I had someone drop me an e-mail on this post and thought it would be a good idea to pass it along for others. This individual was a licenced ham whom I did not ask permission to post this to the wold therefore I have with held his name / call.
From: name/callsign/web address
Subject: Uniden 2600 Crystal mathematics
Date: Tuesday, April 13, 2010, 4:46 PM
I noticed on eham you mentioned changing the crystal in this or a similar radio.
I m a ham (callsign / name), and would like to look at this.
Can you give me the bit of math / radios IF dance, to figure the right crystal for shifting to 12 meters?
Well the short story is .....you change the crystal on the small CPU board. It is labeled x-302 on the schematic. It is a 22.000 Mhz crystal and the way it is used is...if you put a 21.000 Mhz crystal in its place and your radio says you are on 28.000 Mhz you are actually on 27.000 Mhz, You put in a 20.000 Mhz crystal in and you are tuned to 28.000 Mhz, you are on 26.000 Mhz and so on. I have used old computer mother board crystals in the past or old computr video boards, hamfest is good for that stuff. or online, i have ordered them before.
There is also a matter of tuning of the receiver front end and the transmit section (along with a few other things) but is very manageable even with the most modest tools and equipment.
I am not sure of your technical knowledge so I am not sure how much detail you need. depending on what you want to do with the radio it is very good to work with for mods and ect.
There is also an IC chip you can replace ....the main cpu ( the 64 pin big boy)..a company from California used to sell them and I think they still do. It's called Chipswitch. It also needs a few other mods to get it to work with the chip on 12 meters but nothing a junk cb radio won't provide and gives you memory channels,split,better scanning, and more.
Hope this helps , if you need more help let me know.
P.S. It is best to just tune the radio to 12 meters and leave it there but I have switched 2 crystals back and fourth and spread out the tuning but it is a compromise.