On 06/23/2014 05:00 AM, KD7JYK DM09 wrote:
I've played with a couple of 3 element "noise locators" on VHF, both were
useless, no directivity at all, OR, RFI was everywhere. Couldn't tell, went
back to a vertical sense antenna and attenuator and located it that way.
I have a modified MFJ-856 which I found near useless out of the box.
After modification it is better. It has a very deep, sharp null at
90 degrees (off the side) which is more useful for confirming a
source than the broad front peak. Information on the modifications
can be found here:
http://blog.n1bug.com/2012/06/14/
I've gone as high as 950 Mhz search for RFI.
Going higher in frequency helps a lot. I was able to confirm the
pole for a few sources using 445 MHz where 135 MHz was ambiguous
even using the null. I now have one of the old CATV signal meters
which tunes up to 900 MHz. I eventually want to build a log periodic
covering as much of the VHF/UHF range as possible while still being
small enough to carry around, but will probably still carry a couple
of UHF due to their narrower beam width.
--
Paul Kelley, N1BUG
RFI Committee chair,
Piscataquis Amateur Radio Club
http://www.k1pq.org
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