Realistic TRC-421A 10.240 PLL crystal question
- KU_4UV
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Realistic TRC-421A 10.240 PLL crystal question
I just recently purchased a NOS Realistic TRC-421A on eBay. The radio was built in 1984 from what I can determine. I have already replaced all of the electrolytic capacitors in the radio. My question is basically about how to go about aligning the PLL circuit in the radio. I may replace the 10.240 crystal at some point, but I'm not sure what the particular specs on the 10.240 crystal for the radio are, such as impendance, etc. Can anyone help me out as to what the specs for the 10.240 crystal in this radio would be, where I can find a crystal, and how to go about aligning the PLL circuit? I have a basic frequency counter. Thanks!
- MDYoungblood
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Re: Realistic TRC-421A 10.240 PLL crystal question
Hello KU_4UV,
Welcome to the forum. The chances that the 10.240 crystal is bad are slim to none so changing it would be a mood point. A little AM radio could be as much as a half a KC off and still hear and receive another radio. I don't have a schematic to it but there should be a variable resistor or a load "can" close to the 10.240 crystal to make a minor adjustment, it probably is loaded with wax or hot glue.
The simplest way to adjust the frequency is to use a 10kc tone, download one to iTunes or whatever media player on your phone or computer, place the mic close and key, adjust the VR/load to the frequency the radio is on ie: channel 20 is 27.205.0 .
As a new member here could you post a intro in the "Welcome to the Forum" topic, http://www.cbradiotalk.com/viewforum.php?f=89 , so others can say "Hi", thanks.
3's
Greg
Welcome to the forum. The chances that the 10.240 crystal is bad are slim to none so changing it would be a mood point. A little AM radio could be as much as a half a KC off and still hear and receive another radio. I don't have a schematic to it but there should be a variable resistor or a load "can" close to the 10.240 crystal to make a minor adjustment, it probably is loaded with wax or hot glue.
The simplest way to adjust the frequency is to use a 10kc tone, download one to iTunes or whatever media player on your phone or computer, place the mic close and key, adjust the VR/load to the frequency the radio is on ie: channel 20 is 27.205.0 .
As a new member here could you post a intro in the "Welcome to the Forum" topic, http://www.cbradiotalk.com/viewforum.php?f=89 , so others can say "Hi", thanks.
3's
Greg
"321, West Manchester Township, PA"
Official Moderator - CBRT Complaint Department