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Old October 23rd 05, 03:10 AM
Walter Maxwell
 
Posts: n/a
Default Messed-Up Radials Can Generate Spurious Emissions

On Sat, 22 Oct 2005 21:44:25 -0400, Dave Holford wrote:

Walter,

that brings back some old memories.

In the early 1960s I was, for a while, in the control tower at RCAF Greenwood Nova
Scotia. Our ATC voice hotline linking several facitilites in the maritimes had a
constant background of CW from NAA in Cutler, Maine.


Hi Dave, that was probably because of the relatively short distance between
Cutler and Greenwood with respect to the VLF of NAA, along with its very high
power ground-wave signal. Incidentally, In the pre-war days of WW2 NAA was at
Arlngton, VA.

A couple of years later I was stationed in Prince Edward Island where the local
station, CJRW 1240, was about the same strength as a station in New Brunswick, CKCW
1220. In the background there always seemed to be a discernabile signal from NAA. I
always assumed that this was due to the 20 kHz difference mixing with the 24 kHz of
NAA and giving a very steady, but rather high pitched for CW, 4 kHz beat.


That's how I'd explain it, especially if there was non-linear substance deriving
a beat between the two BC stations.

While in Greenwood it was also common to hear the Grennwood NDB (ZX) while in the
car; since the beacon was on the IF commonly used in automobile radios in those days
- 248 kHz? or something close.

The last one was really wierd. Some days when the weather was lousy we would hear an
intermittent and badly distorted BBC signal on a VHF FM frequency. The technicians
were convinced we were either crazy or drunk. Eventually it turned out to be a
mixing problem involving two VHF frequencies and a BBC World Service station on the
15 MHz SWBC band. It only happened in bad weather because one of the mixing
frequencies was the GCA (Ground Controlled Approach) frequency which was only really
active in bad weather.

I don't reallyl think any of the above had anything to do with radials, but they
triggered some long ago memories.

Dave


Very interesting, Dave, I'm pleased that that you shared those events with us.

Walt