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 Post subject: DIY radio transceiver?
PostPosted: 25 Oct 2017, 10:39 
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Joined: 25 Oct 2017, 10:37
Posts: 1
Im building a radio phone and need to know how far the antenna has to be to be able to send a signal up to 5k. I would also like to know if the DTMF tones would be able to go over RF?
The transmiter is a 1 Mhz crystal oscillator on the AM band.
plz help


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PostPosted: 25 Oct 2017, 15:46 
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Joined: 29 Apr 2017, 15:14
Posts: 41
congratulations...but I do not think we got your question.. explain.. what do you mean by, "how far the antenna has to be, to send a signal up to 5k" .. this seem to be the essential part of the question. let us get pass this one first


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PostPosted: 25 Oct 2017, 19:17 
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Joined: 12 Mar 2013, 06:07
Posts: 86
Location: Thunder Bay On.
I don't know the answer to your question but what I do know is that there is a limit of output power governed by the fcc best do some research or you might get some serious attention.


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PostPosted: 30 Oct 2017, 12:50 
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Joined: 30 Aug 2017, 09:49
Posts: 26
I know the answer. Yes DTMF are transmitted all the time. That being said you can be put in jail and revive a $250,000 fine for transmitting with out a license. Just look up BCC part 15 rules. Chances are a local Ham will pick up the broadcast and report it to the FCC.

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Alpha Wolf


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PostPosted: 30 Oct 2017, 13:16 
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Joined: 08 Aug 2009, 03:11
Posts: 2100
Location: Chilliwack, BC
5Km on 1MHz needs a pretty insane antenna. I had a "hobby" AM station and with a 30' tower tuned and loaded, it took over 10 watts to achieve 5K.

If you need a remote control (and all legal like), check into the many hacks for a FRS radio. Out of the box they'll do 5K easy on the GMRS channels.

If you need privacy, also checkout the OP-25 project on Sourceforge.

Everything mentioned here is *not* for beginners, though.

Cheers!

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-= Gregg =-
* Ratings are for transistors - tubes have guidelines*
Home: GeeK ZonE
Work: Classic Valve Design


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PostPosted: 31 Oct 2017, 17:32 
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Joined: 30 Aug 2017, 09:49
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Well you do not need a big tower. I have transmitted 350 miles on 160 meters using my TNT transmitter at only 2.5 watts using a 80 meter dipole using a antenna tuner. I do have a FCC License.. I did mean FCC in my other post it was the crazy spell check.

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Alpha Wolf


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PostPosted: 31 Oct 2017, 22:44 
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Joined: 08 Aug 2009, 03:11
Posts: 2100
Location: Chilliwack, BC
Alpha Wolf wrote:
....using a 80 meter dipole....


Which isn't small.

Given 1MHz is 300M..... :eek:

Cheers!

_________________
-= Gregg =-
* Ratings are for transistors - tubes have guidelines*
Home: GeeK ZonE
Work: Classic Valve Design


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