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4.4 Amplifiers

A CATV amplifier is used to boost an existing GOOD signal so that it can travel further.

You can find these at Radio Shack (get a good quality one), and Circuit City has begun selling them too (at a high price).

The best place to put these is at the junction, BEFORE the first splitter. Putting an amplifier behind your TV or before your cable modem will NOT help at all, because at that point the signal is already bad and weak. You will just end up amplifying a BAD SIGNAL.

There are several varieties of Amps, but you'll probably be okay with a one port. These usually have a gain of 12 to 15db. Make sure you get a 900MHz (or better) amp. These will run you from $30 to $120.

Two port amps usually have a gain of 9 to 13 db.
Four port amps usually have a gain of 6 to 10 db.

NOTE: Amplifiers are to boost EXISTING GOOD SIGNAL in order to increase the distance that it will travel. Do NOT use an Amp to fix a noisy or bad signal; You'll just end up amplifying a bad signal.

Feedback received on this FAQ entry:
  • would the amplifier work with the DTV digital to analog converter / set top box. I installed the set top box today,some stations have weak signal strength. The picture is small with large black borders. The color on two stations are yellow. What is your recommendation. Thank You from Delaware.

    2009-01-01 21:43:25

  • Do you know what impact a 4 port passive return amplifier will have on the return level? increase decrease or stay the same and by how much.

    2008-01-21 19:05:36

  • i'm in miami,FL currently w/ comcast cable broadband i bought my own modem sb5120 motorola eliminated the rental fee on the one they gave me

    2007-12-12 10:36:52 (wanting 2no See Profile)

  • all this info helped me a lot.......i'm going out 2 go buy one now.i'll fill you in w/ the results!

    2007-12-12 10:34:33 (wanting 2no See Profile)

by Raydr See Profile
last modified: 2002-03-01 08:42:19

IMPORTANT: There are a lot of amplifiers that will block your cable modem from talking back to your provider! This obviously defeats the purpose of having one.

Look for this when buying an amplifier:
"Cable modem compatible"
"5-42MHz passive return"

by Raydr See Profile

The following Amps are KNOWN to work with cable modems:

Electroline EDA2100 (Thanks, bouchecl See Profile)
Electroline EDA2400 (Thanks, bmusgrove See Profile)
(I'm assuming that the above are 1 and 4 port models, respectively)
Motorola Signal Booster Drop Amp - Model 484095-001-00 (Thanks, Cory Cooper See Profile)
Scientific Atlanta Surge-Gap(r) Drop (Thanks, Me)
Pico Macom CDA-1A (Thanks, Charter tipster. currently $40 shipped).

The following Amps DO NOT work with cable modems:
The inline amplifier sold at Radio Shack prevents 2-way communication. (Thanks, Chakthi See Profile)

I do not have access to many amps. If you have an amp installed in your home, please provide me with the information for it and whether it works or not!

Feedback received on this FAQ entry:
  • Rocketfish RF-G1179 4-way bi-directional cable amplifier available at Best Buy helped boost the downstream signal with my Comcast Motorola SB5120. My downstream power level improved from -12 dBmV without amp to -5 dBmV with the amp. My downstream SNR improved from 34dB to 35dB. Note this amp introduces some loss on the upstream and does NOT amplify the upstream return signal. My modem is now pushing 5 dB more on the upstream power level, but still within spec. Speedtesting is within spec, so I am happy with it.

    2014-06-17 12:56:49 (paule123 See Profile)

  • Great FAQ! Very helpful in learning more about my cable. Btw, I wired Signal Vision SVA15-2PRSV Amp today then ran the output through a 4-way splitter for all the rooms, and finally another 2-way splitter since my cable modem (SURFboard SBG900) and TV are on the same loop. So far internet and TV are working fine. Actually, TV signal was bad and now is great. The stats from the modem are: Downstream - SNR: 38.2dB; Power: -1.8dBmV Upstream - Power: 55dBmV (somewhat high but before I made changes was 54) Anyway I thought I thank you and share that SVA15-2PRSV amp works with SURFboard SBG900 modem. Thank you Boian

    2009-11-30 02:45:20

  • One thing that I have learned out in the field is that if you are having issues with connections with your cable modem, Amps (no matter what kind it is) is just a patch and not a solution. Majority of the time, there is a cut, exposed wire, bad fitting (long stinger, sucked out fitting) causing the issue. If that's not the case, it can also be that the the Upstream level it's self is either too High or too Low. All modems should not need an amplifier to work properly. If it does, you may have some other problems what needs to be address and corrected before the problem gets worse.

    2009-11-01 13:40:15 (JustaFan See Profile)

  • DataComm's new 70-0039 (1X8) coax HD distribution amp actually has a return gain amplifier - built in RF meter - individual 8 output adjustments - forward gain "step-up" amplifier. This is an awesome piece of equiptment specifically designed for HDTV.

    2009-08-22 14:32:31

  • I have a few other amps that would be HSD/MTA compadable (2-way, some with Rx and Tx amplified, others just Rx). Any questions needing answers with amps, splitters, DCs, fittings, cable, etc. feel free to contact me. I am a Time Warner tech working out of the Central NY division and stumbled on this site browsing aimlessly. Any questions on digital phone, HSD services, cable/digital cable let me know.

    2009-06-13 22:40:05

  • Currently using a Qintar amp (supplied by Comcast) with cable modem and HDTV. Data and Specs: Residential Amp, RAMP2W-1000MS, 5-42MHz Return Path Passive, 54-1000 MHz Forward Path 10dB GAIN. Single in and out, powered via 12V DC 200mA transformer connected via Quad cable. Transformer input is 120VAC, 5W.

    2009-04-04 00:52:06

  • PCT MA2-M is working with Ambit cable modem

    2008-11-03 13:07:41

  • I have the Radio Shack amp. It's the one with 4 outputs and and amplifier. It works fine with my Comcast cable modem and Tmobile@Home VOIP service.

    2008-09-11 16:15:16

  • picked up a philips amp from walmart provides 18dB forward amp of 54-1000MHz return path 5-42 mhz. works well, single line amp.

    2008-07-22 18:13:45

  • Please add the RCA - Digital 4-Way Bidirectional RF Amplifier Model: DT140M, Its a four way splitter and Amplifier. Purchased at Best Buy for under $40.00. Works great. Boosted my Cable Modem and no more black outs. Fishmoss

    2008-06-29 21:41:03

  • Walmart carries the Philips 4-Way splitter that is Amplifier powered, it says Bandwidth 50-900mhz, Gain 12db, response 1dB, but after I bought it hoping to return it if it didnt work i noticed the big black box "not for use with cable modems or digital cable boxes" (the 2 things i need at the end of my line) Anyway i waited too long so Im stuck with it, but I can tell you it doesnt work with cable modems but is sold as an amplifier/4-way splitter

    2008-04-09 16:43:26

  • thanks guyz 4 info on these booster amps

    2007-12-12 10:24:19

  • After years and three cable modems/8yrs, I decided to check my download and upload power and S/N. These were out of range but against advice I purchased a Radio Shack 1 to 4 Bidirectional Amp (Catalog #: 15-2506) It has an adjustable output, so I was able to "tune it" to the ideal S/N and power levels. There has not been a modem dropout and the speeds are stable as well as the fact I can have a TV hookup in the same room. Great product, read the customer reviews about the amp at Radio! (4.5 stars out of 5- 20 reviews)

    2007-12-05 11:06:49

by Raydr See Profile
last modified: 2007-01-02 15:11:53


Simple analogy: Adding more gas to your car does not make it run faster.

Adding a better QUALITY gas to your car may make it run more efficiently. Same with amplifiers.

Thanks for Mike for the question.

Feedback received on this FAQ entry:
  • So basically by being more *efficient* the modem is able to work faster. Speed didn't really increase, you are just being efficient enough to use it :P

    2012-07-19 13:52:51

  • Theoretically, this is true, but practically, there are some unusual cases where an amplifier will make a connection faster. If the signal is weak enough that the modem generates frequent errors or dropouts, then having a stronger signal may reduce the error rate and thus increase throughput.

    2010-08-24 13:52:47

by Raydr See Profile
last modified: 2002-03-01 10:26:18

All that matters is that the amplifier boost from 54MHz to 1GHz up, with a passive return in the 2 to 54MHz range.

by ithxp See Profile edited by Raydr See Profile
last modified: 2002-11-28 18:34:29

When you determine that you need to apply a cable TV amplifier within your CPE (Customer Premise Equipment) cable structure for increasing your signal level to travel an extended amount, it is very important to install the correct style of amplifier. With many different manufacturers offering a variety of amplification products, it is often difficult for the end user to know what is right for them. The first step in determining the amplifier type that you are going to use is to look at what broadband services (such as video, data, and telephone) you will be using, or will be using now or in the future. There are four basic house amplifiers, Forward Gain, Return Gain, 2-Way Active, and Bypass.

Forward gain cable amplifiers can by used in a variety of different situations, from compensating for lower signal strength from your cable provider, raising the strength of the signal from your cable provider, or increasing the signal before multiple line are connected. The forward gain amplifier works in providing an increased signal level into your home on the upstream band of 54-1000 MHz, and still allowing the 5-42MHz return band to be passed on back to the cable provider with little or no loss in signal level. Things to look for when purchasing a forward gain amplifier are, Low noise of 3 dB or lower, low distortion and excellent return loss which should be about 20 dB.

Return gain cable amplifiers are used to correct for weak signal strength on the return path with in the 5-42 MHz band being sent back to the service provider from your home for your high speed internet, interactive television, and telephony services. Some cases that would require a return gain amplifier are attenuation caused from passives install in the home and long cable runs from the service providers tap to your home. Things to look for when purchasing a return gain amplifier are a noise figure level of 5.5, SCTE compliant water sealed connectors, RFI Shielding of 100 or greater, and the housing material.

2-Way Active cable amplifiers are used to compensate for weak signal strength in where both the forward path of 54-1000 MHz and the return path of 5-42 MHz would need to be increased for your high speed internet, Interactive television, and telephony services.

Bypass cable amplifiers work in the same way as forward gain amplifiers to increase the signal level on the 54-1000 MHz band for high speed internet, interactive television and telephony services, and still allowing the 5-42MHz return band to be passed on back to the cable provider with little or no loss in signal level. The difference from the forward gain amplifier is that the bypass amplifier has a built in relay switch designed to bypass the amplification circuitry to bypass mode and provide constant uninterrupted telephony service in the event of a power outage.

Feedback received on this FAQ entry:
  • Antronix FRA8-400 works well with RR cable/modem.

    2010-01-24 10:55:26

by urbroadband See Profile edited by Axilla See Profile
last modified: 2007-09-20 18:10:07