Contents of Tacos digest...FM receivers spot check

Tue Aug 30 13:15:17 CDT 2005

Ian,
If you could share this with the gang that would be great.

Had some excitment here today. Seems someone left a bomb on the access road to the base. I gather the EOD team took care of it, but it did cause a late start. I was not involved execpt to be turned around in traffic.

Guess that's someones way of saying "Yankee go home". 
Or on the bright side, if they diden't care, they woulden't be trying to kill us.

Later dude
Mike

....................................................................................

Alex,
One idea but it's a pain in the buns.

Most consumer FM sets use a 10.7mhz Injection, that's the self generated signal that mixes with the broadcast signal to produce the 10.7mhz IF.

Let's play with some numbers.

As an example, since in Kuwait right now and don't have access to a handy FM set in the DC metro area...

Let's assume that you bring a portable FM radio like a walkman or similar into the store, and they don't bust you for shoplifting.

You tune your portable to 100.7 (let's hope you find a station or two with the right numbers)
If your portable is a low side injection it's injection frequency will be 90.0. (90.0+10.7=100.7)
Walk up to your receiver of interest and see if you get a quieting signal out of it, then step back a few paces and see where it fades off.

Same deal if your portable is a high side injector. Tune your portable for 90.3 and check your subject receiver for 101.0 (assuming it tunes there)

Try and bring a portable radio that has analog tuning, sometimes the steps are set for channel spacing and the 'in betwen' signals will be lost. Perhaps your scanner or ham radio generates Local Osc. in the FM broadcast band.

Lots of problems with this method.

First, many stores have a master antenna system, usually on the roof (No so in auto sound, but that's another story). If this is the case, forget it, your screwed.

Also displays are put togther by sales people, and when has one known their butt from their elbow? Antennas may not even be hooked up.

Another trick is to get the FCC number of the ID plaque and do a web search, the data you seek might be on that.

If you want to mess with the store staff, quiet various radios in the place.

I used to have a small FM transmitter in my truck, a ripping 6mW but it was enough to cover a short distance. If you have one of those FM gizmos that people use on their MP3 players, that will give you a stereo pilot light, and when that goes off will be some kind of figure of merit.

Hope this helps, if not yell at me when I get back.

Mike aka KA2ZEV in Kuwait City.

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Today's Topics:

1. still worrying about that cell phone RF? (hal)
2. Fw: still worrying about that cell phone RF?
(riese-k3djc at juno.com)
3. Re: still worrying about that cell phone RF? (Frank Gentges)
4. FM broadcast radio (Alex Fraser)

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Message: 1
Date: Mon, 29 Aug 2005 18:12:12 -0400
From: hal 
Subject: still worrying about that cell phone RF?
To: tacos at amrad.org
Message-ID: <4313883C.40201 at cox.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

http://www.forcefieldwireless.com/products.html

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Message: 2
Date: Mon, 29 Aug 2005 19:11:14 -0400
From: riese-k3djc at juno.com
Subject: Fw: still worrying about that cell phone RF?
To: tacos at amrad.org
Message-ID: <20050829.191748.3252.0.riese-k3djc at juno.com>
Content-Type: text/plain; charset=us-ascii

Didnt say if it was washable

HAR

Bob K3DJC

http://www.forcefieldwireless.com/products.html

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------------------------------

Message: 3
Date: Mon, 29 Aug 2005 21:41:22 -0400
From: Frank Gentges 
Subject: Re: still worrying about that cell phone RF?
To: hal 
Cc: tacos at amrad.org
Message-ID: <4313B942.4090806 at mindspring.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

I wonder if it will stop BPL emissions so we can listen to shortwave radio?

Frank

hal wrote:

> http://www.forcefieldwireless.com/products.html
>
> _______________________________________________
> Tacos mailing list
> Tacos at amrad.org
> http://www.amrad.org/mailman/listinfo/tacos
>

------------------------------

Message: 4
Date: Mon, 29 Aug 2005 22:00:11 -0400
From: Alex Fraser 
Subject: FM broadcast radio
To: tacos at amrad.org
Message-ID: <4313BDAB.6040905 at comcast.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Is there a simple easy inexpensive way to test FM broadcast radios? I 
want a good receiver and just don't see those specs listed. Could I 
test in the store?

-- 
>>>>>>>>>>>>>>>>----<<<<<<<<<<<<<<<<<
............ Alex Fraser ............
......... beatnic at comcast.net .......
[~]_>^^^^<

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End of Tacos Digest, Vol 30, Issue 19
*************************************

"You are, what you do, when it counts"
The Masso
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