Color me "weird" but . . . interesting NOAA weather radio problem.

[KB2GOM]

Perhaps I am the only guy on planet earth with a "kinda" interest in DXing NOAA weather radio, but there you have it, but we'll get to the interesting part in just a moment.

Today I find myself in Sodus, NY, in the western part of the state, near the shores of Lake Ontario. Rochester, NY, is a bit further to the Southwest. I have with me the following: an Icom V80 with a sharply tuned (I think) commercial antenna that works great on my home repeater (146.94) in Troy, NY; a Uniden BC125AT with a Diamond 77 antenna, and a CCrane Skywave SSB. All receive the NOAA weather channels.

Early this AM, I checked www.wunderground.com for weather in the Sodus area. Snow is expected overnight. So I grab the Uniden 125AT, activate the weather scan function, and find that it receives NOAA weather radio channels 1, 2, and 3, and the audio sound great through my headphones. I try stepping through the weather radio channels on my Icom V80 and find that it receives channels 1, 2, and 3 but with just a wee bit of static in the background. I try switching the antennas between the 125AT and the V80, and there is no appreciable difference.

Now, here's the interesting part: I try the same trick on the CCrane Skywave SSB with its telescoping whip fully extended, and it receives weather channel 1 just fine with excellent audio through the headphones. But channel 2 is way down in the soup, a hair above "barely audible." I try waving the Skywave around, point the whip antenna in different directions and orientations to see if I can improve the signal. I succeed only in nulling it out. Weather radio channel 3 is not audible at all, but channel 4 is coming in well, and so is channel 7 . . . and the other two radios were not receiving channels 4 and 7 at all.

Frankly, I don't know what to make of this. To be clear, I was able to hear that forecast that I needed to hear -- for Wayne County, NY -- on all three radios. But why would there be such a start difference between the CCrane Skywave SSB and the other two radios? As I understand the NOAA weather radio channels are pretty close to each other . . .

So does one of the technical boffins that hangs out here on RR have some insight to offer?

At this point, I am really curious what the answer might be.

 

[ScannerSK]

My guess is there is a lot of radio interference in the area and it is affecting each radio differently depending upon numerous factors such as IF frequencies and intermodulation artifacts. You might subtract the IF frequency used by the various radios from the weather frequencies to see if an image of a lower frequency could be interfering with the weather channels on the various radios.

 

[merlin]

Does your V80 have filtering ? or it may be set to wideband.
It is not antenna related unless wrong for 160 Mhz.
Digging into my Icom archives, I know I have all the documentation ++ for the V80, just can't find it.

 

[nd5y]

How far apart are the different antennas? There is nothing unusual about having different reception using different antennas that are not in the exact same spot. As little as 1/4 wavelength (about 18" at 162 MHz) distance can make a huge difference.

 

[KB2GOM]

Does your V80 have filtering ? or it may be set to wideband.
It is not antenna related unless wrong for 160 Mhz.
Digging into my Icom archives, I know I have all the documentation ++ for the V80, just can't find it.

The V80 and the 125AT "agree" with each; both are receiving NOAA weather radio channels 1, 2, 3. The CCrane Skywave SSB appears to be the anomaly, receiving channels 1, 2 (barely), and 4 and 7, which the V80 and 125AT did not receive.

I just checked, and the NOAA weather radio frequencies occupy a fairly narrow spread: each channel represents one of seven frequencies between 162.400 MHz to 162.550 MHz.

 

[KB2GOM]

How far apart are the different antennas? There is nothing unusual about having different reception using different antennas that are not in the exact same spot. As little as 1/4 wavelength (about 18" at 162 MHz) distance can make a huge difference.

All three tested in my lap at the same location and then tested in another room within inches of each other. I turned one radio on, checked the channels it could receive, turned it off, then tested the next radio, etc. Same results in both cases.

 

[chill1971]

Did you check the actual frequencies received on the radios? Some radios number the channels from lowest to highest frequency and others use the NOAA assigned channel numbers.

 

[KB2GOM]

Did you check the actual frequencies received on the radios? Some radios number the channels from lowest to highest frequency and others use the NOAA assigned channel numbers.

Hmmmm. Interesting idea.

Modern Survival Blog -- https://modernsurvivalblog.com/weather-preparedness/noaa-weather-radio-channel-list/ -- reveals that NOAA weather channels may displayed in two different ways, depending upon the manufacturer: chronological or in increasing frequency order.

The Uniden displays Channel numbers and frequencies, so: Ch. 1, 162.550; Ch. 2. 162.400; Ch. 3 162.475. The Icom V80 lists only channel numbers, but no frequencies. However, it receives the same channels as the Uniden.

This appears to be the chronological sequence – the sequence to which the radio frequencies were allocated over time to the service. This ordered sequence is used by (some) weather radio manufacturers.

1=162.550 Mhz
2=162.400 Mhz
3=162.475 Mhz
4=162.425 Mhz
5=162.450 Mhz
6=162.500 Mhz
7=162.525 Mhz

The CCrane Skywave SSB lists only channel numbers. BUT, if it follows the weather radio channels in increasing frequency --

1=162.400 Mhz
2=162.425 Mhz
3=162.450 Mhz
4=162.475 Mhz
5=162.500 Mhz
6=162.525 Mhz
7=162.550 Mhz

Then the CCrane receives Ch1, 162.400 (which is Ch. 2 on the other two radios); Ch 2, 162.425 faintly (Ch. 4 on the other radios), Ch 4, 162.475 (Ch. 3 on Uniden and Icom), and Ch 7, 162.550 (which would be Ch. 1 on the other two radios).

So all three radios are receiving the same frequencies, but with different channel numbers assigned to them . . . and the CCrane appears to be a hair more sensitive, also receiving the 162.425 channel very faintly.

As Inspector Clouseau would say: "The case is sol-ved."

Thanks to all for your valuable suggestions. You now know more about NOAA weather radio (probably) than you ever wanted to know!