I got my initial experience just experimenting with different designs from
the ARRL Handbook, hobby radios in some of the electronics magazines, etc. I
had 20 years experience as an electronics repair technician. In 1992, I
decided to get an Associates degree in Electronics Technology at Triton
College, in River Grove, Illinois. One of the classes I took over there was
a speech class, so I decided to give a dissertation about radio systems. The
first radio was nothing but an elaborate version of a crystal radio, except
I used an op-amp with diodes in the feedback loop to have a low level
precision rectifier.
It worked well, but I wanted more, so I gave my friend Dean Woodman, NB9Z a
call. I can't tell you how many 2:00 in the morning phone calls I had with
him concerning design problems. He was my greatest mentor, but
unfortunately, he died in a fire about 4 years ago when some gang bangers
burned his house down. Very sad story.
Anyway, I asked him how hard it would be to design a receiver that would
have the system gain like a Collins 651S-1. He said "it's
easy.............just use a couple of MC1350 I.F. ampliers, with a good
mixer ahead of the system".
After that, I designed my first I.F. subsystem with these devices, but
still, I had to devise and AGC system. After trying numerous designs, I
eventually came up with one of my own, using a couple of op-amps.
Next, came the mixer...........my first mixer used a single diode with a
resistive summing network. I never saw this design published, but I thought
I would give it a try. I worked out pretty well, but I decided to give
Mini-Circuits a try. I discovered that company in a Nuts and Volts
advertisement. The SRA-3 mixer worked out pretty well, so well, in fact,
that I decided to make a dual conversion receiver. I used ceramic filters
from old broken CB radios, along with their crystal filters.
At this time, I didn't know how to design synthesizers, so I used a good
signal generator as the 1st LO. I used a conventional Colpitts design as the
2nd LO, running it a 5mW into another diode ring mixer. The results were
encouraging. A year went by, and I graduated with my degree.
As luck would have it, Rockwell-Collins had an advertisement in the Chicago
Tribune for circuit board designers. It is pretty funny...........a week
before that ad showed up I was telling my wife that Collins Radio Company
would be a place for my dream job.
This turned out to be a very good move; there were extensive training
classes on printed circuit board design, not only for signal integrity but
also from the EMC standpoint. An example is when routing digital lines,
using microstrip of the characteristic impedance of the digital devices. For
instance, CMOS families have a typical impedance of 70 to 90 ohms. By
following these guidelines, it is possible to design a radio that doesn't
have digital hash getting into the RF portion of the system. Another thing I
discovered when working over there was the concept of "filament growth",
whereby if two PCB traces are too close together and there is a certain
potential, a filiment of metal can grow between the traces and short them
out. This mechanism can also occur throught layers of FR4 material because
the substrate has a certain amount of porosity.
Continuing on, Mini-Circuits came out with the POS-XX series of VCOs, so I
thought why not give them a try.
I still didn't know anything about synthesizers yet, so I devised a circuit
that used a 10-turn pot as the tuning element. I used three op-amps to
develop the V_Tune for the low end of the pot and the V+X_Tune voltage for
the high end of the pot.
By using a string of metal film resistors and switching them at different
points along the voltage divider for the V_Tune voltage I was able to have a
bandswitched tuning system that tuned in 3MHz sub-bands to cover from 0 to
30MHz.
After this design was completed, I met Gary Pershin, also of
Rockwell-Collins. You may have seen his homebrew designs mentioned on
rec.radio.homebrew. He said "Pete, why don't we design a synthesizer?" I
told him that I didn't know how to do that, so he came up with a design that
used an MC145152 parallel programmable system. I didn't want to use DIP
switches to tune the radio, so I came up with a sequencer design that used
an optical encoder to send a string of pulses to an array of 74190 counter
chips. Gary came up with a good implementation to set the Asynchrous inputs
of the counters to have a default startup frequency of 10MHz. Using an XOR
gate, he came up with a good way to eliminate the tuning error when changing
tuning directions with the Quadrature optical encoder.
He called me one evening and said "Pete, I have acquired synthesis!" We had
our first synthesized receiver!
After I was at Rockwell-Collins for 2 years, I transferred to the
Synthesizer Group, where I took extensive in-house classes about filter
design, receiver design, and synthesizer design. These were graduate level
classes given by some of the best folks in the industry, so I am grateful
for this. When I was in the Synthesizer Group, I worked with some of the
noted experts in the industry, so once again, I had the benefit of their
years of experience.
The next design I came up with was a unit that used a Philips TDA1572 chip
as the I.F. subsystem. This is the design that I had up on my website for
awhile, after getting clearance from Rockwell-Collins to make the design
public.
In the year 2000, my wife really got homesick for Chicago, so we moved back
to our hometown and I took a job with Motorola, working with spread spectrum
technology. I knew this wasn't the job for me, so I left Motorola and took a
job driving a cab for several months; this allowed me to regroup. In June of
2003, I took a job with my present employer, and have been there ever since.
I do want to branch out and start my own company.............this seems the
way to go. I have so many products that I would like to market that would be
beneficial to the SWL community. The reason that I got interested in
receiver design in the first place was because I got tired of the
overpriced, compromised design offerings that were on the market. That is
the biggest reason I set up my radio design website............I wanted to
share my designs for the world so they wouldn't have to go through all the
years of "paying the dues" and doing all of the research. It was a fun
thing.
So, on a final note..............................I only have a 2-year degree
in Electronics, and 90% of my knowledge comes from on the job training,
in-house design classes, and experience. When I finished my education at
Triton College, I gave my favorite professor, Niel Volk, a super-duper MW
receiver that had a tracking front end and a Mechanical Filter in the I.F.
strip. When he said "Pete, I just don't know what to say", I said "oh, just
tell me that this is a cool radio and that you will enjoy it".
Anyway, I hope this gives you a little bit of an idea of who I am and what I
am about!

Pete

"starman" wrote in message
...
Pete KE9OA wrote:

I've already got a good MW design done..........if my employer will only
finish it up and put it on the market.
snipped

Pete,

I've been curious about your technical background, particularly your
formal education. Where did you learn the subject matter which you
implement so well with radio receivers?

Thanks

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Thanks for the great reply Pete. You are doing some extraordinary work
considering that you started with a two year degree. It shows that good
mentoring and job training are just as important as formal education. I
went to a four year college for electrical engineering but you obviously
know more about receiver design than I do. Of course when I was in
college integrated circuits were almost a new technology. :-)

"starman" wrote in message

Pete,

I've been curious about your technical background, particularly your
formal education. Where did you learn the subject matter which you
implement so well with radio receivers?

Thanks

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Thanks, Mr. Starman.....................anytime you have any questions about
receiver design, synthesizer design, etc...........feel free to give me a
shout. That's the cool thing about knowledge.............it's free to share.
I have a philosophy.......it's not "look what I can do", but it is "look
what you can do too!" Keep tuned!

Pete
"starman" wrote in message
...
Thanks for the great reply Pete. You are doing some extraordinary work
considering that you started with a two year degree. It shows that good
mentoring and job training are just as important as formal education. I
went to a four year college for electrical engineering but you obviously
know more about receiver design than I do. Of course when I was in
college integrated circuits were almost a new technology. :-)

"starman" wrote in message

Pete,

I've been curious about your technical background, particularly your
formal education. Where did you learn the subject matter which you
implement so well with radio receivers?

Thanks

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Build me a Redifusion (Radio) that will from right here,West side of
Jackson,Mississippi U.S.A. that will pick up Monticello,Mississippi
U.S.A.in the daytime real good and good good without any fadeing in or
out,without any external hookup antenna and you have got a Winner.Build
that,I will pick up my phone and hand you my debit card number.I don't
use credit cards. www.forthepeople.org/radiostations.htm
cuhulin

I am not sure how far that is, or what frequency this station is on, but
typically, stations from 200 miles are possible. If propagation permits, you
will be able to hear any signal that is out there. I am working on the new
synthesizer for the radio right now, and I may be able to figure out how to
use the on-board oscillator of the TDA1572 with a crystal resonator. These
new changes will reduce the parts count of the radio by around 30 parts. It
may sound silly, but the fewer components there are, the fewer components
will fail. I remember the first time I looked into a 75A-4 receiver and
thought to myself "where are all the parts?"
Right now, I am looking into aluminum extrusions for the chassis, similar to
what Lowe and AOR use in their receivers. It's got to look as cool as it
works. If I can easily come up with a way to switch filters, I would also
like to have a wide and narrow I.F. bandwidth. Hittite makes some good RF
switches that might do the trick. The other way would be to use PIN diodes
with bias chokes, decoupling caps, and bias resistors. The Hittite devices
have better isolation and don't require these external support components.
Mini-Circuits was nice enough to send me a couple of samples of their POS-25
VCOs. These are really nice........they have internal tracking filters, and
I believe that the phase noise is around the -112dBc mark.............a PLL
circuit will clean this up further. If I can achieve a final phase noise of
around -120dBc, I will be happy.

Pete

wrote in message
...
Build me a Redifusion (Radio) that will from right here,West side of
Jackson,Mississippi U.S.A. that will pick up Monticello,Mississippi
U.S.A.in the daytime real good and good good without any fadeing in or
out,without any external hookup antenna and you have got a Winner.Build
that,I will pick up my phone and hand you my debit card number.I don't
use credit cards. www.forthepeople.org/radiostations.htm
cuhulin

I went through College,sort of.Back in 1972-1973,I went to welding
school night classes at Raymond Junior College on the G.I.Bill in
Raymond,Mississippi.That is eight miles or so Southwest of my doggys
couch.Cute gals over there too :{)
cuhulin

Monticello,Mississippi,,, I am guessing is about 70 miles South of
Jackson,you can look it up in a Rand McNally Road Atlas if you want
to.It is a low power radio station,I think,because I can not pick it up
in the day time even with my best radio I own.And a certain one of my
old Radio's is a damn good one too.I know a guy who lives in Monticello
with his wife and family,back around 1973,I bought a 1919 Ford T Model
chassis from him for $250.00.He restores Corvette cars to help keep the
wolf away from the door,if y'all know what I mean.
cuhulin