Thanks Gregg! We are still putting together a group of specs, from this NG
feedback. I have been using a DDS for awhile, but that itsn't as clean as I
would like it to be. Mini-Circuits doesn't have a good tracking VCO that
will cover the 10.7MHz tuning range, so I decided to design my own low
noise, tracking output VCO. My 2nd and 3rd harmonic specs are -25dBc and
-35dBc respectively. With a diode ring mixer, anything greater
than -20dBc puts you in the ball park.

Gregg wrote in message
news:0HW7b.108328$kW.105052@edtnps84...
Behold, Pete KE9OA signaled from keyed 4-1000A filament:

Hi Gregg,
That is exactly what I plan to use..............I have
been
using that topology for several years now, so I've got the Diplexer
design nailed down pretty well.

You sir, are a god! Do you know how many people that are so-called
"engineering professionals" that do not know how to diplex the output of a
diode DBM?

I'm sold, when can I buy it ;-)

I do know what you are talking about.............not everybody thinks about
reducing the noise from the image frequency. My diplexer has a selectivity
of right around 15kHz. I chose the X values to be about 43 Ohms, so the
tuning characteristic is fairly sharp.


I am not sure why more manufacturers don't use doubly-balanced mixers,
especially when you can purchase a Mini-Circuits ADE-3 mixer for around
3 dollars.

Because they can pay 15 cents for a 2SCxxxx.

It all comes down to money. Nothing is about quality, just mark-up and
useless features.

You seem to be doing something that hasn't been done since the late 1950's
- engineering a soul into the unit :-)

You have my highest respect.

Thanks again, Gregg. I contacted one of the high end audio dealers here in
Chicago yesterday, and they seemed pretty excited about the project. We are
definitely moving ahead...................we've already chosen the PLL
(145170), so we just need to verify long term availability. I will be
contacting Murata and Phillips today, about setting up some sort of
relationship. I used to deal with these folks quite a bit, from my Motorola
days.

Pete

That's a definite...........LED backlighting is the way to go. It sounds
like you are in the industry.

Pete

Gregg wrote in message
. ..
Behold, Pete KE9OA signaled from keyed 4-1000A filament:

We were thinking of either LCD, or statically driven LEDs, with the
microprocessor going into sleep mode with no user activity. Oh, I do
like those knobs...........I wouldn't have it any other way. Anyway,
the problem with the flourescent displays is that they are pretty noise.
I plan on this receiver having an MDS of 40 to 50nV, so things have to
be pretty quiet. I think that I will also go with an outboard supply;
this avoids that UL qualification. Another advantage to this approach
is that my outboard power supply can be used with other people's
equipment. Take a look at the power supply on my website, and you will
see that it doesn't take much to design a quiet power supply. On my
general coverage receivers, even when operating off the AC line, when I
tune down to 9 or 10kHz, all I hear is atmospheric noise.

Gotcha on the noise factor. I don't multiplex, but use "static" driven
nixies, so I never thought of the noise.

I use outboard supplies on all my tube low-level audio designs like mic
preamps and mixers. Works awesome!

LCD's are cool. If you choose that route, may I suggest LED backlighting?
That would eliminate electroluminescent driver noise and last forever
compared to incandescent.

My #1 repair call that's not computer related lately is "my lights burned
out". I replace them all with superbright white LED's, or if the customer
wishes, a funky color of their choice :-)

--
Gregg
*Perhaps it's useful, even if it can't be SPICE'd*
Visit the GeeK Zone - http://geek.scorpiorising.ca

http://home.att.net/~n.gianakopoulos...ome.html-.html

The above URL will take you there. As you can see, there are not secret
formulas to any of my designs. Any fairly good PCB designer can duplicate
them pretty easily. There are some pretty cool things there, like a
universal product detector for boatanchors, my own version of Marshall
Leach's Low TIM Stereo Preamplifier, etc.
Have fun!

Pete

Gregg wrote in message
. ..
BTW - what *is* your website? I must have missed the URL somewhere.

--
Gregg
*Perhaps it's useful, even if it can't be SPICE'd*
Visit the GeeK Zone - http://geek.scorpiorising.ca

Thanks, Clifton! Take a look at my website at:
http://home.att.net/~n.gianakopoulos...ome.html-.html
The reason for my setting up that website was to encourage folks to see just
how easy it is to build some high performance equipment. I do need to
qualify, though, that this next design will take those website designs up a
few steps.

Pete

Clifton T. Sharp Jr. wrote in message
...
Pete KE9OA wrote:
Clifton T. Sharp Jr. wrote in message
...
[posted and mailed.]

Those do sound like good ideas, but I think that with what you are
asking
for, the price would probably be around the 250 dollar range.

I figured as much or more myself. I said "$150 might be a nice target"
just to lower the aim, not move the target.

I've got a dozen products on the burner
right now. It's pretty cool, working for an employer that wants to do
these
kinds of things.

If I had the qualifications, I'd probably come be your assistant.

--
"Here, Outlook Express, run this program." "Okay, stranger."

That sounds good.............if you can e-mail me directly, to show me how
to do that, that would be great! I can see that this thread is getting
pretty long!

Pete

RHF wrote in message
om...
Pete,

Until then, you can continue your dialog here.

Or - You could simply start up a YAHOO! eGroup
- - - "High-Performance-MW-Receiver-Project"

There you can create a Message Archive, Photos, Links and Files for
all to share and add to the knowledge base.

Plus the Membership List is a Ready List of 'potential' Customers.

st3a ~ RHF
.
.
= = = "Pete KE9OA"
= = = wrote in message
...
Thanks; this sounds like a good way to go. I am not sure how we are
selling
thing off of our website right now.

Pete

RHF wrote in message
om...
Pete,

Start with a simple Product "Indevelopment" internet website to
provide information and a potential client list: beyond the first
page the webee has to 'sign-up' to view the rest of the website and
you offer an eMail Up-Dates Subscription List. These things can help
in creating the before market BUZZ !

Then when the product is ready to ship, transform the internet website
into a Product "For Sale" Market Basket OnLine Ordering System for
Direct Marketing and Sales.

Simply with "Word of Mouth" and a Internet "Tell A Friend" based
program a large maket can be tapped at a low cost.


st3a ~ RHF
.
.
= = = "Pete KE9OA"
= = = wrote in message
...
I want to thank all of you for your input.................I will be
copying
all of these replies into a Word document, and presenting them to my
employer tomorrow morning. Hopefully, we can make this thing really
fly. I
am really excited about some of the refinements that some of the
folks
at
work have brought up. We had a design meeting that lasted almost 2
hours
this evening, so I think that things look good. Oh, one more
thing......................I believe that we will be selling
directly to
the
public initially, instead of going to distributers. Once we get
this
product to market, I will be there to provide technical support,
answer
any
questions, etc. Thanks again, folks! You are a great bunch!

You bet!

Pete

Clifton T. Sharp Jr. wrote in message
...
Pete KE9OA wrote:
Thanks again, folks! You are a great bunch!

I know you'll thank us by offering a really great radio.

--
"Here, Outlook Express, run this program." "Okay, stranger."

That sounds good; I will definitely look into that one.

Pete

Brenda Ann wrote in message
...

"Pete KE9OA" wrote in message
...
Thanks, Gary. I think that a portable will definitely be on the horizen,
and
the tone control circuit is beginning to sound like a better and better
idea. I think that this can be implemented into the design. The main
thing
is the choice of turnover frequencies of the tone control circuit, for
the
best sound. Back in the early to mid 90s, I used to design and build
custom
acoustic instrument amplifiers, so I've got a bit of experience with
tone
control circuitry.
Thanks for those comments!

Pete

Do you have any experience with the Motorola tone control chips? Those are
quite nice, and just fit right in the normal audio chain with just a few
external components (capacitors, mostly). IIRC, they have about a 12 or 16
dB boost/cut, and I would imagine that you could tailor the crossover
frequencies with the external components..

I thought about that, but I wasn't sure how the skirt selectivity would be.
Right now, even with a Murata CFWS-455H at the 2nd I.F. skirt selectivity is
very good. I think that this is because of the cascaded effects of the
diplexer
(15kHz BW), and the high I.F. filters.

Pete
Frank Dresser wrote in message
...
Have you considered using a single, less expensive IF filter and a Q
multiplier or Q multipliers to change it's shape and bandwidth?

The notch/peak of a Q-multiplier is a very sharp exaggeration of single
tuned circuit. Could a double tuned band pass circuit also be used?
Tuneable band pass notches at both the upper and lower sidebands with a
peak
in the middle would be very useful and would reduce the need for several
fixed filters.

I use a Heathkit Q-multiplier. When it's tuned to the center of the IF
frequency, advancing the regeneration control will smoothly sharpen the
peak
and progressively cut the side bands until it breaks into oscillation.
It's
like an IF frequency tone control! Pretty cool. Another good trick is
tuning in the sidband farthest from the interference. Then I bring the
carrier back up with the Q-multiplier. Or I can use the tunable notch to
get rid of hets.

Frank Dresser

That would be a very cool thing. I did some checking around for good high Q
tuning caps, and with the exception of Palstar (he builds his own high
quality caps), nobody seems to make them. That analog tuning dial with a
small digital display would be pretty cool looking, somethink like the Bruel
and Kjaar? (excuse my spelling) test equipment, or the Sansui 919 AM/FM
tuner.

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

That's the amazing thing about this design; it does have that tube
like sound. As far as performance, we are talking about 18 tube
performance, not 6 or 7 tube performance. I do understand your
doubts, but I think that you will be pleasantly surprised.

I had a 28 tube radio - Collins R-392. My Radio Shack DX-440 (Sangean
803A)
easily equalled it in performance on MW.

I'm a bit of a weirdo, so bear with me. I want a huge analog slide rule
dial with a small digital counter embedded in the center. In other words,
I
like to tune analog, but want digital accuracy. I hate digital stepped
tuning, which is why I no longer use the DX-440.

I like knobs. You can grasp a knob and turn it. I hate sliders.

You should see my HF receivers.................I use variable frequency BFO
injection for that reason.

I want 2-4-6-8-10 filters.

I like the idea of a rotating ferrite bar for casual listening, but want
an
antenna in jack as well.

Definitely

Sync detection is great.

That could be on the horizon, as an add-on. The 2nd I.F. chip that I plan
on using (TDA1572) has a buffered, 50 Ohm I.F. output, just for this reason.
The reason that I haven't considered Sync detection right now, is because I
have haven't yet been able to locate a source of the chips. It seems that
these devices are either on allocation to the large radio manufacturers, or
they are discontinued, and those same radio manufacturers have made lifetime
buys of the remaining stock.

Pete

How about a backlit dial that is continually lighted.

How about a dial pointer that continously changes color, based on signal
strength? If I could find a steady, fairly priced source of good tuning
capacitors (ceramic standoff types), I would go this route. Actually, I
will go with 1kHz tuning steps; this gives a pretty good "analog" feel on
the MW band. I am also thinking about having the radio set up for 9 and 10
kHz steps, but for the 9kHz steps, I would need to also have the unit set up
for the European bandplan. I guess it wouldn't be too hard for our software
guy; he is pretty good.

Pete

Thanks, Doug. I did look at that circuit, and I also looked at a circuit
that used a 4046 Phase Detector. I will definitely consider this one. As
for myself, there is nothing like that sound of the selective fading, to
bring back those youthfull memories of my early DXing days.
On another note......................I could use an Analog Devices AD607. I
tried that chip in the past, but it seemed pretty finicky to work with,
getting the phase shift network to work properly. Maybe I will give it
another try............this would have the Sync Detector self-contained on
only one chip. As with many other chips AD gives an application note for a
10.7MHz based circuit....at 455kHz, you are on your own.

Pete

Doug Smith W9WI wrote in message
...
Pete KE9OA wrote:
option. If we can find a reliable source of Sync Detector chips, that
could
also be an option, but usually, these types of devices are on allocation
with the larger radio manufacturers. I went through just this type of
thing
when I was working for one of the research divisions at Motorola. If we
weren't buying 10,000 devices a week, vendors of some of these specialty
items were not interested.

FWIW there's a sync detector circuit on page 15.34 of the current ARRL
Handbook. (I think it's been in the Handbook for several years) It
uses two NE602s and a NE604, the latter seems to be a FM IF/detector
chip. It's a fair number of parts (may be too expensive simply due to
component count) but I don't think any of them would be particularly
hard to get.

Having used it on the ICF-2010 IMHO you *REALLY* need to consider a sync
detector, dropping other features if necessary. Especially if you hope
to sell to program listeners as well as DXers.
--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com