KE9OA's High Performance MW Receiver
 

Hello, Pete!

Is there any word on your design process going forward?

VY 73s,

Steve Lawrence
Burnsville, MN


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Behold, Stephen M.H. Lawrence signalled from keyed 4-1000A filament:

Hello, Pete!

Is there any word on your design process going forward?

/me wonders too ;-)

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

Behold, Pete KE9OA signalled from keyed 4-1000A filament:

Right now, I
am working on a low noise VCO design, with a tracking filter at the
output.

Hi Pete,

Hadn't you mentions DDS?

Anyway, what about a Colpitts running at 1/2 Fo, then buffering on the
second harmonic. This was a trick used by pre-SS ham's to get a nice,
clean VFO out.

Another, I forget the name, is a Colpitts with the emitter tuned to 1/2
Fo, obtaining a fairly pure spectral output.

Just an idea ;)

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

"Pete KE9OA" wrote in message ...
As far as the receiver itself, we have located a pretty good
CPU..................my boss wants to put in some fancy features, such as a
spectrum display, etc. I would also like to aim this receiver at the average
person, so I am thinking about bass and treble controls.

I may not be the average person... but some random thoughts away from
"fancy features":

1. A tuned front end? It really does make a difference.

2. Still using DDS for the LO? Make sure the encoder knob "feels" like a
good old variable capacitor (or variable inductor). I have been
universally disappointed by the shaft encoders used on current
synthesized radios.

3. The closer any spectrum display can be made to a good old panadaptor,
the better. They did that user interface right. Again, I'm disappointed
by the spectrum displays on current production hardware, but I may
be the last guy who still likes knobs over a bazillion mode buttons.

Tim.

Pete KE9OA wrote:
Also, what about a regeneration circuit................would this be a good
thing?

I've seen the regeneration in the Kiwa loop demonstrated, and it's
certainly an *interesting* feature. I'm not really convinced it's all
that important if the attached receiver has adequate selectivity.

(on the other hand, if you're thinking about selling the antenna
stand-alone to people who want to use it with someone else's receiver,
the regeneration may be worth doing)

don't want it to suffer the R75 curse! I have been revisiting the Analog
Devices AD607 chip; this would make Sync AM possible, but this chip doesn't
have envelope detection. Analog Devices only has an application note for a

Speaking just for myself, I think if there's a decent synchronous
detector, there's no need for an envelope detector.
--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com

I do understand that one......................anyway, I will be going with a
PLL type of synthesizer. I will be using a DAC to provide the tuning voltage
for the tracking front end. I may have a feedback system that monitors the
RSSI; this way, the front end can be optimized pretty easily.
As far as that tuning knob, I agree..................it is good to have that
analog feel. I also like knobs vs. menus. If you take a look at my general
coverage models, I even use a variable BFO; this way, you can set the
carrier reinsertion point down at the right point on the filter slope
(approximately -24dB). There's just something about those old receivers!

Pete

Tim Shoppa wrote in message
om...
"Pete KE9OA" wrote in message
...
As far as the receiver itself, we have located a pretty good
CPU..................my boss wants to put in some fancy features, such
as a
spectrum display, etc. I would also like to aim this receiver at the
average
person, so I am thinking about bass and treble controls.

I may not be the average person... but some random thoughts away from
"fancy features":

1. A tuned front end? It really does make a difference.

2. Still using DDS for the LO? Make sure the encoder knob "feels" like a
good old variable capacitor (or variable inductor). I have been
universally disappointed by the shaft encoders used on current
synthesized radios.

3. The closer any spectrum display can be made to a good old panadaptor,
the better. They did that user interface right. Again, I'm
disappointed
by the spectrum displays on current production hardware, but I may
be the last guy who still likes knobs over a bazillion mode buttons.

Tim.

Thank you, Mr. Smith. You answered my question a couple of posts back in
this thread. The Analog Devices AD607 seems like a good thing to follow up
on.
As far as the loopstick, I still may develop that regen circuit for the
stand alone unit.

Pete

Doug Smith W9WI wrote in message
...
Pete KE9OA wrote:
Also, what about a regeneration circuit................would this be a
good
thing?

I've seen the regeneration in the Kiwa loop demonstrated, and it's
certainly an *interesting* feature. I'm not really convinced it's all
that important if the attached receiver has adequate selectivity.

(on the other hand, if you're thinking about selling the antenna
stand-alone to people who want to use it with someone else's receiver,
the regeneration may be worth doing)

don't want it to suffer the R75 curse! I have been revisiting the
Analog
Devices AD607 chip; this would make Sync AM possible, but this chip
doesn't
have envelope detection. Analog Devices only has an application note for
a

Speaking just for myself, I think if there's a decent synchronous
detector, there's no need for an envelope detector.
--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com

RHF wrote in message
om...
PETE,

It is good to hear that this 'project' is still in the works.
- - - My comments [RHF] have been inserted into your message.

kutgw ~ RHF
.
.
= = = "Pete KE9OA"
= = = wrote in message
...
Hi folks,
Things have been going a million miles an hour! Right
now, I
am working on a low noise VCO design, with a tracking filter at the
output.
I have also been looking at a dual conversion chipset that Phillips came
out
with for the auto radio industry. These devices are used in the
Cambridge
Audio Model T500 FM/AM Tuner. Performance is pretty amazing on the MW
band,


[RHF] Regeneration in a 'stand-a-lone' Shielded Ferrite Rod AM/MW
Antenna would be a nice/useful feature. This would naturally be
'tunable' across the AM/MW Band and function as a 'tuned' RF Front end
for the Radio - Would It Not?

This will definetely be a tunable device; it is the only way to go.

[RHF] The Spectrum Display is a 'nice idea' for an Option of
Accessory:
- But what does that do to the price and basic afordability?
- - A built-in AM Sync Detector and PBT are a more important features
to me.

If I go with the single conversion route, I wouldn't be able to have the
PBT, but Sync AM is definitely in the works. I will definitely be working on
a steep skirted filter that has a flat passband.

[RHF] The "MODS" on the R-75 eGroup for the R75's AM/MW Sync-Detector
make it a good performer.
http://groups.yahoo.com/group/icomr75/files/

[RHF] Also the basic AM/MW Sync-Detector in the Grundig Satellit 800M
is a good performer.

I have played with that receiver, and it does sound good. I want to come up
with a design that tracks the signal all the way down into the noise. I
think that a big part of it will be having a long enough time constant on
the loop filter, so that if a signal fades out, there is enough hysteresis
to "hang on". The tradoff is acquistion time of the system, but I think that
I will be able to find a happy medium.
About the R75................I never did do the Sync mod to mine. I never
use that function. About the only thing I do is remove those MW attenuators.
Anyway, it looks like the majority of my e-mails have asked about Sync
detection, so this is the path I will follow on this design. Thanks for all
of your input!

Pete

Tim Shoppa wrote:

"Pete KE9OA" wrote in message ...
As far as the receiver itself, we have located a pretty good
CPU..................my boss wants to put in some fancy features, such as a
spectrum display, etc. I would also like to aim this receiver at the average
person, so I am thinking about bass and treble controls.

I may not be the average person... but some random thoughts away from
"fancy features":

1. A tuned front end? It really does make a difference.

2. Still using DDS for the LO? Make sure the encoder knob "feels" like a
good old variable capacitor (or variable inductor). I have been
universally disappointed by the shaft encoders used on current
synthesized radios.

US Digital has a line of optical encoders that spin freely
and with no hint of inbalance or friction, let alone actual
detents.

I played with one and was as impressed by its performance as
I was shocked by its price. :) Then again, $50 for an
optical encoder that lasts forever is probably a lot better
than $25 for one that feels "clicky" and mechanically wears
out after a short time, especially in the "Craft" end of
production volumes.

I still am rather annoyed at Drake for putting such a
lousy encoder on the R8B. For that kind of money, I'd
expect something with a lot better longevity and feel. I'd
have gladly paid an extra $50 for the radio for the
"optical" option, if Drake had offered it. I bet a lot of
you would too, given how much better they work. :)

-- Ross


3. The closer any spectrum display can be made to a good old panadaptor,
the better. They did that user interface right. Again, I'm disappointed
by the spectrum displays on current production hardware, but I may
be the last guy who still likes knobs over a bazillion mode buttons.

Tim.

Doug Smith W9WI wrote:

Pete KE9OA wrote:
Also, what about a regeneration circuit................would this be a good
thing?

I've seen the regeneration in the Kiwa loop demonstrated, and it's
certainly an *interesting* feature. I'm not really convinced it's all
that important if the attached receiver has adequate selectivity.

(on the other hand, if you're thinking about selling the antenna
stand-alone to people who want to use it with someone else's receiver,
the regeneration may be worth doing)

don't want it to suffer the R75 curse! I have been revisiting the Analog
Devices AD607 chip; this would make Sync AM possible, but this chip doesn't
have envelope detection. Analog Devices only has an application note for a

Speaking just for myself, I think if there's a decent synchronous
detector, there's no need for an envelope detector.

Agreed -- I'd never miss an envelope detector if I had a
good Sync. detector, but this is clearly ASSUMING the sync.
detector circuit degrades gracefully as it loses lock on
extremely weak signals. If it's going to pop rapidly in and
out of sync. in response to fast & deep fading instead, I'd
argue that would be a huge complaint area. The original
Drake R8 had OK sync., but it really couldn't handle signals
that faded below its ability to maintain phase lock. Same
with my Sony 7600G. I turn off sync. for very weak signals
to avoid the PLL sweeping around and making squeals and
other annoying noises as lock is acquired and lost rapidly.

Just a thought.

-- ross


--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com