Red Wave Radio

I am interested to know if anybody is building or has built reveivers using the ne602 device.

I am particularly interested in the design of rf and oscilator coils for such devices and am interested in any
design specifications any one can submit.

EG preselector coils homebrew if coils home brew socilator coils home brew.

I would like to put together a database of designs that could be shared widely.

Thanks

Malcolm Fairleigh

The NE602 (and it's derivitives; SA602, NE612, A, AN etc.) has been around for
about six years . Although not a particularly "strong" mixer, the easy
implementation, coupled with low power supply requirement has made it a
deservedly popular chip. It can provide "adequate" signal handling
characteristics in receiver applications in all but the most hostile
environments (see below).

It would be difficult to derive a table or quick reference for the many coil
combinations that are possible. However, much valuable information on the '602
may be found in;

"NE602 Primer"- Carr, Elektor Electronics Jan. '92 (has formulas for
calculating oscillator coil values etc.).

"Simple Receivers from Complex I.C.'s"- Parrott,  Ham Radio (USA) Dec. '88.

"Using the NE602"- Zavrel,  Technical Correspondence, QST May '90.

"Using the NE602 in Ham Circuits"- Carr's Corner, 73 Amateur Radio Feb. '93.

"Single-chip Frequency Converter"- Covington, Radio-Electronics Apr. '90.

Two things not specifically mentioned in any of the above; when using the '602
in direct conversion receivers (particularly where an RF amp. is used); much
improved performance will be had if the internal oscillator is not used, but
rather, use a separate metal- boxed VFO (when using the internal osc. it is
difficult to keep the osc. signal from entering the input of the RF amp.,
causing "tunable hum" and other unwanted effects), and, contrary to some
reports that the '602 is rather too weak as a mixer, if the builder uses a
separate osc., and applies the input signal (at pins 1 and 2) in "balanced
mode" i.e. true push-pull, without grounding pin 1 or 2 for RF, and
extracts the wanted product also in balanced mode, the strong signal
handling of the chip will be significantly improved.

73, Kind Regards, Drew, VK3XU.  Telstra Research Laboratories.

"The Neophyte Receiver", QST, Feb. 1988, pp. 14-18
"W1AW at the the Flick of a Switch, QST, Feb. 1993, pp. 56-57 [$30 kit]
"An Optimized QRP Transceiver, QST, Aug. 1980, pp. 14-19 [or see "The
QRP Three
    Bander Transceiver for 18,21,24 MHz", pp. 30-19:25 in 1993 "ARRL
Handbook"]
"Sudden Receiver", 73 Magazine, Oct. 91 [also available as a kit from
Kanga]

The Handbook also says:

        The input and output networks can be either single-ended or balanced
        for AC.  The input and output impedences are about 1.5K for the single-
        ended configuration and about 3.0K for the balanced configuration.

and shows a example matching circuit for 45 MHz

           |      NE602
           --------------------...
               IN A     IN B
                |        |
         _______|        |
         |      |        |
        ---     | =      |
  47 pF ---     C /|     |
         |      C/       |
o--------+      C .209-  |
         |     /C .283uH |
 220 pf ---   / C        |
        ---     |        |
         |______|________|
50 ohms             |
   IN              ---  
                   --- 0.1uF
                    |
o-------------------

The "Neophyte" just uses a cheap 7:1 FM broadcast IF transformer for its
input, and there's a several section input filter on the W1AW receiver.

That may not be what you were asking for, but perhaps someone else might
find it helpful.  One thing you may want to consider, particular if you
live
in/near an urbanized area is that you will probably want some kind of
input
filter, as i understand that the NE602 is prone to being overloaded by
strong signals in adjacent bands compared to mixers such as the SBL-1
(which lack an internal LO).

                                -- KD6PAG  (networking old-timer, RF newbie)

Here on the West Coast, the foreign broadcast isn't as strong as it is in,
say New England. Only one evening did I hear AM getting through the
Optimized rig. I tracked it down to a private religious SWBC station near
San Francisco (about 600 miles from here), KGEI, operating at 7360 kHz. I
_measured_ its signal at 100 mV (yes, that's mV) RMS at the station end of
my vertical antenna coax!

Have fun!

73,
Roy Lewallen, W7EL

Quote:

>I am interested to know if anybody is building or has built reveivers using
the ne602 device.

>I am particularly interested in the design of rf and oscilator coils for such

Quote:>design specifications any one can submit.

>EG preselector coils homebrew if coils home brew socilator coils home brew.

>I would like to put together a database of designs that could be shared

I am begining the design of a superhet tranceiver for 20M.  Due to cost and
availablity, I have chosen to use the ne602 for my mixers/(de)mods.  Most of
the information that I have has come from various amateur texts however once
the actual projects gets underway (hopefully within a month) I should have some
data available that I have collected.  You can watch my web site for my notes
and info available (I'm just setting it up so it's a little sparse.

http://www2.southwind.net/~zclobes/electron.html

Good luck and I'd be interested in taking a look at any info you may have.

Thanks,
Zack, AA0XQ