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Author Topic: VHF Momentary loss of signal  (Read 191 times)

N0AKX

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VHF Momentary loss of signal
« on: June 05, 2021, 03:44:15 AM »

Hi,

I just set up my 2M radio at the new home. While listening to a repeater, I am experiencing momentary loss of signal, evenly spaced, almost like a pulsating loss of signal. As comparison, if it were a bedroom lamp, imagine someone flickering off the switch for like 0.5 seconds, and turning it back on, continuously.
It appears I am having the same issue on any receive, not just one particular repeater. Anyone know what may be causing this interference? Thank you.
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W1VT

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Re: VHF Momentary loss of signal
« Reply #1 on: June 05, 2021, 04:23:42 AM »

It sounds like front end overload.  A strong signal is desensing your radio.
Ideally, your radio would have a 2M bandpass filter to remove strong signals outside the 2M band, but many radios are lacking in this feature.
Instead, hams prefer DC to daylight receive.  A cheap way to implement this feature is to get rid of the 2M bandpass filter.

Zak W1VT
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W9IQ

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Re: VHF Momentary loss of signal
« Reply #2 on: June 05, 2021, 04:45:41 AM »

Just as a very remote possibility, do you have any power generating windmills in your area?

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

K0UA

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Re: VHF Momentary loss of signal
« Reply #3 on: June 05, 2021, 08:22:07 AM »

Priority channel scanning?
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73  James K0UA

VE3TMT

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Re: VHF Momentary loss of signal
« Reply #4 on: June 05, 2021, 12:51:39 PM »

Priority channel scanning?

Seconded
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N0AKX

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Re: VHF Momentary loss of signal
« Reply #5 on: June 05, 2021, 03:21:01 PM »

I thought it was Priority Scan as well but it is not. It certainly acts identical! It happens on all my radios, even an HT…
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WB6BYU

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Re: VHF Momentary loss of signal
« Reply #6 on: June 06, 2021, 11:58:28 AM »

What is the interval between dropouts?

Do you have an APRS transmitter set up to transmit on that interval?

K0UA

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Re: VHF Momentary loss of signal
« Reply #7 on: June 06, 2021, 08:19:58 PM »

Buy one of those cheap Chinese Spectrum analyzers (less than 100 bucks) and find the signal. Or set up a 2 meter rig to do a wideband channel scan (might take a long time, but no cost) once you find the signal, shut off the power to your house and see if it is in your house. And I mean be thorough and shut off all cable boxes, UPS's and every thing to be dead except you battery powered radio. Did the signal go away?.  Start flipping breakers. If it is outside the house, go mobile and try to find it.
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73  James K0UA
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