In a message dated 1/8/2007 3:48:07 PM Eastern Standard Time, tod@k0to.us
writes:
The MFJ-1025 does not have an internal preamp.
Some radios, in particular the FT1000MP series, provide an RF OUT and an RF
IN jack on the back of the radio. The RF IN jack can be selected from the
from panel and is used with beverages, K9AY loops, Pennants, EWE's and the
like.
The RF OUT jack connects the transmitting antenna to this output when the
radio is receiving. This permits one to use the transmitting antenna to
connect to the AUX or the MAIN input of the MFJ . Now you can use an
external antenna for listening or you can use it for providing a sense
antenna input (connected to AUX) or you can use the TX antenna as a sense
antenna to remove signals and/or noise (or add signal) to the RX antenna .
This is discussed on the ON4UN book.
Sorry - I misstated the preamp issue - it does have a jumper. However, Im
not sure the preamp has a separate gain control. I have an ANC4 which also
has a preamp for the noise but it is not very useful as I find it necessary to
be able to twidle the noise preamp level. Note that because of a BCB band
filter in the 1025/6 the noise input is subject to a degree of loss --
modifications for this are on W8JI's site (I think). Another very useful mod
is to
put in relays to allow reversing the noise input with the main input.. Ive not
done the latter mod but I have experimented in manually reversing the noise
and main antennas (not for transmit of course) and find better null
possibilities that way but I think those could be matched by bigger and better
noise
antennas. 73 Pete W2PM
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