RadioBanter - View Single Post

Arid ace · December 4th 16, 02:52 AM posted to rec.radio.shortwave

On Sat, 3 Dec 2016 13:53:39 -0800 (PST), wrote:

On Saturday, December 3, 2016 at 3:40:01 PM UTC-5, Arid ace wrote:
For quite a while, the second harmonic of Radio San Carlos is on air. Here in
Panama at some 600 Km from the transmitter, even during daylight hours up to S9,
with fades going as deep as S2. Before transmission ends at 01 AM UTC, it peaks
to S9+25 hence it's likely this station can be heard even in Europe. It's not
likely the engineer in charge will enjoy sending QSL cards for reception of the
2nd harmonic, more than 40 dB stronger here than the fundamental. No
transmission on Sunday.

Good DX,
Jan
To be honest- I do not recall a harmonic being stronger than the fundamental frequency. Sounds like a very freaky propagation condition or a simple transmitter problem.

As the station is rather popular, any problem affecting MW transmission would
have been reported long ago. The deep fades at daytime hint at ionospheric
propagation, improved by a vertical antenna operated at twice its working
frequency: high angle lobe(s) and higher gain than at operating frequency. Half
an hour after sunset, the field strength is comparable to R. Rebelde (Cuba),
then goes down a little. However R. San Carlos is supposed to be running just
3KW (WRTH) whereas R. Rebelde usually is running 50 KW. A situation that has
been unchanging for several months - hence the interest in reception at a larger
distance.