MXM SupeRX/TX 40 Rig Info

 

My SupeRX/TX 40 -- now on 7030 kHz

Click on schematics for a better view

Details on the receiver: https://archive.org/details/73-magazine-1991-04

Details on the transmiiter: https://archive.org/details/73-magazine-1991-12/page/10/mode/2up

Article on MXM Industries of Smithville,Texas:  

https://www.worldradiohistory.com/Hambrew_Magazine.htm

Click on images for a better view

Click on images for a better view

A QRP CW Contact (Video) with the Winterfest MXM SupeRX/TX 40 (1 Watt, Crystal Controlled Transmitter)

I picked this transceiver up at Winterfest for one dollar. 40 meters. Superhet receiver with 455 kc ceramic filter and 2 NE602s. Crystal controlled one watt transmitter on 7039.5 kc. I emailed Jeff KA2BKG and asked him to slide up a bit to my freq. I am glad he did. Thanks Jeff.

More Inspiring Mail! Another "First Ever Receiver was Homebrew"

Frank's Lowfer Beacon Receiver

It was great to hear from someone else who, like Scott KQ4AOP, heard his very first signals on a homebrew receiver.  That is a really wonderful way to start.  Frank's first receiver was built around the NE602 chip.  I had trouble understanding this IC but I finally cracked the code: 

https://soldersmoke.blogspot.com/2021/11/how-to-understand-ne-602-and-gilbert.html 

The picture that Frank sent is of a more recent project, this one a Lowfer receiver that picks up signals from beacons. 

-------------------------

Hello Bill, 

I just wanted to message you and tell you I really enjoyed your book Soldersmoke. I've been listening to the podcast as well.  On the latest one you mentioned a fellow who heard his first ham radio signals on a homebrew receiver, and that's how it was for me as well! There were lots of articles about using  the NE602 in the electronics magazines back in the day. I put one of the circuits together and it worked pretty smoothly... I eventually got my ham radio licence (KC8JJL) sometime in the 90's. The first time I met a ham was when I showed up to take the test!  

I don't do much transmitting these days but I still love to listen and tinker.  Here's a picture of a direct conversion LF receiver I put together... It uses an NE602 and is varactor tuned. It only covers from around 300Khz to just over 400khz  but there are still a few beacons I can hear in MI and WI. 

Frank James

KI4IO in India and Nepal, and Discrete Homebrew Gilbert Cells

Jerry KI4IO is such an amazing homebrewer that he has been dubbed "The Wizard of Warrenton." The picture above shows Jerry during the early 1980s in the shack of Father Moran 9N1MM in Nepal. Jerry was also in India.  (I previously posted the info on Jerry's time in India and Nepal, but I didn't have this picture.  The picture makes it worthwhile to post the story again.)  From Jerry's QRZ.com page: 

-------------------------------

While in India I was licensed at VU2LHO and worked a lot of US hams with a 135' flat-top and open-wire feed. I had the antenna strung between two bamboo towers atop the embassy housing 2nd-story roof-top. I also put up a 3/8 wave vertical on the roof for 10 meters. That little antenna had 110 radials stapled into the roof screen and worked very well! The rig was a HW-101. I was in Kathmandu, Nepal from early 1980 to late 1982. I could not obtain a license there, but became good friends with Father Moran, 9N1MM, and would often spend time up at his place putting his Drake station on CW. Pretty cool being real DX! Back in the states in late 1982.

Here I am at one of my many visits to Father Moran's shack. 

---------------------------------

Check out Jerry's QRZ.com page: https://www.qrz.com/db/KI4IO

I got in touch with Jerry because Pete Eaton reminded me that Jerry had homebrewed a discrete transistor version of the NE602 Gilbert Cell Mixer, a device that I am very interested in. Nick G8INE also built one. 

Putting a Barebones Superhet on 17 Meters with an NE602 Converter (Video)

Armed now with a NanoVNA, I took a look at the passband of the 5 MHz filter in my Barebones Superhet (BBRX)  W4OP built it on a Circuit Board Specialist Board.  He put a 5 MHz CW filter in there;  I broadened the passband for phone by changing the values of the capacitors. Here is what the passband now looks like in the NanoVNA: 

This is what DeMaw would call an "LSB filter."  You would get much better opposite sideband rejection by using it with an LSB signal, placing the BFO/Carrier Oscillator slightly above the passband, in this case near 5.002 MHz. 

When I first built the down converter to get the 18.150 MHz signal down to the 7 MHz range (where I had the receiver running) I used an 11 MHz crystal for the NE602's local oscillator.  But this created a big problem:  18.150 - 11 =   7.150 MHz.  That is in the 40 meter band, but note:  NO SIDEBAND INVERSION.   Then in the BBRX  7.150 MHz - 2.150 MHz = 5 MHz  (the filter frequency) but again:  NO SIDEBAND INVERSION.   The signal started as a USB signal and remained a USB signal. 

I briefly tried shifting the BFO frequency to the other side of the filter passband.  If I could get it to around 4.985 MHz, it might work, but because the filter passband was so large, and because the crystal frequency was so low, I was unable to shift the crystal frequency that far.  In any case the results would have been less than ideal because of the "LSB" shape of the filter.  Back to the drawing board. 

I decided to cause one sideband inversion. 

At first I put a 25.175 MHz crystal module in my down converter.  This shifted the 17 meter phone band down to the 40 meter CW band.  It worked, but I cold hear strong 40 meter CW  signals being picked up by the wiring of the receiver (the box is plastic!).  I went back to the module jar in search of frequency that would move 17 meter phone to the 40 meter area (so I would not have to re-build the BBRX front end) but outside the actual 40 meter band.  

I ended up using a 25 MHz crystal in the down converter. 25 MHz - 18.150 MHz = 6.85 MHz WITH SIDEBAND INVERSION.  After checking on the NA5B Web SDR to see that there are no strong signals in the 6.835 to 6.89 MHz range, I retuned the output circuit on the converter and tweaked the input capacitor on the Barebones.  I shifted the VFO frequency down to 1.835 to 1.89 MHz and put the BFO at 5.002 MHz.   The receiver was inhaling on 17 meter SSB.  

One more change to the BBRX:  in his June 1982 QST article, DeMaw warned that trying to get speaker level audio out of the 741 op amp that he used would result in audio distortion.  And it did.  So I put one of those little LM386 boards I have been using into the BBRX box.  I just ran audio in from the wiper of the AF gain pot.  It sounds good.  

In effect this is my first double-conversion receiver.  I usually prefer single conversion, but this project has highlighted for me one of the advantages of double conversion for someone like me who eschews digital VFOs:   Starting with a crystal filter at 5 MHz,  with double conversion I could keep the frequency of the LC VFO low enough to ensure frequency stability.  That would have been impossible with a 5 MHz IF in a single conversion 17 meter rig.  But if I were starting from scratch for a 17 meter rig, I could stick with single conversion by building the filter at 20 MHz,  keeping the VFO in the manageable 2 MHz range. 

Now, on to the SSB transmitter.   The Swan 240 dual crystal lattice filter from the early 1960s needs some impedance matching. 

How To Understand the NE-602 and the Gilbert Cell Mixer

 

I think the key to understanding the Gilbert Cell Double Balanced mixer is to separate out the three tasks that this device completes, and consider them one at a time, using different diagrams: 

1) It mixes two signals to produce sum and difference outputs. 

2) It balances out the RF input. 

3) It balances out the LO input. 

                                                                  Task 1 -- Mixing

The Gilbert cell is like the diode ring mixer in that it switches the polarity of the input signal at a rate set by the Local Oscillator. Another way of saying this is that the mixer multiplies the input signal by 1 and by -1. 

Steve Long of the University of California described the essence of this mixing this way (using the diagram above): 

 

An ideal double balanced mixer simply consists of a switch driven by the local oscillator that reverses the polarity of the RF input at the LO frequency.  http://literature.cdn.keysight.com/litweb/pdf/5989-9103EN.pdf

In an effort to see this for myself, I drew (noodled!) this diagram: 

There are four transistors -- two differential pairs with RF coming into the bases of the pairs. 

The LO is a square wave.  The LO alternately turns on transistors 1 and 4, then 2 and 3.  When 1 and 4 are on, we are in period 1 -- here there is no switching of polarity.  Portions of the RF waveform are passed to the outputs.  But when the LO turns on transistors 2 and 3, portions of the RF wave form are "crossed over" to the opposite output.  Polarity is reversed.  We see this in period number 2. 

Take a look at the resulting output waveforms.  This is the same waveform we see coming out of a diode ring mixer.  I really like this drawing because in that complex waveform you can actually see the sum and difference frequencies: 

I could see this diode ring waveform myself on my oscilloscope: 

https://soldersmoke.blogspot.com/2020/11/diode-ring-magic.html 

TASK 2 -- Balancing Out the RF Input 

In a diode ring, and in other diode mixers, the balancing out of the input signals really takes place in the trifilar toroidal coils that are part of the circuit.  Barrie Gilbert needed an integrated circuit mixer that did not use coils.  

Again referring to the above diagram, Steve Long of the University of California put it this way: 

The ideal balanced structure above cancels any output at the RF input frequency since it will average to zero.

To fully understand this I find it helps to look at the Gilbert cell circuit drawn in a different way.  Here is a drawing from Alan Wolke W2AEW that I found very helpful. It comes from his excellent YouTube video: https://www.youtube.com/watch?v=7nmmb0pqTU0

Suppose the RF waveform at I1 is causing the current through R1 and R2 to increase.  At the same time, the opposite phase current through I2 will be causing the current through R1 and R2 to DECREASE.  So there is no net effect of the RF signal at the output.  The RF is balanced out. 

TASK 3 - Balancing Out the Local Oscillator Signal 

Here too I used my own drawing, and was guided by the words of Steve Long: 

It also cancels out any LO frequency component since we are taking the IF output as a differential signal and the LO shows up as common mode.  

The important thing to realize here is which transistors are being turned on and off by the local oscillator signal.  On one half cycle of the LO, transistors 1 and 4 are on.  So  the LO signal at the LO frequency are both pulling the same amount of LO frequency current through the resistors. So you have the same change in voltage at the output terminals.  And the output terminals are differential.  The LO signal results in no voltage difference between the terminals.  So the LO frequency is balanced out. 

The same thing happens on the following half of the LO cycle.  Here, transistors 2 and 3 are turned on. Again, both transistors pull the same amount of LO frequency current through the resistors. There is no differential voltage.  So no LO frequency energy passes to the output.  LO frequency is balanced out. 

--------------------------------

I am surrounded by Gilbert Cell Mixers and I have been using them in my homebrew rigs for many years. I use them in up-converters for my RTL-SDR receivers.  I have one in the downconverter for my 17 meter receiver and had one as the mixer in my first SSB transmitter. I built a 40 meter SSB transceiver with NE602s on either end of the crystal filter. Years ago, I built a DSB transceiver with several NE602s.  My SST QRP CW transceiver is made with NE602s. I have on my bookshelf Rutledge's book "The Electronics of Radio" that is all about the NORCAL 40 transceiver, built using NE602 chips.  But until now I really didn't know how these chips worked.  Truth be told, for me they were mysterious little black boxes, and that bothered me.  Now I feel a lot better about using these clever devices.  I plan on stocking up on the old style (non-SMD) NE602s.  

Apparently Barrie Gilbert rejected the idea that he invented the circuit that bears his name.  It seems that Howard Jones first used this circuit in 1963, with Gilbert developing it independently (in an improved form) in 1967. 

 Barrie Gilbert was quite a guy, with electronic roots in the world of tinkering: 

https://www.microwavejournal.com/articles/33425-living-and-learning-with-barrie-gilbert 

https://vintagetek.org/barrie-gilbert/

A 75 Meter AM Quarantine Converter for the Q-31 Receiver (video)

A while back Fred KC5RT sent me a nice collection of parts, including some 6 MHz crystals.  I had been thinking of making a converter to put ahead of my Q-31 receiver.  When Fred's 6 MHz rocks arrived, I knew that The Radio Gods Had Spoken (TRGHS).  

I found some NE602 chips in the junk box.   I used an Altoid-sized box for the case.  The toroids are from W8DIZ.  I use trimmer caps from KC5RT to resonate the input and output circuits.  

Hooray!  Now I can listen to 75 Meter AM on the Q-31.  I may have to build a transmitter to go with this contraption.  

Thanks again Fred. 

AC9JQ's Mini Digi VFO/BFO Al Fresco with OLED (and noise test)

From Dean AC9JQ:

Just completed the VFO/BFO/Arduino/OLED module for my radio.  I also have the LPF, BPF and crystal filters completed and tested.  Next will be the audio amplifier and NE602 modules.  I will probably build one of the NE602 modules and test things out as a DC receiver.  My ultimate plan is to have the rig no more that 1"x3.5"x3".  I still have a lot of "stuff" to stuff into that size of box.  I'll keep you posted.


I have been able to contain the entire Arduino/Si5351/OLED into a small cube in the front.  The rest of the radio has to fit on two levels in the rest of the area behind the Arduino/Si5351/OLED.  I think I will build the audio section and on NE602 mixer and run it as a direct conversion first to vet out any noise or other problems.  Bill, that small coax that you pointed out will really help on this build.  I used a small piece as a power feed-thru and will use it to feed out the VFO/BFO signals, thanks again for that pointer.

I decided to test for noise on the TIA transceiver test bed.  See the video of the results.  Not too much noise.  I'm only using my indoor magnetic loop for an antenna.  Video is kind of sloppy, but taking off the antenna and turning up the volume shows how little noise is left in the system.  Now time to stuff the rest of the radio into the tight quarters.

https://youtu.be/kXf7-7FtxEU

I purchased OLED from ebay.......

http://www.ebay.com/itm/401234789687?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

0.91'' 128x32 IIC I2C Blue OLED LCD Display DIY Module DC3.3V 5V For PIC Arduino | eBay www.ebay.com IIC interface. OLED display, no need backlight, self-illumination, the display performance is better than the traditional LCD display, also lower consumption. VCC: Power (DC 3.3 ~5v). Display Color:Blue. | eBay!

They are nice and compact, although as time goes on, I'm sure they will be harder to read.  I'm hoping to have an alfresco version in a week or two.  I used much of Pete's code from the shirt pocket transceiver upgrade, modified the code to address the smaller display and add USB/LSB capabilities. 

73's  Dean AC9JQ

SolderSmoke Podcast #197: Farhan, Fame, 'Fest, Testgear, SSB History, Dishal Dystopia, QRP CW, MAILBAG

SolderSmoke Podcast #197 is available:

http://soldersmoke.com/soldersmoke197.mp3

Up in NYC, met Dave W2DAB. got Steve Silverman's HP 8640B Sig Gen.

Farhan's visit to SolderSmoke HQ

Got me a TEK1401A Spectrum analyzer

Farhan at "Geekfest" @W7ZOI   http://w7zoi.net/Farhan-visit.html

BITX40 Modules.  5,000 already.   1,000 a month.

The BITX pronunciation problem. 

QRP Hall of Fame.  I suspected April 1 reprisal!    "I am unworthy" 

Like in Wayne's World: https://www.youtube.com/watch?v=lBEn3a4TIUw

Dusting off my Tuna Tin 2, Herring Aid 5 and Farhan's key from India.

The Manassas Hamfest:  OLD crystal gear.   20's and 30's stuff. Leon Lambert RX and Philmore Fixed Crystal Detector. 

 Reminder of how YOUNG the radio art is.

RELATED:  Bell System 1953 Transistor Documentary.  11 year old Pete and his CK722.

Bought some good stuff from Charles AI4OT.

Armand WA1UQO gave me a big collection of Electric Radio.  So much history and HB wisdom in there. Frank Jones and Lafayette Radio.  Jim Lamb and 1930s SSB.  

Is the CK-722 the source of Pete Juliano's affinity for Juliano Blue?

Was Wes Hayward already using Juliano Blue?

"Your rig sounds real good for a homebrew rig!" 

"Well, your rig sounds pretty good for a Yaesu!"

Related topic: Going over the Waterfall:  The SDR Superiority Syndrome.  Feathering.

ARRL Arduino Book   by Popiel.    Very nice.  Right level.  Lots of good info.

BENCH REPORT:

Pete's Dishal Dystopia --  Is the perfect TRULY the enemy of the good enough?

Bill's  NE602 RIG: 

Replaced OLED.  Blue one seems noisier.  Shielded it with  copper flashing.

Made me yearn for bigger boxes WITH A HOOD!

DOCUMENTING WITH LTSPICE

MAILBAG:

Special Thanks to our correspondent in the Dayton Xenia Metropolitan area -- Bob Crane W8SX.

Jack Welch, AI4SV 5R8SV -- Our Man in Antanarivo -- Sent me a GREAT BOOK "I, Libertine" by Frederick R. Ewing.   EXCELSIOR!

https://qrz.com/db/5r8sv

Bruce KC1FSZ https://www.qrz.com/db/kc1fsz  Building Scratchbuilt BITX.  On the way put the VFO where the BFO should go and had a DC RX.  FB

Greg, VK1VXG   Suggestion for WA8WDQ on Arduino serial plotter

http://www.instructables.com/id/Ultimate-Guide-to-Adruino-Serial-Plotter/

Ben KC9DLM  Mercury PTO.  In a syringe!   No thanks! Maybe add some high voltage and selenium.  And a radium dial!  Yea!

http://webshed.org/wiki/Mercury_PTO

KY3R's metalized cigar boxes!  FB On Blog.

Richard WB2PEF has revived his Doug DeMaw 8P6 rig.  FB.  But bothered by PTT thump.

Update on Dave AA7EE (from Mike KC6SAX)

AI4OT and N2CQR

N2CQR AND W2DAB

LTSpice .asc file for the Organic Chip NE602 Rig

A link to the .asc LTSpice file for the NE602 rig  appears below.   Perhaps some brave soul  more skilled in LTSpice than I am might want to turn this drawing into a real simulation.  Some of the parts (like the NE602s) have actual simulated components behind the drawings.  Others (like the relays and the LM741 and LM386) are just drawings.  But go ahead and flesh this thing out.  Who knows, it might come to life in the PC and start making QSOs on 40!

Here is the .asc file:  http://soldersmoke.com/NE602 Rig.asc

My Organic Chip Rig with an LTSpice Schematic

CLICK ON IMAGE TO ENLARGE

This is a rig that came together through a process of Spontaneous Construction.  It started out with an innocent effort to get  an Organic Light Emitting Diode display to work with an Si5351/Arduino combination.   Then I figured I'd make a superhet receiver with it.  Then Pete said I should make it a transceiver.

Most of my earlier transceivers so closely followed the schematics of Farhan or others that it didn't really make sense for me to prepare a new schematic.  This one was different.  So I decided to prepare a proper schematic.  I tried a few of the free-ware CAD or drawing programs, but each of them had a learning curve at the entrance. So I turned to LTSPICE.  I have already climbed that learning curve.  

The results appear above.  Click on the image to make it bigger.   I'm sure there are errors in there.  And I think some of my parts choices might be less than optimal.  But it works well.

The filter was deigned with the help of AADE software.

The idea of using two NE602s with a filter between them came (I think) from the Epiphyte.

The band pass filters were designed with ELSIE software.

The RF power chain is mostly from Farhan's BITX40 module, with the pre-driver and driver modified for a bit more gain.  Farhan's amp is the most stable power amplifier I have ever used.  It hasn't given me any trouble, even at 20 Watts. Strongly recommended.

The microphone amp is derived from the 741 op amp circuit used in the (in)famous Wee-Willy DSB rig.

The receiver AF amp also comes from Farhan's BITX40Module.

Please let me know if you spot errors or have suggestions for circuit improvement.

A link to the .asc LTSpice file appears below.   Perhaps some brave soul  more skilled in LTSpice than I am might want to turn this drawing into an actual simulation.  Some of the parts (like the NE602s) have actual simulated components behind the drawings.  Others (like the relays and the LM741 and LM386) are just drawings.  But go ahead and flesh this thing out.  Who knows, it might come to life in the PC and start making QSOs on 40!

Here is the .asc file:  http://soldersmoke.com/NE602 Rig.asc

DiFX! My New NE602 Rig is On the Air

Pete would call this a DiFX:  a transceiver that is Different from a BITX.  This started with my effort to get an Si5351 working with a little 1 inch square OLED screen.  Tom Hall AK2B helped me with the software (thanks Tom). Once I got that done, I figured I could build a simple receiver with a homebrew 11 MHz crystal filter, two NE602 chips, and an LM386 AF amplifier.  That was working great, then Pete told me to turn it into a transceiver.  I used some of Pete's boards (thanks Pete).  

The Epiphyte transceivers also use two NE602's, but they ingeniously switch the BFO and VFO between the two chips.  I didn't switch the oscillators -- instead I switched the inputs and outputs of the two chips using two DPDT relays (thanks Jim).  A third DPDT relay switches the antenna between T and R, and turns on and off the PA stage and the AF amplifier.

This is a DIFX, but there is some BITX circuitry in there.  The power amplifier stages are right out of the BITX Module, as is the AF amplifier (thank again Farhan).

The only real problem I ran into had to do with the very low power out of the NE602 VFO mixer on transmit and the impedance matching between the NE602 and the PA chain.  I had to increase the gain on the first RF amp (pre-driver) using ideas from Steve Weber's 40 meter SSB CW QST contest rig (thanks Steve).  I experimented with various connections between the NE602 and the BP filter.  Finally I got it going.

The heat sink on this one is different too:  it is just the chassis.   The IRF 510 is bolted (insulated) to the aluminum box.

I fired it up this afternoon and in spite of horrible conditions on 40, quickly had a nice rag chew with KJ4ZMV in Indiana.  I haven't even built a mic amp yet!  I am running the D-104 right into the NE602 balance modulator.  There are no signs of unwanted modulation or spurs.

FB!   TRGHS!   VIVE LA DIFFERENCE!

  

VK3HN: SOTA, HB, SSB, and QRP FB!

Peter VK3YE sent me the link to this amazing site.  Wow, Paul VK3HN does great work, both with the homebrew rigs and in describing his work on them.  Check it out: 

https://vk3hn.wordpress.com/2016/10/25/summit-prowler-one-a-homebrew-7mhz-ssb-qrp-transceiver-for-sota/

Great stuff.  Thanks Peter!  Thanks Paul!

Bert's EMRFD Direct Conversion Receiver

Very nice Bert.  Sounds great.  I like the pill bottle coil core.  Lew McCoy used them in his designs. I do think that air core coils do provide better stability than ferrites or iron powder.   I kind of like the SW broadcast background music.  I also like the internal 9V battery.  Glad to see someone else resurrecting an old DC RX project.  


Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

NA5N on the NE602

I continue to mine the Gadgeteer News archives.
Here is a good one from NA5N.
Orignally posted on Gadgeteer news, 2 December 2006

NE602=NE612=SA602
(Originally posted by NA5N on QRP-L)

Gang,
The ever famous NE602's are manufactured in the Philips
Semiconductor plant in Albuquerque, about 85 miles north of me. I visited
there last summer and had a nice discussion with an applications engineer
about the history of the NE602's. Goes something like this:

This long story will prove that NE602 = SA602 = NE612 = SA612
(for those of you who don't want the gory details -hi)
The original NE602 was designed/manufactured by SIGNETICS for
the 45MHz FM wireless telephone market. A little later, the wafer was
redesigned a bit to allow the internal oscillator to operate to 200MHz and the
RF to 500MHz. This was redesignated the NE612, and was intended to
replace the NE602. However, customers kept ordering the NE602, getting
angry at Signetics because their distributors were out of stock, etc. So when
they made the chips, they made a jillion NE612's, and labeled some of them
NE612 and the rest NE602 to satisfy the users of both parts. This is why
contemporary data books show the exact same specifications for both NE602
and NE612. They came from the same wafer.

Then Signetics was bought out by Philips, who evidently
continued this practice for a short time, then decided it was rather
redundant. So they announced that the production of NE602's has been discontinued
and listed it as an obsolete part ... giving QRPers around the world
various fits of apoplexy to suicidal tendencies that doomsday had struck.
What wasn't well understood is Philips continued to support production of
the NE612, as they do today.

Then to make matters worse, disaster struck the Philips plant
in Albuquerque in the spring of 2000. A wild grass fire in
northwest New Mexico threatened three main electrical lines that run from
the "Four Corners" electrical generating plant to Albuquerque. Smoke
from the fire caused one of the high-voltage lines to arc, tripping the
circuit off line. Virtually the entire electrical load for Albuquerque
and southern New Mexico was now transfered to the two remaining feeders,
which could not handle the full load, causing brownouts, voltage spikes,
etc. until they too failed. Where I live in Socorro, New Mexico, I
remember the brownouts hit about 4:15pm, outages on and off until the
entire grid went down about 5pm, and stayed off until about 11pm. One of the
longest power failures in US history. We just figured it was Y2K about 3
months late. (PS - I worked 40M CW QRP that night by candlelight, and it
was the quietest conditions I ever heard on 40M!!! And every QSO I
heard seemed to be a QRPer). The extreme voltage fluctations as the
feeders were failing caused a transformer at the Philips plant in
Albuquerque to catch on fire. I remember seeing it on the TV news, in which they
said it caused mostly smoke damage from the burning transformer and
burned a couple of storage rooms. That was all-no biggie. Well, it
turned out one of the storage rooms that was burned was where they stored
the film masters for making the semiconductor dies, and the NE612 film
master was now molten emulsion. These film masters were the originals
from the old Signetics company. So Philips had to completely redo the
artwork for the majority of their IC's. Additionally, it turned out the
smoke damage was excessive and the IC fabrication facilities were
left unusable. Philips was basically unable to manufacture IC's at
the Albuquerque plant for months. It was about 8 months before
they got all their wafer machines back on line, which left a huge hole in
the semiconductor industry. I know it just about killed several
cell phone manufacturers because delivery contracts for parts were
suddenly postponed for six to eight months.

The world wide supply of NE602/NE612's virtually dried up
during 2000 as a result of this fire and the nearly year backlog of
manufacturing quotas. The first run of NE612's in 2 years finally occured in
September 2000.This huge shortage of NE612's, combined with the fact that
NE602's have been discontinued/obsolete, is what convinved QRPers that
these nifty little chips were no more. I was told 20,000 units were
manufactured in 2000, or what Philips believes is a 2 year supply. This is
also why the release of the K1 (with 5 NE612's!) was delayed from the
promised "after Dayton" to late in the year, as were other kits. It just
wasn't clear when Philips was going to schedule the NE612's for production.

So yes, the NE602 is dead, but the perfectly compatible NE612
is still available, and Philips has no plans at the present to
discontinue that part number.

For final clarification:
NE602 = plastic DIP, rated 0C to +70C ... OBSOLETE
SA602 = plastic DIP, rated -40C to +85C ... OBSOLETE
NE612 = plastic DIP, rated 0C to +70C ... AVAILABLE
SA612 = plastic DIP, rated -40C to +85C ... AVAILABLE

or, to answer the final question ...
NE602 = SA602 = NE612 = SA612

72, Paul NA5N

W3JDR 's LTSpice NE602/SA612

Here's something we've needed for a long time: an LTSpice model for the ever-popular NE602/SA612 chip. Joe Rocci, W3JDR, developed this one back in December. You can download it, along with the LTSpice program (free!) from links on Joe's page:
http://w3jdr.ham-radio-op.net/ Thanks a lot Joe!

Speaking of Spice, Jim, AL7RV, has been e-cursing me for getting him involved with this highly addictive program. Jim has come up with an ingenious idea for making the simulation experience more realistic. I will tell you all about it in the next podcast.