Descrambling Cordless Phones Using ONLY Radio Shack Parts
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Note: This only covers those speech inversion 46/49 MHz cordless phones,
not the spread spectrum 900 MHz ones.


What you need
~~~~~~~~~~~~~

	- Radio Shack PRO-2042 scanner, part number 20-464
	  Or any radio that you can tap the 455 kHz last I.F. strip.

	- Radio Shack DX-390 shortwave receiver, part number 20-214
	  Or any radio capable of tuning (in sideband) 455 kHz +/- 10 kHz

        - 10 k 1/4 watt resistor, part number 271-1335

        - 0.01 uF ceramic capacitor, part number 272-131

        - Chassis mount BNC, part number 278-105

	- RG-58 patch cable, part number 278-964

	- BNC to phono adapter, part number 278-250

	- Phono to 1/8" mono adapter, part number 274-330

	DON'T EVER TALK TO RADIO SHACK EMPLOYEES!!!!!!!!!!!!!!!!!!!!
	DON'T EVER TALK TO RADIO SHACK EMPLOYEES!!!!!!!!!!!!!!!!!!!!
	DON'T EVER TALK TO RADIO SHACK EMPLOYEES!!!!!!!!!!!!!!!!!!!!
	DON'T EVER TALK TO RADIO SHACK EMPLOYEES!!!!!!!!!!!!!!!!!!!!
	DON'T EVER TALK TO RADIO SHACK EMPLOYEES!!!!!!!!!!!!!!!!!!!!


D34 Location
~~~~~~~~~~~~

For reference: Back of scanner has the antenna jack. 
               Front of scanner has the LCD display.
               Top of circuit board is where the speaker is. 
               Bottom of circuit board is where the board is covered with 
               surface mount componets. 


D34 is a small, surface mount diode located on the bottom of the main circuit
board of the scanner. 

First, locate the silk screen marking for D34 on top of the main circuit board,
it's near the back of the scanner, near the antenna jack. Make a mental note of
which way the cathode is pointing. (the bar in the symbol)

Now, flip the scanner over. Approximate where you think the diode will be, cuz
it won't be labeled!! With the scanner upside down, and the front facing you, it
will be in the upper left corner, near the antenna jack. It will look like a 
small black rectangle with a stripe on one side and the marking "2A" on the
body. Or, at least that's what mine looks like. I hope they are all the same.

Solder to the cathode of the diode, the end with the stripe. DONT'T overheat
the diode or you'll lift it from it's solder pad. It's best to follow a trace
and solder to a open pad or safer component it's connected to.


Hook up
~~~~~~~

Using the patch cable and adapters, hook your PRO-2042 scanner to your DX-390
receiver's 1/8" antenna jack.


Using
~~~~~

* Tune the DX-390 to 455 kHz with the BFO switch on. 

* Turn the RF gain all the way to zero, and adjust the volume to a normal
  normal level. 

* Now turn on the PRO-2042 and tune to a known scrambled cordless phone
  conversation. You should hear the scrambled audio on your DX-390 speaker.

* Tune around with the 1 kHz setting from 450 to 460 kHz. Stop when you get
  a strong, clear signal.
  You may have to tune a little off of the normal 455 kHz frequency if the 
  signal from the scanner is too strong. (or attenuate it)

* Use the BFO to adjust the received cordless phone audio. You should be able 
  to descramble the audio by carefully adjusting the BFO settings.

* It takes a little adjusting, but does work. Check the data sheet for 
  the Motorola MC13110 cordless phone subsystem for more infomation on
  how the signal is actually scrambled.