[RFI] What I use to find Interference Sources

KD7JYK DM09 kd7jyk at earthlink.net
Sat Aug 1 03:22:20 EDT 2015


:I am currently building a small Log Periodic for 144 to 450, and using
: either an FT-817ND, or a TH-F6, either rig does AM.  I ordered one of

What about one of those cheapo $30 Chinese HTs with a store-bought or
homebrew LPDA?  Can't get much cheaper or easier than that.

I think it helps, no matter how little help that may turn out to be, to at
least have something that operates in the same frequency range the power
company's little AM receiver and Yagi operate in.

Example.  A "radio tech" came out.  He's a Ham, handles many Ham repeaters
in the region (by the way, the worst functioning and most poorly maintained
based on years of experience and observation of the equipment, installations
and maintenance by dozens of Hams), handles all the power company comms,
mobile data terminals, et cetera.  If it's got an antenna, he handles it.
He "knows about interference", "knows the rules, regulations and laws", you
ask him, he knows it all, he even makes a lot of it up so he knows ever
more.  I attempted to have a basic conversation with him, that failed.
Tried to talk Ham radio and interference, that failed.  HE mentioned the
part about tracking it down at higher frequencies to pinpoint the source, a
common tactic I was surprised he knew.  I grabbed a random radio and
antenna.  Spun the dial, found the loudest noise at UHF for that
combination.  I already knew the source, a pole about 150' away.  Yep, he
agreed it was pretty bad, then asked what frequency I was hearing it on.
465 MHz.  Complete and total mental shut-down.  Utterly incapable of
fathoming such a number.  I didn't know whether to laugh, cry or pee myself.
"That's not a Ham band", as if it mattered...  "Do you hear it on any Ham
bands?".  "Yes, all Ham bands below 465 MHz and even 900 MHz, although I
have to be at the source and the results are inconsistent".  I think at that
point his brain turned to tapioca or something that usually comes out of the
back of a horse in large piles.  The response was to have someone else
fiddle with a bolt on a different pole about a mile away, criticize a 10m HF
antenna for not working on 14 MHz and literally throw an 800 MHz polyphaser
at me, "Here, you need this".  When I asked how it applied to HF, he rudely
yanked it from my hand and walked away in a huff.

Brilliant, another genius.

After talking to someone after that who actually had a clue, and enough of
one to run away from the power company as quickly as possible and get into
the private sector, he agreed that if I had something that had a passing
resemblance "to what the radio techs use", but, MORE IMPORTANTLY within the
same frequency range, "since to them, those numbers mean something", I might
have better luck.  The extent of that has been, "What frequency are you
hearing that on?"  "320 MHz, same as your receiver".  "Oh, great! Now we're
getting somewhere!".  Yeah, I felt like I took the fast track straight to
Hell...  They still couldn't find the noise or fix anything.

Kurt



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