[IRCA] Sept 2: Average but Asian for Me + Dial/Frequency Accuracy

["John H. Bryant" <bjohnorcas@xxxxxxxxxxxxxx>]

Everyone else seemed to have quite a DU morning.  I did not. Had 
slightly below recent average number of hets and audio, but with the 
early period (1220 to 1240) definitely favoring North China/Manchuria 
and North Korea.  No sign of ADK beacon on 530 in the Aleutians. 
Later, at max dawn it was a pretty decent Japanese opening, including 
a real boost right at dawn (for a change).  At dawn, there was a 
little DU activity, but not much.... low DU audio on 531, 558, 567, 
1503 and 1512.  If I didn't know better, I'd think that my Aussie 
Super-size EWE was not working well.

I had off-channel signals on 702.03 (only signal there, thanks Guy) 
747.056, 1016.95, 1025.955 and the usual 1205.95 CNR KK Service


There have been several discussions of frequency accuracy, drift, 
etc, in the last 48 hours.  I tend to agree with Chuck H. that most 
methods have way too many oscillators involved as well as 
temperature-sensitive components, to begin to talk very confidently 
of readings to the single Hertz or finer.  However, there are a few 
techniques that seem to offer that level of accuracy.

The WinRadio 3xx Series can get within +or- a couple of Hertz or 
maybe three, at least by methods that I understand.... The active 
Spectrum Scope is rather a wonder and is essentially a virtual 
oscilloscope looking closely at the RF Spectrum around where the 
receiver is tuned. It has a zoom in and out capability, with the 
widest view offering plus/minus 10 kHz and the closest look (where I 
generally keep it) shows plus/minus 2 kHz. The carrier of each 
received signal stands out as a spike... a steady spike that only 
undulates with propagation. THe modulation of each signal, if it is 
getting through, appears as rapidly changing spikes and ripples. Most 
of the time, the only thing worth watching is the carrier, of course.

The resolution of the scope is such that I think it would be very 
obvious if the tuned frequency were "off" from reality more than a 
couple of Hertz.... The spikes would not be symmetrical about the 
centerline of the scope, when tuned to the assigned frequency. I have 
yet to notice a NAm station that did not appear perfectly on freq.... 
meaning within 3 or 4 Hertz..... so thermal drift and oscillator 
inaccuracy of the 3xx series appear to be within those limits. Its 
easiest to tell when I'm seeing an off channel signal when there is 
also an on-channel carrier on that frequency.... There are two 
distinct spikes and they undulate at differing rhythms since they are 
coming through different paths in the ionosphere.  Then, there is no 
question that there is at least one signal off frequency and its 
relatively easy to measure the aprox. difference between the two.

Its more difficult to notice an off channel signal when it is the 
only signal on that frequency and the difference is rather 
small.  Guy mentioned to me an off-channel that he as hearing on 702 
high and I paid attention for the first time, this morning.  Sure 
enough.  My excuse for missing this one is that it was all alone and 
recently has only been in briefly right at dawn.  In fact, its acting 
like the 2BL signal from a propagational point of view.... surely it 
wouldn't be one of the flagship ABC stations off by 30 Hertz?????

Anyway, as Chuck also pointed out, there are likely only a handful 
(literally) of people on the planet that are interested in this subject...

So, I'll close!

John Bryant  
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