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Signal Amplifiers (Amps, Preamps, Distro Amps)

1M views 4K replies 493 participants last post by  dsspredator 
#1 · (Edited)
This Preamplifier Comparison Chart was modified by holl_ands from an original chart at Solid Signal to show Max Input for two Strong Signals. It was reformatted into PDF form by stampeder with permission of holl_ands for the digitalhome.ca OTA Forum.

If you have any questions about the data in the chart please post in this thread.

Also see tczernec's Loss Calculator Spreadsheet in this post: http://www.digitalhome.ca/forum/showpost.php?p=877838&postcount=604. To use it, make sure to download it rather than using it online.

Another excellent tool is majortom's Cascaded Noise Figure Spreadsheet: http://spreadsheets.google.com/ccc?...rN2poRTVIalpwT3c&hl=en&authkey=CPbi9aYO#gid=1

Cheers
 

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#2,277 ·
rfdude, would the KT-200 fit inside the housing for your old RS pre-amp? Just make sure you seal everything up nice and water tight. That would have the added benefit of giving you mounting brackets.
 
#2,280 ·
Check peano's profile pictures. He bought a standard box, I think it's a 4x4x2.
The only thing I don't like about peano's design is he drilled holes for the U-bolt. If I were doing it, I would attach a piece of angle iron to the mounting tabs and have the U-bolt go through that. Holes in the bottom aren't so bad as they are shielded and add drainage, but holes in the side or top are more likely to be a source of leaks.
 
#2,283 ·
There may not be enough mounting tabs to make adding an iron angle practical. I think there is only 2, and they are not lined up but rather on each side of the box.
There may be some challenges doing it, but IMHO, it is worth the effort to not have holes in the side of the box.
 
#2,284 ·
Uh oh, HWP got a new OTA toy - HDHomeRun

I got a new HDHomeRun today (the white dual tuner version).

It comes with some basic signal analysis tools that my TVs don't have.

I am suffering from my first weather-related drop-outs of OTA channels (ION rf23 WPXJ). My TVs have shown that the channel is either "not available" (very bad) or "no signal" (a little bad).

With the HDHomeRun I can see that rf23 is present after all at about 48% pretty consistently.

I have a Kitztech 100 hooked up in the basement before the splitter. I own a Channel Master 7778. I tried to go up on the roof last weekend and install it at the mast, but I got onto my first-level roof and then decided my ladder did not have a solid enough grip on the pitched roof to allow me to go up to the second level. I called Yaamon and he said "no mon, wait 'til spring when the shingles warm up." I can't argue with the expert.

Anyway, my antennas are on the roof. Two antennas (see signature) connected currently with a UVSJ followed by a 35 to 45 foot run of RG6 down to the basement, passing through a grounding block, before we hit the Kitztech 100.

With the winter changes, I have lost ION rf23, and I'm getting some annoying glitches on WGRZ rf33.

When I do safely get my new 7778 pre-amp up to the roof, will I be able to get RF23 back? (pretty consistent 48% on the HDHomeRun under the current set-up)
 
#2,285 ·
HWP,
I don't think anyone can tell you with 100% certainty if it will improve enough to stabilize everything you want stabilized, 24/7/365.
For "What if" scenarios, I would plug your own numbers in to this cascaded noise figure spreadsheet,
from Google Docs. Plug in such that it reflects your as is configuration, and then the proposed configuration, lets see what the difference is, in dB Noise Figure wise.

The sheet might Need a little "tuning up", so if ya get some flakey numbers let me know and I'll try tuning it up for a What If study...
 
#2,286 ·
Agreed with Majortom above.
Further, if I recall correctly, HWP, you live in an older area with aerial hydro feeds? I too live in an older area with aerial hydro. And I have found that with the dry air of winter, the noise level from electrical interference is much higher. And while such interference typically impacts VHF the most, I've seen some transient interference ("star" flashes) on UHF channels--particularly the lower UHF channels (TVO 19 especially). It's not terrible (compared to VHF) by any means. But it could be enough--in combination with typical winter effects on distant reception--to kill ION for you.
 
#2,288 ·
I got a new HDHomeRun today (the white dual tuner version).

It comes with some basic signal analysis tools that my TVs don't have.
If you're like me, you'll find the HDHR to be rather addictive. I probably spend as much time watcing the SS, SNQ and SEQ indicators as the programming content. :)

I'll just add that Silcondust has a good explanation (presented in layman's terms) of what the three numeric values represent:

http://www.silicondust.com/forum/viewtopic.php?t=4474
 
#2,289 ·
Thanks all,

I had lost track of that Google file as well and was thinking of it. Thanks!

My computers are too old to really watch TV using the HDHomeRun so the only thing I've been using are those signal tools.

Fun to learn about all this stuff!

The pre-amp will go on the roof when it is safe. Having a healthy dad is more important than watching qubo.

Jasse88, yep, I've got hydro wires running along my street. My antennas are about five to ten feet above and about thirty or forty feet away from them.

I wish I had my backyard tower back. In 2005 I had the roofers take that ugly tower down when I reshingled. Five years before I learned about OTA TV. What a tragic error!

re nelson: You're right. I've been using the signal meter a lot. I always found all those annoying TV shows got in the way of my OTA TV hobby anyway! I have just discovered something after reading the last few responses to my post. My HDHomeRun tuners are more sensitive to overload than my TVs. Elsewhere on the OTA threads I was mentioning that since I lost rf23 ION, I have also been getting a minor annoyance on WGRZ NBC rf33. After reading recent posts here, I decided to disconnect my Kitztech and rescan with the HDHomeRun. Still no ION, but finally WGRZ got picked-up. So my HDHomeRun only registered WGRZ when the amp was removed. I guess my glitch with WGRZ has been overload. That being said, I lost three other channels in order to gain WGRZ without the Kitztech so it's going to remain a part of the system for a while. I'll live with my periodic problem with GRZ.

Nothing is ever simple when you're trying to use one aiming location for five or more transmitter locations.
 
#2,290 ·
Any concerns with power feed to cascading preamp-distr amp

I have CM7777 about 10 ft away from antenna, and considering adding a distribution amp (CM3414) in the basement to split signal to 3 TV.

The current setup is good enough for 1 TV.

Do you need to take special precaution to ensure there is no DC coupling between the two amps. My concern is both power supply will be driving the amps and this cannot be good.

Any advice ?
 
#2,292 ·
Skycan,

As long as the pre-amp's power inserter is "upstream" of the distribution amp, there is no cause for concern regarding DC power supplies.

However, it's not particularly common to require both a distribution amp and a pre-amp. Usually, the pre-amp has sufficient gain to overcome most downstream losses from splitters and coax. For example, the named amp's 26 dB of UHF gain should be more than sufficient for a 4-port splitter (7-8 dB) plus 200' of RG6 (end to end - 11-12 dB @ 700 MHZ) plus a bit of margin.

I'd suggest installing the 4-port splitter and re-evaluating your situation to see if a distribution amp is indeed necessary.
 
#2,295 ·
It took me along time to understand signal quality vs strength regarding the use of a preamp. I have a Research Communications preamp, model 9262 with a gain of 23 dB. The noise figure boosts an excellent 0.4 dB.
I have this mast mounted in a weather proof enclosure near the antenna. It has more than enough gain for 100 foot run and a three way splitter.
I have enough gain for one more television if needed.
My issues regarding reception here in London are quality signals and not signal strengths.
 
#2,298 ·
I've added the link to Post #1 to make it easier to find.
The sheet might Need a little "tuning up", so if ya get some flakey numbers let me know and I'll try tuning it up for a What If study...
Just tuned this up for 3 scenarios, like so:

Scenario 1: Antenna->Balun->JMPR->Preamp->Downlead->Splitter->Coax Drop->Receiver ->2.3 db Improvement :)
Scenario 2: Antenna->Balun->Downlead->Splitter->JMPR->Preamp->Coax Drop->Receiver-> 3.8 dB Degradation (not likely anyone would connect this way, but...):confused:
Scenario 3: Antenna->Balun->Downlead->Preamp->JMPR->Splitter->Coax Drop->Receiver -> No improvement whatsoever :(

it's been from MS Excel-> OpenOffice, a couple times, so..
a.) check and make sure ya can still open it, and see the new one.
b.) check and make sure I didn't fat finger any formulas.
 
#2,300 ·
#2,301 ·
Mad

ok so overnight i lost all my signals, only slight image thru snow on the 2 very strong VHFHi analogs

i suspect its the latest kitztech up at the antenna, up on the roof, and now i dont want to get killed trying to climb the iced roof :mad:

1. is there a way to know for sure, testing it electrically or otherwise without climbing the roof

2. what preamps exist which dont block all signals from reaching receiver should the amp malfunction?

thanks
 
#2,302 ·
Balm: The power supply in the house is fine? I know it's probably something you checked first, but it's always a good idea to double check the easy things first.

I'm not aware of a consumer pre-amp that has fail-over capability. To do so would require more components and complexity, which would obviously increase the cost. And while some of us would gladly pay for that consideration, most wouldn't.

Perhaps Tin Lee of Toronto could build such a pre-amp? If you're serious about it, I would ask him--he's always up for a challenge. ;)
 
#2,306 ·
Jase88,

thanks, i think you feel my frustration ;)


i can do more to check the supply, ive already had one faulty injector, but so far no go...(so far i checked the outlet, ensured a proper supply connection into the injector, and then replugged the power supply)

is there any continuity test i can do on the coax itself, in case its damaged by say the ice build up

also, in the fall i THOUGHT i had resealed the kits weather box thoroughly, but i suspect with all the rain, then cold, something still got in it, man !

re. signal pass thru, i thought someone in one of these threads mentioned an amplifier that did pass thru the signal when off...ill have to search more..


thanks again
 
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