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Old 02-13-2018, 7:52 AM
dlwtrunked dlwtrunked is offline
Join Date: Dec 2002
Posts: 470

Originally Posted by Thunderknight View Post
I think that loop has an amplifier at the loop, if it does, there is a limit to how much filtering at the radio will help. Ideally, you would filter BEFORE the amplifier, but I’m not sure that is possible with the Wellbrook.
Three comments:
1. The amplifier is indeed in the base of the loop (and potted to hide its design). The other piece is only a lower injector and signal separator.
2. It is not possible to insert filters between the loop and amplifier.
3. Keep in mind that with a loop like this, *the amplifier is only trying to make up for the low signals of the loop*. It is unlikely the problem is originating in the Wellbrook as it does not see strong signals at it input. For this reason, the spurious signals are the common old problem of a receiver not being able to withstand AM broadcast band typical strong signals (and undoubtedly has the problem with a good wire antenna) and attenuating them before the receiver is a good (and in this case only) choice.

Putting it before the amplifier is only required if the problem originates in the amplifier with it seeing very strong signals at its input which is likely not the case here. (I have 2 Wellbrook antennas.) Otherwise, your filter rule does hold--low signals originating from loops like this is a special case.

Last edited by dlwtrunked; 02-13-2018 at 8:08 AM..
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