Topband
[Top] [All Lists]

Re: Topband: Short Receive Antennas

To: "Jerry Keller" <k3bz@arrl.net>,"Donald Chester" <k4kyv@hotmail.com>, <Topband@contesting.com>
Subject: Re: Topband: Short Receive Antennas
From: "Floyd Sense" <fsense@copper.net>
Date: Tue, 14 Dec 2004 07:16:56 -0500
List-post: <mailto:topband@contesting.com>
I've used an MFJ-1026 (think this is the 1025 with a built-in whip) to null broadband noise coming from my TV. I found it worked very well for that purpose, but had much less success when trying to null or peak signals on 160 using two external antennas. The reason: too difficult to adjust the gain and phasing controls on other than constant-carrier signals. Probably not impossible to do, just more trouble than I needed. The manual warns against using the RF sensing to do the T/R switching and urges you to use the PTT line to switch the unit.

73, K8AC

----- Original Message ----- From: "Jerry Keller" <k3bz@arrl.net>
To: "Donald Chester" <k4kyv@hotmail.com>; <Topband@contesting.com>
Sent: Monday, December 13, 2004 8:41 PM
Subject: Re: Topband: Short Receive Antennas



Talking about "noise cancelling", what about the MFJ-1025 which claims to provide a "60 db null to wipe out noise and QRM" using a separate external receive antenna (maybe a beverage or a small loop??). It even has an "RF sense T/R switch" that "automatically bypasses the receiver when transmitting".
Has anyone tried one of these things? Does it work at all?


73, Jerry K3BZ

----- Original Message ----- From: "Donald Chester" <k4kyv@hotmail.com>
To: <Topband@contesting.com>
Sent: Sunday, December 12, 2004 2:49 PM
Subject: Re: Topband: Short Receive Antennas




You might want to look at an article in QST by K6STI, who
experimented/made a "noise-cancelling" antenna. It was
a wire antenna, 25 or more feet on a side, with open wire feed
lines from two opposing corners that went to a center pole and
box with a matching xfmr, etc.  One of the feed lines was twisted 180 deg
to cancel local noise signals.  QST article was Sep 1995, page 33.
and pages following....might be worth a look.

I built one of those a few years ago, and still have it. While it occasionally provides better reception than my other antennas, most of the time its performance is disappointing. I pretty much consider mine wasted effort.



_______________________________________________ Topband mailing list Topband@contesting.com http://lists.contesting.com/mailman/listinfo/topband


_______________________________________________ Topband mailing list Topband@contesting.com http://lists.contesting.com/mailman/listinfo/topband



_______________________________________________
Topband mailing list
Topband@contesting.com
http://lists.contesting.com/mailman/listinfo/topband

<Prev in Thread] Current Thread [Next in Thread>