM
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Why I don't watch KPJK

Why I don't watch KPJK and will not until the FCC buys them a new transmitter next year.

I caught the transmitter on for ~ 17 days sending no useful information at all. Both exciters were bad.

SHF

https://sfbayatsc.koherence.com/inde...mon_channel=43

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post #17863 of 17921 Old 08-22-2019, 02:26 PM
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Originally Posted by EF9500 View Post
Just wasted 3 hours of my life putting the 30-2476 out on the roof. Signal was no better, possibly worse on channel 13. I tried every area on the roof. So back up in the attic it went. I moved it one day over, signal seems good, a/c not interfering. Strange that one bay over fixed it. Wondering if my kt-200 will give me slightly better signal. That's coming tomorrow.

There's no way that the signal can't be stronger with the antenna on the roof vs the attic. Despite what they may say, almost no TV shows actual signal strength. They show Signal-to-Noise Ratio even if they call it Signal Strength. Depending on what your problem is, it is completely possible to get no SNR improvement moving the antenna from the attic to the roof. Based on your results, I'd say that the KT-200 will not improve your reception.

Without connecting a spectrum analyzer to your antenna, I'm guessing you have some sort of interference problem that does not get better when moving the antenna.

We do run into cases here where we can't solve the problem because we don't have enough information. Yours is beginning to sound like one of them.
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post #17864 of 17921 Old 08-22-2019, 02:43 PM
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There's no way that the signal can't be stronger with the antenna on the roof vs the attic. Despite what they may say, almost no TV shows actual signal strength. They show Signal-to-Noise Ratio even if they call it Signal Strength. Depending on what your problem is, it is completely possible to get no SNR improvement moving the antenna from the attic to the roof. Based on your results, I'd say that the KT-200 will not improve your reception.

Without connecting a spectrum analyzer to your antenna, I'm guessing you have some sort of interference problem that does not get better when moving the antenna.

We do run into cases here where we can't solve the problem because we don't have enough information. Yours is beginning to sound like one of them.
I wish you were here, to witness what I experienced. Vhf is really a strange frequency. I swear something inside my house is actually boosting the signal. I have a Sony TV that gives a detailed signal along with errors. Everywhere on the roof, I experienced lower signal with errors. Inside my attic, I have a solid lock, with no errors the last 2 hours. I really can't explain it. I do thank you, and everyone else with the help. My wife and neighbors think I'm nuts with this odd hobby. Lol.

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post #17865 of 17921 Old 08-22-2019, 03:09 PM
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Originally Posted by EF9500 View Post
I wish you were here, to witness what I experienced. Vhf is really a strange frequency. I swear something inside my house is actually boosting the signal. I have a Sony TV that gives a detailed signal along with errors. Everywhere on the roof, I experienced lower signal with errors. Inside my attic, I have a solid lock, with no errors the last 2 hours. I really can't explain it. I do thank you, and everyone else with the help. My wife and neighbors think I'm nuts with this odd hobby. Lol.

I have a Sony too and its diagnostic screen has a real Signal Strength meter. See attached image. You can tell a real Signal Strength meter if the Signal Strength and Signal Quality (SNR) displays do not track each other. If they do then they're both Signal Quality meters.

If you have a Diagnostic screen like mine then you should see a higher number on the Signal Strength display when the antenna is on the roof regardless of the SNR. What does yours show?
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post #17866 of 17921 Old 08-22-2019, 04:17 PM
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I have a Sony too and its diagnostic screen has a real Signal Strength meter. See attached image. You can tell a real Signal Strength meter if the Signal Strength and Signal Quality (SNR) displays do not track each other. If they do then they're both Signal Quality meters.

If you have a Diagnostic screen like mine then you should see a higher number on the Signal Strength display when the antenna is on the roof regardless of the SNR. What does yours show?
Mine looks just like that. Outside, 38, inside 50. It really makes no sense, but hey, I'm ok with it, as long as it's locked, with no errors.
I will be doing a before and after with the kt-200, compared to the RCA. Not really expecting much.

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post #17867 of 17921 Old 08-23-2019, 12:40 PM
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Mine looks just like that. Outside, 38, inside 50. It really makes no sense, but hey, I'm ok with it, as long as it's locked, with no errors.
I will be doing a before and after with the kt-200, compared to the RCA. Not really expecting much.
Thirteen will increase power in 2020. Not much but it hopefully it can help in your fringe situation.
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post #17868 of 17921 Old 08-23-2019, 01:28 PM
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Thirteen will increase power in 2020. Not much but it hopefully it can help in your fringe situation.
So the kt-200 added about 3 to 5 onto my numbers with the rca. Wasn't expecting a miracle. Anything is better than none. I will say that rca preamp is damn good for the $.

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post #17869 of 17921 Old 08-23-2019, 03:59 PM
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So the kt-200 added about 3 to 5 onto my numbers with the rca. Wasn't expecting a miracle. Anything is better than none. I will say that rca preamp is damn good for the $.
Hi EF9500,

I've been tracking your posts and the replies, as I may soon help a coworker try to pull in our market's RF 13 signal from their cottage which is out-of-market. I have in mind to recommend the 30-2476 to them.

But, I have a theory from my novice knowledge related to your location and RF 13. I'm wondering if you're having FM radio signals giving you second order harmonics? Man, I sound techie.

If you have strong nearby FM signals from 105.0 (so 104.9 officially) up through 108 (okay, 107.9), their second order harmonics hit in RF 13's range of 210 to 216 Mhz.

Both the RCA Preamp and KT-200 mention having FM Traps, but neither provide specifics on how much they attenuate (block) the signal.

~~~~~~~

Out of curiosity, when you had the 30-2476 on the roof, did you have a preamp in-line? If not, I'll point out any FM signal would be getting gathered in.

Then, when you moved back into the attic, perhaps that provided enough "environmental attenuation" of any local FM source in your area that it helped with the improved RF 13 reception.

~~~~~~~

Using just your zip code in both FMFool.com (which is likely also out-of-date, and lacks FM translators) and radio-locator.com (which only provides vague signal indications), it looks like you might have local broadcasts within the FM 105-108 positions.

~~~~~~~

If you care to spend a bit of money pursuing better FM suppression (which likely won't help, but we don't know), about the only place I know of that still has a full-FM-band filter in-stock is this place in Canada:

https://angelelectronics.ca/shop/ota...jection-filter

When I ordered 3 from them 14 months ago, it was about a month before they processed the order and sent a tracking number. Then it was about a week to get from their place to mine (in Michigan).

Again, I'm likely sending you on a wild goose chase--but wanted to float the thought that possibly the FM Traps in the preamps are doing you some good.

Cheers! ~~ Statmanmi

Kent County, MI
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post #17870 of 17921 Old 08-23-2019, 07:04 PM
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Well, tonight vhf is gone. Ugh. Vhf is seriously a joke, it's so unreliable.

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post #17871 of 17921 Old 08-24-2019, 06:22 AM
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I've ordered a Blake DMX16A and JBX21A ...
Hi Mattdp,

Please, could you tell where you ordered the Blake DMX16A and JBX21A?

Also, what was the price?

And the shipping cost?

Thanks.

.
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post #17872 of 17921 Old 08-24-2019, 04:06 PM
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Hi Mattdp,

Please, could you tell where you ordered the Blake DMX16A and JBX21A?

Also, what was the price?

And the shipping cost?

Thanks.

.
I ordered directly through their website at Blake-Uk.com. They contacted me back the next day and quoted me $402.76 for shipping, at which point I asked to cancel the order.
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post #17873 of 17921 Old 08-24-2019, 09:04 PM
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Watch 4k tv free!

I was shocked by the ad for the "NEW" Clear TV antenna just before the start of the 49ers Chiefs game tonight.

The original one appeared to be a hacksaw blade and a "F" connector.

https://buycleartv.com/

I can't find the online version of the ad yet, but if you do find it have a vomit bag handy, I almost needed one.

How this ad can remain on the air I don't understand.

SHF

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post #17874 of 17921 Old 08-25-2019, 04:24 AM
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I was shocked by the ad for the "NEW" Clear TV antenna just before the start of the 49ers Chiefs game tonight.

The original one appeared to be a hacksaw blade and a "F" connector.

https://buycleartv.com/

I can't find the online version of the ad yet, but if you do find it have a vomit bag handy, I almost needed one.

How this ad can remain on the air I don't understand.

SHF

Looks like a scam sam.

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post #17875 of 17921 Old 09-02-2019, 07:03 AM
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Since your uhf stations are spread out in a 80 degree spread i suggest a DB8e with one 4 bay aimed northeast and one southeast for maximum uhf capture area and horizontal beamwidth.
Maximum capture area is what is needed when uhf stations are not line of sight and nothing has greater capture area than a phased array bowtie.
You can then either keep the RCA 751 for 7-13 or buy a Winegard HD7000 to take advantage of the low vhf 2-6 channels as well.
Most all the major relevant local LA station towers are located in one location on Mt. Wilson -- 64 degrees true from me, and the couple that aren't I seem to be getting in fine, oddly enough. So I don't really need an omni-directional.

I went with the CM-4228HD, and have been experimenting with it at various heights. I have about week left where I can return it.

Also, FYI for whoever may want to know -- ANT751 picks up lo-VHF. It's picking up my lo-VHF channels just fine. So I doubt the HD7000 would perform differently or better.

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post #17876 of 17921 Old 09-02-2019, 07:44 AM
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Originally Posted by Calaveras View Post
A friend lives in a location that's similar to yours except worse. TV Fool says the signals should be strong enough to receive but he can't receive any of them. Turns out that there are reflections off of other hills that are much stronger than the direct path signal. No antenna has a good enough pattern to reject all the reflections enough to receive the direct path signal. None of the prediction programs can take reflections into account.

I'd be willing to bet that your signals get stronger as you raise the antenna but higher may be more favorable for reflections too. If you got high enough the direct path signals would overcome the reflections but that could well be impossibly high.

If you haven't tried it, I'd take a chance on an XG91. It has the best pattern of any commercial antenna I know of. No guarantees but if any antenna will do it, the XG91 will. The XG91 is UHF only. You'd need a separate high VHF antenna.
I think your theory about multi-path being prevalent up higher in my little valley situation is probably right. I finally moved the CM-4228 down low where the ANT751 is (3ft above roof line), and it's the best UHF reception I've gotten so far. Those marginal channels are coming in now about 50% of the time instead of about 20% of the time.

The CM-4228HD beats out the ANT751 for UHF when at the exact same height, which I suppose is to be expected considering the gain difference in my relevant 470-610MHz range (6-8dBi vs. 13-15dBi).

The VHF performance of the two antennas is virtually the same. Again, not surprising considering the roughly similar gain (6-8dBi) for both.

Oddly though, the CM-4228 will not pick up RF 13 at all, no matter what. The ANT751 picks it up rock solidly, no problems. This is a puzzler. So the mighty little ANT751 wins by a nose for VHF, and I have to keep it in the game if I want RF 13, which is an essential and good station in LA.

So right now I've got the ANT751 @ 3ft, and the very bottom of the CM-4228HD only 1ft above it @ 4ft, both running to the RCA preamp, and this has been the most complete reception I've gotten so far.

I realize that having the antennas this close is not ideal for avoiding interference, but if I move the 8 bay higher, I lose the marginal channels.

I may try mounting the ANT751 up high on top for VHF -- separate them by 3-4 feet that way, opposite the norm.

Last edited by adream8; 09-02-2019 at 08:21 AM.
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post #17877 of 17921 Old 09-02-2019, 07:57 AM
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Thanks! The more I read about this the more I think it has some limited applications but there are too many obstacles for it to be a viable option for almost everyone trying to receive DTV at their home. I'd prefer to stick to practical solutions for the average person wanting OTA TV.
Anybody got a spare $5MIL so I can buy the property at the top of my ridge so I can put up repeaters and get a coupla UHF stations?



They're REALLY good stations.
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post #17878 of 17921 Old 09-02-2019, 11:53 PM
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[QUOTE=adream8;58502644...

Oddly though, the CM-4228 will not pick up RF 13 at all, no matter what.
...[/QUOTE]

The CM4228HD is a UHF antenna. It has "some" reception on VHF-Hi, I get RF 12 and RF 7 solidly. It's the reflector that does the VHF reception.

RF 5 I have lost hope on for next year but RF 5 "May" be duplicated on RF 27 as the station purchased another station with the money the FCC gave the station to move to VHF-Lo.

You do know that RF 13 is a VHF-Hi signal. I remember my father putting up a special VHF antenna for RF 13 which I watched snowy moves late at night with the snow over my head outside (I was small!). The rest of the Madison, WI stations were UHF!

If you will PM me with your Lat. and Lon. I will use my topographic program to check your location and send you pictures of the path to the Transmitters in 3D if useful. (E-Mail address needed).

Those may help you understand what you are fighting, yes you can use
https://www.rabbitears.info/searchmap.php

For $60 I got a program that produces graphics much like what I see on the weather casts of the news leading station in San Francisco.

SHF
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post #17879 of 17921 Old 09-03-2019, 04:30 AM
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I have a RCA 751E about 14ft high outside. I get all the chans without break up, but all seem to show a weak signal or half power. Would a Channel Master Pre amp help? It is the model 17-30 dB gain model.

All the chans avg around 30 to 42 miles away to the southeast of me.

I guess no one knows.

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Last edited by CHASLS2; 09-03-2019 at 05:02 PM.
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post #17880 of 17921 Old 09-03-2019, 04:39 AM
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Originally Posted by SFischer1 View Post
The CM4228HD is a UHF antenna. It has "some" reception on VHF-Hi, I get RF 12 and RF 7 solidly. It's the reflector that does the VHF reception.

RF 5 I have lost hope on for next year but RF 5 "May" be duplicated on RF 27 as the station purchased another station with the money the FCC gave the station to move to VHF-Lo.

You do know that RF 13 is a VHF-Hi signal. I remember my father putting up a special VHF antenna for RF 13 which I watched snowy moves late at night with the snow over my head outside (I was small!). The rest of the Madison, WI stations were UHF!

If you will PM me with your Lat. and Lon. I will use my topographic program to check your location and send you pictures of the path to the Transmitters in 3D if useful. (E-Mail address needed).

Those may help you understand what you are fighting, yes you can use
https://www.rabbitears.info/searchmap.php

For $60 I got a program that produces graphics much like what I see on the weather casts of the news leading station in San Francisco.

SHF
Actually, while the CM-4228HD was designed primarily as a UHF antenna, it is rated as both a high gain UHF and moderate gain hi-VHF antenna.

Yes, I know that RF 13 is a hi-VHF signal.

I'm getting RF 7-12 absolutely fine on it with no problems whatsoever. I'm even getting RF 2-5 (lo-VHF) fine. The antenna is performing through the whole VHF spectrum (2-13) just as well as my ANT751.. EXCEPT for RF channel 13.

The two antennas have the about same hi-VHF gain rating (~6-8dBi), so the roughly equivalent hi-VHF performance doesn't surprise me.

What does surprise and puzzle me, is that if I put each antenna in the exact same spot with the exact same heading, and at varying heights, the ANT751 will get RF 13 solidly every single time with no problems or dropouts whatsoever. While the CM-4228HD will not pick up RF 13 AT ALL, EVER. So the issue's not the tower signal if RF 13 is always rock solid on a tiny little 3 foot Yagi.

Considering both antennas pick up the rest of the VHF spectrum equally well, this leads me to wondering if the antenna I got is defective or mis-calibrated from the factory.

(Perhaps it's bent or uneven or unaligned in a way that's just enough to cut off reception of only the top end of the hi-VHF range? .. I get RF 11 & 12 & just fine.)

I'm going to call Channels Master tomorrow. I have a few days left for my 30 day return.

Anyone ever experience something like this on the CM-4228HD?

Any ideas on what might be going on here?

Last edited by adream8; 09-03-2019 at 04:43 AM.
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