Attenuation, modulation, frustration...

[MarkEagleUSA]

I'm having trouble receiving my local PD (453.300). The transmitter is less than 1/4 mile behind my house. About a month ago, there were problems where the mobiles couldn't hit the repeater or hear transmissions from HQ. For about a week, the radio service worked on the system, many times late at night.

For the past couple of weeks (since, I assume, the repairs were done), I only get very faint, sometimes muffled reception from both HQ and the mobiles (and I'm not hearing any more complaints from the field). This occurs on every scanner I own including my ancient Regency HX1500, BC92XLT, BC246T, and my brand new BCD396T. Even if I travel away from the tower, the problem remains.

On both the 246 and 396 I've played with all the attenuation and modulation settings thinking I could somehow improve the reception. So far no luck. On the 396, I've even played with the AGC to see if that helps... no dice.

The FD uses 151.190 off the same transmission site and that works fine, as do all the surrounding communities I listen to. Being somewhat of a novice when it comes to this stuff (no technical knowledge of radio comms), I really have no clue what (or IF there is anything) I can do to help the reception.

Anyone have any ideas (assuming anyone even understands what I'm saying :? )?

 

[hiegtx]

Attenuation, modulation, frustration..

Mark, since the problem extends over several models of scanners, from the older Regency HX1500 (I have one of those dinosaurs as well) to the newest 396, I would presume that the radios themselves are not the main problem.

You indicate that you get very faint, muffled, reception. If the scanner is stopping on the channel, but the audio sounds very faint, that could be symptomatic of an overload. If the repeater's transmitting antenna is less than 1/4 mile from your house, it's at least a possibility. If I'm reading you correctly, your problems may have started after the radio service worked on the system in response to complaints of poor reception from the field. It's at least possible that they installed a gain type antenna that is now overloading your scanners, or changed to a higher wattage transmitter. Maybe both. Either way, an overload would produce some of the symptoms you list. Field units, being farther away in most cases, would not be as affected.

My suggestion would be to try one or more of the radios with no antenna at all. See if you can receive the frequency in question. If you have one of the stubby antennas used on some of the Nascar scanners or frequency counters, use that. Or substitute a short length of wire or a paper clip for the rubber duck. Reducing the amount of antenna would reduce the signal strength captured. See if any of that helps.

Also, are there any other transmitter antennas near you? If so, intermod could be a contributing factor.

Good luck. That's where I'd start trying to isolate a similar problem.

Steve

 

[N4DES]

It could be local interference from another device in your home that has a spur on that UHF freq. I would also try turning off all electronic devices (PC's, VCR's, other scanners) to see if this removes the problem.

 

[MarkEagleUSA]

Re: Attenuation, modulation, frustration..

Either way, an overload would produce some of the symptoms you list.

Initially, this is what I thought as well. However, the symptoms remain even if i drive 5 - 10 miles from home.

My suggestion would be to try one or more of the radios with no antenna at all.
...
See if any of that helps.

I can get reception (at home) witout an antenna, but it's still very faint. If I happen to go by RadioShack today, I'll see about getting a stubby antenna to test with.

Also, are there any other transmitter antennas near you?

There's at least 2 cell towers close by (I think they are on the same property as the PD/FD antenna). If it were intermod, why doesn't the reception improve as I travel away from home?

 

[N_Jay]

Did they go narrowband?

 

[MarkEagleUSA]

narrowband?

I've tried the FM, NFM, and WFM settings on the 396 with no apparent difference.

 

[N_Jay]

narrowband?

I've tried the FM, NFM, and WFM settings on the 396 with no apparent difference.

Is it only that one frequency?

 

[MarkEagleUSA]

This is the only frequency I have the problem with. Everything else I have programmed works fine and reception is at least twice the volume of this one. This happens on each of the 4 scanners I use, and I've tried at least 2 different antennas on each of them. It also happens whether I'm sittingat home, driving around town, and even at work where I'm about 8 miles away as the crow flies.

Like I said, this started back when the mobile units were complaining of not being heard and not hearing HQ, and after several days of hearing the radio service doing radio checks at various times during the day (and night). I assume they were fixing the problem.

 

[Voyager]

I assume they were fixing the problem.

Or trying to and not having much success. I wouldn't worry about it if other units are reporting problems too. It sounds like receiver sensitivity, TX power, frequency, or antenna issues.

Joe M.

 

[N_Jay]

narrowband?

I've tried the FM, NFM, and WFM settings on the 396 with no apparent difference.

You should hear a difference between the settings with a good or bad signal.

I'm betting on a change to narroeband.

 

[MarkEagleUSA]

I wouldn't worry about it if other units are reporting problems too.

Well... they're not complaining anymore (at least not in the past 2 weeks or so). It's not like I can call them and say "hey, I can't receive your transmissions anymore"!