3
$\begingroup$

I'm new at Ham Radio, in fact still studying for Technician (so I can't transmit) but I purchased a used Icom IC-746, dipole antenna kit and most recently a Hexbeam antenna. The power supply is an Alinco DM-330MV.

While studying for the Technician exam I've been listening, mostly on 10 meters, and I've noticed an odd interference pattern - every 145-146 KHz I hear a steady series of beeps or chirps. I've hear them at 28.134 MHz, 28.280 MHz, 28.425 MHz, and 28.571 MHz. I don't think they are the result of a transmission, as I don't hear them on any internet connected SDR radios I've tried. They also don't seem to cause any movement on the S meter. The beeps/chirps go away when I disconnect the antenna, but are there for both the dipole and the hexbeam (which use different cables).

They may be present on other bands and frequencies, I just haven't experimented that heavily yet.

In terms of troubleshooting, I have shut down the computer, cable router, wi-fi, network switch and other things I've been able to unplug. I don't have a battery powered radio I can test, but I'll try borrowing one from the local club.

Here is a YouTube video showing the issue:

You Tube video of the beeps on two frequencies

Does this ring a bell with anyone? I've looked around and I can't seem to find the same situation in another post or forum.

EDIT - I'm currently away from home, so it will be a few days before I can do the troubleshooting steps, but I appreciate the tips. I will report back once I've had time to try them.

EDIT #2 - I'm back, I've plugged the antenna cables in and powered up the transceiver and it seems that the issue has gone away. While I was out my son replaced a broken ice maker in our fridge, but as far as I know, that was the only electrical work done in the house. I'm glad the chirps/beeps are gone, but frustrated that I won't know what caused them. I'm also not sure what is the correct way to handle a moot question like this in StackExchange, but I appreciate the troubleshooting tips.

Improve this question
$\endgroup$
3
  • 2
    $\begingroup$ Try disconnecting the transmission line from the antenna, but leave it plugged into the radio. If you still hear the beeps, your transmission line shield (am assuming coax) is behaving like an antenna and you'd benefit from an RF choke at the transceiver. If you only hear the interference when the antenna is connected, then you've got a local QRM problem, and it'd be worth using a small loop to find the direction of origin. $\endgroup$
    – webmarc
    Commented Dec 22, 2023 at 20:02
  • 2
    $\begingroup$ FWIW this is not too bad — the signal meter is reading S0, which means that if there was actually anything to hear on 10m it would probably overpower the noise quite easily. $\endgroup$
    – hobbs - KC2G
    Commented Dec 23, 2023 at 6:53
  • 2
    $\begingroup$ Might be worth trying to duplicate this reception with another radio or an SDR to make sure it isn't an image from another frequency. Also might be useful to connect a smaller antenna to see how local the noise is, and maybe eventually do direction finding... $\endgroup$
    – user10489
    Commented Dec 24, 2023 at 14:27

0

Reset to default

You must log in to answer this question.

Browse other questions tagged .