Portable Radio Overloading

[pjxii]

Not sure if this belongs in the antenna forum but since it mainly pertains to portables that new SWLs start using it'd probably be best in equipment discussion.

Here is a good video showing why too much antenna on a portable is bad idea.

. https://m.youtube.com/watch?v=rM6zTd-Dn0M

 

[ka3jjz]

Unfortunately the video doesn't really tell you how to solve the issue. Yes, using an external attenuator will help, but the ideal way is to use a passive preselector. These devices act like a tunable 'gate' which will severely attenuate any out of band signals. Both MFJ and Cross Country have such devices, and while it's possible to build your own, it's a bit tricky - proper bonding is critical.

You can find the links to both devices at the bottom of;

Improving HF Reception - The RadioReference Wiki

This issue can hit SDRs, too, like the RTL-SDR with the various updates for HF reception, the Funcube and others. Very old desktops that are single-conversion would also see improvement

Mike

 

[Boombox]

Just use a shorter antenna, that also helps with portables like this one.

The guy doesn't tell us how long the antenna is that he is using, which would have helped, I think. Nor does he say how close he is to nearby MW and FM broadcasters (FM can bleed over here and there in the SW spectrum).

That radio looks like a Sangean ATS-808. They are pretty good radios for portables. Using a radio like that one is best off using a shorter external antenna. I have an ATS-505 clone that works well off of 30 ft. of wire.

Thanks for posting the video, though. A lot of newbies need vids like this to tell what the 'weird noise' is that they hear on their radio, and overload is one of them.

 

[pjxii]

Thanks for posting the video, though. A lot of newbies need vids like this to tell what the 'weird noise' is that they hear on their radio, and overload is one of them.

That's exactly why I posted it. It's easy for a beginner to assume that 75' of wire on a portable is a good thing. It's not a perfect video as far as explaning what to do about overloading but it demonstrates the basic point, I think.

 

[ka3jjz]

Most any of the smaller portables may overload given the right conditions and length of the antenna. You might get away with a 70-80 foot wire if you're out in the boonies without a lot of MW or FM stations, but move to an urban area with lots of these stations and you're almost sure to run into overloading issues.

Portatops (like the Eton E1) and the better desktops would likely handle the amount of energy such an antenna can present, but these little radios simply get swamped and can't handle it. I just wish the individual - who is a ham - did a bit more on this, but it is what it is.

Mike