Author Topic: AM FM CB v Receiver question  (Read 3773 times)

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Offline gbee

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AM FM CB v Receiver question
« on: April 28, 2011, 10:26:20 AM »
I'm getting very religious listening to so much mass broadcasts but they are the only thing constant enough for my own experiments.

I can pick up a local church on Ch36E FM
I pick it up on a DX-364 on 28.120 on AM [this device does not have FM]
And I need to use FM at 28.150 on an AR8600

In each case if I change the modulation from AM to FM or USB I get the voice distortion, but how am I getting a good quality audio from a device that pertains not to have FM?
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Offline freecb

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Re: AM FM CB v Receiver question
« Reply #1 on: April 28, 2011, 10:35:01 AM »
the lord is busy in many ways  :shock:
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go on Bertie bud

Offline a4martman

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Re: AM FM CB v Receiver question
« Reply #2 on: April 28, 2011, 11:08:55 AM »
Amen brothers! The Lord works in strange ways!!! :D
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Offline microwave

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Re: AM FM CB v Receiver question
« Reply #3 on: April 28, 2011, 12:02:48 PM »
If the radio is slightly offset in centre frequency then the demodulator is acting as a slope detector and happily demodulating what it now sees as an AM signal. This is because when offset from the constant carrier at the centre frequency the detector is responding the the amplitude variation on the slope of the signal due to the FM modulation. Since a detector is used to demodulate an AM signal it will happily work on anything is "sees" varying in amplitude.

So basically the detector in the AM radio is acing as a slope detector on an FM signal which is tuned off centre.
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Offline gbee

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Re: AM FM CB v Receiver question
« Reply #4 on: April 28, 2011, 12:15:44 PM »
Thanks for the replies. :)

My receiver is DX-394 [not 364] but question answered thanks.
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Offline fm_radio

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Re: AM FM CB v Receiver question
« Reply #5 on: April 28, 2011, 18:33:21 PM »
Quote from: "gbee"
I'm getting very religious listening to so much mass broadcasts but they are the only thing constant enough for my own experiments.

I can pick up a local church on Ch36E FM
I pick it up on a DX-364 on 28.120 on AM [this device does not have FM]
And I need to use FM at 28.150 on an AR8600
Gbee.....what frequencies are you getting those church broadcasts on and how many? Locations?
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Offline freecb

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Re: AM FM CB v Receiver question
« Reply #6 on: May 07, 2011, 23:00:13 PM »
i hear them on 27 815 fm mayfield or blarney chruch
i hear whitechruch as well 27 635 i think i will check on sunday
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go on Bertie bud

Offline gbee

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Re: AM FM CB v Receiver question
« Reply #7 on: May 08, 2011, 10:22:09 AM »
Quote from: "fm_radio"
Gbee.....what frequencies are you getting those church broadcasts on and how many? Locations?

27.665  21E
27.815  36E
27.215 21D  St Joseph's

I'm not moving around but I've heard, Mahon, St Joseph's, Glounthaune, from Mahon, but I think  they reuse the same frequencies, as the priests often sound different and they usually only mention the church in passing while mentioning something else.
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Offline fm_radio

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Re: AM FM CB v Receiver question
« Reply #8 on: May 08, 2011, 13:42:38 PM »
Never knew that they were using these in the city.....Mahon and Mayfield

27.665 is Glounthaune
27.815...there are 3 here. One is Carrigtwohill, no idea what the other 2 are

This is a list of frequencies that I have heard but could not ID. Perhaps if anyone lives nears these, they might be able to say what they are..

27.065 MHz (FM)..........2 on this frequency
27.161 MHz (FM)..........??
27.205 MHz (FM)..........??
27.285 MHz (FM)..........??
27.315 MHz (FM).........Blarney, Cork? or near it?
27.335 MHz (FM).........? (Week day 9:30am mass)
27.355 MHz (FM)..........??
27.365 MHz (FM)..........??
27.395 MHz (FM)..........??
27.505 MHz (FM)..........2 on this frequency
27.605 MHz (FM)..........??
27.615 MHz (FM)..........??
27.618 MHz (FM)..........??
27.681 MHz (FM)..........??
27.731 MHz (FM)..........??
27.735 MHz (FM)..........??
27.775 MHz (FM)..........??
27.791 MHz (FM)..........? (Sat 10am, 6:30pm mass)
27.815 MHz (FM)..........2 on this frequency. Carrigtwohill near Cork City & ??
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Offline 5566

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Re: AM FM CB v Receiver question
« Reply #9 on: May 08, 2011, 21:47:04 PM »
Depending on where are you located then 27.285 might be Gort town church (have no idea what's that parish name is). Nicely located on the hill with pretty high point for antenna and at least 100 watts.
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Offline gbee

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Mayfield Our Lady Crowned
« Reply #10 on: June 22, 2011, 10:26:51 AM »
Heard broadcasting on:

27.98080   FM 48E

27.98125   FM 39F* UKFM blowing 30++ [Note on my radio I have UKFM in Band F] With spill over to adjacent channels.
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Offline 5566

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Re: AM FM CB v Receiver question
« Reply #11 on: June 22, 2011, 11:49:45 AM »
CTE747 or BP300
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