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From: elzea@sersun0.essex.ac.uk (El-Zein A A)
Newsgroups: sci.electronics
Subject: Local Oscillator Question ( naive)
Message-ID: <3066@servax0.essex.ac.uk>
Date: 2 Feb 90 18:55:44 GMT
Sender: news@servax0.essex.ac.uk
Reply-To: elzea@sersun0.essex.ac.uk (El-Zein A A)
Organization: University of Essex, Colchester, UK
Lines: 65



	I wonder if anybody can help me with this or give me a feedback:

	I have designed a local oscillator which should oscillate at 122.5 MHz.

	This LO is intended to down convert a 151.5 MHz signal to a 29 MHz one. 

	The 151.5 MHz signal has an amplitude of ~ 50 uV. The LO circuit is  

	shown below.


          ------------------------------------------ +6 V
                     |               |
                     |               |
                24K  \               ( 
                     /               ) RF choke ~10mH	
                     \               (
                     |               |
                     |               |-------------------------------------
                 1nF |            | /                        |            |
            ____| |__|____________|/                         |            |
           |    | |  |            |                          |            |
           |         |            |\                        ---39pF       |
           |         |            | \                       ---           )
           |         /               |                       |            ( 60nH
           |         \18K            |__________        -----|            )
           |         /               /         | 220pF  |   ---           (
           |         |               \470     ----      |   ---100pF      |
           |         |               /        ----      |    |            |
           |         |               |         |        |    |            |
           |        --------------------------------------   --------------
           |                         |                             |
           |                       ------                          |
           |                        ----                           |
           |                         --                            |
           |_______________________________________________________|
                                                                  


	I have 2 questions : 

		1- Do you think this circuit will work ? 

		   If not then why not and how can you make it work?

		2- I have to choose between a double-balanced hot- 

                   carrier-diode mixer & a dual gate FET mixer. Which

		   one do you think is more appropriate to use
		   
		   with the above circuit and why ?


	Any information will be appreciated.

	The above questions might seem like exam-questions, but I did

	this to avoid confusion. SORRY.

					Thanks in advance.
						
					 	Mustapha,