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Old 25-Apr-2016, 8:10 PM   #21
rabbit73
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Your tests confirm the voltage drop problem in a long coax run. The RG11 not only has less signal attenuation, but it also should have less voltage drop for a preamp.

Quote:
Originally Posted by dustyz View Post
I found this link, and it's very educational for those who don't understand the basics, like me. :-)
http://www.hdtvprimer.com/antennas/basics.html
There is a lot of good basic information on hdtvprimer.com, but some of the preamp and antenna models are no longer available.

Keep in mind that every reception location is unique and requires a custom solution.

Calaveras also did a page on noise and preamp gain:
http://www.aa6g.org/DTV/Noise/noise.html
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Last edited by rabbit73; 25-Apr-2016 at 8:12 PM.
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Old 25-Apr-2016, 8:18 PM   #22
rabbit73
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This diagram shows how much difference a preamp can make in receiving weak signals:



This is for weak signal DX:

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Last edited by rabbit73; 25-Apr-2016 at 8:22 PM.
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Old 27-Apr-2016, 12:40 PM   #23
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***UPDATE***

I installed the 7777 last night, and WOW did it make a difference. I went from having a few unwatchable channels on the Tivo to 10-15 good channels! Massive boost! The most important channels come in clearly.

We also had a nice storm roll through last nite, with gusts up to 60mph in some nearby areas. It gave my antenna mast a good test, and it passed just fine. That's a plus. We did lose almost every channel during the heaviest part of the storm, but that's expected in our location & with the route of the weather. I can deal with that.

Thanks for the help guys. I'll probably try to tweak a few more things here and there, just to solidify what we already have, but I'm very happy with the setup.
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Old 27-Apr-2016, 2:10 PM   #24
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Thanks for the update with the good news. I'm always glad to hear that our ideas work.
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Old 27-Apr-2016, 3:20 PM   #25
Billiam
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Yup. Glad to hear it worked. Pre amps are funny just like antennas. One will work better than another or worse depending upon where and how it is uses. I used a CM 7777 for a while a few years ago in a rural town near KC. But on a whim I switched to a Winegard 8275 and got better results with the Winegard at that location. Signals that were pixelating with the 7777 were rock solid with the Winegard. All depends upon the antenna you use and other factors like cables I suspect.
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Old 10-Nov-2016, 1:13 PM   #26
dustyz
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Another update...

Over the summer our channels started to disappear. I redirected to the 290 angle shown on the TVFool report and picked up several steady signals. That slowly seemed to drop off over summer, to under 6 reliable channels by October. I assumed it was largely because of foliage. When the antenna was installed, it was early spring after all.

So fast forward to last weekend. All signals went out. No channels at all. I lowered the antenna and checked connections, cables, etc. I rebooted the Tivo that the antenna was connected to, and the preamp. Nothing. I ended up moving a HDHomerun out to the antenna, effectively eliminating the cable run but still using the preamp, and tested signal strength.

What I found was interesting. The signal strength was 100% on most stations, but had no quality. BUT, I could completely remove one side of the DB8e, effectively making it a DB4e, and I picked up more channels than I've EVER had. Stations from different directions, solid signal qualities, it was nice. (That's actually how I'm using it at the moment.)

If I connect the UHF combiner back up, using both sides of the antenna, the signal is gone. Connect only one side to the combiner, making it unloaded, and it's still gone. Nothing works through the combiner, period. I threw in a 2 way splitter, to see if it worked, and got the same results.

I spoke with Antenna's Direct, and they said having both sides of the antenna pointing in the same direction makes it very directional. However, pivoting them 30 off one another really helps signal strength. I tried that... no luck. It didn't change anything.

Am I over-powering the tuner? It's most certainly sounding like it. Is there an easy way to test that? I put a splitter in the line, midway to the house, and connected both the Tivo and the HDHomerun, and it didn't change anything.

Last edited by dustyz; 10-Nov-2016 at 1:26 PM.
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Old 10-Nov-2016, 6:55 PM   #27
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Quote:
I threw in a 2 way splitter, to see if it worked, and got the same results.
How were you using the splitter? Did you add the splitter after the combiner but before the preamp input as an attenuator, or did you replace the DB8e combiner with a splitter in reverse as a combiner?
Quote:
I put a splitter in the line, midway to the house
Why, to act as an attenuator? Did you insert it between the preamp and the power inserter? Is it a power passing splitter?
Quote:
Am I over-powering the tuner? It's most certainly sounding like it. Is there an easy way to test that?
Yes, insert an attenuator between the power inserter and the tuner.

How do I test my Titan 2 High Gain Preamplifier (CM7777) preamplifier to make sure it is working correctly?
http://support.channelmaster.com/hc/...ing-correctly-
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Last edited by rabbit73; 10-Nov-2016 at 7:07 PM.
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Old 10-Nov-2016, 7:27 PM   #28
dustyz
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Quote:
Originally Posted by rabbit73 View Post
How were you using the splitter? Did you add the splitter after the combiner but before the preamp input as an attenuator, or did you replace the DB8e combiner with a splitter in reverse as a combiner?
I replaced the DB8e combiner with the splitter in reverse. (A recommendation from Antenna's Direct to test the combiner.) I also placed it mid-line as a attenuator, which since it doesn't pass power, I realize was a mistake. I'll move it between the power inserter and tuner tonite.

Thanks for the link.

While I'm getting into it, can you think of anything else I should try? Antenna's Direct also said a local cell tower could be interfering with the CM-7777.
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Old 10-Nov-2016, 8:06 PM   #29
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Quote:
anything else I should try?
Quote:
and an inline surge connector in the middle
Which surge connector? Is it still there?
Quote:
Antenna's Direct also said a local cell tower could be interfering with the CM-7777.
That is possible if it is close enough and it is using frequencies just above TV CH 51.
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Last edited by rabbit73; 10-Nov-2016 at 10:01 PM.
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Old 10-Nov-2016, 8:13 PM   #30
dustyz
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Quote:
Originally Posted by rabbit73 View Post
Which surge connector? Is it still there?
That is possible if it is close enough and it is using frequencies just above TV CH 51.
Yeah, it's still there. I did pull it out when testing, and just put a coupling in there, no difference.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
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Old 10-Nov-2016, 8:27 PM   #31
rabbit73
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That is supposed to be a good one, but coax surge protectors have a device connected between the center conductor and the shield that is known to degrade weak signals. I only use a grounding block which just grounds the shield and meets the requirement of the NEC for an ADU (Antenna Discharge Unit), especially if it is a "Listed" device.



Maybe ADTech will stop by and help you with the DB8e problem in post #26.
Attached Images
File Type: jpg TII Surge Protector2.jpg (78.8 KB, 807 views)
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Last edited by rabbit73; 10-Nov-2016 at 10:33 PM.
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Old 10-Nov-2016, 10:14 PM   #32
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I've been working with him directly via email.
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Old 25-Jan-2017, 5:03 PM   #33
dustyz
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Ok, I've finally found time to work on this setup again. I've been talking with ADTech about it via email, but figured I'd get more eyes on the problem. I'm sure he appreciates that. ;-)

I'm going to clear up a few things first, then share some info I've collected.

Here is the accurate TVFool report, with the adjusted 32ft elevation for the DB8e:
http://www.tvfool.com/?option=com_wr...e6a40f8dc0b42b

Here is the FMFool report:
https://drive.google.com/open?id=0By...ktwUVk5UnUzU00

My Antenna layout and setup:


Notice the panels/elements are off broadside about 10 degrees each, and should probably be closer to 15-20 each, but...

The spread for the DB8e @ 0 degrees:


The spread for the DB8e @ 15 degrees:


I have 4 cell towers within 10 miles. Number one is only 1.2 miles away, but just north of us @ 6 degrees. Numbers 2, 3, and 4 are all in the 240-280 degree range.

As we've discussed before, I've always had trouble getting what I though I should with the DB8e. Last summer I disconnected one panel on the DB8e, bypassed the combiner, and effectively made a DB4e to test. I received more channels than I ever though I could. It worked great for a while, but when the leaves fell over the winter, I lost nearly all channels.

I recently connected the DB8e back up, as I thought it should be. The setup linked above is how it's currently configured, and Channel 7(28) will occasionally show up on the TV... nothing else. Assuming overpowering, and per the recommendation of this place & ADTech, I added a splitter between the pre-amp and the DB8e, knocking the input signal an additional 3db. Here is a 24-1000Mhz RTLSDR scan from that:


So, I've effectively started over. I try to run two tests a night, lowering the tower to make tweaks. I've made scans prior to the surge protector, and although they show gains on a few channels, not enough to warrant the overall loss.

Based on the information above, what do you all think I should try next? Or, better yet, what tests would help identify the problem?

Thanks, I know there's a lot of information. I appreciate the help.
Attached Images
File Type: jpg Antenna Config (Small).jpg (39.7 KB, 642 views)
File Type: jpg DB8e 15 off.jpg (51.2 KB, 584 views)
File Type: png Scan 24.0-1000.0MHz - DB8e - 2-1 Splitter Attenuator - ChannelMaster - At TV - 288-308 (Small).png (45.6 KB, 568 views)
File Type: gif Channels.gif (15.6 KB, 271 views)
File Type: gif DB8e 0 off.fw.gif (24.8 KB, 548 views)
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Old 26-Jan-2017, 12:38 AM   #34
dustyz
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Two more scans tonite. The antenna direction and elevation did not change from the scan in my previous post above.

One, I completely removed the attenuation, preamp & injector from the mix, and took my scan at the same TV location connected straight to the RG11:


Two, I kept the attenuation, preamp & injector removed, but replaced the surge protector with a grounding block/coupling, scan completed at the TV:


The results were very close. The grounding block/coupling actually decreased the signal slightly. I'd say that's because my ground wasn't cleanly connected to the block... I noticed that after the scan.

Last edited by dustyz; 26-Jan-2017 at 2:14 PM.
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Old 1-Feb-2017, 3:54 PM   #35
dustyz
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Two things...

Antennas Direct Tech support is awesome, and have been extremely patient and helpful via email. ADTech helped me learn, research, identify, and fix our channel loss issue.

It ended up being the preamp. I think the 7777 is amplifying, but at a much lower level than it should be. The loss in the coax was negligible. I still need to run some tests to verify the preamp is getting the correct voltage from the injector & not just overpowering the tuner. To be continued...
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