Newbie question on nearby AM transmitter interference.

[dldfw]

Hi! I recently found my oldish Grundig G5 receiver, and thought it would be fun to start listening to shortwave again. I used to live in the country and I had decent reception, but since moved.

The antenna was very loose and I had terrible reception. The rubberized coating had also become sticky, so I decided to open the radio and clean the casing. I retightened the antenna and put it back together, and tried to scan the shortwave band. I was able to tune a couple of stations, but there was a constant, much louder signal from a local talk radio station. So I thought I had broken my receiver, and started doing some research on newer receivers (I'm undecided between the Tecsun 660, the 880 or the Sony 7600GR).

However this morning as I was leaving the house, I noticed for the first time four massive antennas about 900 feet from my house (funny how you never notice those things). A search on Google Earth gave me the coordinates, and through the FCC site I saw that they are registered to Susquehanna radio, so I am pretty sure these antennas are broadcasting the talk radio station.

So my question is, would another receiver be able to filter out that signal and let other (shortwave) signals through, or am I doomed to be overpowered by crappy talk radio as long as I live here?

 

[a29zuk]

Gee, I live about 3/4 of a mile from a local AM station. along with two others about five miles away that beam their signal in my path. I bought a Palstar R30CC to combat the overloading issues. It does a pretty good job. But I don't know about 900'. You may need a better receiver along with a passive preselector at your location or build a special filter for the frequency the AM station is on. But I don't even know if that will work.

Good luck,
Jim

 

[cmdrwill]

The AM station would want to be a good neighbor. They may be able to help provide a filter. ....

It would not hurt to contact their chief engineer.

 

[jim202]

Trying to get rid of strong signals is almost trying to get water to run uphill. It gets into everything.

I had a battle with an FM station on a tower about 500 feet away for one customer. We ended up putting ferrite cores on everything that went into and out of the radio. We put a notch filter on the antenna cable just before it went into the radio. We grounded the coax to a low resistance ground and tied the radio chassis to the same ground.

The audio stages of the receiver were picking up the station and we had to put bypass caps into the audio output section of the receiver. It was a bear to get the RX and TX audio cleaned up enough to have the base radio useable.

Don't expect an easy road living right next door to the towers. You will need to obtain the exact operating frequency of their signal if you plan to try an in line antenna notch filter.

If that is an old radio in a wood case, you might even have to try and make a metallic shield out of something like copper screen that you can make fit on the inside of the radio and solder all the seams together to keep the shielding tight. How you do the front of the radio is going to be a chore with the knobs and display.

Good luck on the task at hand trying to clean up the radio to make it usable.

 

[ka3jjz]

This is a very difficult issue to solve. As the G5 is a portable in a basically plastic case, no matter how much filtering you put onto the power supply and antenna, you're going to get a brute force overload just from the signal bleeding through the case and literally swamping the radio.

Using a small active loop might not attenuate the signal enough, and even here, the overload of the signal getting into the radio through the case itself remains unresolved.

The only (expensive) suggestion I would make would be to use a good quality communications receiver (like the R75, Palstar or Alinco R8T) and use a bandstop filter for MW. Ground the radio properly. That MIGHT give you a chance - but remember to keep EVERY lead into and out of that radio as short as you can and you will likely need to choke off everything (I had this exact problem many years ago - and this is what I ended up having to do with a Drake R7A....)

Mike

 

[k9rzz]

First post? Hey, welcome to Radio Reference!

Thought you could use some GOOD news. =:^]

 

[Boombox]

I have a Grundig G2, which is also a very sensitive portable off the whip.

I do not live within the immediate vicinity of any AM radio stations, but I do get local AM interference now and then on the SW bands on my G2.

I've found that shortening the whip antenna eliminates the local AM interference, and the SW stations still come through. I've been able to listen to a full band of stations on the 49 meter band with the whip antenna only at 5-6 inches, some stations coming in with even less whip antenna up.

So you might try shortening your whip before taking any more drastic measures.

 

[ka3jjz]

This is unlikely to be any real answer, unfortunately. The OP is so close to those antennas that it won't matter much - the RF from the antennas will go right through the plastic case like it wasn't even there.

Mike