What is "Front End" on your scanner?

[conrad314]

Is front end static on a powerful signal?

I just put up an Austin Ferret and now i have static on a few channels that my old radio shack Model: 20-176 antenna received fine.

Any thoughts?

 

[kb2vxa]

The front end of any receiver consists of the antenna input, the RF and mixer stages. What are you calling "front end static"? What are you calling "static"? FYI there is no such thing as static on an FM signal so you'll just have to come up with a better description of what you're hearing.

I suspect it's white noise usually present on weak signals, your Austin (IMO a real POS antenna) is just a bit deaf on the frequencies in question, could be just plain deaf. Strong signals tend to overcome antenna shortcomings, weaker ones always show up their deficiencies so I strongly suspect you downgraded your antenna system.

 

[conrad314]

I guess white noise is a better description. I'm getting this white noise on a very strong signal with the Ferret. If i unplug the ferret and use any other antenna the signal comes in clear. Is that an overloaded front end? I thought i was upgrading my antenna going with the ferret.

 

[hoser147]

That is probably the case, the Ferret is bringing too much RF in desensing (or overloading) the front end of the scanner.

 

[conrad314]

My next question: Is that bad for my Scanner (396) and how can i fix the overload?

 

[kinfolk]

conrad314,

I had the same problem when I upgraded my antenna system. I determined that my overload was being caused by a nearby FM broadcast transmitterabout 5 or 6 miles away. I ordered a notch filter and that cured my problem. I now have the strong incoming signals with no noise. This could be your case also. The Austin Ferret is a could wideband antenna and can cause the front end overload that it sounds like you are experiencing.

 

[iMONITOR]

Dynamic Range
http://www.radio-electronics.com/info/receivers/dynamic_range/dynamic_range.php

 

[prcguy]

I thought the scanner front end was the area around the grill, headlights and bumper.

 

[kb2vxa]

OK let's get one thing straight, overload is unnoticeable when you're tuned to the signal that's doing it. That's the very nature of FM, if a signal you're NOT tuned to overloads the receiver it's a horse of a different color. Desensitization (desense) is only noticeable when the receiver becomes insensitive to another signal, sensitivity can fall to next to nothing when tuned to something strong enough and you'll still hear it loud and clear.

Case in point, if a mobile in front of my house is in simplex conversation with me I hear it perfectly BUT if I'm listening to something else at the time what I'm listening to almost disappears when the mobile transmits. That happens a lot with repeaters, when the mobile pulls up I lose the repeater but if I switch to reverse mode (receive on the input, transmit on the output) we hear each other perfectly.

"I'm getting this white noise on a very strong signal with the Ferret."
Most unusual.

"If I unplug the ferret and use any other antenna the signal comes in clear."
Still unusual considering the above.

"Is that an overloaded front end?"
Doesn't sound like it but I cannot deny the possibility. Try turning on the attenuator on that channel and see what happens if anything and report back. I've heard plenty of bad reports on the Ferret but this one is a bit of a mystery.

 

[conrad314]

Ok i played with the Att...and nothing happened. I put my old antenna back up and tested both antennas with my Uniden 396 and a friends Radio Shack Pro 135. Both scanners pick up alot of white noise with the ferret. Both scanners were clear as day with the Radio Shack model 20-176 antenna. Switched the cables think one was bad, same result. I give up with the ferret...

One mostly new ferret for sale...any takers?

 

[kinfolk]

Do you live in or near an urban area?

 

[conrad314]

Just east of Kansas City MO. So yes

 

[kinfolk]

As I posted before, it may be an overload situation from a nearby FM broadcast transmitter. An fm notch filter did the trick for me. The Austin Ferret is especially sensitive on VHF Hi band and that band is most affected by FM broadcast overload. Go to Scannermaster and check out the HPN-30118. I purchased this filter just weeks ago and it cured all my problems which sound very familiar to yours.

 

[kb2vxa]

OK, one last question. When you switch antennas are they on the same mount in the same spot or different? The only way to properly compare antennas is by taking careful measurements and observations and they MUST be in EXACTLY the same spot or you'll get different results even with the same antenna. It's kinda funny that way, you'll immediately notice "shifting signals" in a mobile even when you move only a few feet or inches, even on the base antenna blowing in the wind.

"The Austin Ferret is especially sensitive on VHF Hi band and that band is most affected by FM broadcast overload."

That's a characteristic of the antenna alone, not common to all antennas "sensitive" on hi band. Case in point, a high gain band specific antenna is LEAST likely to be affected by out of band signals. I'm becoming more and more convinced the antenna is much like the animal, fun to play with but mischievous so never turn your back on it and has yet another notable ferret characteristic, stinks like hell when wet.

 

[conrad314]

I'm hesitant to spend another $50 bucks. If it doesn't work...well i just don't know.

 

[kinfolk]

I understand your reluctance. I felt the same way before I ordered mine. Can you list several of the frequencies that are being most affected and how many bars of signal you are getting on those freqs?

 

[conrad314]

One freg. is 155.79000 and i receive that signal with full bars.
Second is 42.24000 with full bars. That is why i'm hesitant, low vhf is unclear too with full bars.

And yes kb2vxa, i had the antennas right next to one another.

 

[kinfolk]

Do you know how far away the nearest FM broadcast tower is?

 

[conrad314]

No i do not. How would i know the tower is FM?

 

[kinfolk]

One way would be to call your local FM station(s) and ask them where their transmitter is. Being that you live near a large metrpolitan area the chances are you have at least one nearby. Do you have a scanning buddies nearby that may have a notch filter that you could borrow? Am I correct that you are getting the 5 bar signals on the Austin Ferret but they have noise in the background?