A preamp only helps if it sits in the right place, gets its DC power and stays dry. This guide covers how to install an antenna preamplifier from start to finish: mounting it on the mast, wiring the indoor power inserter so DC actually reaches the amplifier, sealing the outdoor connections, placing the grounding block, and checking for overload once the system is running.
How do you install an antenna preamplifier?
Mount the preamp on the mast just below the antenna with a short jumper to its input. Run the downlead to a power inserter indoors, placed before any splitter so DC can travel up the coax. Seal the outdoor connectors, add a grounding block that passes DC, then rescan and check for overload.
Parts and tools for a mast mounted amplifier install
Choosing the preamp itself, including noise figure, gain and filters, is covered in how to choose an antenna preamplifier. Once you have one, gather the rest before you go up:
- The preamp and its power inserter. They are normally supplied as a matched pair; use the inserter and power supply that came with the preamp.
- A short coax jumper from the antenna to the preamp input, plus the downlead to the house.
- Compression F connectors and the tool to fit them.
- Weatherproofing: connector boots or sealant as the preamp instructions specify.
- A grounding block that passes DC, and the bonding conductor to reach the grounding electrode system.
Step 1: take a baseline, then mount the preamp
Before adding anything, scan with the antenna alone and note the channel count and the signal readings for a few weak and a few strong stations. That baseline is what you will compare against later.
Then mount the preamp on the mast as close below the antenna as the hardware allows:
- Clamp the preamp to the mast with its supplied hardware, oriented the way its instructions show.
- Connect the antenna to the preamp input with the shortest practical jumper. Cable loss ahead of the amplifier adds straight to system noise.
- If the preamp has separate VHF and UHF inputs, match them to the antenna’s outputs as the instructions describe.
- Connect the downlead to the preamp output and tie it down the mast.
Aim the antenna before you finish, since a preamp cannot fix a bad heading; how to aim a TV antenna walks through it.
How to install an antenna preamplifier power inserter
A mast mounted preamp has no outlet nearby, so it takes its DC up the same coax that brings the signal down. The power inserter sits indoors, near an outlet, and has two coax ports: one toward the preamp (usually labeled for the antenna or amplifier) and one toward the TV or splitter. Its power supply plugs into the inserter.
The rule that matters: every device between the inserter and the preamp must pass DC. Coax, connectors and a DC passing grounding block do. A splitter usually does not, unless it is a power passing type, and then often only on one marked port. Put an ordinary splitter between the inserter and the preamp and the preamp sits unpowered on the mast.
Check the port labels before you connect anything. Many preamp instructions warn that connecting the inserter’s amplifier port to the TV can damage the inserter, so the TV side always goes to the port marked for the TV or receiver.
Preamp power inserter and splitter layouts compared
The table shows the common ways installers wire the inserter and a splitter, and whether DC reaches the preamp in each. Splitter placement itself is covered in how to install a coax splitter.
| Layout (antenna side first) | DC reaches the preamp? | Notes |
|---|---|---|
| Preamp, inserter, splitter, TVs | Yes | The standard layout. The splitter sits on the TV side of the inserter, so it never needs to pass DC. |
| Preamp, ordinary splitter, inserter on one output | No | The splitter blocks DC, so the preamp is unpowered and often passes little or no signal. |
| Preamp, power passing splitter, inserter on the passing port | Yes | Works when the inserter sits on the port marked as power passing. Other outputs feed TVs normally. |
| Preamp, power passing splitter, inserter on a blocked port | No | Same symptoms as an ordinary splitter. Recheck the port markings. |
If the system also needs a distribution amplifier, the reasons and the order are in distribution amplifier vs preamp.
Weatherproofing the preamp and outdoor connectors
The preamp and its connectors spend their life outdoors, and the FCC DTV troubleshooting guide notes that outdoor antenna performance can degrade over time from exposure to the weather, telling readers to check for loose or corroded wiring.
- Fit compression connectors on every outdoor end; compression vs crimp F connectors explains why.
- Point connectors down where the housing allows, so water runs off rather than into the threads.
- Seal each connection with the boots or sealant the preamp maker specifies, after the connector is tightened.
- Leave drip loops below the preamp and before the cable enters the building.
- Cap unused inputs if the instructions call for it.
Water in the cable raises loss over time, as coax cable signal loss describes.
Grounding block placement with a preamp
The grounding block goes where the coax enters the building, as the grounding guide explains, which puts it between the preamp and the inserter. That means it sits in the DC path, so it must pass DC; most coax grounding blocks are straight through and do, but check the rating.
Keep the order simple: preamp, downlead, grounding block at the entry, then the inserter indoors. Do not move the inserter outdoors to save a cable run; it is not built for weather. Bond the block and mast as set out in how to ground a TV antenna.
Check for overload after the install
With power on, rescan and compare against your baseline. Where the preamp helps, weak channels hold steadier or appear for the first time. If channels that came in before the preamp now break up or vanish, especially strong local ones, suspect overload.
The FCC guide says that near a station’s broadcast tower, reception of that station and others can be impeded by strong signal overload, and suggests an attenuator or removing amplifiers. In practice, work through it in this order:
- Lower the preamp gain or switch in its attenuation, if it has those controls, and rescan.
- Add an inline attenuator ahead of the tuner and rescan.
- If strong locals still fail, the site may not need a preamp at all; the reasoning is in the selection guide linked above.
Where to find preamps and mounting parts
The antenna preamplifier category lists mast mount preamps, and the antenna mast category and coax cable category list the parts around them, all within the antenna, tower and satellite division.
For pricing and availability, ask your sales representative through the Bursma contact page or the Wyoming, MI branch near Grand Rapids, or open a Bursma dealer account.
Frequently asked questions
Should the power inserter go before or after the splitter?
Before it, on the antenna side. Wired preamp, inserter, splitter, the splitter never has to carry DC. The only exception is a power passing splitter with the inserter on its marked passing port.
Can I mount an antenna preamp in the attic or indoors?
A preamp works best at the antenna, ahead of the downlead loss. With an attic antenna, mount the preamp right at the antenna in the attic. Mounting it indoors at the far end of a long run gives up most of its benefit.
How do I know the preamp is getting power?
Many inserters have a power light, but that only shows the inserter is on. The real test is the scan: if unplugging the inserter makes no difference, DC is not reaching the preamp, usually because of a splitter or block in the path.
Why did I lose channels after adding a preamp?
Either the preamp is unpowered or it is overloaded by strong signals. Check the DC path first, then lower the gain or add attenuation and rescan.