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General Scanning Discussion - For general questions not specific to a model of scanner or general discussion of use of a scanner. Manufacturer specific posts should be directed to the appropriate forums below and location specific posts should go in the appropriate regional forum..

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Old 03-20-2017, 11:07 AM
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Default Car radios superior AM/MW reception

I am a rookie so bare with me. I am wondering why the most basic automotive receivers can pick up AM so much better than a Tecsun PL680 or Grundig Satellit 750 or Eton Field & if there are any parts I could take out of an car radio to transfer to one of these radios to help them? For example, My work van is a 07 Ford E250 & has a base model am/fm radio & it can pick up AM from 100+ miles away no problem where my Radios listed above struggle to get many of them or wont even register a few of them. Even in the city where there is a lot of noise they still come thru in the work van, I took my PL680 with me a few times to compare & went out of the city where there was less interference, the PL680 still struggled & the van signal was loud and clear, I tried the same with one of our other shop trucks, a 2003 Ford superduty & its AM reception was even better. Is there a larger or better quality ferrite rod antenna in these radios that my shortwave radios might benefit from? I have a Factory ford radio that I removed from my 04 F150 laying around that I could tear into if there is any benefit. The main reason I ask is because a lot of times I travel up north fishing etc where there is very little radio to listen to & can only receive am or sw. & I would like to have a stronger AM signal without setting up external antennas etc. I am especially disappointed with my Grundig Satellit 750s reception.
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Old 03-20-2017, 11:10 AM
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Quote:
Originally Posted by Kellxr7 View Post
I would like to have a stronger AM signal without setting up external antennas etc. I am especially disappointed with my Grundig Satellit 750s reception.
The lack of an external antenna is the problem, not parts in the radio. Focus your research on finding a radio that can connect an external antenna, and an antenna that receives the frequency band(s) you're interested in. Internal antennas always significantly compromise performance.
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Old 03-20-2017, 12:22 PM
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AM radios in vehicles are very well matched to the antenna, and that is the key to their good performance. Most of the time a vehicle is in the clear and away from RF noise making devices where an AM radio inside your house can be easily shielded by house wiring, wire mesh under stucco, foil backed insulation, etc.

Sometimes the design of the radio and its internal antenna is partially to blame. If its just AM broadcast from .54 to 1.7Mhz, then you might consider another radio that is known for great AM reception like some of these: https://radiojayallen.com/am-portabl...t-2016-update/

BTW, I have a GE Superadio III and it picks up far more and distant stations than any other self contained portable I've owned.
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Old 03-20-2017, 12:22 PM
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Quote:
Originally Posted by jonwienke View Post
The lack of an external antenna is the problem, not parts in the radio. Focus your research on finding a radio that can connect an external antenna, and an antenna that receives the frequency band(s) you're interested in. Internal antennas always significantly compromise performance.
I have a Satellite 750. I run simple speaker wire out the back of the house and out the fence line about 30 yards.

The difference between the built in antenna and the external one is even more stunning than the comparison being made between car radios and the 750.

Day and night.

If you want to listen to AM or SW radio and you don't want to use an external antenna, you are going to listen to very little of what is out there. The external antenna is the most significant part of the radio. I connect my antenna to the Tecsun pl660 and the 750. Both radios are relatively useless on AM or SW without it.

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Old 03-20-2017, 12:37 PM
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Since cars can travel into fringe areas outside of major cities, dedicated car receivers generally have a RF amplifier stage before the intermediate frequency IF stage. The RF stage amplifies the incoming signal before it's converted in the IF stage. In other words, the RF stage 'boosts' the incoming signal.

Radios like the Tecsun 680 don't have this extra stage. The signal from the antenna goes right into the IF stage. (This is called direct conversion). Direct conversion radios generally don't have the sensitivity of ones with one or more RF stages before the IF.

You can add this functionality to a direct conversion receiver by adding a tunable outboard RF amp. These are known as preselectors. The amplification they provide increases the signal and the sharper tuning reduces interference from adjacent frequencies and it helps eliminate images.

I'm not endorsing MFJ, but here is a link to one preselector they offer: MFJ Enterprises Inc. If you look around you'll find them made by other companies.
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Old 03-20-2017, 1:08 PM
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Quote:
Originally Posted by jwt873 View Post
Since cars can travel into fringe areas outside of major cities, dedicated car receivers generally have a RF amplifier stage before the intermediate frequency IF stage. The RF stage amplifies the incoming signal before it's converted in the IF stage. In other words, the RF stage 'boosts' the incoming signal.

Radios like the Tecsun 680 don't have this extra stage. The signal from the antenna goes right into the IF stage. (This is called direct conversion). Direct conversion radios generally don't have the sensitivity of ones with one or more RF stages before the IF.

You can add this functionality to a direct conversion receiver by adding a tunable outboard RF amp. These are known as preselectors. The amplification they provide increases the signal and the sharper tuning reduces interference from adjacent frequencies and it helps eliminate images.

I'm not endorsing MFJ, but here is a link to one preselector they offer: MFJ Enterprises Inc. If you look around you'll find them made by other companies.
In addition to this, you can also purchase booster amplifiers to add to your car on top of the RF amp in the car ahead of the IF stage.

Adding these kinds of things to something like a Tecsun or Grundig portable will only help if you are sitting out in the middle of the desert somewhere, where they won't amplify all the surrounding RF noise and defeat the purpose of adding them.

Adding them to a portable that does not have an external antenna to provide additional signal to amplify, will only serve to amplify non-signal, or household noise produced by tons of electronics in the average home. It will actually make it more difficult to receive an actual AM signal coming from outside the house. It could marginally help if you use in conjunction with an external antenna, like in a car.

Mark
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Old 03-20-2017, 2:36 PM
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One option is to use a car stereo in your house. I did this for a short while one time.

Shawn
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Old 03-20-2017, 5:34 PM
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+1 on what everyone has said - car radios are designed to work very well in 'hostile' environments. Many years a go I had a car radio that had a tube tuner and a transistor audio amplifier - this thing could haul in stations from all over NZ and the eastern coast of Australia in the evenings on a normal extending antenna. Tuning the antenna is the best part - the antenna and it's cable are actually part of the tuned RF amplifier.

I have a GE Superadio ll - that goes like stink too!
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Old 03-20-2017, 5:45 PM
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Quote:
Originally Posted by Kellxr7 View Post
The main reason I ask is because a lot of times I travel up north fishing etc where there is very little radio to listen to & can only receive am or sw. & I would like to have a stronger AM signal without setting up external antennas etc.
You can drag your car radio (and antenna and 12V battery) along or use a high performance AM portable (like a used GE Superadio) or deploy a loop antenna: https://www.amazon.com/Kaito-Tunable.../dp/B001KC579Q
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