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Old 20-Oct-2010, 9:54 AM   #1
GroundUrMast
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Question Low Noise Pre-Amp

http://www.antennasdirect.com/store/...e_amp_kit.html

The advertised "1.8 dB maximum noise figure" of this amplifier is the best I have seen in the OTA consumer market. Any first hand experience with this amplifier?
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Old 20-Oct-2010, 4:45 PM   #2
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Here are some other really low noise figure TV band amps to consider:

http://www.kitztech.com/ (VHF & UHF, 24 dB gain, 0.4 dB NF)

http://www.researchcomms.com/television.html (UHF-only, 20 dB gain, 0.4 dB NF)

With both of these companies, you must provide your own weather-proof enclosure if you want to install the amp outdoors.
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Old 20-Oct-2010, 5:13 PM   #3
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Originally Posted by GroundUrMast View Post
The advertised "1.8 dB maximum noise figure" of this amplifier is the best I have seen in the OTA consumer market.
I'm not sure if this is a typo or not, but Solid Signal's information page (here) on this product says the maximum noise figure is 2.8 dB rather than 1.8 dB. Newegg also lists this product (here) as having a noise figure of 2.8 dB. It looks like maybe Antennas Direct's own web site may have it listed incorrectly.
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Old 20-Oct-2010, 5:53 PM   #4
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Originally Posted by mtownsend View Post
I'm not sure if this is a typo or not, but Solid Signal's information page (here) on this product says the maximum noise figure is 2.8 dB rather than 1.8 dB. Newegg also lists this product (here) as having a noise figure of 2.8 dB. It looks like maybe Antennas Direct's own web site may have it listed incorrectly.
Our website is essentially correct. I'd rather see it say "Average 1.8 dB NF". The product was improved last year but the old data is still out there on various resellers' sites over which we have no control.

The CPA19 is almost as quiet but has far better overload resistance characteristics.
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Last edited by ADTech; 20-Oct-2010 at 6:47 PM.
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Old 20-Oct-2010, 6:14 PM   #5
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Our website is correct. The product was improved last year
That's great news! It's nice to see that Antennas Direct keeps working to improve their core products.

I hope I'll get a chance to test one of these soon. It looks like an excellent amp to recommend for fringe reception.
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Old 20-Oct-2010, 6:20 PM   #6
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Originally Posted by ADTech View Post
Our website is correct. The product was improved last year but the old data is still out there on various resellers' sites over which we have no control.
Is there a reliable way to distinguish the new design from the old? I would hope the model number would have changed so that old stock could not be passed off as equal to the new improved design.
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Old 20-Oct-2010, 6:25 PM   #7
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Quote:
Originally Posted by mtownsend View Post
Here are some other really low noise figure TV band amps to consider:

http://www.kitztech.com/ (VHF & UHF, 24 dB gain, 0.4 dB NF)

http://www.researchcomms.com/television.html (UHF-only, 20 dB gain, 0.4 dB NF)

With both of these companies, you must provide your own weather-proof enclosure if you want to install the amp outdoors.
Though the kitztech price is at the extreme upper end of what I would term 'consumer market', Impressive numbers in both cases!
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Old 20-Oct-2010, 7:44 PM   #8
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Is there a reliable way to distinguish the new design from the old? I would hope the model number would have changed so that old stock could not be passed off as equal to the new improved design.
It is printed right on the label of the amplifier module. Just slide the cover open and take a peek.

The old ones were actually testing far better that the published 2.8 dB NF. A few tweaks (very few) were made for a different issue and it improved overall performance including NF, hence the change in published spec.

FWIW, it's my opinion that, by the time you get to small (< 1 or 2 dB) dB differences in NF values on the pre-amp making a difference in reception, you're so close to the "ragged edge" that it's not much of a real performance difference when you actually hang metal in the air. If you're that close to the edge, atmospherics are still likely to push you off the cliff when things go bad. But, a little extra sliver of margin isn't a bad thing out in the deep fringe.
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Old 16-Mar-2011, 11:35 PM   #9
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Does Antennas Direct publish the maximum signal input or output numbers for the PA-18 and CPA-19?
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Old 18-Mar-2011, 4:48 PM   #10
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I haven't seen anything formal, but, based on an email exchange last year with our design engineer, his best recollection was that the PA18 was tested to have an IP3 of around 10-15 dB while the CPA19 was somewhere between 25 and 30 db.

I'll ask to see if he has anything more definitive.

My general rule of thumb is to reserve the PA18 for rural locations only where there's nothing around. The CPA19, although its a wee bit nosier (perhaps a half a dB or so) can generally be used anywhere a pre-amp is called for. The CPA19 also has a deep notch filter to reduce signals between the high-VHF and the UHF bands, usually military, public service, and general radio communications as shown here:

http://www.antennasdirect.com/clearstreamcpa19gain.html

The CPA19 is also more robust in terms of ESD survivability.
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Old 30-Sep-2011, 6:43 AM   #11
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Originally Posted by GroundUrMast View Post
Though the kitztech price is at the extreme upper end of what I would term 'consumer market', Impressive numbers in both cases!
The KT price for their KT-200 with 0.4 db NF is $80.. Just a few bucks more than CPA19... Seems reasonable to me (compared with other amplifiers I guess).. it's not like the price is $200 or something outrageous.
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Old 30-Sep-2011, 7:53 PM   #12
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The price has changed...

Be careful to understand the signal handling capability of what ever amp you select. An overloaded amplifier is worse than none at all.
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Old 16-Dec-2011, 5:41 AM   #13
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I want one

The model I'm looking to get is the http://www.kitztech.com/
Model KT-100VG TV Antenna Booster Standard Version
The one with variable gain and separate power input (not through the coax)
I would build a weatherproof box and run power to put it on the mast/tower
What i want the amp for is the noise factor, SWR stabilization and just enough
gain to overcome the losses of the system and the noise factor of the tuner(s)
the amp would be attached to a high gain > 18 Dbi antenna to be aimed only at towers more than 50 miles away . The variable gain adjusted to less than 90% (for the strongest station) on my cheap converter boxes signal meter.
The amp/antenna would not be expected to supply local channels to the system.
I hope to gain 3-7 dB increase in sensitivity by using the amp.
Some where I saw someone say that variable gain was really variable attenuation?
This seams like a good way to encourage clipping.
And I would hope that varying the feedback/gate/grid is how the gain is adjusted.
I want to know what you (all) think.

http://www.tvfool.com/?option=com_wr...3e476ecbd7806e
Again the amplified antenna would never be pointed at the local towers (limit switches).
edit:
sales rep states
Quote:
The KT-100VG uses input attenuation which will increase the noise figure.
Input attenuation will not encourage clipping, it will prevent it.
So I guess if the amp sees a to high signal it auto attenuates the input making weak signals that much weaker.

Last edited by ghz24; 21-Dec-2011 at 6:37 AM. Reason: addition
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Old 23-Dec-2011, 6:58 PM   #14
otadtvman
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Quote:
Originally Posted by mtownsend View Post
Here are some other really low noise figure TV band amps to consider:

http://www.kitztech.com/ (VHF & UHF, 24 dB gain, 0.4 dB NF)

http://www.researchcomms.com/television.html (UHF-only, 20 dB gain, 0.4 dB NF)

With both of these companies, you must provide your own weather-proof enclosure if you want to install the amp outdoors.
Here's another low noise amp to consider:
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Old 21-Jan-2012, 7:30 AM   #15
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I bought one, the KT-200 model coax external.

In general, it gave me about a +3dB increase in SNR, and maybe about a 20% increase in signal strength.

For example, w/o it, my TV would show 60% signal and SNR 16. With KT-200 in-place I got about 80% signal and SNR 19.

One issue I have found with it, is that if you leave it connected and ON all the time, periodically (every 2 months or so), the unit seems to "die." Then I found I had to unplug/turn it off overnight and plug it back in and it seemed to work again...

Go figure..
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