Does this sound like overloading?

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ikarus280

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So, last week I ventured out and bought a mag roof mount antenna from the good ol' Shack.

This is it: Magnet-mount mobile scanner antenna - RadioShack.com , and it supposedly covers 25-1300 ranges, in other words, all of it.

My local PD is still on conventional 460 frequency, and it works amazing for it. However, the state P25 trunked system, (with 154-156 range of freqs) which is a phase I APCO-25 is not so great - everything got A LOT quieter (as in, less traffic, not volume-wise) since I installed the antenna. I still have a portable 800 antenna, and I've used it to see if it is in fact the issue, but I haven't heard enough traffic to determine the case.

Local MOT 800/900 Type II and Type IIi work just fine - even with better reception sometimes. Even the citywide P25 simulcast system seems to work better than the statewide system (relatively, of course, simulcast decode sucks).

Also, the full antenna, per the photo in the link, has two coils on it, and three sections. I removed the middle section, and it's shorter, and missing one coil. How much effect would that have on my reception?

Scanner is RS-106, and I'm in southcentral AK. Does this sound like an overloading issue?
 
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wmbio

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"P25 trunked system, (with 154-156 range of freqs"...If your going to get overload or desense, this is the first band that seems to be affected...Try turning on your ATT for these channels, that may sound strange but if the reception gets better with it ON it is the problem...You may also want to scan the weather band, pick a channel and turn on the ATT...again if it gets better it's overload. Removing coils my not help.

I use a $3.00 FM filter from MCM to reduce my intermod, the same filter can be found at Radio Shack.
...works great....http://www.mcmelectronics.com/product/33-341

Enjoy
Wmbio
 

ikarus280

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Thanks. I turned on ATT, and got a somewhat better reception, although the improvement mostly showed while my vehicle was stationary. So it's safe to say the overloading is caused by the 88-108 frequencies? If I do get a FM trap, is this a plug and play device, or would I have to cut the antenna wire to tap it in there? Sorry, totally new concept to me.
 

wmbio

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NOT PLUG AND PLAY....Depending on the end on your antenna, which should be BNC. ..You will need, the filter, 2 of these adapters..to screw onto the filter connect the antenna, BNC Plug to "F" Jack Adapter - RadioShack.com

And a short BNC TO BNC jumper cable to connect the filter to the radio. No cable cutting this way.

Enjoy
Wmbio
 
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kb2vxa

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Most likely a matter of reception in general, just because it has a wide frequency range doesn't say it receives equally well throughout its range. A single band antenna is reasonably predictable but with this sort of thing the sensitivity curve looks like a roller-coaster, not all things being equal.
 

ikarus280

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Thanks for the input, guys. I may as well try the FM filter, doesn't sound like an expensive fix. As far as reception- I analyze the system and get five bars with 95% decode rate or better on all nearby control channels. My WX works clearly as well.
 
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