Cell Phone Jammer or Receiver Problem?

[higinbotham]

I am trying to duplicate a problem with my radio - an ICOM R-8500 tonight with out luck. I purchased it in 1999. Are there jammers that will block an extremely wide area of bands? Below is a copy of my email to ICOM about my issue. The key work at the end of my paragraph is "intermittent" which may be my radio problem. Has anyone had experience with jammers before and know what features they exhibit that we can recognize it as jamming. I wonder if law enforcement has this capability to blanket an area where they are monitoring activity??
Thank You
William B. Higinbotham, NY, USA

The issue is that when I turn it on, the unit SWR signal is low initially. I can receive signals fine. Then I notice that the signal cuts off and all I can hear is a subtle white noise. The SWR signal strength jumps up to 3 and greater (4) as I go up in frequency. This subtle white noise prevents me from signals less than the present signals that I am trying to receive. This problem use to take a while at first and I thought maybe it was interference. But it now takes about a minute to happen. This happens while in scanning mode for sure. If I listen to a single frequency such as AM 1370Khz. I hear a static like click noise and the noise level goes back to low and later kicks back up intermittently.

 

[mikepdx]

1. What does 'SWR Signal' and 'SWR Signal strength' mean?

2. Try this:
Power the radio with a 12VDC battery and turn off the MAIN breaker in your house.
Turn off all other battery powered devices in your home - cell phones, wireless weather station, etc.

That just eliminated almost every single noise source in your home.

Is the problem still there?

 

[mancow]

Radio issue. Something has gone wrong. Bad capacitors perhaps.

 

[prcguy]

A cell phone jammer would not affect AM broadcast band.
pecguy

 

[PACNWDude]

Definitly the Icom radio.

This has been a problem with some other Icom radios in the past.

At a former job, many IC-M602 radios, (VHF Marine) would have intermittent receive problems in a high RF environment. Initially co-workers thought another radio was "jamming" the Icom. Instead the receive circuitry was picking up the other signals and being damaged.

Other models had some issues with RF shielding and screws missing from the main circuit boards. If the radio is out of warranty, you could check to see if the circuit board has all of its screws holding it to the metal case.

Your best bet is to have Icom look at it though, they built it, so should be the best to repair it.

(Barrage jamming, or blocking wide portions of radio bandwidth, can be done with the hardware some government agencies and others have though.) It just doesn't sound like this is happening.

 

[higinbotham]

I greatly appreciate all the feedback. The only thing I did was change the speaker a while ago. I never opened any other parts than the cover. ICOM seals their units better than duck tape! I did a CPU reset initially, but was still having the effect at the time. Like one of the members stated, I was going to go to a different location to see what happens. It appears to not be happening now. I am going to take the unit to a local Amateur Radio Club and ask the members there. I love this radio. I would like to buy the high stability crystal for it. But after reading what is involved to install it, I decided to wait till I can afford someone to install it. Happy Listening during this holiday season to all.
Billy

PS: MIKEPDX was correct in that I incorrectly stated SWR when I should have said signal meter strength. Ooops

 

[RFI-EMI-GUY]

This reminds me of back when I bought a used ICR-71a. The seller said he did not know how to work it and thus could not guarantee it worked. We worked out a price on the phone that was favorable and the seller brought it by my house to close the deal. I hooked it to my G5RV and turned it on. After properly adjusting the squelch and RF gain controls it was blasting some great DX from the speaker. The seller was pretty impressed!

 

[RFI-EMI-GUY]

Try testing it on several bands. Does it work on the FM Broadcast band? Try each band and note any discrepancies.

I hate to say this, but check the manual to make sure some filter switch or scan mode hasn't been pressed by someone handling it or knocking about. I have a shack full of gear that is used occasionally and sometimes the cat turns a knob.

 

[RFI-EMI-GUY]

Did you use an exact replacement speaker??? If the coil resistance/impedance is off, there could be a problem.

Save your money on buying the Hi Stab crystal unless you are tuning amateur satellites in the 23 cm band!

I greatly appreciate all the feedback. The only thing I did was change the speaker a while ago. I never opened any other parts than the cover. ICOM seals their units better than duck tape! I did a CPU reset initially, but was still having the effect at the time. Like one of the members stated, I was going to go to a different location to see what happens. It appears to not be happening now. I am going to take the unit to a local Amateur Radio Club and ask the members there. I love this radio. I would like to buy the high stability crystal for it. But after reading what is involved to install it, I decided to wait till I can afford someone to install it. Happy Listening during this holiday season to all.
Billy

PS: MIKEPDX was correct in that I incorrectly stated SWR when I should have said signal meter strength. Ooops