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I suspect that it will do as well as or slightly better than the RCA. It's a tiny bit quieter (0-.75 dB) on UHF and a little bit (5-6 dB) more robust on overload tolerance.

Of course, it's my conclusion that the "1 dB of noise claim" missed the mark.
 

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If we can tear majortom away from his “boat anchors” long enough it will be interesting to see how his performs.
Still waiting on suitable rf chokes that won't load down the VHF band to show up. Hope to have them by Friday.
 

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Comparison of Pre-amps

I ordered my RCA TVPRAMP1R pre-amp on a Thursday and it came on Monday. So I compared the "No pre-amp" signal to my older CM7777 pre-amp signal and to the new RCA TVPRAMP1R . (lots of roof climbing)
The sweet spot is where I can get the most channels in without turning the antenna.
In case of the DB8e it’s 154o for me and the best reception for the Seattle channels is 168o.
My TV Fool is
www.tvfool.com/?option=com_wrapper&Itemid=29&q=id=46ae879a94e6f5

The results:


I hope that inserted correctly.
In any case I get way better reception without either pre-amp. It's like comparing the better of two bad jobs.
I have now removed the pre-amps and they are relegated to the surplus electronics box.

Laurie in Ladner BC with a DB8e, and a rotator to a CM7000 DVR used as the primary tuner
 

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one thing I have changed in my system recently was installing not one, but two of the AD FM Bandstop Filters ($3.99 ea from AD site) in cascade between the antenna and my Winegard AP 8700 input. It's been about a week or two now, and so far I'm liking it. I saw some improvement in VHF Hi (local and distant), and have been seeing the distant OMNI RF 47 (-2dB NM) from Toronto more reliably and over a wider range of azimuth. How much of that is due to Summer? Can't say for sure, but I can say it hadn't come in reliably at all, all summer long prior. Was raining yesterday and it was still coming in.
 

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laurienicol, did you do your tests with the FM trap enabled? One or more nearby FM transmitters could be the problem.
 

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that's likely, as well as in laurienicol's tvfool looks like there are two main transmitter sites, in nearly opposite directions. There really isn't anything marginal within reach to begin with that would justify a preamp. Unless of course just trying to make up for downlead and splitter losses.
1 edge and 2edge signals are over 100 miles away at -16 dB NM or less. So a preamp won't help those. A Single bay GH antenna without reflectors would probably do well there with a bidirectional antenna pattern.
 

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laurienicol, did you do your tests with the FM trap enabled? One or more nearby FM transmitters could be the problem.
The default for both the CM7777 and the RCA, is FM trap enabled. I checked the CM7777.
I didn't change either. Also the leads are to the combined inputs.
I should just guess I'm lucky that I have a more or less clear shot down the Gulf of Georgia to Seattle and get as many channels as I do.
I'll give up spending money now (until the next big idea comes along).
My offer still stands to lend out my extra stuff to anyone else local who wants to try.

Laurie in Ladner BC with a DB8e roof mounted on a rotator.
 

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Laurie,

Your symptoms are either of an inoperative pre-amp or of something overloading, whether the tuner or the amp. It might be any of these things or some combination.

First verify that there's nothing between the pre-amp and its power inserter except coax. A common issue we run into is the presence of a DC-blocking splitter in the line. Double-check that first.

Then, I'd suggest a double FM filter as majortom installed at the input of the pre-amp (you have a LOT of local FM) and a variable (or several fixed) attenuator at the output of the power inserter.
 

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I put the power inserter next to the CM7000 DVR (used as the tuner). The pre-amps were within 18" of the DB8e combiner.

Interesting enough, the RCA power inserter has 2 or 3 inches of RG59 or smaller cable built into it. This was connected to the DVR directly. While I was changing things up, I tried the RCA power inserter with the CM7777 and got the same results as with the RCA pre-amp. The CM7777 power inserter was connected to the PVR with about 18" of RG6

The cable from the antenna comes down the outside wall to a ground block at about 35 feet. It then goes under the house directly to the PVR for another 25 feet.

It would be weird if both the RCA pre-amp and the CM pre-amp were defective.

Laurie in Ladner BC with a DB8e
 

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There has been instances of a downlead coax not able to pass DC power, but still pass enough RF to be usable. The best way to confirm would be to hook everything back up, climb back up and measure it up on the roof with a Voltmeter at the preamp end of the downlead.
If that were the case I probably would have expected ya to lose more stations than that though.:confused:
 

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The numbers in post #3662 say you've either got inoperative amps (cabling problem) or an amplifier/tuner overload issue.

Do you have a multi-meter to see if you actually have pre-amp power supply at the amp? You should read somewhere around 9 volts for the RCA and around 16-18 volts for the 7777(old or new version?).

edit: LOL! Tome beat me to it while I was typing!
 

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LOL, that happens to me all the time.
Ran into a bad coax jumper the other day btw, I was scrounging for pre made jumpers and first 1 of 4 pulled off an old direct TV antenna system. Sure enough, it wouldn't pass DC. Cut it in half, tossed in the trash and grabbed a different one. So it does happen.
 

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There has been instances of a downlead coax not able to pass DC power, but still pass enough RF to be usable. The best way to confirm would be to hook everything back up, climb back up and measure it up on the roof with a Voltmeter at the preamp end of the downlead.
If that were the case I probably would have expected ya to lose more stations than that though.:confused:
By Jove! That could be it, but it'll have to wait for better weather for me to get out the ladders (2 needed) to climb the roof.
I did check the cable at the ground block. I took the RG6 from the antenna off at the ground block as well as the ground wire from the antenna. No continuity from the fitting on the outside of the cable to the ground wire from the antenna. But also no continuity from the copper wire to the shielding, as expected. It could be a bad fitting on the wire.
I'll check the current at the antenna end when I get better weather again and SWMBO goes out shopping or my brother comes over and I send him up on the roof. I have spare f-type fittings if I need to fix the cable.
Great suggestion that would explain all.
Thanks
Laurie in Ladner BC, with new a DB8e on a very steep roof.
PS: I'm lucky enough to have one of the older version CM7777's
 

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Also the leads are to the combined inputs.
The combined input it only combined if you switch the pre-amp to combined mode (but that is also the default on the RCA). I wouldn't trust defaults though as manufacturers have been known to ship things in other than default state (first hand experience from the manufacturer's end).

I have also had first hand experience with a coax cable passing RF, but not passing DC properly. In my case it would work at first but the power injector would overload and shut down. I kept returning "faulty" equipment until I finally discovered the real problem. You can now get inexpensive coax testers. Not sure how good they are (they seem to only detect shorts and opens), but might be worth a look.
 

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Interesting issue with CM7777 amp

I had an interesting issue with the CM7777. I have an antenna setup (version of the GH) and CM7777 on my boat. This week I was in Toronto and when I turned on the system was expecting 20 to 30 channels. Instead I had six and they were not very good!

After some troubleshooting it became apparent that the CM7777 was the issue. It was flooding out due to the strong signals! When I jumped it out I got over 20 stations.

I did some more research and this amp is not recommended for areas with very strong signals!
 

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That's a fairly common problem with preamps, especialy high gain models. Even if the preamp dosn't overload, the TV tuner often does. In urban areas, it's often better to invest the extra money in a better antenna setup. If line or splitter losses are an issue, a low gain, overload resistant preamp is recommended.
 

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There has been instances of a downlead coax not able to pass DC power, but still pass enough RF to be usable. The best way to confirm would be to hook everything back up, climb back up and measure it up on the roof with a Voltmeter at the preamp end of the downlead.
If that were the case I probably would have expected ya to lose more stations than that though.:confused:
Weather cleared, Beryl went out for an hour. Installed the RCA power supply. Checked the voltage at the roof level (9.42 V) and re-installed the pre-amp. Still a 20% drop in signal. Removed the pre-amp again. Ladders hidden away. Beryl home.

Laurie in Ladner with a DB8e on the roof and (2) pre-amps in his "spares" box
 

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Current draw built up slowly as the unit heated up to a maximum of 78.8 ma so (if I looked at the right rotor) your rotor supply should handle the amp. just fine. With less than 80 ma draw, a 1200 ma regulator seems like overkill!.
Was able to test the RCA Amp while on the ground with a little telescoping omni antenna. Worked OK on the ground with my modification to grab power from the ROTR 100 control box. However it draws too much current from the ROTR 100's Antenna/Preamp Port. Just looked it up in the manual and that port is only rated for 17V @ 50 mA.
The preamp itself was drawing 95mA from the power insertor @ 9.4 VDC output. Works for a minute or two until the current limit of the ROTR 100's preamp out kicks in and shuts down. I hadn't realised it was only good for 50 mA prior to diving in to this. Will probably run another coax sometime, just for power/control of the ROTR 100. Back to the Winegard for now.
 

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majortom,

The preamp itself was drawing 95mA from the power insertor @ 9.4 VDC output.
I’m not good with math, but I think that’s double what your rotor is rated to support. I still have one RCA in bench stock so if I get some time tomorrow or Monday I’ll check my current draw again. I’m pretty sure after 1-2 hours it was drawing 78-79 ma. With an 8 volt on-board regulator, I am surprised the Winegard doesn’t draw that much or more. I’ve got an AP-2870 & HDP-269 that I’ll check just to satisfy my own curiosity. I bought 500’ of RG-6 @ Home Depot last summer for $35.00 and used 125’ of it to run a separate power line to my PCT drop amps. Cheaper than running 2-conductor stranded wire at the time.
 

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i didn't measure what the insertor+preamp was drawing from the rotr 100 preamp port, just what the preamp was drawing from the insertor.

Here's where I ended up choke mod wise, 1.8 mH
http://db.tt/Hq1XWTBd
a quick comparison of the spectrum as seen by the 950q, about an hour apart.
Antenna-> 2x FM filter -> ap8700
http://db.tt/Lf26cWPQ
Antenna-> 2x FM Filter -> RCA Amp
http://db.tt/nkCmY1fT
I do think it'll work alright. Will just have to rearrange a bit to run separate coax for the rotor,
while restoring the insertor back to normal.

Edit: on the bench I just measured 95 mA drawn from power insertor + preamp connected to my variable bench supply set to 17 VDC.
 
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