Topband: Tecsun 660

[donovanf at starpower.net]

Hi Jeff, 


My consistent practice is to identify the highest frequency where 
I can hear the RFI in my shack. I then use my directive antennas 
to determine the bearing on which I should search. I can 
consistently determine azimuth within better than ten degree 
accuracy on any band. I begin my search on that frequency 
with the PL-660 in wide band AM mode, walking or driving 
along the line of bearing. 


The PL-660 has a built in loopstick antenna very useful for 
direction finding but active only in the AM broadcast band 
(540-1700 kHz). Above 1700 kHz it uses a short retractable 
whip antenna (slightly useful for direction finding) or an 
external antenna. 


Usually (but definitely not always) the RFI can be heard on higher 
frequencies as you get closer to the source, in many cases up the 
the aircraft band or all the way up to 450 MHz (on a different 
receiver). So far my most distant RFI was AC power line RFI 
very strong at my QTH that originates four miles away, It was 
a serious visible arc on a 34 kV subtransmission line (not a local 
13 kV distribution line). The power company was very 
motivated to repair it quickly. 


This recent RFI was very different than anything I've ever 
experienced, I could hear the RFI only on the 160 meter band 
(about 1500- 2000 kHz) It sounded like white noise with no 
audible 60 Hz (or 60 Hz harmonic) component, The only 
way I could locate it was by using the PL-660 S-meter with 
the PL-660 in wideband AM mode. It turned out to be a 
malfunctioning Travellers' Information Station transmitter 
at 1700 kHz. Local hams have an excellent relationship with 
the county Office of Emergency Management that operates the 
transmitter and they turned it off within hours of being notified 
of the problem. 


This is only the second RFI that I've experienced that affects 
only 160 meters. The first one was very intense RFI that 
sounded exactly like classic AC power line RFI but strangely 
it affected only 160 meters and the AM broadcast band. 
It turned out to be a malfunctioning electric fence charger 
one mile away that was stuck continuously on, not pulsing. 
Unfortunately the landowner (an electrician!) was very 
belligerent about refusing to replace his fence charger, but 
some aggressive "social engineering" motivated him to 
change his behavior. 


73 
Frank 
W3LPL 


----- Original Message -----

From: K1ZM at aol.com 
To: donovanf at starpower.net 
Sent: Tuesday, February 16, 2016 10:08:22 AM 
Subject: Tecsun 660 

Hi Frank 

I read your emails on your RFI search. 

Youmay have mentioned it, but what FREQ BAND did you use on the TECSUN in 
your search for the source? 

Was it the AIRCRAFT BAND on FM? 

The reason I ask is that I have a similar radio - that is very similar to 
the radio you used - just made by SONY. 

I wonder if I could use it like you did? I am 99% sure it has the aricraft 
FM band in it. 

Pls let me know when you can. 

Tks 

73 JEFF</HTML>