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tone noise on well defined spaced frequencies.

mb91w126

mb91w126

Active Member
Jul 24, 2013
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well this is odd.

27.465 I receive 1 bar of a low frequency clean steady tone, as if created by a signal generator.
27.435 I receive 3 bars of a some what higher frequency clean steady tone
27.405 I receive 4 bars of a some what higher frequency clean steady tone
27.375 I receive 4 bars of a some what higher frequency clean steady tone
27.345 I receive 4 bars of a some what higher frequency clean steady tone
27.305 I receive a very faint higher frequency clean steady tone

the in between frequencies are all quiet.

Any thoughts??
 

Without knowing any other details it sounds like it could be be power supply noise. I stopped using a Ratshack switching supply becuse of the noise it generate on 10 meters.

Edit: you didn't mention if the radio was channelized or you were tuning with a vfo. If your flipping a channel selector it's probably not the noise that is channelized, it's the receiver. Tune the same hash with a vfo and you'll see where the noise spike is.
 
Last edited:
Nice Astron supply. You can still check it by trying another PS on it. I would. It's really just step 1 to locate the source of the noise spike.
 
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I think tbat power supply is a linear type and not a switching type so it should be clean. Hmmmm....it appears every 30 kHz. Try every 15Khz and see if it is also on 27.360, 27.390, 27.420 etc. Any new televisions in the area?
 
my new tv puts constant but low signal noise on my radio from 26mhz-28mhz
also my satelitee power box [direct tv] when plug in does same thing but
more signal up to 3-5 s-units but very loud. blocks some locals around
40 mile range . glad i had it shut off ..lol
 
do you have a computer or wi fi near you or cordless mouse ..I had a programmable thermostat for my heat screw up my receive once
 
midnight special said:
i am leaning toward a leaking cable tv line creating harmonics,,,,
Click to expand...


My money is NOT on cable TV line. The old analog sub-band frequencies used on the older CATV are not used anymore. Channel T-10 was in the range of CB frequencies but it has not been used for YEARS. Most CATV is digital now and a lot is fiber-op so no leakage anyway. Besides that even if the CATV line was leaking it would not cause harmonics. The key is the precise frequency steps. Televisions have a 15 Khz horizontal scan rate that can cause noise especially some of the plasma screens.
 
local cable here is digital and analog,,,, it carries dsl and phone too,,, i get a lot of noise from it all over the spectrum when ever it dries up and dosent rain for a while....even worse is the electric company uses that bpl stuff so they can read the meter from the main office, no one to come and read meters anymore,,, hell they even can shut your air and hot water heater off in peak hours and give a discount on your bill for it....it takes a special box and wireing for it but it is noisy when it is operating..
 
midnight special said:
local cable here is digital and analog,,,, it carries dsl and phone too,,, i get a lot of noise from it all over the spectrum when ever it dries up and dosent rain for a while....even worse is the electric company uses that bpl stuff so they can read the meter from the main office, no one to come and read meters anymore,,, hell they even can shut your air and hot water heater off in peak hours and give a discount on your bill for it....it takes a special box and wireing for it but it is noisy when it is operating..
Click to expand...

Maybe there is some digital crap coming from the cable then. I doubt it is from the analog stuff however as channel T-10 has long been unused. I never even thought about the wireless power meters however. we don't have them here where I live but it could be a possibility. I thought they worked on UHF similar to the cellular network however. Once you get into any form of BPL all bets are off as to noise sources.
 
I have ADT Security with the wireless sensors and no noise for me. I do however have W-I-D-E-B-A-N-D hash noise from the power supply in my front loading washer. You can hear the noise change as the drum turns-stops-and reverses. It does not extend higher than about 17-15m however. :) It just messes with 20m and 40m mostly. :(
 
My noise lasted for about 3 days then has since disappeared.
My wife was home with her blackberry so it may have been it's radio.
Also my daughter had her old Toshiba (2009) laptop running so it may have been that also.

All is quiet for now.
Thanks for all the insightful suggestions.
 
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