| Author |
Message |
    
Dogfacedsoldier
Member
Username: Dogfacedsoldier
Post Number: 87
Registered: 10-2004
| | Posted on Friday, January 20, 2006 - 8:30 pm: | 
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my freind hads a pair of trc235 handhelds and they are 3ch 2w radios they are preset for ch14 but have slots for 2 more channels and he wants one chal to be 13 so that crystals combanation do i need to do it?(i.e 10.xxx and a 10.xxx or 37.xxx) |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1070
Registered: 9-2004
| | Posted on Sunday, January 22, 2006 - 1:42 am: |
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the receive crystal and the transmit crystal will be 455khz (.455mhz) off.
the Transmit crystal will be the actual freq. that you are on, and the receive crystal will be .455mhz
lower.
example:
ch.14 (27.125) TX
ch.14 (26.660) RX
so, ch.13 (27.115)TX
ch.13 (26.650)RX
i think!
matt |
Hotwire
Advanced Member
Username: Hotwire
Post Number: 828
Registered: 1-2005
| | Posted on Monday, January 23, 2006 - 12:46 pm: |
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I always wondered that about walkies. Why is the recieve freq different than the transmit? Its not like that on a regular radio or at least thats what the counter says. Anyone know? |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1082
Registered: 9-2004
| | Posted on Monday, January 23, 2006 - 4:26 pm: |
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because most walkies use a 455khz IF (intermediate freq.)
which means that .455 gets added to the receive crystal freq.
its been a while since ove thought about this, but i seem to remembeer that you could switch the TX and RX crystals around and be on a channel outside the CB band.
you have to do it to both walkies though!
i've still got ALOT to learn when it comes to the mixer circuits.
matt |
Dogfacedsoldier
Member
Username: Dogfacedsoldier
Post Number: 88
Registered: 10-2004
| | Posted on Monday, January 23, 2006 - 9:30 pm: |
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so id need a 27.185 and a 26.730? |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1083
Registered: 9-2004
| | Posted on Tuesday, January 24, 2006 - 12:34 am: |
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if you look at the crystals that are in there now for ch. 14 and they are 27.125 and 26.660 then yes.
matt |
Dogfacedsoldier
Member
Username: Dogfacedsoldier
Post Number: 89
Registered: 10-2004
| | Posted on Tuesday, January 24, 2006 - 11:24 pm: |
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k i dont have any of them all i got its some 10's and 37's from a cb with plug ins anybody know where i can get the crystals for ch19 (27.185 and a 26.730?) |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1090
Registered: 9-2004
| | Posted on Wednesday, January 25, 2006 - 4:54 pm: |
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you are going to have a hard time finding crystals to buy anymore. rad shak used to be the place, but they've sent back all their old stock of this kind of stuff.
you'll have to have the crystals made for you, and they'll be upwards of $10 a piece, if you can find a place to make individual ones.
try doing a google search for crystal manufacturers.
you may find a surplus parts dealer online, but thats about it,
good luck in your searches,
matt |
