UPD2824, swap the 10.240 reference crystal, will it work?

[towerdog]

So I got this old TRC-465 out of storage and feel the need to mess up something. I know they made channel kits for these, like exp back in the day, and I am thinking these just switch the 10.240 crystal with something else for upper and lower channels. Is that it or were these kits like an external oscillator to inject new freq into the TX and RX. I am trying to figure out how these things mix frequencies. I am thinking maybe a push button dpdt switch beside or on top of the ref crystal and a plastic rod to a button somewhere on the front since it does not have much room. Maybe also I could "bend" the crystal to get +10khz, stability wouldnt matter on those secret hidden channels anyway cause we talk on those with AM

 

[Robb]

The 10.240mhz reference xtal is just that, it is there as a reference to keep the pll on track so that it keep it on the specified channels when the channel selector is used. A calculated relationship between the pll and the xtal is imperative. The pll itself has a go/no go range of operation, so using a different xtal will just cause it to become unlocked (which means it will not allow it to stay focused on any one freq and this 'unlocked' condition will not allow the radio to TX or RX.

When someone wants to give a radio like this one more channels, the do so by changing out - or switching to a different xtal farther downstream at the next oscillator circuit. and/or they replace the pll for a 2816 - IIRC . . . been awhile . . .

 

[towerdog]

The 10.240mhz reference xtal is just that, it is there as a reference to keep the pll on track so that it keep it on the specified channels when the channel selector is used. A calculated relationship between the pll and the xtal is imperative. The pll itself has a go/no go range of operation, so using a different xtal will just cause it to become unlocked (which means it will not allow it to stay focused on any one freq and this 'unlocked' condition will not allow the radio to TX or RX.

When someone wants to give a radio like this one more channels, the do so by changing out - or switching to a different xtal farther downstream at the next oscillator circuit. and/or they replace the pll for a 2816 - IIRC . . . been awhile . . .

Thats what I was afraid of. Anybody know where I could find schematics and manuals for a galaxy or expo kit?

 

[towerdog]

thats what I was afraid of. Anybody know where I could find schematics and manuals for a galaxy n or expo kit?

 

[loosecannon]

keep looking around online for the 10.240 crystal mod. im not sure, but i think i read somewhere about someone doing this mod to this radio, but not too sure.
also check the old Secret CB books.

as for info on your radio and the expo N kit, try these links:

schematic for your TRC465:

http://www.cbtricks.com/radios/realistic/trc_465/graphics/page49_50_sch.pdf

expo kit general info:
http://www.cbtricks.com/miscellaneous/vco/expo/index.htm

expo N kit install instructions:
http://www.cbtricks.com/miscellaneous/vco/expo/model_n.htm

hope this helps.
LC

 

[Justme]

In most trransceivers the 10.240 signal is also used as ist intermediat mixing frequency, changing that frequency wil not be good for the receiver section.

 

[towerdog]

http://funkservice.at/en_pll-modul.htm a new PLL chip seems like a much better idea than injecting new mixing frequencies.

 

[tecnicoloco]

http://funkservice.at/en_pll-modul.htm a new PLL chip seems like a much better idea than injecting new mixing frequencies.

Yeap and works a lot better than the old Expo N

Might take 2 weeks after you order to get it in the US from Germany