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Old 10-Jan-2018, 7:25 PM   #1
Junior Member
Join Date: Feb 2014
Posts: 5
Lost all reception

Hey all,
I installed a DB8e antenna and RCA preamp a few years back. Has been working beautifully since about 3 days ago. Now I get no signal whatsoever on any of the 3 TVs. The first day it happened, I unplugged preamp for a minute, then plugged back in and it started working. It has gone out again since then and unplugging does not solve.
This leads me to believe the preamp is shot. But do they go bad periodically? Is 3-4 years about the expected lifespan? Is there a way to check to see if it is, in fact, the preamp? Anything else I should look for, test, etc?
Thnx guys
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Old 10-Jan-2018, 11:28 PM   #2
Retired A/V Tech
Join Date: Aug 2012
Location: S.E. VA
Posts: 2,265
Hello, kllrbee

A preamp can go bad, but so can any of the connections between the antenna and the TV.

Your original TVFool report is no longer on the server, but if you have a channel that is strong enough, you can run a new known good coax directly from the antenna to a nearby TV (bypassing the preamp) to see if the antenna is OK.

If the antenna is OK, then reconnect the preamp and slide the combined/separate switch on the preamp back and forth, and then leave it in the combined position.

If the preamp still doesn't work, you will have to check the preamp. First measure the voltagre from the power inserter without the preamp connected:

If the voltage out of the power inserter is OK, then measure the voltage to the preamp at the upper end of the coax that connects to the preamp:

If that is OK, then measure the voltage to the preamp with the preamp connected; this is called voltage under load. This is a little more difficult because you need access to the center conductor when the preamp is connected. I use a T-adapter.

If the voltages check OK and the preamp doesn't work, try another preamp. Buy it from Walmart, Amazon is selling returns that haven't been checked out.
If you can not measure it, you can not improve it.
Lord Kelvin, 1883

Last edited by rabbit73; 10-Jan-2018 at 11:49 PM.
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Old 11-Jan-2018, 12:13 AM   #3
Junior Member
Join Date: Feb 2014
Posts: 5
Thnx very much for the detailed reply. Very informative.
I wrote my post over my lunch break at work today. The signal has been out since sunday, so I just assumed it still was. Of course when I got home and checked, all is good!! Working exactly as it was before.
Im glad its working again, but Im confused as to why it would be out for that long and then just come back.
Very strange...
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Old 11-Jan-2018, 5:12 AM   #4
Senior Member
Join Date: Sep 2012
Posts: 465
Moisture, cold/ bad solder joints, or oxidation on the switch contacts.
Those RCA switches have been noted as problematic many times here in the past.
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