InterceptRadio.com Forums

I’m trying to monitor a group using Motorola SP50+ handheld radios using a Pro 92 scanner, but can’t seem to do it. I borrowed one of the radios and could monitor the group with it from my room. I used the scanner in search (PL) mode and found multiple frequencies (470-490 Mhz) and the PL code 74.4 when I activated the channel on the radio I had. The scanner couldn’t catch the other radios.

I entered several of the frequencies and PL code I found into a scan bank and unlocked all channels. I still couldn’t catch a conversation.

Why can the radio hear the others, but the scanner can only hear the one that I’m using in the same room? The other radios are only about 1000 – 2000 feet away.

Any suggestions on what the problem might be would be helpful. Thanks.

First, set your scanner to scan the freqs without entering PL's into your scanner. See if you are able to hear the other radios now.
If not, and you are able to hear them fine on the SP50+ radio in the same location, it would indicate that your scanners receiver is not as sensitive as the portables receiver. Your scanner may have a problem. At least check for a clean and tight connection at the antenna.

If you were searching (not using a freq counter), it's possible that at point-blank range, you locked onto an image frequency instead of the real one. You said "multiple frequencies" for one channel? And 470+ in the Seattle area? Try subtracting 21.4 and searching again in the 450's.

Flash

Thanks for the responses.

I thought that the radio might be more sensitive, but the other radios are close by and the one I had picked them up loud and clear.

I found the PL code by searching the frequency range and keying the radio. When the scanner stopped on a frequency, I noted it and the PL code. I entered them into a scan bank, but the scanner wouldn’t catch the channel when I keyed the radio. The scanner seems to search and scan properly other than this problem.

Since the first frequency didn’t work, I thought that It might not be the correct frequency, so I searched again and when it found the first frequency, I pressed search to find the next one. The scanner stopped on about 25 (I'm sure there were more) other frequencies and displayed the PL code. At each frequency, I could talk on the radio and hear it on the scanner. The scanner still couldn’t hear the other radios. I entered some of the frequencies into a scan bank and still had no luck with the radio I had or the other radios. I tried to find a pattern with the frequencies I found, but didn't find any.

It does seem to be an image frequency type issue. If it is, how can I find the correct frequency without trying every frequency I find in search mode?

What is the significance of subtracting 21.4 from the frequency?

The referees at an annual pool tournament in Las Vegas use the radios. I’m also a referee and want to monitor the action when I’m not on duty.

21.4 is twice a typical 2nd IF frequency; 0.91 is twice the typical 3rd IF...

I'm not familiar with the SP50+, but I'd go back and search again with wide limits (UHF and VHF) and from across the room to cut the signal strength. The real frequency will come blasting through, probably even with your scanner antenna removed.

Flash