Has anyone tried this amp from http://www.kitztech.com/ specs are as follows:
Bandwidth 40 Mhz - 1000 Mhz
Noise Figure: 1 db or less across the band
Gain: Adjustable from 0 - 20 db
Output IP3: >+32dbm
It has a 10 day right of return. If it does not improve your reception you may return it, within 10 days minus shipping.

I have a long coax run (240')...I am using a Winegard 8780 preamp already and splitting the signal before it gets to the first TV...I'm thinking this amp may help due to its low noise and adjustable gain.

Comments anyone?

I use it with my attic antenna. Wasn't happy with a Channel Master preamp (7777) and replaced it with the Kitztech. Like this preamp - does better for me than the CM. Have had it for 3 months now.

Noticed that the CM's performance would vary depending on what was attached to it despite disclaimers to the opposite. Eg. lost 5 db on the VHF side when UHF was attached - removed the UHF and got back the 5 db VHF. Said screw that type of performance...

At one point was considering the ResearchComms one because of the low noise figure but the $240 price drove me away. Then saw the Kitztech at 1 db noise (or below) and ordered it. Works for me.

Thanks for the info, bwam...I just ordered one of the Kitztech amps...you'll probably be banished from the forum for trashing the "beloved" Channel Master 7777!...LOL!...it seems like most people here are in love with them and won't try anything else.

Thanks for the info, bwam...I just ordered one of the Kitztech amps...you'll probably be banished from the forum for trashing the "beloved" Channel Master 7777!...LOL!...it seems like most people here are in love with them and won't try anything else.

If memory serves me well, I had read some time ago at a forum that dual inputs into the CM preamp affected its performance. No one believed that other poster at that time saying that it was impossible but I ran into the same situation a year later.

I had a VHF and a UHF antenna going into the CM but since I came to distrust its performance, I decided to alter my strategy and go with a separate preamp at each antenna (Kitztech with its lower noise figure) and join the two with a Winegard CS-7750 VHF/UHF Separator/Coupler (0.3 db insertion loss).

A year later I added a second UFH antenna and put a Kitztech on that. Now I have two UHF antennas going into a jointenna, the output of the jointenna going into the UHF leg of the Winegard combiner, and the VHF going into the VHF leg of the combiner. Three preamps (one at each antenna) and the signals have been rock solid.

I use tie wraps to fasten the preamp to the pole that holds the VHF antenna with a 3' cable going from the antenna balun to the preamp. For my 4228, I just let a 1' cable dangle from the balun through the back reflector cage and the preamp connected to that dangling in the air. My other UHF (91xg) is the same thing - just let a 1' cable dangle from the balun out the back reflector cage with the preamp connected to that dangling in the air. I wanted the shortest possible cable from balun to preamp. So that the coax with the preamp attached to it wouldn't do anything to the antenna, I used some tie wraps to secure the cable to the boom after the balun and before the reflector cage (though I don't think this was necessary). Since both my UHF antennas are tilted 10 degrees upward, the preamps doesn't rest against the reflector cages.

I was so obsessed with getting the noise and the insertion losses down in the system, I replaced my CM UHF/VHF 0539 combiner (.5 db insertion loss) with the Winegard (.3 db insertion loss). Whoops another CM subversive attack! I was on a mission to maximize the performance of all my components so I even ordered those 1' cables (balun to preamp) from BlueJeans (1694 Belden coax with Canare connectors - I was impressed with the BlueJeans description of their coax cables and connectors). My wife looked at all this OTA obsessive activity and said, "Is this a male thing - are you going to give it a rest?!?!"

Then after it was all settled and done, the first evening she watched "Desperate Housewives" in all of its uncompressed HD glory and said, "OK, now I get it!"

I am going to order 2 tomorrow, like the variable gain and low noise and will let you know how I make out.

thanks

But my antennas are indoor - aren't yours outside? How are you going to get the power up to them?

BTW I'm still interested in what Hokie Jim will report about the ResearchComms preamp but the price factor drove me away when I inquired a year ago. With the $50 Kitztech price, I was able to put one at each antenna (they're fairly small in size).

Because of their low noise figure, I was even thinking of using one as a distribution amp, putting an 8 way-splitter after one and playing around with its gain dial to see what signal level I could achieve to offset the 8-10 db loss at the splitter without overloading the receiver. However I already had a good drop amp (Electroline) that didn't significantly add any noise. So my setup is essentially antenna-->preamp-->jointenna-->combiner-->dropamp (with up to a 100' out). The cables from the 3 antenna preamps are 12' long to the jointenna/combiner/dropamp stage (and yes the malady continued and I did put prime BlueJeans cables between those as well).

There's got to be a psychological disorder called "OTA Obsessive Behaviour"... I go to sleep counting decibel levels. BTW Rick the OnAir GT receiver now has with the latest release of its software a sound indicator to tell you the signal strength (not just display the numbers). The faster the beeps, the higher the signal strength. So one can move the antennas around and listen to the beep rate without having to look at the display.

My next toy will be a new laptop with the OnAir GT receiver.


One heads-up about the OnAir GT. Make sure that the laptop you get has a compatible video card. The OnAir sparkles when it can use the nVidia hardware for display. It also functions well with ATI. The AutumnWave site has a listing of the video adapters the GT is suited for:

http://www.autumnwave.com/index.php?option=com_easyfaq&task=cat&catid=43&Itemid=179

When I first bought the GT I wasn't aware of that and didn't get good display performance with my desktop computer (eg. sports events with fast action didn't come out well). Then I went out and bought an nVidia card for my desktop and boom the video performance was amazing. My laptop already had an ATI that conformed to the GT's video requirements and so it was OK from the start. This is what I like about the GT - the ability to take it from computer to computer.

Ok folks...bad news on the Kitztech...I received one and I got the same digital signal strength with or without the LNA...same story with analog...I have contacted the seller and requested a return...I asked him to test the one I'm sending back to him with an actual OTA signal and not on a bench...I connected a channel master 0068DSB preamp (VHF 16db 3.0 NF - UHF 23db 2.2 NF) just before the tv...the cm did a MUCH better job of amplifying. The Kitztech may be a "too good to be true story." Only time will tell as others report their findings.

yep I adjusted the gain...on the plus side, the seller responded within 5 minutes on how to return it.

Has anyone with a lab put this amp to the test? 1db noise and $50 seems a bit on the "too good to be true" side.

Ok folks...bad news on the Kitztech...I received one and I got the same digital signal strength with or without the LNA...same story with analog...I have contacted the seller and requested a return...I asked him to test the one I'm sending back to him with an actual OTA signal and not on a bench...I connected a channel master 0068DSB preamp (VHF 16db 3.0 NF - UHF 23db 2.2 NF) just before the tv...the cm did a MUCH better job of amplifying. The Kitztech may be a "too good to be true story." Only time will tell as others report their findings.

Interesting results. Both my Samsung and OnAir receivers indicate between 27-31 db when I use the Kitztech. Without a preamp I get about 7 db.

1db noise and $50 seems a bit on the "too good to be true" side.

How about a "build your own" for $35 with a noise figure of .49 db and a gain of 20:

http://www.g0mrf.freeserve.co.uk/432LNA.htm

The following one currently on eBay is also intriguing:

UHF TV ultra low noise (.4 db) amplifier by Verstärker at 18 db gain.

The reserve on this one is at least $50 on eBay - don't know what it really goes for but I didn't want to bid to try and meet the reserve without committing myself to buying it past $50...

Has anyone tried this amp from http://www.kitztech.com/ specs are as follows:
Bandwidth 40 Mhz - 1000 Mhz
Noise Figure: 1 db or less across the band
Gain: Adjustable from 0 - 20 db
Output IP3: >+32dbm...
Comments anyone?

If someone opens one of these up, they should try to figure out just how the gain control works. If it is it just a variable attenuator ahead of the input amplification semiconductor, then it will lower the final S/N ratio.

The KT-100VG also provides a variable gain control to give you just the right amount of signal for your system.
That is not a reassuring claim, since the most critical objective of the gain control isn't to provide the right amount of signal. It is to develop and sustain the highest possible S/N ratio without qualitatively degrading the dignal by dveloping excesive intermodulation distortion. That's not to say that avoiding tuner input overload is never a concern, but it is not the primary concern when someone believes that need an ultra low noise preamp to conserve the S/N of the weakest signals.

Can someone explain this "IP3: > +32dBm" rating? Intermodulation distortion ratings that I am familiar with are expressed in multiple terms. There are benchmark maximum levels of intermodulation distortion for different applications, and an amplifier's rating is expressed in terms of number of equal strength channels and a per channel signal level at which that load will develop that level of intermodulation distortion. With analog satellite signals, the consensus benchmark 3rd order IMD maximum is -35dBc. With DBS digital satellite, it is -40dBc. I haven't yet seen a benchmark threshold for broadcast HDTV signal 3rd order IMD.

An amplifier rating might be that it develops 3rd Order intermodulation distortion of-32 dBc (decibels below carrier) with a single channel output signal strength of, say, 50dBm. As it was explained to me, doubling or halving the number of channels increases or reduces the 3rd Order IMD by three dB. I have been told that increasing or reducing the output level by one dB increases the 3rd Order IMD by either two or three dB. When I tried to resolve the issue over whether the ratio of change in output level to change in 3rd Order IMD was was two dB or three dB, I stumbled across a pissing match thread between self designated physicists which I was not qualified to further evaluate.

But in any event, this is the second thread I have read in recent months in which the manufacturer of a preamp product expressed intermodulation distortion as a single unreferenced undenominated number, so I don't know if our industry now has some benchmark spec for number of channels and output rating used, or if both posts were citing the same number furnished by the same manufacturer.

I doubt that most people have any idea how finicky RF circuitry is. You could assemble two of these amplifier kits and get different performance from them just because a 1" jumper wire was bent differently, which affected its impedance.

Furthermore, gain, noise and insertion loss figures are averages at best, as broadband devices react differently at different frequencies. I generally ignore claimed, fractional dB advantages when comparing RF performances.

I doubt that most people have any idea how finicky RF circuitry is. You could assemble two of these amplifier kits and get different performance from them just because a 1" jumper wire was bent differently, which affected its impedance.

Furthermore, gain, noise and insertion loss figures are averages at best, as broadband devices react differently at different frequencies. I generally ignore claimed, fractional dB advantages when comparing RF performances.

Leaving aside the issue of overload, how much does the noise figure affect things? For instance, I have the CM 7777 preamp with 2.0 noise figure for UHF. The Kitztech at 1.0 noise. I was interested at one point in the ResearchComms one at 0.4 noise. The gain on all of these is similar.

Are the noise figures, when they vary from 0.4 to 1.0 to 2.0, significant when they are all say below 3.5? Are these numbers - from .4 to 2.0 - significant enough to affect reception? Or does the noise figure have to be above a certain threshold to really impact reception negatively?

If my SNR is at a comfortable level (no frequent dropouts), does the lowest noise figure buy me anything (if these come at higher and higher prices) since HD picture quality is constant whether the SNR is 23 db or 31 db? And I'm only addressing digital not analog TV.

under my set of variables the hdp269 with 3db noise, 12 db gain , and high overload tolerance performed better than an amp at 1db noise and 18 db gain attenuated down to the appropriate levels. you could actually see the difference on the distant signals.

So how would one determine what is best for one's situation unless one bought different preamps and tried them out?

And do you personally have a price point? Would you try out a ResearchComms preamp at $240 (the last price quoted to me by them)?

many users here do not have the luxury of having equipment at their disposal. sometimes you just get lucky.

it is like buying any other component based on specs alone...be it surround amps, dvd players, panel tvs, speakers, etc. you get the unit set up in the room and it sounds or looks like crap...or at the same time you picked a winner, a great catch.


You're right about the luck aspect. I bought a Vizio 47" HDTV last week. Even though the Vizio thread at this forum indicated problem after problem, I decided to take a chance because the price was right. After a week of use, the TV set doesn't exhibit any problems (the ones mentioned in the Vizio thread). Fortunately...I got a good unit (I also supplemented my luck by going directly to the manufacturer knowing I would get the latest build which was rumoured to be error-free rather than purchasing it off-the-shelf from a distributor with older builds in their inventory).

BTW was pleasantly surprised that its internal ATSC tuner was Samsung! Very sensitive - same performance as my external Samsung 260F receiver.

I know I took a chance and luckily it paid off but I wouldn't recommend this TV to anyone else unless they wanted luck to play a major factor (see the Vizio thread for all the complications)...

Got my refund from Kitztech....seems to be a straight up guy.

If someone opens one of these up, they should try to figure out just how the gain control works. If it is it just a variable attenuator ahead of the input amplification semiconductor, then it will lower the final S/N ratio.


It almost certainly uses what is known as an Operational Transconductance Amplifier (OTA). The current into an operational amplifier is controlled by a pot and a voltage and thus the gain is varied. It is how most variable gain amplifiers are implemented and can found on many integrated circuits.

It almost certainly uses what is known as an Operational Transconductance Amplifier (OTA). The current into an operational amplifier is controlled by a pot and a voltage and thus the gain is varied. It is how most variable gain amplifiers are implemented and can found on many integrated circuits.
The pricey ($400) Blonder Tongue distribution amplifiers are still more primitive than that. They place just a variable attenuator ahead of the 30dB gain power amplifier stage. On their 43dB and 50dB gain models, the variable gain attenuator is between the preamp and the power amp. It leaves us to pad into a rather narrow window when attempting to optimize that amplifier's performance.

the owner explained to me that the gain on that unit was adjusted in the circuit by changing impediance. how does that relate to the above?

That amplifier could very well be a different design. But, OTA amplifiers meeting all the requirements of a VHF/UHF LNA are inexpensive and commercially available from IC makers like Analog Devices. Put a low noise OTA in front of a medium power RF OP amp and bingo, you have a commerically viable mast mounted TV amplifier with adjustable gain.
The gain of an OTA is varied by controlling a current with a voltage and therefore they are also know as variable transconductance amplifiers (gM). A variable gM stage could also be somewhat viewed as an equivlent variable impedance. It may be what he was refering to. The noise figure is sure to vary with gain, but it is not dB for dB.

In order to prevent oscillation, high-gain RF ampifiers invert the input.

If you simply cascade two amplifiers, the strong output signal can readily leak across to the
antenna and hence to the input...resulting in positive feedback...which is to say OSCILLATION:
http://www.bext.com/_CGC/2000/postings.htm#Self-Oscillating%20Preamps%20-%20Two%20Problems

In order to prevent oscillation, high-gain RF ampifiers invert the input.

some do, some don't. There are precautions that must be taken in any design.

Would you care to list some non-inverting high gain RF amplifiers, so that we all may avoid them????

For my 4228, I just let a 1' cable dangle from the balun through the back reflector cage and the preamp connected to that dangling in the air.
I was on a mission to maximize the performance of all my components so I even ordered those 1' cables (balun to preamp) from BlueJeans (1694 Belden coax with Canare connectors - I was impressed with the BlueJeans description of their coax cables and connectors).


I've also got a Kitz Techologies amp and a CM4228.
I've managed to basically screw the balun directly into the amp using a
"Barrel F Connector Male to Male" I got on ebay at TKO CSS.
Basically a cable of zero length.
Getting it in place was almost like playing twister, but I managed to do it.

Now the main source of noise is the balun......

I'm now having a bizarre experience with the kitz amp:
my old tv (samsung from 1991) was giving up the ghost, so I bought a cheap chinese made one (20 inch prima, $80 new, 2008):
in terms the prima without the amp blows the samsung without the amp away.
However, for some reason, the amp will not work with the prima but works with the samsung.

Just got my preamp from kitztech. Working great for me. Using for now with double bow tie indoor antenna. Feeding lcddigital 7 inch tv. I get about 3-4 stations that move from "bad" go "fair" on the signal display, or "fair" to "good".

Net result is I get 3 more stations up to a watchable level with minimal dropouts.

I am about 11 miles from most stations. tvfool lists my signals at -37 dbm for the strongest ones, but that I did for my 25 ft outdoor antenna, so signals at my indoor antenna would be a weaker. I count about 20 stations listed in the -37 to -49 dbm range.

The stations that became receivable tvfool lists at -50 and 2 at -55.

Just got my preamp from kitztech. Working great for me. Using for now with double bow tie indoor antenna. Feeding lcddigital 7 inch tv. I get about 3-4 stations that move from "bad" go "fair" on the signal display, or "fair" to "good".

Net result is I get 3 more stations up to a watchable level with minimal dropouts.

I am about 11 miles from most stations. tvfool lists my signals at -37 dbm for the strongest ones, but that I did for my 25 ft outdoor antenna, so signals at my indoor antenna would be a weaker. I count about 20 stations listed in the -37 to -49 dbm range.

The stations that became receivable tvfool lists at -50 and 2 at -55.

You have some wierd reception problems that we can't scientifically remedy. They are most likely a combination of multipath and excessive signal attenuation due to man-made terrestrial blockages. If I were you, I'd do more antenna experimenting.

How do your analog UHF signals coming from those same towers look, with and without the preamplifier installed?

The Zenith converter is the first box I've tried that can really handle my multipath. It is so bad that back in analog days I got the Magnavox ghost eliminator and there was one UHF channel that would regularly crash it so I had to stop using it! My old LG tuners crash too often enough to be really annoying, since they have no easy reset. Most UHF analog has double or triple ghost images.

I have about 3 hills around me that both block the direct LOS signals in spite of what tvfool claims, and also reflect back at my antennas.

I am experimenting with antennas. I think I have the best possible and use a Glen Martin 17ft tower in my yard for the more difficult channels with dual blake horizontal stacked UHF antennas with tilt capability and a cut yagi for the high vhf. Currently using a Winegard high gain preamp (4800). I am trying the Kitz preamp and have also ordered a Research Communications unit.

Signals to -55 dbm I can get with the indoor antenna. My outdoor antenna used to get signals to -86 dbm most days. Now it only does to -82 or so, which I assume to be overload since the slightly stronger stations still work though less. We only had high power analog when I started on this but now the stations with power have doubled.

I just got a Samsung tuner to replace some older ones and that performs about half-way between the Zenith box and the older LG or Samsung tuners.
It is not adequate.

I am sick of having to move my antenna due to rain, or resync daily because my rotor drifts in the wind. That I am also working on fixing. Ordered a Pro Sistel rotor, and will go back to low def and just use the Zenith if it works best, till there are good real HDTV tuners.

One more problem is channel surfing. That works fine with the Zenith. With any other tuner and I have tried over 5 kinds, I have to re-aim the rotor for individual stations from the same tower to get the nulls in the best spots.

I must be in one of the worst locations. In fact the old generation 1 Panasonic worked better than some of the newer tuners till I had to junk it due to the sw flaw in the audio selection. My reflections were too strong or too long a delay for most tuners till now.

One of my next experiments will be to re-try my old Para Scope Channel Master. That had more multipath issues but also more gain. I think now it might work with the Zenith box.

The good news in all this for us around Boston is we are getting digital on VHF next year for channels 7, 9, 10, 11, 12 and 13. tvfool shows an 8 but that is way weaker than I have ever received except in August for minutes at a time even with analog.

You have some wierd reception problems that we can't scientifically remedy. They are most likely a combination of multipath and excessive signal attenuation due to man-made terrestrial blockages. If I were you, I'd do more antenna experimenting.

How do your analog UHF signals coming from those same towers look, with and without the preamplifier installed?

I covered part of your question above. The with and without preamp I will check soon as the rain clears up as I want to do that on my main outdoor antenna. Maybe next weekend. I will check with and without preamp as well as each kind of preamp where the cable comes into my basement.

The indoor antenna on my 7 inch set just gets lots of snow on analog. Better with the preamp but I will see the ghosts better on my main set up.

OK, I tested with my outdoor antenna and the kitz tech still worked well. Analog station with bad ghosts was virtually the same with or without it. And I got one channel (WMUR) in digital very strong on signal meter using both the kitz tech and a zenith converter box. Remove either the Zenith and go to my old LG HD tuner, or remove the kitz preamp and that station vanishes!

I am still getting less than I should (missing about 5 stations I used to get!), so my next step will be to clean up my antenna connections and check everything. It has been up about 9 years untouched. I had thought my Winegard AP4800 might be overloading now, but looks like I still have some other problems. There was some overload maybe, as with the Kitz the signal meter seems more stable on locals, but that was not my main problem. So more to investigate.
In any case, the kitz worked in my basement as well or better than the 4800 did on my mast. I could get WMUR with both but signal level and antenna aim tolerance was far better with the kitztech.

WMUR is listed at tvfool as -86 dbm. The stations rated just a little weaker than this (and there are many in the -87 to -100 range) do not come in but at least show on the signal meters with the Kitz in the line.

Just heard my Research Communications unit got shipped. Hoping that will help as I can mount it on the mast easily. Then I can use the kitztech on my indoor antenna.

Update: got my preamps. Now I can't get along without them!
See http://www.avsforum.com/avs-vb/showthread.php?t=1024730&page=2 esp post #55.
for more of my preamp testing results. My best reception is with both Kitztech and Research Communications in series. Research Communications is on the antenna side since it is UHF only as well as lower noise.

Just FYI as this amp doesn't appear to incorporate front-end filtering I'd recommend filtering the input before deciding it's a poor performer. Almost every amp I've tried benefits from it. Using the hi port of a hi/lo combiner works well if you don't need low band vhf. For uhf only, the uhf port of a u/v combiner should do it. For wideband performance, an FM trap would be in order.

FWIW, I wouldn't bother with the coax powered version.
1. It's $10 more,
2. It introduces another device into the mix, the power adder. Two more F fittings to deal with (initial loss and future deterioration of those fittings from moisture etc.).

As far as mounting it outdoors, a 20 (or 22) gauge pair would be more than enough to power the amp remotely. Installing it inside a weatherproof enclosure (which you would have to do anyway with either model) would/should protect it.

One could also use the LPF-700 to filter the high end of OTA UHF, as long as there isn't an analog station above RF51.

One could also use the LPF-700 to filter the high end of OTA UHF,
The filter in the link has 1.5 DB insertion loss. What is the advantage of using it with the Kitztech vs the CM7777? Seems to me a Kitztech with 1 DB NF and filter loss of 1.5 winds up being a .5 DB worse then the CM preamp. Am I missing something?

Probably not. I was just pointing out the ability to filter out RF above channel 51.

Wouldn't this same issue apply to the FM trap, UVSJ, and HLSJ devices?

In my experience appropriate front-end filtering has produced at worst no difference and at best a significant improvement in signal levels and quality. The differences seem to hold for both high and moderate quality preamps.

What actually happens to SNR at the preamp someone else would need to answer.

That is because for most people their intermod noise (esp with Preamp)
is more of a problem than ultimate sensitivity....

ULNA from AbilityHDTV is 0.8 dB NF, outdoor weatherproof, and can be attached directly to the antenna 'F' connector. Very small solid package, about 1-1/2" long x 1/2" diameter, with power injector & wall transformer inside residence. Since the main purpose of an antenna amplifier is to overcome coax loss, the amplifier loses most of its benefit if not placed BEFORE the coax, splitter(s), etc. Low noise figure is lost if there is 3-10 dB (or more) of signal losses in front of the amplifier. Signal losses have the same effect as noise, lowering the signal below the receiver sensitivity threshold.

As to the filtering/band-pass comments, high output linearity makes this usually unnecessary. The relevant spec here is IP3, or third-order intercept. The ULNA is a whopping +27 dBm, so with 20 dB gain, you're good for up to +7 dBm at the antenna input as all signals will be amplified without intermod from overdriving.