RNet 450 XTAL Calc
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RNet 450 XTAL Calc
Anyone have the service manual or the calculation to determine the crystal frequencies for this unit?
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- Posts: 1030
- Joined: Wed Mar 13, 2002 4:00 pm
- What radios do you own?: Motorola, Icom, Sunair (HF).
Re: RNet 450 XTAL Calc
The formula differs a bit depending on which split you have.hoser wrote:Anyone have the service manual or the calculation to determine the crystal frequencies for this unit?
If you have a UHF RNet unit covering from 403-433MHz, the crystal frequency formula is Fxtal = (Fcarrier - 45MHz)/7.
If it's a 450-470 unit (and I know from personal experience that they'll go down to at least 446 with no problem), the formula is:
Fxtal = (Fcarrier - 45MHz)/8.
I hope that helps. Happy tweaking.
Bruce Lane, KC7GR
"Raf tras spintern. Raf tras spoit."
Thanks very much! The unit is a 450 Model with Tx=Rx=464.5000MHz
The formula for the 450 model works since the top of one of the xtals reads '52437500' which is obviously 52.4375MHz. This one is closest to the BNC connector and has a part # of KXN6331.
But...........
The other xtal (furthest away from the RF output BNC) has '17203703' printed on its top? Its a Motorola part # KXN6330
Whats the deal with this other xtal? ANy ideas?
The formula for the 450 model works since the top of one of the xtals reads '52437500' which is obviously 52.4375MHz. This one is closest to the BNC connector and has a part # of KXN6331.
But...........
The other xtal (furthest away from the RF output BNC) has '17203703' printed on its top? Its a Motorola part # KXN6330
Whats the deal with this other xtal? ANy ideas?
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- Posts: 1030
- Joined: Wed Mar 13, 2002 4:00 pm
- What radios do you own?: Motorola, Icom, Sunair (HF).
Sure. That's your transmit crystal. The transmitter and receiver have separate crystals. This is The Way It Works for nearly all crystal-controlled land/mobile (and most old amateur) FM transceivers.hoser wrote:Thanks very much! The unit is a 450 Model with Tx=Rx=464.5000MHz
The formula for the 450 model works since the top of one of the xtals reads '52437500' which is obviously 52.4375MHz. This one is closest to the BNC connector and has a part # of KXN6331.
But...........
The other xtal (furthest away from the RF output BNC) has '17203703' printed on its top? Its a Motorola part # KXN6330
Whats the deal with this other xtal? ANy ideas?
In fact, I have to apologize. The formula I gave you was for the RECEIVE side only. The transmit side formula is Fcarrier = Fxtal * 27.
If you take 17.203703 MHz, and multiply it by 27, it comes out within a hair of 464.500 MHz.
FWIW: International Crystal can supply you with replacement crystals for any frequency you wish for about $40 plus shipping, total. I would also strongly recommend that you purchase the RNet service manual, Motorola part #68-80901Z35.
Happy tweaking.
Bruce Lane, KC7GR
"Raf tras spintern. Raf tras spoit."