Question: What kind of amp do I need?

Ckone

DTVUSA Jr. Member
#1
Hi all, so glad to find this forum. Wish I had found it before I installed my antenna, but hopefully you all can set me on the right course. I tried posting this anonymously but maybe that doesn't work. Hope I don't end up double posting.

So I've installed a ChannelMaster CM-4228HD on a 5' chimney mounted mast, about 28' off the ground. I've got a 60' run down the house and into my basement to a 4-way splitter that then feeds my 4 tuners which are 5' to 30' from the splitter. Here is my TV Fool: TV Fool

So this resulted in my getting 2 of the 5 major networks I wanted. One of the devices is a Silicon Dust HD Homerun that will give me signal levels, which are in percentages. Not sure how they translate to dB. The levels I'm getting are 38% to 67%. Silicon Dust recommends OTA levels be 60% minimum, preferably 80%. Channels I'm concerned with are real channels 7, 13, 28, 33, and 44

So I tried removing the splitter and that drove my levels up to 50% to 83%. They all could be received at that point but were not great reported "signal quality" and I could see some blocking up of the picture.

So I think I need an amp. Not sure if a preamp or distribution amp is the best way to go, any recommendations or pointers on how to tell? Thanks in advance.
 
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#3
So I've installed a ChannelMaster CM-4228HD on a 5' chimney mounted mast, about 28' off the ground.
28' above ground level altogether -- like the Fool report says, right? Which direction is it pointed? That's very important info you left out.

I've got a 60' run down the house and into my basement to a 4-way splitter that then feeds my 4 tuners which are 5' to 30' from the splitter.
Why did you choose to go all the way to the basement, then back up to the second floor? Was it wired that way for cable? So it's 60' altogether for one set, I guess. Less cable would mean less signal loss, and a LOT less potential for leaks or kinks in the coax -- which might never show up in a cable signal.

So this resulted in my getting 2 of the 5 major networks I wanted. One of the devices is a Silicon Dust HD Homerun that will give me signal levels, which are in percentages. Not sure how they translate to dB.
You're not alone. Nobody has a clue on that.

Channels I'm concerned with are real channels 7, 13, 28, 33, and 44
Welp, 7 and 13 are VHF. The 4228HD is not a VHF antenna, so that's part of your problem right there. Any little VHF comes off the back of the 4228HD. These are all at 234° on the compass dial, so it will be impossible to aim this antenna toward all five stations.

So I tried removing the splitter and that drove my levels up to 50% to 83%. They all could be received at that point but were not great reported "signal quality" and I could see some blocking up of the picture.
Honestly, per the Fool report, you have enough signal to get 28, 33, and 44 without an amp, even after subtracting 7 dB for the splitter. Forget 7 and 13 for the moment. If you can't get those three UHF stations, I'd be looking at the coax, at the balun, at the splitter ... everything else before an amplifier. Are you in the middle of a forest, by any chance? Got a big building to your south-west, between you and the transmitter? Electrical noise from big appliances is another possibility. Put the amplifier at the bottom of your list.

Rick
 

Ckone

DTVUSA Jr. Member
#4
Thanks for the help, Rick.

Antenna is pointed at 234. I went all the way to the basement because that's where most of the gear is.
Nothing is back up on the second floor, one TV is on the far side of the house on the first floor. I could shorten most of the runs by 20' if I move the splitter and wiring closer to the antenna, I'll figure out a way to do that. I should also double check the declination setting on the compass I used to aim it. Not looking forward to extra trips up on my high roof, so I'm trying to get all my ducks in a row before I work on it again.

So forest... not exactly a forest but it is pretty heavily tree cover around here. There are a quite a few trees between me and the top of the ridge I am on, and they are a good 60' high. So I'm going through that. Would an amp help with that?

Did I pick the wrong antenna for this? I should have looked at the VHF before I got this, I was under the impression the channels had all moved...
 
#5
When I first read your post, and looked at your TV fool report my first thought was wrong antenna, but your results should still be better then what you are getting. The CM-4228HD is a very directional high gain UHF antenna that will produce mixed up results when pressed into VHF service. I took time to look for more information on the VHF performance of the antenna Channel Master simply states. Average gain (dB): 5.0/12.0 VHF/UHF. Here is what I found.
New CM4228HD (As Shipped)
VHF SWR, and gain is all over the place. That might explain your problems with 7, and 13. The other channels your having trouble with makes me wonder what direction the antenna is pointed. The CM4228HD has a narrow UHF half power beam width less then 30 degrees on the upper UHF channels. I did see the co-channel problem with 33 if that is the cause of your problem on 33 an amplifier will only make it worse. I also wonder what kind of strong nearby FM signals you might have. An FM filter is sometimes needed. Checking signal with out the splitter was the right thing to do. I would be suspicious of a coax or balun problem. I've seen coax connector problems in good looking professionally installed connectors, and bad baluns that are new right out of the box. If I did the connectors I know they need checked. A single strand of braid can cause a short. Tight bends in coax are not a good idea. Checking coax for end to end continuity, or shorts can be done with an ohm meter. I prefer an analog meter for a quick check of basic continuity.
Adding an amplifier to an antenna system can solve signal distribution problems, but will always add to the complexity of the antenna system, and decrease the reliability. More things to go wrong. More problems to troubleshoot when something does go wrong.
To answer your question. What kind of amp do I need? With your current antenna I would suggest a preamp with good overload resistance and out of band filtering. From my reading the RCA TVPRAMP1R, or Channel Master 7778 come to mind. The CM7777 is know to easily overload, and should be avoided in areas where strong signals are present. A preamp could help on channel 7, and 13 where the SWR is excessive on the CM4228 causing signal loss from reflections on the long feed line degrading the digital waveform. There have been problems reported with the RCA TVPRAMP1R most of them have been operator error from having the separate combine switch set wrong, and a few have failed.
I think Rick covered about everything I didn't. We are trying to help.
Steve
 

Ckone

DTVUSA Jr. Member
#7
Thank you all for the help. I checked the compass I used to point the antenna and the declination was not set, so the antenna is off about 13 degrees. I'll correct that and see how much that helps. Happily I found an app to check the signal on my HD Homerun from my phone so I can watch that from the roof! Not like yelling down to my dad "How does it look" like the 80s. I'll also double check the connectors and look for sharp bends in the coax. If that doesn't get me where I want to be I'll try the preamp. Currently 7 is the strongest channel I'm getting, which seems odd since it is VHF but in the world of RF it seems like there are so many factors that you really need to know your stuff to understand what is going on.
 
#9
I could shorten most of the runs by 20' if I move the splitter and wiring closer to the antenna, I'll figure out a way to do that.
Good idea. And how old is the coax you're using? We generally recommend tri or quad shielded RG-6 cable. I'd try all new cable at the same time I moved the splitter, unless your cable is very new, healthy looking RG-6.

WAIT. Maybe try a different splitter first. The fact the only station you get is the lowest frequency makes me wonder -- this is YOUR splitter, right? Purchased new, and checked for frequency range?? A satellite splitter won't cut it.

I should also double check the declination setting on the compass I used to aim it. Not looking forward to extra trips up on my high roof, so I'm trying to get all my ducks in a row before I work on it again.
Smart idea.

So forest... not exactly a forest but it is pretty heavily tree cover around here. There are a quite a few trees between me and the top of the ridge I am on, and they are a good 60' high. So I'm going through that. Would an amp help with that?
Ouch. Sounds like just the situation that'd screw up a Fool report. Not enough trees to stop radar from bouncing off the ground, but plenty enough to mess with reception. No, an amp won't help with that at all.

The math of an amplifier is weird, and the way they add amp gain to antenna gain in the ads is extreeeeeeeeemely misleading! What an amp can do is potentially make your splitter go away, as a problem source (about 7dB improvement) and make the cable run and receiver noise become irrelevant (another 3dB perhaps). No more than that.

Did I pick the wrong antenna for this? I should have looked at the VHF before I got this, I was under the impression the channels had all moved...
Hey, one good thing about VHF -- it can plow through the trees better'n UHF. If the trees are the main source of your problem, you might need to move around the antenna to find a hotspot. Not very enticing up on the roof, I know. I also noticed several stations coming from other directions. Maybe there's a different direction that avoids the trees and still gets a nice lineup... ? Think about that while you're outside looking at the trees, with your newly calibrated compass.

On the 4228HD, we have a "SUPER moderator" with a tree problem, and he strongly believes Yagis are better than big bow-ties, for seeing through the trees. Just based on that, and your VHF stations, I think we would have recommended a Yagi with added high VHF elements. But we really should be clear on the best direction(s) to point, before picking any antenna(s).

Rick
 
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Ckone

DTVUSA Jr. Member
#10
Thanks for the additional info, Rick. The coax is new RG-6, just pulled out of the box I bought a year or two ago. I could go get some quad shielded if that is likely to help. The splitter is kinda an unknown, labeled Radio Shack VHF/UHF/FM and no other info on it. I did purchase it, but not sure when...So I should replace that, any pointers as to what specs or brands I should look for?

The tree situation is better toward the northeast, as the ground slopes down in that direction and the trees are further away from the house. So I'll take some signal strength readings at 55° as well as checking 234°. I guess I'll do this without my questionable splitter.

Thanks again for all the help. I'll probably head up on the roof tonight after work.
 
#11
Thanks for the additional info, Rick. The coax is new RG-6, just pulled out of the box I bought a year or two ago. I could go get some quad shielded if that is likely to help.
Naw. I doubt it. If the insulation is rough to the touch, it's probably the good stuff.

The splitter is kinda an unknown, labeled Radio Shack VHF/UHF/FM and no other info on it. I did purchase it, but not sure when...
That actually sounds fine to me. VHF and UHF is what you need. You did get some reception with the splitter, and 7 dB loss is expected with any 4-way split.

So I should replace that, any pointers as to what specs or brands I should look for?
Nothing fancy. Anything that covers 5 to 699 Mhz or more should be fine. I trust em more when they list the loss figure. Something like this: New Extreme 4 Way Digital Cable Coax Splitter 5 to 1002MHz BDS104 Out 7dB | eBay

The tree situation is better toward the northeast, as the ground slopes down in that direction and the trees are further away from the house. So I'll take some signal strength readings at 55° as well as checking 234°. I guess I'll do this without my questionable splitter.
Great plan. It sounds more and more like the trees are the culprit.

Rick
 
#12
Well, I think you can sidestep the trees at 234° and still get a nice lineup:
Code:
WZME 42 MeTV    87°
WEDW 49 PBS    116° ?
WTNH 10 ABC     82° ?
WCTX 39 MyN     82°
WVIT 35 NBC     58°
WCCT 20 CW/This 58°
WTIC 31 Fox     58°
WEDH 45 PBS     58°
WEDY 41 YaleUn 100° ??
WFSB 33 CBS     55°
WHPX 26 ION     96° ??

Low NM stations:
WNHX 51 Ind    100° ???
WUVN 46 Uni     55° ?
You can put the 30° bandwidth of the 4228 to good use by aiming at 69° on the compass. WEDW is strong enough, it might come in on a hope and a prayer. If not, you have PBS on WEDH. WTNH is only questionable because it's VHF, so if you want ABC. you might need to set up with a separate dipole and attach with a UVSJ combiner. Cheap. Easy enough. I think the Yale University station is skippable, and the two barely possible low NM stations are no great shakes either.

So barring other obstacles, you have ABC, CBS, NBC, Fox, PBS, CW, ThisTV and MyNetwork. I could certainly live with it!

Rick
 

Ckone

DTVUSA Jr. Member
#13
Thanks all for all the advice. So I finally got up on the roof tonight to reaim the antenna and check it out. I was able (barely) to get a wifi signal up there and watch my signal strength from the roof. I found looking northeast toward 69 things weren't much better. And pointing the antenna confirmed this, couldn't get all 5 networks I wanted. So I corrected the direction of the antenna (had been at 222) and shot it at 234.

So this has improved my levels to the point where I appear to have a passable signal on all 5 of these channels. So for now, I'm going to roll with this setup and see how things look through the fall. Should get better actually as leaves drop (I can see em falling now!). But I have one final question. If I have further issues, I'm considering a) adding 5' to the mast to get a better signal and get the antenna away from the chimney and b) adding a preamp like the ChannelMaster 7778. Would this be a reasonable next step?

For now, I'm checking out all my tuners and set and happy as a clam. Getting my simpletv and windows media center back up and recording again and seeing what all I can pull in. I seem to have some interesting stuff from NYC. And I'm off to check out the other forums and see if I can find some way to contribute.
 
#14
I most generally try to steer others away from the common line of thinking that adding an amplifier is the great signal cure all. By about 2002 after about 20 years of trying different TV antennas and amplifiers, and mostly not knowing what I was doing. I had written off amplifiers as a big waist of money. In about 2006 having not had an out door antenna for a few years, and a grave yard of Winegard, Channel Master, and Antennacraft out back. This is rural Wyoming I've never put up an antenna the weather didn't take down. I went down town to buy a cheap outdoor antenna brought home a VU-90XR put it up about 15 feet, aimed it toward a known high VHF signal easily received that one, and the 2 strong low VHF signals off the back side plus some new UHF translators I hadn't seen before. The temptation of an amplifier bit me again when I saw the next Radio Shack ad. Things were a bit different this time the coax run was longer, there were more high VHF/ UHF translators, and I had a bit more knowledge. This time the amplifier actually did make a significant improvement in signal. I do read the other forums, but seldom post. I joined this one when I saw a simple question go unanswered for a few days.
Steve
 
#15
I corrected the direction of the antenna (had been at 222) and shot it at 234. So this has improved my levels to the point where I appear to have a passable signal on all 5 of these channels.
GREAT NEWS!

If I have further issues, I'm considering a) adding 5' to the mast to get a better signal and get the antenna away from the chimney
Is the chimney between your antenna and the transmitters at 234°? If that's the case, you need to address it. If not, I don't see the point of adding another 5' when antenna is at 28' and trees at 60'. It's possible this could help (I'm not up to the trigonometry today -- depends on how far you are from the trees and height of the transmitters) but it seems unlikely. Moving the antenna around in any which way might find you a sweeter spot as the signal winds around the trees, but as long as it's good, personally I'd stay off the roof.

and b) adding a preamp like the ChannelMaster 7778. Would this be a reasonable next step?
NO! Well, maybe ... Now, the CM7778 does not have separate lines for VHF and UHF. Neither does the "new" CM7777. I think there's a strong chance you'll wind up getting a separate VHF antenna. So here's my plan of action:
1) Wait to see if your five channels remain acceptable.
2) If not, and VHF is a problem, get a separate VHF antenna and join with an RCA TVPRAMP1R. The TVPRAMP1R is a virtual clone of the CM7777 BEFORE they removed the separate line, and at ~$22 it's almost as cheap as a UVSJ combiner. Some of our moderators had good luck with it.
OR
2) If you really have a serious problem, ditch the 4221HD and get an HD8200P UHF/VHF Yagi, for which you will not need a combiner, and probably don't need an amplifier. Always nice to leave out the preamp if possible. It's the first thing to die in a snow storm.

I'm off to check out the other forums and see if I can find some way to contribute.
We need all the help we can get. :thumb:

Rick
 
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#16
I do agree with Rick the RCA TVPRAMP1R has proven it's self to be a very good amplifier, and quite overload resistant. The price tag is right. I do believe that other brands have also had failure problems. I know longer have the brand loyalty I would have expressed toward Channel Master, and Winegard 10 years ago.
Steve
 

Ckone

DTVUSA Jr. Member
#17
OK, if I go with an amp I'll try the RCA TVPRAMPIR. For now, I am going to just stick with my current setup with a 5' addition to the mast. This isn't to increase signal strength as much as to move the antenna away from the chimney. So the antenna on a 5' mast is basically right on TOP of the chimney, and I burn oil so that can't be great. Before I reaimed it, it wasn't right over the chimney but now it is. I think I'll give it 5' to cut down on the amount of fumes blanketing this thing.

Then I'll button up all the cabling and see how we do through the fall and winter. So far the signal seems pretty solid. I had one issue that may be the PC I was streaming on rather than the tuner. Thanks again all!
 

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