Carlsbad, San Diego: Older 8 bay bowtie, no signal? - Page 2 - AVS Forum | Home Theater Discussions And Reviews
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post #31 of 79 Old 11-01-2015, 12:11 PM
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I'm surprised you get FOX on Ch19, but not KUSI on adjacent Ch18 (I think they share the same Antenna). You might want to try moving the CM4228 up and down 6-12 inches, if you can. Personally, I don't see anything on their schedule that I would consider a "Must Have":
http://www.locatetv.com/listings/kus...dt#07-Nov-2015
LocateTV also shows other channels via pull-down menu selector.....

The CW on Ch23 is located in Tijuana....further away and a somewhat different direction....at the BOTTOM of the TVFool, so it's NOT going to come in from your location. But you probably COULD receive The CW on Ch31 located on Mt Wilson (L.A.).....which would require a Rotator (or a second UHF Antenna) for those rare occasions you WANT to watch their (I think) superlative shows:
http://www.cwtv.com/shows

Since you don't NEED the 8-El Yagi for Ch8/10 reception (CM4228 surprises us yet again)....you might want to point it to the NORTH to receive LA Traffic Reports (ABC on Ch7 & FOX on Ch11) and esp. KCAL on Ch9 which carries many L.A. Sports programs:
http://losangeles.cbslocal.com/category/sports

You should also be able to pick up MY NETWORK (MyN) on Ch13, that has a number of shows that might be of interest:
https://www.mynetworktv.com
http://www.foxla.com/my13

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post #32 of 79 Old 11-02-2015, 03:07 PM - Thread Starter
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Thanks Hollands, I'll check them out, I will be getting the Yagi tomorrow, I may throw it in a few different directions just to see what I can get. . .
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post #33 of 79 Old 11-14-2015, 04:26 PM - Thread Starter
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As an update, I had signal loss and pixellation on the Charger game last Monday night, so I'm headed up to put up the hi-gain VHF antenna. I'm going to try first on the same mast as the 4228, any suggestions? I think it needs to be pointed at 180, the same as the UHF. Will report back, but any suggestions welcome. It will go into the RCA amp up there. . .
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post #34 of 79 Old 11-14-2015, 04:55 PM - Thread Starter
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went up to the roof, but need additional mast, I do have the mast mount for my Voom dish that i just removed, if the VHF is in front of the UHF (about 6 ft away), but connected to the same preamp on the UHF mast, will that cause problems? My two easiest options are to double the height of the existing antenna mast, or to place the VHF antenna on the Voom mast, which is at the pinnacle of the roof line, and more-or-less directly inline with the UHF antenna.

Thanx for any opinion,

Joel
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post #35 of 79 Old 11-15-2015, 10:18 AM
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You need AT LEAST 4-ft (8-ft even better) HEIGHT difference to make sure that signals are minimally affected by one Antenna being in FRONT of the other [which is what I THINK you are describing].

However, this wouldn't be a problem is you can ensure that the Antennas are pointed in DIFFERENT directions so that one doesn't "Look" thru the other....perhaps this would involve reversing the Antenna mounts???

You might also want to consider mounting one Antenna above the other....which I modeled and found that Gain isn't noticeably affected until the Metal-to-Metal separation was about 1-ft.....although maintaining excellent F/B & F/R Ratio performance required AT LEAST 4-ft (8-ft even better) HEIGHT difference.
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post #36 of 79 Old 11-16-2015, 03:24 PM - Thread Starter
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OK, thanks, local HD and Lowes are out of the 5 ft. masts, I may order a 10 footer but WAF will decline immensely at that height. . . will try first with a 5 ft. and check results. The Hi VHF I got from MCM had a dreadful diagram and no instructions, not sure if I built it properly. . .
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post #37 of 79 Old 11-16-2015, 03:52 PM
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The Hi VHF I got from MCM had a dreadful diagram and no instructions, not sure if I built it properly. . .
Yeah, that's assembled wrong.

Go here (http://www.mcmelectronics.com/produc...-2475-/30-2475) and zoom in on the photo to see how it goes together. Ah, hell. Better yet, call them up and make them support the cheap Chinese crap they're selling. You can also download the "manual" from their website.
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post #38 of 79 Old 11-17-2015, 03:09 PM - Thread Starter
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yeah, the quality does seem quite crappy, which I guess is consistent with the cheap price, but if it works, I'm good. None of the wingnuts and bolts seem to match quite as they were intended, I'll try to zoomed pic version later, thanks for the suggestion. . .
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post #39 of 79 Old 11-17-2015, 04:40 PM
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I just recently bought one of these. I'll try to take some pictures shortly to show correct assembly for you. FWIW it seems to work very well so far. I'm picking up an ABC affiliate 73 miles away with it sitting on the couch back in my living room (no preamp, 25ft of rg6 connected to my TiVo OTA) I'm waiting on the holiday break to join it with my uhf antenna on the mast outdoors
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post #40 of 79 Old 11-20-2015, 08:45 AM - Thread Starter
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Thanks CP, thats encouraging.
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post #41 of 79 Old 11-20-2015, 09:12 AM
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Sorry completely forgot about the pictures too, I'll take some tonight if you still need them?
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post #42 of 79 Old 11-21-2015, 01:12 PM
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MikeBear posted measurements and several PHOTOS of the Stellar Labs 8-El Yagi here:
http://www.digitalhome.ca/forum/186-...ml#post2583505

He posted an annotated Manufacturer Drawing here, showing construction details:
http://www.digitalhome.ca/forum/186-...ml#post2584354

Which I used to construct a 4nec2 Model to analyze Performance, as described here:
http://www.digitalhome.ca/forum/186-...ml#post2585162

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post #43 of 79 Old 12-12-2015, 10:55 AM - Thread Starter
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Thanks, I missed these replies as I got distracted (squirrel) by other stuff, and the vhf channels were working, but intermittenly, especially with weather. I'm now trying to construct the Y-10 properly, but am getting the various connections incorrect. MCM is not open for tech support on weekends, has anyone assembled one of these guys recently? There aren't that many moving parts, but I can't seem to get the right connection for the main boom, the two square pipe pieces are the same size, so there is no slipping one into the other, and the connector does not appear strong enough to hold the lateral weight.

Any assist appreciated,
Thanks,

Joel
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post #44 of 79 Old 12-12-2015, 11:45 AM - Thread Starter
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Sorry, disregard, combo of impatience and lack of faith on my part, got it together and up, now re-scanning on my Tivo. . .
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post #45 of 79 Old 12-12-2015, 04:42 PM
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Yeah, the instruction manual is really bad.

You have some of the elements in the wrong places.





Drawing by MikeBear
http://i59.tinypic.com/rkd4py.png


manual
http://antennafiles.linuxx.org/~mrf/...bs_30-2475.pdf
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post #46 of 79 Old 12-13-2015, 09:37 AM - Thread Starter
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I thought it didn't look quite right, the channel scan actually went down a bit on most of the LA channels, understandable with the direction nature of the Stella labs, but still can't get a couple channels in San Diego. Its difficult to "point" this while on the roof, especially by myself, so I'll try to get a compass orientation and get the angle correct again. (wife not impressed with the second "shopping cart" either, so I need to optimize this).

Will re-arranging the elements make a significant difference in performance? If so, I need to pull the whole thing down and start again, its crazy they don't just label the pieces, it would make it much, much easier.

Thanx for any input,
Joel
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post #47 of 79 Old 12-13-2015, 11:04 AM
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Quote:
Will re-arranging the elements make a significant difference in performance?
Probably yes. The shorter one in the back reduces the gain because that element is a reflector element that needs to be longer than the driven element. The longer one in the front blocks the signals coming in from the front because it is the right length for a reflector instead of a director. In other words you are forcing the antenna to pick up signals from the opposite direction.

You can ask holl_ands if he sees this thread; he does computer modeling. He modeled the 30-2475 on a DHC thread, but needs to make a correction because one of the director elements that is close to the driven element dipole is hidden because of the angle that the Stellar Labs artist used for the original drawing. MikeBear used the same drawing to add the measurements of the elements for computer modeling, so the problem continued.
http://www.digitalhome.ca/forum/186-...mparing-6.html
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ts difficult to "point" this while on the roof, especially by myself, so I'll try to get a compass orientation and get the angle correct again.
I like to use the green signal lines on the 90 degree satellite view in the tvfool interactive map browser to pick a landmark for aim.
http://www.tvfool.com/index.php?opti...pper&Itemid=90

In the close view it switches to 45 degrees so you have to uncheck 45.
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(wife not impressed with the second "shopping cart" either, so I need to optimize this).
You could be doing things a lot worse than experimenting with antennas. I can recall Roseanne saying that it is important for a wife to let her husband have his dreams so that he will not notice that she is running his life.
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post #48 of 79 Old 12-13-2015, 01:51 PM - Thread Starter
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Its difficult to "point" this while on the roof, especially by myself, so I'll try to get a compass orientation and get the angle correct again.
I like to use the green signal lines on the 90 degree satellite view in the tvfool interactive map browser to pick a landmark for aim.
http://www.tvfool.com/index.php?opti...pper&Itemid=90

In the close view it switches to 45 degrees so you have to uncheck 45.

Not sure how to get the green line directional map on TVfool, in my mapping, cbs and abc are due south, and seem to be coming in well with my setup, but the CW station is not hitting at all, and I lost some of the LA stations I was getting before. (I expected that)

Before I drag it off the roof again, I will try to confiym the proper config of the elements and proper direction for pointing.

Thanks for the help,
Joel
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post #49 of 79 Old 12-13-2015, 03:12 PM
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Quote:
Originally Posted by jbailey895 View Post
I thought it didn't look quite right, the channel scan actually went down a bit on most of the LA channels, understandable with the direction nature of the Stella labs, but still can't get a couple channels in San Diego. Its difficult to "point" this while on the roof, especially by myself, so I'll try to get a compass orientation and get the angle correct again. (wife not impressed with the second "shopping cart" either, so I need to optimize this).

Will re-arranging the elements make a significant difference in performance? If so, I need to pull the whole thing down and start again, its crazy they don't just label the pieces, it would make it much, much easier.

Thanx for any input,
Joel
In another thread (I've tried to find it, but honestly can't remember which one) someone indicated that they had channels in separate directions so they removed two of the reflectors on the antenna. In their case they said it had little to no impact on their ability to receive their "Front side" channels, and increased the "back side" channels significantly. I'm sure someone here can identify which two you want to remove, if you want to try that.

Thank you to everyone for the diagrams too. It turns out mine was assembled incorrectly as well. I've got one of the reflectors on the front. I swear the small one was attached to the very back of mine when I got it, however. They shouldn't stick it back there if it doesn't belong there. Awful instructions for certain. I still haven't put mine on the mast. I'm going to correct my mistake and see how it changes my results.

As far as aiming goes, if you have an iPhone I suggest the TV Towers app. I've found that it works very well for me. It's much easier for me to visualize than a standard compass direction, and seems accurate enough in my experience at least.
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post #50 of 79 Old 12-13-2015, 04:28 PM
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Not sure how to get the green line directional map on TVfool,
Go here and enter your information:
http://www.tvfool.com/index.php?opti...pper&Itemid=90

which takes you to the map

move the cursor (drag and drop) to the antenna location

check the box to turn on the green signal lines, which are based on true north

If you use a compass, use the magnetic numbers on your report

some smartphones are not accurate
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post #51 of 79 Old 12-13-2015, 04:51 PM
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Originally Posted by rabbit73 View Post
Probably yes. The shorter one in the back reduces the gain because that element is a reflector element that needs to be longer than the driven element. The longer one in the front blocks the signals coming in from the front because it is the right length for a reflector instead of a director. In other words you are forcing the antenna to pick up signals from the opposite direction.

You can ask holl_ands if he sees this thread; he does computer modeling. He modeled the 30-2475 on a DHC thread, but needs to make a correction because one of the director elements that is close to the driven element dipole is hidden because of the angle that the Stellar Labs artist used for the original drawing. MikeBear used the same drawing to add the measurements of the elements for computer modeling, so the problem continued.
http://www.digitalhome.ca/forum/186-...mparing-6.html
Yes, I recognize that there is an OPTICAL ILLUSION at work when looking at the 3D Figures....there are FOUR Directors in front of the Folded Dipole and there are THREE Reflector Rods, with the middle one slightly further BACK along the Boom than Upper and Lower Rods, as shown in MikeBear's detailed set of PHOTOS:
http://www.digitalhome.ca/forum/186-...ml#post2583505

I don't think that MikeBear assembled HIS Stellar Labs Antenna wrong....clearly it matches the Image posted on the MCM and Stellar Labs websites, follows the "Traditional Conventions" for Yagi Element sizes (progressively Smaller from Back to Front, except FIRST Director Length adjusted for best SWR) and when modeled has low SWR and Gain in the ballpark of what I would expect, so I doubt that there is a "missing" element right in front of the Folded Dipole. If you look at the PHOTOS that MikeBear posted, you'll clearly see that the First Director is indeed very close in front of the Folded Dipole....as would be expected to control SWR:
http://imageevent.com/holl_ands/yagi...agistellarlabs

BTW: "Traditional Convention" of progressively shrinking Yagi Dimensions from Back to Front are frequently NOT the best OPTIMIZED Dimensions, as found for numerous Yagi Antennas marked OPT or OPTIMIZED. And making the Front THREE Directors the SAME Length may help in production, but it is NOT an OPTIMIZED solution...and as I discussed earlier, the METAL in the TWO Extra Reflectors would have been better utilized as additional, shorter Directors instead....on a Longer Boom....perhaps Constrained by moving the Short Vertical Support at the Rear to extend the Boom at the FRONT:
http://imageevent.com/holl_ands/yagis

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post #52 of 79 Old 12-14-2015, 08:09 AM
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This is the antenna that MCM markets as the Stellar Labs 20-2475: http://www.qiaohua.com/products/v-9h.htmThey refer to it as a 9-element in their model naming convention (5 directors, 3 reflectors, 1 driven element).

It actually has very decent performance for a 5' boom length. It could probably be optimized for our slightly narrower VHF band (174-216 vs. 174-230 as designed), but the improvements would likely be very modest.

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post #53 of 79 Old 12-14-2015, 09:12 PM
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I KNOW that the First Director was very close to the Folded Dipole....it's burned into my brain....I even saw it in MikeBear's Drawing (it's the one marked as 23-1/8 in long. 2.5-in in Front of Folded Dipole)....what I CAN NOT understand is WHY it didn't get into my final 4nec2 File.....SORRY....

Here is the CORRECTED 9-El FD Yagi analysis for the MCM & Stellar Labs 30-2475. Barely ANY change in Gain (tenths of a dB) but SWR is reduced from 3.0 to an Excellent 2.2 [as I've said before, if the First Director is very close to the Active Element, it primarily acts to control SWR....and NOT so much additional GAIN]:
http://imageevent.com/holl_ands/yagi...agistellarlabs

F/B & F/R Ratio Minimum was only 10 dB at 174 MHz, less than the 16 dB claimed in their advert cited by ADTech above, but their Gain numbers are in the right ballpark if we ASSUME that they are in dBd (vice the usual dBi = dBd + 2.15 dB). I also think that their Frequency Range is CLEARLY a typo on the low end (should be 174 instead of 147 MHz)....but the high end of 230 MHz makes sense.

There are only TWO countries that use below 174 MHz for TV Channels: PRC (China, 167 MHz lowest...only 1 Channel lower than 174 MHz) and Morocco (162 MHz lowest). These are QUITE A BIT ABOVE a 147 MHz spec point, giving credence to my theory that 147 was a simple typo error:
https://upload.wikimedia.org/wikiped.../VHF_Usage.svg
Internationally, several countries use up thru 230 MHz for TV Channels....and only South Africa is even higher (254 MHz). But if you look at EVAL Performance Summaries, you'll see that Gain on 230 MHz drops to only 0 dBi...

It is NOT EASY to orient the 3D Figure to clearly show ALL of the Elements....here's a small improvement:


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post #54 of 79 Old 12-15-2015, 05:33 AM
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Originally Posted by holl_ands View Post
I KNOW that the First Director was very close to the Folded Dipole....it's burned into my brain....I even saw it in MikeBear's Drawing (it's the one marked as 23-1/8 in long. 2.5-in in Front of Folded Dipole)....what I CAN NOT understand is WHY it didn't get into my final 4nec2 File.....SORRY....

Here is the CORRECTED 9-El FD Yagi analysis for the MCM & Stellar Labs 30-2475. Barely ANY change in Gain (tenths of a dB) but SWR is reduced from 3.0 to an Excellent 2.2 [as I've said before, if the First Director is very close to the Active Element, it primarily acts to control SWR....and NOT so much additional GAIN]:
http://imageevent.com/holl_ands/yagi...agistellarlabs

F/B & F/R Ratio Minimum was only 10 dB at 174 MHz, less than the 16 dB claimed in their advert cited by ADTech above, but their Gain numbers are in the right ballpark if we ASSUME that they are in dBd (vice the usual dBi = dBd + 2.15 dB). I also think that their Frequency Range is CLEARLY a typo on the low end (should be 174 instead of 147 MHz)....but the high end of 230 MHz makes sense.
holl_ands in a different thread on another forum a user reported that they removed both the upper and lower reflectors to pick up stations in multiple directions. At their location they stated it didn't affect their front facing channels, but they got significant signal gain from the rear stations. Is there any way you could do a simulation of that scenario to see how removing upper/lower reflectors from the rear impacts both front/back signal patterns?
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post #55 of 79 Old 12-15-2015, 07:12 AM - Thread Starter
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Ironically, after reviewing the info again, I had merely switched the front receptor and back reflector, and now I believe I have the stock configuration, although with our clear weather, I'm getting better reception with more channels in both direction (SD and LA) without the Yagi. Once the atmosphere gets obscured again, I'm sure I'll be back up on the roof. I still can't get the CW with either, but reliability of 8 and 10 are my paramount goals, and I think the Yagi helps for that.

I've also posted on the grounding thread (without response yet) about grounding the mast, since my feed into the house is on the other side from where I believe the cable grounding block is. Can anyone confirm a simple way to ground the mast? I do have lines from my old Voom dish heading towards the TV and power panels, can I just attach one of those lines to the mast, and combine with a splitter on the cable grounding block? (pic of what I think is the grounding block attached) If so, how do I attach the coax to the mast on the roof?

Thanks,
Joel
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post #56 of 79 Old 12-15-2015, 08:46 AM
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Originally Posted by jbailey895 View Post
Ironically, after reviewing the info again, I had merely switched the front receptor and back reflector, and now I believe I have the stock configuration, although with our clear weather, I'm getting better reception with more channels in both direction (SD and LA) without the Yagi. Once the atmosphere gets obscured again, I'm sure I'll be back up on the roof. I still can't get the CW with either, but reliability of 8 and 10 are my paramount goals, and I think the Yagi helps for that.

I've also posted on the grounding thread (without response yet) about grounding the mast, since my feed into the house is on the other side from where I believe the cable grounding block is. Can anyone confirm a simple way to ground the mast? I do have lines from my old Voom dish heading towards the TV and power panels, can I just attach one of those lines to the mast, and combine with a splitter on the cable grounding block? (pic of what I think is the grounding block attached) If so, how do I attach the coax to the mast on the roof?

Thanks,
Joel
A few ideas/questions/suggestions for you... If you're losing channels when you combine the two antennas then the 4228 must be receiving some VHF signal and feeding it into the pre-amp. You might want to just combine it before the pre-amp with a UVSJ, or use a UVSJ to split just the UHF signals from the 4228 before you combine. The labeling on the pre-amp says VHF and then UHF/Combined, which would lead one to believe that it would pass any VHF signals it receives on the UHF/Combined port as well. If your 4228 is picking up any VHF those signals will clash with your VHF only antenna. Likewise the VHF antenna will pick up some stronger UHF signals as well. In my situation my two strongest UHF stations come in perfectly with just the VHF antenna we're talking about so I have to use a UVSJ when I test it with my other antenna.

Another possible point to consider, and I'm waiting on holl_ands to weigh in on this, but your channels 8 & 10 are much stronger than the LA stations. If you want those LA VHF channels I would try pointing the antenna that way, and see if the VHF antenna pulls them in. If it does experiment by removing the upper and lower reflectors from the VHF antenna and see if you still get your channels 8 & 10 from San Diego off the back of it (with it still pointed towards the LA channels). The angles are almost perfect for that (see screenshot below of the transmitter locations). A user on the satellite guys forum recently bough the same antenna and reported that he did that, and had good reception of stations from both sides. Again in your case it might not work, but if you want to experiment it would be easy to try. I'm hoping holl_ands will do a plot analysis to see what affect this might have.
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post #57 of 79 Old 12-15-2015, 10:01 AM
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The labeling on the pre-amp says VHF and then UHF/Combined, which would lead one to believe that it would pass any VHF signals it receives on the UHF/Combined port as well.
That would be incorrect. In the "Separate" position, the internal UVSJ is already engaged and VHF is attenuated from the UHF/common port. See image below, click on thumbnail, if needed, to view.There is no need for an external device unless the discrete VHF amplifier has failed. I have one of those sitting on my workbench.


Quote:
If it does experiment by removing the upper and lower reflectors from the VHF antenna and see if you still get your channels 8 & 10 from San Diego off the back of it (with it still pointed towards the LA channels).
Removing the reflectors will do two things (at least): Reduce F/R ratios thus improving reception "off the back" and will reduce forward gain which reduces reception off the front. It likely will also affect the radiation patterns elsewhere, modelling should show what to expect. FWIW, I frequently suggest such a modification on a number or our antennas when bi-directional reception is desired and the signal ratios suggest it will work.
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Tech support for Antennas Direct

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post #58 of 79 Old 12-15-2015, 02:31 PM
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SURE, I'll do some 4nec2 Runs without some/all of the Rear Reflector Rods in the Stellar Labs 9-El LPDA....
And Upper/Lower RR's moved FORWARD, more like a Corner Reflector....and a couple more RR's....
I also planned to do some runs to find the OPTIMUM solution(s)...just for drill...and comparisons....


YUP, it's a Coax Ground Block for Cox Cable Coax, and requires a HEX SOCKET/DRIVER to loosen the Bolt holding down the GROUND (White) Wire...that "probably" is connected to "Ground" (Neutral or Green Safety?) inside your adjacent Electrical Breaker Box. You can REPLACE with a TWO COAX Ground Block, as long as it has TWO separate Wire Screw Downs:
http://www.summitsource.com/eagle-aspen-dual-ground-block-directv-approved-port-high-frequency-coax-cable-type-ground-block-satellite-antenna-voltage-protect-connection-mount-outdoor-dish-digital-video-signal-part-pvgb2hf-p-7113.html

Or simply add a second ONE COAX Ground Block (I would simply bolt the ends of the Ground Blocks together...with a second Nut to securely LOCK it in place...I'm just THAT kind of Engineer)....this would also provide a separate place to connect the AWG10 Antenna MAST Ground Wire, without "sharing" a common screw down (avoid if possible):
http://www.summitsource.com/dish-net...hf-p-9697.html

Connection to Antenna Mast is via Wrap Around Antenna Mast Ground Clamp, which has JAWS to make secure metal-to-metal contact to the mast and a Screw Down for connection of the AWG10 Ground Wire:
http://www.summitsource.com/vanco-pi...FVFffgodoM4L9A

BTW: If it's convenient, you could alternatively connect the Antenna Mast Ground Wire to the COLD Water Pipe BEFORE it ENTERS the House (NOT at one of the various outdoor spigots...since lightning currents would flow THRU the House to Ground....a NEC Code Violation):
http://www.summitsource.com/eagle-gr...mp-p-7260.html

PS: There may be some locations that require heavier AWG8.....
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post #59 of 79 Old 12-15-2015, 04:05 PM - Thread Starter
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Thanks guys, this is really helpful info. its been really windy lately, so going up on the roof, alone, and trying to get this done has been challenging, your help is appreciated :-).
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post #60 of 79 Old 12-20-2015, 10:22 AM - Thread Starter
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OK, I put up the Yagi this am, and rescanned the Roamio, getting mid 60's signal strength on all the major San Diego networks. I lost some of the LA networks (probably from the reflectors on the back), but I think I'm good. Most of the programming is the same between LA and San Diego. . .
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