: Signal Amplifiers (Amps, Preamps, Distro Amps)



uhf
2009-10-28, 09:42 AM
Good Morning Stampeder,
On your Post # 1494 was the link to the Mega-Amp. Is there any more info available? Please keep us "Posted".
Thanks:D

stampeder
2009-10-28, 02:33 PM
And good morning to you - I haven't heard a thing about those amps in response to that, unfortunately. Mind you, if someone had ordered one its possible that it hasn't arrived in North America yet.

quatro
2009-10-30, 11:12 AM
Hello,

just a question. How does the combination of amplified tv splitter would work with preamp CM7777. Will it work to help improve signal or create a malfunction or danger? Thanks.

mogwai
2009-10-30, 12:46 PM
You do run the risk of running an amp into distortion if the signal is too great from the source. The idea of the preamp is to make up for your down lead losses (IE how much cable and anything else you have between your antenna and end point.) and the CM adds 28dB of gain to the mix. I'm currently running one with no splitter and about 65' of RG6 down lead and no problems with over driving signals. Depending on your distribution needs, you might try a passive 2 port splitter first and see how that works. In my rig I tried a passive -3.5db 2 port splitter with negligible results and ended up with decent signal at both ends. If I was going to 4 end nodes, I'd probably hook up my Electroline EDA-2400 drop amp/splitter.

goforit
2009-10-30, 01:53 PM
mogwai:


When you read the TV Fool report- what is the numbers to watch out for- for overloading your tuner?

mogwai
2009-10-31, 12:59 AM
The way that I looked at my tvfool was to check the strongest signal (-38.5dBm) and then start playing with the losses and gains

-38.5 dB best signal
+14.0 dB from antenna
= -24.5dB
-5 dB loss from splitters and down-lead
= -29.5dB
+28 dB gain from pre-amp
= -1.5dB

It's generally considered safe to hit +10dB without experiencing overload.

Hope this helps.

jdemaris
2009-10-31, 03:12 PM
Hello,

just a question. How does the combination of amplified tv splitter would work with preamp CM7777. Will it work to help improve signal or create a malfunction or danger? Thanks.
I've got three antenna sites on my property. One is 150 feet from the house, one 350 feet, and one 550 feet. All my signals are fringe or extreme-fringe and none of my antennas can get any useable signal without a preamp.

The site at 150 feet has a Channel Master CM7777 preamp and RG6 cable and works fine.

The site at 350 feet has a Winegard AP8275 preamp, RG6 cable, and a cheap 24 dB line-amp half-way home. Also works fine.

THe site at 550 feet has a Winegard AP8275 preamp, RG11 cable and a cheap 24 dB line-amp at the 350 foot mark. It too works fine.

My point is that preamps run in-line with line amps/distribution amps work fine, when needed due to long wire runs.

When it comes to preamps and claims about low-noise and gain, I'm not a firm believer in the big advantage of low-noise that comes with higher cost.

At all three of my extreme-fringe antenna sites, I've swapped in many different preamps - same time, same place, same antennas, VHF and UHF. I've tried the Channel Master CM7777 at $50-$60 each, Winegard AP-8275 at $35-$45 each, AntennaCraft 10G212 at $27 each, and the ultra-low noise British preamp made by Research Communications model # 9262 that cost a little over $100 US dollars with shipping from overseas. Note that the Antennacraft 10G212 for $27 is also sold by Radio Shack stores for over $70 (what a rip-off).

Tried these amps with with following antennas: Winegard HD8200 UHF/VHF combo, Wade VIP-307 VHF hi-low, DB8 UHF only, XG91 UHF (ganged pair), Winegard 9032 UHF (single and ganged and stacked pair), Antennacraft Y-10-7-13 highband VHF, and Winegard YA-1026 low-band VHF. I ran these tests at home in central rural New York, in the northern Adirondack mountains in New York, in northern New York near the Canadian border, and in northern Michigan and also near the Canadian border.

I have not observed any remarkable difference in reception. For my poor channels that sometimes pixelate and drop out - they were the same with all the amps I've mentioned.
CM-7777 has dual inputs that can save a person the $4 cost of a VHF/UHF combiner.
The cheapest Antennacraft 10G212 preamps have an indoors FM trap switch and also a variable gain-control which is a nice feature that none of the higher priced amps have.
Subsequently, they seem to be a pretty good deal.

Maybe some lower-noise amps make a difference with certain TV tuners - I don't know. I've got a new Sansui 19" LCD digital, an older Syntax Brillian Olevia 42" LCD digial, and several old TVs with Magnavox or Coship digital converters. So, at least with them, these amps worked pretty much the same.

Amp specs for what I tried:

Channel Master 7777 is VHF 23 dB and UHF 26 dB, noise 2.8 and 2 dB

Winegard AP-8275 amp is: VHF 29 dB and UHF 28 dB, noise 2.9 and 2.8 dB

Antennacraft 10G212 (also sold by Radioshack) Adjustable gain up to 30dB VHF/UHF Noise Figure: <4.0dB VHF, <3.5dB UHF

Research Communications (Great Britian) # 9262, 23 dB gain UHF with .6 noise.

Note that my most problematic channels are 29 and 50 on UHF. The Antennacraft amp with 3.5 dB noise worked just as well for me as the Research Communications amp with 6/10ths of a dB of noise. I found that a little dissapointing. I can buy four or five of the Atennacraft amps for the price of that one Research Communications amp.

There may be other environments where results will be different, but not in mine. I live in extreme fringe areas. At home I am surrounded by mountain tops with no clear shot at any transmitter towers. In northern Michigan, no mountains and am near Lake Huron and not too far from Sault Ste. Marie at the US/CA border, etc.

stampeder
2009-10-31, 03:25 PM
Thanks for that, jdemaris, you deserve a medal for all your extreme-fringe OTA testing! :)

mlord
2009-10-31, 03:47 PM
I strongly suspect that the reason the pre-amp noise figures don't seem to matter in those setups, is because of the noisy inline amps that are needed for the very long runs. If those were also low-noise models, then you might see some advantage.

Cheers

jdemaris
2009-10-31, 05:08 PM
I strongly suspect that the reason the pre-amp noise figures don't seem to matter in those setups, is because of the noisy inline amps that are needed for the very long runs. If those were also low-noise models, then you might see some advantage.

Cheers
Not in my case. For every test, I checked at the antenna sites first with a digital TV and its built-in signal meter. That's before any long wire runs and line-amps. I test all my hookups that way. I have a 4WD mobile-rig with a built in AC power supply, digital TV, etc. Comes in handy when testing TV reception at remote sites.

If after testing I find the signal at home is somehow degraded as compared when run directly at the antenna - I know something needs to be upgraded. In fact, that is the reason I have two line-amps. I had several channels at my further antenna that came in strong and consistent at the antenna, but pixelated at home (after 550 feet of coax).
Putting in a $15 line-amp fixed the problem.

In every test I ran, with all those preamps, including the worst channels - things were basically the same when tested on site with NO line-amps, and at home with a lot of wire and running the line-amps.

I'll add, that from all I've read, the noise-factor of the line-amp has little significance as compared to the noise factor of the preamp. The major factor is supposed to be the first transistor (noise maker) that the antenna wire sees - which is at the preamp.

DigitalRocks
2009-10-31, 07:49 PM
jdemaris,

Awesome information... thanks for the great detailed results!

So then your opinion is the AntennaCraft 10G212 is a good buy? I am currently using thier basic model that only gives out 16 dbv hf/22 db uhf gain - 10G201. I am in an area where i have some LOS and both fringe signals that I would like to improve. Currently using an AntennaCraft HBU 33 combo antenna on the house on a tripod, no obstructions around. Happy with it, but like everyone else here I want more channels on a regular basis. On colder days i'm noticing some of my channels are very hard to get past 50 miles away.

Now from all the reading I have done, i understand you can overload an already powerful signal with too much amplification. What i'm wondering, would the adjustable amp be a good option? If I were to specifically want to pull in a fringe signal I figured I could crank up the amp and possibly help the fringe signal, and turn it down later if I'm not worried about getting that channel later. My dilemma is trying to get a weak signal that is at 51 miles away, WUPW Toledo. It isn't extremely far, but its transmitter has a null pointed towards us in Canada so the signal is occasionally there at night, but not there during the day.

I know that the amp can only make a signal stronger if the signal is being picked up by the antenna, which makes me think maybe i need both to obtain these channels... here is my tv fool:

http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id%3d8adf5956f0a34e

I can pickup everything up to WNWO, but everything below is scarce.... i will see some of them at night when trolling around with the rotor for signals, or with the tropo we have had recently. Any suggestions would be great, thanks.

intravino
2009-10-31, 08:32 PM
Good Tests jdemaris.

jdemaris
2009-11-01, 10:57 AM
I want to make it clear that I am just reporting on my own installations and the results that I observed. Obviously, my "tests" are not scientifically controlled. That being said, I've yet to encounter evidence of a marked difference between the expensive and cheap high-gain amps - except one. Having ANY amp makes a huge difference, though. I did one install where the cheaper amp works better on one targetted channel that the other high-priced amps and I have no idea why, other then the slight amount of extra advertised gain it has.

My mindset is this. I can read tech info ad nauseum, and I have. If I based all my plans on tech info alone, and/or anecdotal claims, I'd still be using satellite TV from Direct TV.

Antennaweb showed there was the chance of maybe getting one channel where I live - so if I'd listened, I'd never of even tried an antenna install. I later discovered that TV Fool was much more useful, but still way-off about how some signals reach my property.

I've read articles about the "digital cliff" of approx. 65 miles. Yet, I now get several from 120 miles away.

I've read articles claiming digital TV must be line-of-sight. I get over a dozen consistently and NONE are line-of-sight. Some don't even come from the direction of the transmitter, going by compass points. Some are off by 30 degrees.

I went to my local Radio Shack store to buy some wire and got talking to the owner about the digital changeover. He told me he has stopped stocking any over-the-air antenna supplies since nobody in this area can get any TV reception since the change in June.
This is central New York in a mountainous area and the nearest transmitters are 60 miles away from any direction and all with hilltops and trees in the way.

I've read that a preamp cannot make a small antenna behave like a big antenna. If that was true, again - I'd of gotten nowhere and still be using Direct TV from a dish.

I've read company posted gain charts for antennas as well as privately created computer models of raw gain and net gain of popular antennas. Those specs do not reflect what works for me, especially on high UHF. I have a new model DB8 that does signifigantly better then a single XG91, a stacked pair of XG91s, and a ganged pair of XG91s. The charts indicate otherwise.

Where I live, I used to get one over-air-channel (late 1970s) with a preamp and a huge Wade VIP-307 VHF antenna. It was snowy but it was all we got. I then built my own 14 foot wood and chicken wire dish for muli-satellite reception and changed over to that. Years later, Primestar became available with a small single satellite dish system and I changed to that. Years later again, Primestar got taken over by Direct TV.

This June, I started paying attention to all the talk about the digital changeover because I lost my only AM radio station for awhile. I was trying to find out why radio was affected by a TV change.

As a result of the info I'd gleaned on news shows about digital TV, I got thinking that the TV would no longer work in my RV that we take across Canada every year to norhtern Michigan. It had an analog TV. So, for that reason alone, I bought a new digital TV just for my camper to be used only on trips in areas where some TV actually exists by air. When I was setting up the new TV in my camper, I also bought a new amplified tiny Lava antenna on Ebay. It looks like a joke and is maybe 2 feet long. The ad for it looks like a gimick for morons and claims 80 mile reception on UHF and VHF. The $35 is half the price of a genuine RV antenna so I figured it might be worth having even if only worked half-as-well as claimed. Well, I drove up the mountain behind my house just screwing around with it - and got almost a dozen TV channels. I was truly suprised, and perhaps a bit angry at the same time. Angry over all the BS I've heard.

So, my point here is - a small antenna certainly DID behave like a big antenna and I got a dozen channels with it, in an area where Antennaweb said I might get one with a huge antenna, and none were line-of-sight. It is this event that led me to spending this summer and fall experimenting with antennas and preamps. Like I said, that little Lava antenna is a joke and I'd never consider using it full-time outdoors. But, it IS amazing for what it is. I bought two more at auction ($25 US dollars each) branded as "Super Voltex 4000" and they seem to be the same as the Lava. Around 2 feet long with a built in amp and rated at 30 dB gain.

Now, about what I mentioned earlier - about a cheap amp working on one channel better than a higher priced amp. I was working on a foreclosed house I bought in northern Michigan. Before the digital change, we had gotten 3-4 TV channels on rabbit ears. My wife's parents live 50 miles away in the City of Alpena and they were gettting 2 channels before the change. After the change, neither of us got any channels. Our camper however, with the cheap crappy little toy antenna got many channels. So, I did some work. My purchases were limited to a Michigan Radio Shack store since I had little time to order online and wait for deliveries. I did, however, have with me a big Winegard HD8200 antenna, a Winegard 9032 UHF antenna, a Channel Mater CM7777 amp, etc.
I went to work at my wife's parents who only wanted to get back the two channels they had gotten previously before digital. Their house is along a river, but sits in a hole and has a hill-top and trees between the house and transmitters that are 30-40 miles away. Target channels were 11 and 24. I installed one of those cheap Voltex toy antennas inside their house in the attic. Both channels came in pretty well except 24 would pixelate now and then. I then installed the big Winegard UHF only 9032 with a CM7777 preamp. Channel 24 worked worse. I then installed a a combo UHF/VHF Radio Shack antenna. It's a mid-sized antenna. Model 15-264 with a 85" long boom and 31 elements. With no amp it got nothing. With the CM7777 amp, it worked about the same as the little toy antenna I'd first tried. Channel 11 was fine but 24 would pixelate and freeze now and then. Signal meter showed "low." I then stuck in the cheap Antennacraft 10G212 amp and 24 then came in consistently with no pixelization. If I turned the gain-control down on it even a little, the pixels came came back. So, I left it as is. That was back in August when the trees still had leaves. It is still working fine as I check often. Note however that I bought that "$27" amp at Radio Shack and they charged me $70 for it. They call it model 15-2507 and double the price. In this case, this preamp rated 30 dB gain with 3.5 dB noise is working better then the CM7777 amp rated 26 dB gain with 2 dB of noise. I assume the higer gain is the factor here, regardless of the noise factor.

stampeder
2009-11-01, 12:49 PM
DigitalRocks, apart from your inquiry about the AntennaCraft 10G212, we'll need to keep discussing your particular local reception issues in the Windsor thread (http://www.digitalhome.ca/forum/showthread.php?t=81123) and not in this thread. ;)

cheers

Daemons
2009-11-05, 02:44 PM
I would suggest you look at something like the Channel Master 3410, or 3412
I use the 3412, and it really helps in stabilizing the signal.

I have a question about these distribution amps.
My HTPC uses a card that has separate Analog and Digital inputs so I need to use a splitter, and losing some signal in the process.
I would get a CM3412, but I do plan on getting another card for more digital tuners, so I will need 3-4 inputs total.
Can I use a CM3414 and use only 2 outputs for now? Do I need to use 75ohm terminators on the 2 unused outputs?
I'm only using about 35' of regular (60% ?) RG-6, and no pre-amp. I read that with small cable runs, the distribution amp can cause more problems.
Am I better getting a quality 2 way splitter right now, and wait to get the CM3414 for when I need the more inputs?

Marc

hoopitup2000
2009-11-05, 11:54 PM
Marc, the 3414 would be an excellent choice for your situation. It is very resistant to overload, and should work fine as long as you are at least 7 miles or so from any strong TV or FM transmitters. The unused outputs should be terminated, although I have never noticed any problems with them left un-capped. Short cable runs should be of no concern either.

Daemons
2009-11-08, 01:56 PM
Marc, the 3414 would be an excellent choice for your situation. It is very resistant to overload, and should work fine as long as you are at least 7 miles or so from any strong TV or FM transmitters. The unused outputs should be terminated, although I have never noticed any problems with them left un-capped. Short cable runs should be of no concern either.
Ok. cool. Just to make sure, is a PCT-MA2-4P the same as a CM3414?
I was told PCT made them for Channel Master, but I want to make sure I'm not being had.

Thanks.

Marc

hoopitup2000
2009-11-08, 10:38 PM
Ok. cool. Just to make sure, is a PCT-MA2-4P the same as a CM3414?
I was told PCT made them for Channel Master, but I want to make sure I'm not being had.

Thanks.

Marc
That is correct Marc. They do have the PCT name on them.

99gecko
2009-11-09, 01:36 PM
Bumping this question I asked several decades worth of pages back,... hoping for an answer (without having to go to another forum).
Is there any reason why I can't use a SW44PI instead of the supplied CM 0747 for powering a CM 7775? The SW44PI is used one for powering sat switches, but is a T-style inserter - that is, the power inserter is comprised of two units: the power adapter ---> coax carrying DC ---> inserter. The CM 0747 is a single (brick) unit, meaning that that the power adapter and inserter are in the same unit. The benefit of using a T-style power inserter, is that I am currently using diplexers that do not pass power on the ANT side. To use the CM 0747 without removing the diplexers I would have to add the CM0747 outside where it is exposed to the elements and I have no AC nearby to power it. I'm not sure that a diplexer exists that passes power on both legs - it is counter-intuitive I think. I would prefer to use an existing abandoned rg59 run to feed power remotely to a T-style inserter, rather than running a new RG6 feed solely for OTA.

SW44PI specs:
47-2300 MHz
+ 18 VDC
Inserter loss <= 1.0 dB
Return loss >= 12 dB

The CM 0747 is + 18 VDC, but I have no data for losses.

I'm concerned about the return loss figure of the SW44PI.

Anyone have any ideas? I think the voltages should be correct, but I just want confirmation before I screw up my gear.

I'd rather try this CM 7775 pre-amp out, before outlaying more $$$ for mlord's recommend RC 9260 (WAF ;))

cheers.

mlord
2009-11-09, 09:07 PM
I'd rather try this CM 7775 pre-amp out, before outlaying more $$$ for mlord's recommend RC 9260 (WAF ;))
:)
Actually, my current recommendation is KitzTech -- incredible bang for the buck from them right now. I'd take that over CM any day.

Cheers