From: rdewan@casbah.acns.nwu.edu (Rajiv Dewan)
Subject: Re: Using MC3362 for a SuperHet Receiver
Organization: Northwestern University, Evanston Illinois.
Distribution: usa
Date: Thu, 19 Nov 1992 15:55:03 GMT

In article <1992Nov18.230709.7273@cbnewsm.cb.att.com> jeffj@cbnewsm.cb.att.com (jeffrey.n.jones) writes:
>In article <1992Nov18.201655.12206@netcom.com> joe@netcom.com writes:
>> I've been experimenting with both the Motorola MC3362 and MC3363 (the
>> 3363 is with an RF amplifier built-in).  The chip is fantasic in that

It also has noise amplfiier and squelch circuits built in.

>> is is a complete narrow band FM dual conversion receiver on a chip.
>> The first IF is 10.7 and the second is optimized for 455Khz.  The IF
>> amplifier is also a high gain limiter before the quadature detector.
>>
>> Also, the 1st Local Oscillator was able to be moved to below 7Mhz for
>> low frequency operations.  I minimized the effects of the inductive
>> part of the resonant circuit (lower drift).
>
>I want to make a superhet 10 meter receiver out this of chip. On the
>1st local oscillator how did you set up the resonant part of it? Have

Look at Gary Breed's design in Dec '90 - Jan '91 QST.  He uses the varactor.
As the capacitance shift of the varactor over its operating range is not
large, the tunable bandwidth is small at lower HF frequencies.  

This can be overcome with some innovation.  One possibility is to transvert 
the HF input (after a band pass filter) by mixing a 45MHz LO (single frequency)
and then build a receiver for around 45MHz.  The 45MHz freq is a convenient
one because it is a common TV IF frequency and cheap filters are available.
At that frequency, you will be able to cover much larger portions of the band
using the 3363 chip directly.  In fact, the VCO on the chip interfaces nicely 
with MC145152 (and other) PLL chips for a nice synthesized HF radio.

If you are willing to build your own filters for the transverted output, (such 
as Cohn) then you can pick the first LO cleverly so as to build a 10m/6m 
receiver.  Just knock off the first LO and mixer and substitute a different 
front end.  All this can be easily done using PIN diodes.   
Essentially, you will be building a 6m receiver and a transverter for 10m. 

>you tried using the varactor built into this chip? Also want to use a
>9 mhz mechanical filter after the first LO and use the second for the
>BFO. Both of the chips sure have great possibilites! By the way where 

Ah! Nice filters but the chip is designed to accept garden variety
ceramic filters. With others you will have to match the impedance and
insertion losses.  I do not quite remember the figures, but the mechanical
filters (of the Collins type) have high insertion loses (10db more than
a ceramic filter). 

>did you buy this chip and how much did it cost? 73!
>

US Cybernetic's (they advertise regularly in Nuts & Volts magazine)
has MC3363 (which is only available in a surface mount package from
Motorola) mounted on a carrier for easier use by home brewers.  Their
price is pretty reasonable too - $5 each.  I just ordered a few from them.

Rajiv                                 
aa9ch    
Address: r-dewan@nwu.edu
Phone:   None. Only CW.
And occasionally AMTOR.