cobra 89xlr extra upper channels

[mr_fx]

I have a cobra 89xlr i am trying to mod... i need to push it into the 28.200 -28.300 mhz range

Recieve does not matter... this will only be transmitting... recieve does not matter... i also dont care about being able to switch between cb and 10m HAM band

Things i have tried

Replacing the the 10.240mhz crystal with something higher... this was unpredictable

Tried replacing the 10.635mhz crystal with 11.325
No dice

Connected pin 21 and pin 19 on the 858 pll
This got me into the 27.765 mhz or so range... mot quite there...

In all cases the vco seems to loose lock at around 27.675. Retuning L20 seems to help this

 

[Robb]

Suppose that you are trying to make a 10m beacon xmitter?

Why was the ref osc xtal unstable? You may need to load the xtal with more/less capacitance until it reads the freq it was cut for. I know some plls have a minimum freq they will accept; not sure of the 858 pll is the same or has a freq/max.

Another thing to overcome is the need to broadband the xmit circuit. Sure that either unit_399 or Xit13 is familiar enough with these chassis to make it simple once they read this thread.

 

[loosecannon]

http://www.cbtricks.com/pub/secret_cb/index.htm

check out this link.
go to volume 11, and look at the first few pages.

this is for SSB 858 radios, but it will give you some ideas on which pins to try changing the state of.
LC