The 10.0525 is doubled in this 02A to 20.105 then fed to the mixer. I thought of the 20mhz xtal but I would likely have to make my own oscillator.
-
You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
Pll02A crystal info needed.
- Thread starter Techno1
- Start date
Thanks for sharing that. I assumed (4*10.0525)-37.66=2.55, but I hadn't considered it mixed twice to get the PLL input like that 37.66-20.105=17.555 and 20.105-17.555=2.55. My brain was searching for the simplest solution.
Would be interesting to know if the 20.105MHz crystal would work in that oscillator.
Would be interesting to know if the 20.105MHz crystal would work in that oscillator.
I bet it could, would need an oscillator board with varactor tuning for the clarifier
Edit, I think it can be made to work in the existing circuit with a few changes, so no oscillator board required.
I thought that oscillator already had the varactor control on it. I am looking at the 79-892 schematic from cbtricks and it looks like the varactor is brought into circuit at the emitter via C18.
I imagine some of those caps would need to get smaller around Q3 and on the trimmer side of the inductor but it might be possible. IDK
I imagine some of those caps would need to get smaller around Q3 and on the trimmer side of the inductor but it might be possible. IDK
It does, I was talking about making my own oscillator and needing varactor diode, but I think a xtal swap and a few circuit changes alone should work. I'm using a Sam's for the schematic...
Diodes are signal switching. The band switch forward biases one at a time selecting which crystal is connected to the oscillator. The diodes are not halving anything. The doubler is just a tank circuit tuned to 20MHz so you can put 10MHz or 20MHz into it and it will do its job the same, output 20MHz.Here's a pic of the export band mods, it wouldn't take much to adapt with a bit of veroboard. 20Mhz for the win
Looking at the circuit I believe it still uses the doubler, the crystal has a diode in line so maybe that halves the frequency anyway.
View attachment 77706
I have a question. How many channels does anyone use these days?
I must admit that I really like old CB's and I can understand anyone that wants to keep these radios working at their best, me too. I have a few (???) older sets both Cybernet and Uniden though mine are the export versions (usable on UK freq's). But tbh I only use 1 or 2 channels on our UK band (27.601-27.991Mhz FM) and my radios will do 200 channels AM/FM/SSB, so most not used, but odd times I'll have a listen on 27.555 USB and have a flick around 'mid band' (FCC).
So... keep it legal? Yes if you can. The OG is (imho) worth more than modded any day of the week, but becoming more difficult as the decades pass, so we must do what we must do maintenance wise.
Channels? Obviously local 40 is a must, but extras? Mmmm, Hi band (27.415-27.855?) for the triple nickel maybe? If you must but keep it to yourself (Shhhh). Not much else is any use these days tbh.
I must admit that I really like old CB's and I can understand anyone that wants to keep these radios working at their best, me too. I have a few (???) older sets both Cybernet and Uniden though mine are the export versions (usable on UK freq's). But tbh I only use 1 or 2 channels on our UK band (27.601-27.991Mhz FM) and my radios will do 200 channels AM/FM/SSB, so most not used, but odd times I'll have a listen on 27.555 USB and have a flick around 'mid band' (FCC).
So... keep it legal? Yes if you can. The OG is (imho) worth more than modded any day of the week, but becoming more difficult as the decades pass, so we must do what we must do maintenance wise.
Channels? Obviously local 40 is a must, but extras? Mmmm, Hi band (27.415-27.855?) for the triple nickel maybe? If you must but keep it to yourself (Shhhh). Not much else is any use these days tbh.
Kinda like fast cars. You don't plan to go 165MPH all the time, but knowing you can probably puts the same smile on your face. Same thing with 27.585MHz. I may never use it, but knowing I can if I wanted to.... Sign me up.
Last edited:
Yep, that's pretty much it. Not because there's a pressing need, just to see if I can do it.