Unwanted Weather reports

[Rawkee1]

I have a BCD 996P2 and a Radio Shack Pro 2067. Lately, sometimes when I get a transmission broadcast on UHF, the pro2067 will start broadcasting a channel on the NOAA weather channel that’s not programmed on it. When the UHF transmission ends, the weather broadcast ends. How can I fix this interference? This does not happen all the time.

 

[GTR8000]

You can try enabling attenuation on the offending channel, but there's probably not much you'll be able to do about it if you live near a strong NWR transmitter. Those GRE scanners had lousy front ends, which is why a strong nearby VHF signal can bleed through even on UHF.

 

[MDScanFan]

That is an intermodulation product. A couple strong signals are received by your scanner at the same time. Within the scanner the signals mix and produce a signal at a different frequency (the UHF channel you are hearing the issue). The NOAA broadcast is a constant signal. Some other intermittent strong signal is being received that is mixing with the constant NOAA signal and resulting in the intermittent signals you are hearing. There is some basic math you can perform to figure out what the likely frequency of the offending signal.

A 162 MHz notch filter on the NOAA signal would likely remedy the issue.

Scanner Filter FAQ | PAR Electronics | Filters for the commercial 2 way market, MATV, FM broadcast, laboratory, marine industry, amateur radio, scanner and short wave listening enthusiasts

PAR Electronics Inc. Filters for the commercial 2 way market, MATV, FM broadcast, laboratory, marine industry, amateur radio, scanner and short wave

www.parelectronics.com

PAR Electronics | Filters for the commercial 2 way market, MATV, FM broadcast, laboratory, marine industry, amateur radio, scanner and short wave listening enthusiasts

PAR Electronics Inc. Filters for the commercial 2 way market, MATV, FM broadcast, laboratory, marine industry, amateur radio, scanner and short wave

www.parelectronics.com

 

[AM909]

@Rawkee1 : Here's a map of the relevant transmitters. If you click on the callsigns in the Station Listing, you get a better picture of where the site is. They used to include the power levels, but don't any more. In the NTIA file, though, they are mostly co-ordinated for 100, 300, or 1000 watts. In MA:

KEC73	1000	414228N, 0703352W
KHB35	500	421244N, 0710652W
WNG574	300	423730N, 0703842W
WWF48	125	423812N, 0731000W
WXL93	500	421814N, 0715351W
WXM68	300	424153N, 0723618W
WXM82	300	420947N, 0732825W

E.g.: assuming they constructed the NTIA-coordinated power level (not a given), if you're anywhere near KEC73 at Camp Edwards, you'll have your work cut out for you.

 

[wtp]

move the radios further apart.
also would you be splitting an antenna between the two ?

 

[Rawkee1]

Separate antennas. The radio that’s blurting out the NOAA station is the Radio Shack Pro 2067. Not always, but when I get a UHF transmission on the BCD 996p2 at 472 Mhz, the 2067 sings the weather. Not all the time tho. The radios are about 2’ apart.

 

[AM909]

On what frequency is the 2067 hearing the weather broadcast?

 

[Rawkee1]

On some of the railroad frequencies.

 

[AM909]

Something like 472.5 - 162.5 - 150.5 = 159.5 is theoretically possible, though I don't think I ever found a 3-component mix like that. Might just be because it's so hard to track down. Does the weather transmission sound normal or is it really loud (like 2 or 3 times the deviation it should be)?

 

[wtp]

i have taken the frequency out of my radio, but.
i have a 396T and an XT.
when the XT had someone talking on our old 800Mhz system the T would get a 'birdie' on a 260 or 270 frequency.
it would not do it while scanning only during a conversation.
our county has gone to a 700 system and i have not found anything yet.
so it might have something to do with the I.F. so you might have to stat doing some math.
if i recall it might have been my pro92 that got the 800 band and cell phones.
the math was like 800 freq divided by 2 and add 16.05 3/4 of double the IF of that radio)
so 888.0 would be heard on 444+16.05=460.05 and i had to be fairly close to a transmitter.

 

[Ubbe]

Lately, sometimes when I get a transmission broadcast on UHF, the pro2067 will start broadcasting a channel on the NOAA weather channel that’s not programmed on it.

A transmitter close by are too strong for the receiver and it overloads. That's probably the reason why you have such problems finding a suitable roof antenna as a too good one will just exaggerate the problem and a lower gain antenna will perform better, but you really should notch out that offending transmitter frequency to solve the problem and increase your coverage range.

/Ubbe

 

[Rawkee1]

When 472.3125 comes over the 996p2, the 2067 receives 162.40. The transmission of the weather station isn’t nearly as clear or load as if I tuned into that weather on its own. It’s also happens intermittently, not all the time. It’s a strange situation.

 

[Ubbe]

It takes a spectrum view over the frequencies, perhaps a simple SDR dongle, and some time to find which frequency that are active every time you see the overload issue.

/Ubbe