Behold, Photodano1 signalled from keyed 4-1000A filament:

Is it going to be in kit form? )

That'd be sooo coooool! :-D

--
Gregg
*It's probably useful, even if it can't be SPICE'd*
http://geek.scorpiorising.ca

Thanks, Eric, and all the other folks! I just got through building up the
2nd pass of the prototype, and it looks good. The MDS is less than .1uV, and
the system doesn't go into clipping until 50,000uV, so I would still like to
bump that up a bit. The sensitivity figure is with no RF amplification ahead
of the mixer. I am using a doubly-balanced diode ring mixer, followed by a
diplexer, crystal filter, and another matching network, followed by a
TDA1572. Audio distortion is .5%, with a 100uV signal.
I still would like to be able to implement the 1572's on-board oscillator,
but it just doesn't seem to work with a fundamental mode crystal. Using the
recommended values from Philips only yields an oscillator with the LC
network dominating the circuit.
Next week, I will start the Sync detector design. This weekend, I will be
winding some prototype loopsticks. I was able to purchase a few samples of
ferrite rod stock from Elna, but unfortunately, the minimum order from them
is 3,000 pieces @ $1.50 each. Sure beats Palomar's prices, at $15.00 each!
There are still a few other issues with the design................with a
1kHz tuning step size, the loop filter needs to have a natural frequency of
about 15Hz. This gives a settling time of around 100mSec, which is okay, as
long as you don't make large tuning changes (memories). There are some
solutions..........one of them is to use a DAC to pretune the VCO to the
desired frequency, and let the PLL take over afterwards. National
Semiconductor does have some chips in their LMX-XXXX series of synthesizer
chips, but unfortunately, the fractional N types with the speedup circuit
that I had in mind don't go low enough in frequency. Then, you have the
fractional N sidebands to contend with, unless you use a Modulated
Fractional N Divider (MFD). This technique used Sigma_Delta Modulation to
translate the noise sidebands far out from the carrier, so they are much
easier to filter. Hewlett-Packard used that design in their 8642 series of
signal generators, but in my web scouring, I did discover that Philips
supposedly had a Sigma-Delta type of synthesizer. Now, that sounds
interesting...............

Pete

Eric F. Richards wrote in message
...
Thanks for keeping us in the loop on this, Pete, I'm *really* looking
forward to this one hitting the market.

Eric

--
Eric F. Richards,
"Nature abhors a vacuum tube." -- J. R. Pierce, Bell Labs, c. 1940

Anytime, Gregg. I live very close to WBBM, 780kHz, and no IM products were
noted on 1560kHz. Things are moving ahead!

Pete

Gregg wrote in message
news:vrGzb.8122$d35.6541@edtnps84...
Behold, Pete KE9OA signalled from keyed 4-1000A filament:

........in the "RF Alley" that I live in, with
three 50kW MW broadcasters, no overload problems were noted. I will
keep all of you posted on the progress of the design.

All thanks to that diode-ring mixer ;-)

Thanks for keeping us posted Pete!

--
Gregg
*It's probably useful, even if it can't be SPICE'd*
http://geek.scorpiorising.ca

No, this will be an assembled unit.

Photodano1 wrote in message
...
Is it going to be in kit form? )

Pete KE9OA wrote:

The MW receiver is progressing pretty well.................I have completed
the synthesizer, and am now doing the final pass on the receiver board
itself. MDS measures at .2uV right now, with strong signal handling up to
about 900mV.
Next week, I plan to design the sync detector, but there are a couple of
things to keep in mind. If there are two closely spaced signals, the
stronger signal will capture the system. For this reason, I may also include
the envelope detector function.
The initial results are very encouraging....................in the "RF
Alley" that I live in, with three 50kW MW broadcasters, no overload problems
were noted. I will keep all of you posted on the progress of the design.

Pete

How are you designing the PC board(s) for this receiver? Do you use some
CAD software?


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Pete KE9OA wrote:

Yes, Marvin.................we will be marketing this receiver. Our software
guy still has to write the programming code for the synthesizer, along with
the code for the graphics LCD. I should have all of the RF design completed
by the end of the month, so the ball will be in his corner. I am hoping for
a March or April ship date, but you know how schedules can slide. As far as
style, I am thinking of making it about the size of the Drake SW8. Let me
know what you are looking for, folks!

Pete

Did you have to outsource the LCD display or did you find an off the
shelf one that's suitable? How will you backlight the LCD?


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I so use a CAD program. For the prototyping, I print out the artwork on an
Inkjet transparency, and use boards that have a photosensitized resist. Our
jobber wants 250 dollars for each prototype run, so it is cheaper for me to
do it myself.
Once I get everything designed, we will go to our board house, and have some
real boards made up. It is quite a bit of work, spotfacing all of the holes
on the ground plane, and soldering feedthrough wires, to connect the top
ground plane to the copper flood on the bottom side of the board, but it is
the only way to get a board with a nice low impedance RF ground.
Another interesting thing.................it is a good idea not to lay down
your ground vias on a fixed grid; instead, drop them around the board in a
pseudo-random fashion. This way, you can minimize the chances of having
resonances in the structure.
I remember one project that I was working on a few years back. The designer
decided to lay down all of the ground vias on a 50 mil grid. This was a
900MHz hybrid synthesizer, that used a mixing scheme to translate the tuning
range. Anyway, the board had a very sharp resonant peak right in the middle
of the image band. The engineer that I was working with didn't believe that
this was the case, until we started drilling out the vias with a Dremel
tool.
A good way to check a PC board for undesired resonances is to take the
unpopulated board, and connect an SMA launch at each end of the board (input
and output). Connect a network analyzer, and you should see a flat noise
spectrum, if the board was properly designed.
Another trick of the trade for checking VCOs is to connect a network
analyzer to the inpur of the VCO. Set up the analyzer for a Smith Chart type
of display. You will know if you have your feedback capacitors optimized for
the tuning range of interest, if you are centered in the maximum magnitude
region of negative resistance. This was a pretty common technique at
Rockwell. When I mentioned this to the folks that I was working with in my
department at Motorola, they had never heard of this method.

Pete

starman wrote in message
...
Pete KE9OA wrote:

The MW receiver is progressing pretty well.................I have
completed
the synthesizer, and am now doing the final pass on the receiver board
itself. MDS measures at .2uV right now, with strong signal handling up
to
about 900mV.
Next week, I plan to design the sync detector, but there are a couple of
things to keep in mind. If there are two closely spaced signals, the
stronger signal will capture the system. For this reason, I may also
include
the envelope detector function.
The initial results are very encouraging....................in the "RF
Alley" that I live in, with three 50kW MW broadcasters, no overload
problems
were noted. I will keep all of you posted on the progress of the
design.

Pete

How are you designing the PC board(s) for this receiver? Do you use some
CAD software?


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Pete KE9OA wrote:

starman wrote in message


How are you designing the PC board(s) for this receiver? Do you use some
CAD software?

I do use a CAD program. For the prototyping, I print out the artwork on an
Inkjet transparency, and use boards that have a photosensitized resist. Our
jobber wants 250 dollars for each prototype run, so it is cheaper for me to
do it myself.
Once I get everything designed, we will go to our board house, and have some
real boards made up. It is quite a bit of work, spotfacing all of the holes
on the ground plane, and soldering feedthrough wires, to connect the top
ground plane to the copper flood on the bottom side of the board, but it is
the only way to get a board with a nice low impedance RF ground.
Another interesting thing.................it is a good idea not to lay down
your ground vias on a fixed grid; instead, drop them around the board in a
pseudo-random fashion. This way, you can minimize the chances of having
resonances in the structure.
I remember one project that I was working on a few years back. The designer
decided to lay down all of the ground vias on a 50 mil grid. This was a
900MHz hybrid synthesizer, that used a mixing scheme to translate the tuning
range. Anyway, the board had a very sharp resonant peak right in the middle
of the image band. The engineer that I was working with didn't believe that
this was the case, until we started drilling out the vias with a Dremel
tool.
A good way to check a PC board for undesired resonances is to take the
unpopulated board, and connect an SMA launch at each end of the board (input
and output). Connect a network analyzer, and you should see a flat noise
spectrum, if the board was properly designed.
Another trick of the trade for checking VCOs is to connect a network
analyzer to the inpur of the VCO. Set up the analyzer for a Smith Chart type
of display. You will know if you have your feedback capacitors optimized for
the tuning range of interest, if you are centered in the maximum magnitude
region of negative resistance. This was a pretty common technique at
Rockwell. When I mentioned this to the folks that I was working with in my
department at Motorola, they had never heard of this method.

Pete

That's really interesting. I've studied how Drake designed the PC boards
for their R8 series of receivers. I'm going experiment with the
grounding system to see how it affects the synthesizer noise which shows
up at certain frequencies, mostly in the higher HF range. It's much less
on the 'B' model than earlier versions but I think there's still room
for improvement.

Thanks for the reply.


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PETE,

IMHO: The Drake SW8 would be a nice package size for both
a Desk Top (AC) or with batteries for mobile/portable use.

~ RHF
..
..
= = = "Pete KE9OA"
= = = wrote in message ...
Yes, Marvin.................we will be marketing this receiver. Our software
guy still has to write the programming code for the synthesizer, along with
the code for the graphics LCD. I should have all of the RF design completed
by the end of the month, so the ball will be in his corner. I am hoping for
a March or April ship date, but you know how schedules can slide. As far as
style, I am thinking of making it about the size of the Drake SW8. Let me
know what you are looking for, folks!

Pete

Marvin Kroll wrote in message
...
Is there any other information available about this receiver?
Is it meant to produced commercially?

"Pete KE9OA" wrote in message
...
The MW receiver is progressing pretty well.................I have
completed
the synthesizer, and am now doing the final pass on the receiver board
itself. MDS measures at .2uV right now, with strong signal handling up
to
about 900mV.
Next week, I plan to design the sync detector, but there are a couple of
things to keep in mind. If there are two closely spaced signals, the
stronger signal will capture the system. For this reason, I may also
include
the envelope detector function.
The initial results are very encouraging....................in the "RF
Alley" that I live in, with three 50kW MW broadcasters, no overload
problems
were noted. I will keep all of you posted on the progress of the
design.

Pete

Pete, best of luck with your endeavor. I'm sure that whatever you
come up with will be more than worthy, but here's my two cents
anyway:) What about the audio? If you could duplicate the deep bass
response and crystalline highs of the Grundig Satellit 600 and 650 you
would have a radio for the ages. That's what we all want, the best
listeners' radio which is also a superb dxing machine. A handle would
be nice also.

Bon Chance,

Grumpus


"Pete KE9OA" wrote in message ...
Yes, Marvin.................we will be marketing this receiver. Our software
guy still has to write the programming code for the synthesizer, along with
the code for the graphics LCD. I should have all of the RF design completed
by the end of the month, so the ball will be in his corner. I am hoping for
a March or April ship date, but you know how schedules can slide. As far as
style, I am thinking of making it about the size of the Drake SW8. Let me
know what you are looking for, folks!

Pete

Marvin Kroll wrote in message
...
Is there any other information available about this receiver?
Is it meant to produced commercially?

"Pete KE9OA" wrote in message
...
The MW receiver is progressing pretty well.................I have
completed
the synthesizer, and am now doing the final pass on the receiver board
itself. MDS measures at .2uV right now, with strong signal handling up
to
about 900mV.
Next week, I plan to design the sync detector, but there are a couple of
things to keep in mind. If there are two closely spaced signals, the
stronger signal will capture the system. For this reason, I may also
include
the envelope detector function.
The initial results are very encouraging....................in the "RF
Alley" that I live in, with three 50kW MW broadcasters, no overload
problems
were noted. I will keep all of you posted on the progress of the
design.

Pete