snip


The design I evolved for my variable frequency superhet leaves
behind all of the many AM radios I have repaired as new and tested
in my kitchen for comparison. Even an old Quad AM tuner I have is no
better.

Patrick, have you published the schematic for your radio? How amenable
is your design for turning it into a kit? And what are its overall
specs?

Overall specs are excellent as detailed in many previous
postings.
No, I havn't posted the full schematic, and no, I am not aiming
to supply details to anyone else to make into a kit for sale.
So you'll have to do your own R&D, at your own expense,
using your time, not mine.



It sounds like a good MW DXer combined with high audio quality.

A TRF fixed F tuner with say two j-fets could be cobbled up
with preset RF transformers, in the same format as the double tuned
IFTs and with necessary couplings and input LC to broaden the pass
band. Miniature sized coils and cans could be used and each module
with the RF amps would fit on a board about 70mm x 40 mm, which is
2,800 sq.mm.

Thanks. The single frequency tuning board you sized is somewhat close
to the size I essentially guessed at. So we'll go with your estimate
of 70mm x 40mm.

120 such modules could then fit on a board about 350,000 sq.mm,
so that 10 boards would each be 35,000 sq mm, and about 190 mm x 190
mm, and thus all fit in a box the same size as a variable tuner
radio from the 1940s. Chuck in an extra board with tubed detector
and audio preamp, and 120 position switch, and a PS, and you're
done.

Another way to look at this is by a volumetric analysis, since one can
take advantage of plugging modules in a motherboard-like fashion.
Let's assume the modules will be 70 mm by 40 mm, and let's assume we
have to space the modules 19 mm apart because of the height of the
components soldered on. (Is this reasonable? -- 19 mm is the spacing
between PCI boards on a PC MB.) This means each module must minimally
take up a volume of 53,200 mm^3. 120 modules therefore will occupy a
minimum of 6,384,000 mm^3 (6.4 liters). This works out to a cubic box
186 mm on a side, or in English units 7.3" on a side (alternatively,
it works out to about 390 cubic inches for those not used to working
in metric.)

Of course, a cube is aesthetically and practically not the way the
modules would be distributed. So let's assume we plug the modules into
the "motherboard", with the long side (70 mm) sticking up. This would
yield a single motherboard footprint of 142 square inches, or about
one foot on a side, and about 3" tall. If we split it into two
motherboards, each holding 60 modules, then the footprint would be
8.4" on a side, with a height of about 6".

Yes, this is not an insignificant volume, but it is not a huge volume.
I notice that the three gang tuning air capacitor on my Philco 37-670
occupies a space of 3"x4"x7", or about 84 cubic inches, about 1/5 the
volume of the 120 module "box" (in a channel TRF, the tuning capacitor
would not be used.) Also remove the small volume taken up by the IF
section (no idea how much volume that typically takes up in a tube
set, but it is not tiny.)

Now, let's look at the 20 module motherboard. Here, the necessary
one-level motherboard would have an area of 24 square inches. Thus, a
6"x4" motherboard (make it 7"x5" for some clearance) will hold 20
modules, plugged in. The height will be 3". Now this seems reasonable
when the end-user only intends to tune in 20 local stations. It is
smaller in volume than the 3-gang tuning air capacitor on my Philco.
Of course, it will only tune 20 stations, and nothing in-between.

From the perspective of tuners in general (not specific to tube type
tuners, but also solid state and digital), the channel TRF does not
make sense. But with respect to a tube-based tuner, it does seem to
make sense for *some* applications. Since the only ones who will even
buy or build an AM tube tuner are tube-o-philes or tube-o-holics
(those who are attracted to tube-based equipment for whatever
aesthetic reason), the aspect of "commercial application" as we
understand it for ordinary radios does not enter the picture.

Those who simply want to get some job done with a radio (listening to
local stations, DXing, etc.), and are not overly enamored with any
particular under-the-hood architecture, will certainly NOT gravitate
to any tube-based tuner because of the much better and cheaper options
out there in the marketplace (digital and SS designs -- I don't know
of any tube-based high-end general coverage receiver being built
today -- and I'd be surprised if someone is attempting it.)

As Patrick noted, and which I agree wholeheartedly, pure digital is
the future of radio for utilitarian purposes (if BCB and FM radio
itself even has a future!)

But that's the point. In this discussion we are not talking about
building a radio for those who want to get a job done, but those who
are enamored with tubes and want the best possible sound out of the AM
tuner.

Then the cabinet size for the tubed tuner will be enormous compared to
using fets,
and there will be 240 tubes in there for all the single channel tuner
modules.
A tubed tuner with 120 x two tubed modules is an absurd idea.
Its a waste of time trying to suggest such a kit with tubes.
So please try to be practical, instead of a perpertual waffler.
I think practicalities will force you to abandon tubes, and adopt
SS or go to a decent superhet. I am not sure you will figure this out,
since you just don't seem to know enough, imho.

For this purpose, the channel TRF is certainly a viable
candidate, along with a tuned TRF (as John Byrns is apparently working
on), as is the more traditional IF design (which Patrick says he is
working on.)

If the components for each tuner board cost $20, then about $3,000
for the 120 + PS, box, etc, all would be a steal, and a quite cheap
sort of "high-end" price. An asian maker of boards might reduce the
cost by 20 dB to $2 each.

Obviously, the component cost is significantly higher than for a
traditionally tuned circuit because one is using a larger number of
components, most of which will not even be powered while the tuner is
selected to a particular channel frequency. So in a sense, this is a
significant inefficiency.

But for a tuner intended to tune in local stations, the channel TRF
tube tuner appears to have some things in its favor. As a
tube-o-phile myself, one can make several strong arguments in favor of
the channel TRF tube tuner: 1) the circuitry is "clean", no IM mixing,
2) the bandpass filters are *perfectly* optimized for each channel --
no compromises (this is a *huge* attraction), 3) provides the ability
to plugin different bandpass filters for a particular station (if
needed), and 4) *may* be more amenable to a kit than would a full-
blown superhet design.

Now, if a tube-o-phile wants a tube tuner for serious MW DXing (for
whatever reason -- I would not use a tube tuner for *serious* DXing),
then the channel TRF is not down and out, but certainly has its work
cut out for it to try to compete with the continuously-tuned TRF, and
of course with traditional superhet designs. The need to include all
120+ BCB channels does work against the "channel TRF".

(On the other hand, I can see a serious MW DXer build a single-
channel TRF design of three or four RF amp stages where the bandpass
sections are "swappable" to tune the channel wanted to monitor.
Here the design will simply have a single slots for each bandpass
filter stage -- no channel switches. Just swap the mini-boards to
retune to a different frequency.)

I eagerly await your completion of a prototype of just one single
iddy biddy TRF tuner board which has all the discussed and wanted
capabilities with respect to audio BW, distortions, sensitivity,
selectivity to allow local station listening where weak and powerful
stations exist which are only 40 kHz apart, all without spurious
noise, interference, cross modulation, etc.

First, I assume that sensitivity is largely a matter of the RF amp
itself (and number of RF amp stages), not the bandpass filter itself
(although the filter should not overly get in the way of RF amp gain.)
But if the bandpass filter plays a greater role in sensitivity than I
realize, shouldn't an optimally tuned bandpass filter in the channel
TRF concept significantly outperform the limited and sub-optimal
single or double stage bandpass filters one is *forced* to use for
continuous tuning?

Second, each tuning module (for a single frequency) is, by and large,
independent of all the other modules. Thus, this simplifies the design
process since one doesn't have to share the same bandpass component
values from channel to channel, except maybe the RF transformers. This
should make it much easier, not harder, to achieve the performance
goals.

In the channel TRF, we are no longer constrained to single or double
tuning -- we can, for example, have the equivalent of quintuple
"tuning" for a 5th order bandpass filter if we want. I'm assuming
that, for a given frequency, the designer will have full control over
the values of all the LC components (and not just one or two,
excluding the RF transformer, though) in the bandpass filter, thus
making it much easier to achieve selectivity, distortion and other
performance goals, all the while simplifying the main part of the
circuit -- to make it cleaner -- fewer kludges needed.

(I keep looking at advanced radio circuits and see such a spiderweb of
wiring between the various stages, wondering why the hell it is all
there -- I wonder how much of that complexity is due to not being able
to properly optimize the RF bandpass filters for a given frequency,
thus requiring all sorts of work-arounds to get good overall
peformance.)

It is a remarkable achievement for a radio designer to meet the
several specification goals Patrick listed for an AM BCB tuner (his
list appears to be an "all things for all users" dream list) and which
is continuously tunable from 500 khz to 1800 khz (thus necessitating
most of the tuning components be shared.) I have no doubts that
Patrick has come up with a great design.

Superhet definitely helps with accomplishing this feat, but from what
I see, there are a lot of ****ty superhets out there, so if superhet
alone were sufficient, the perfect radio would have been designed
years ago. (Isn't the AA5 that perfect radio? -- it is, depending upon
the definition of "perfect" -- it is "commercially" perfect for the
masses.) IF is not the magic bullet (albeit it is a powerful one), but
simply a nifty tool to get from here to there. But like all nifty
tools, they have their limits and their place. One does not use a
hammer to drive in a screw, for example.

Almost the entire amount of AM radio reception theory that has ever
filled the minds of conscious humans has been repeatedly explained
so far in this thread, so you have all the knowhow you ever wanted,
so what's the hold up? Stop dithering, and go to it man!

Actually the know-how has not been explained in full! :^)

Well then if you don't think you have bothered all of us for long enough
to extract our knowledge to do anything, then try
some study and in-workshop experiments to get yourself up to speed on
RF designs.
If you want it, then you do it.


Thanks for your feedback. It is definitely adding useful information
to this thread.

Jon Noring

I leave you to your AM tuner meanderings, and wish you well
in your R&D.

Patrick Turner.

snip,


Note again that Patrick himself said that IF is not needed when one is
building a single frequency receiver -- and from his comments he is a
very strong advocate of superhet design for a tunable receiver. That's
all the channel TRF is: a single frequency receiver, duplicated n
number of times (where n is the number of channels one wants to tune,
which are switched in and out.)

The downsides of a channel TRF are obvious: plumbing (wiring)
complexity for an all-channel BCB tuner, and not being able to
continuously tune all frequencies within the BCB.

I would think that a kit should be simple, the proposed solution is not.

At 120+ channels, the channel TRF is intimidating (the switch box and
individual tuning circuits), but at 15-20, with the plugin
architecture I am thinking of, it does not look that complicated,
especially if a lot of the architecture and components we see used in
PCs can be utilized.

120 separate AM channels with perhaps 480 discrete LCs and two tubes each is an
entirely
overcomplex and impractical idea.

Pigs would fly before you make a profit selling any kits.

You'd need a 6.3 volt x 72 amp power supply just for the filaments alone,
as well as 2 amps x 300v for the B+.

Please re-arrange your mind's thinking to permit practical and saleable and
effective ideas only.

Patrick Turner.

Patrick Turner wrote:

Patrick, have you published the schematic for your radio? How amenable
is your design for turning it into a kit? And what are its overall
specs?

Overall specs are excellent as detailed in many previous postings.
No, I havn't posted the full schematic, and no, I am not aiming
to supply details to anyone else to make into a kit for sale. So
you'll have to do your own R&D, at your own expense, using your
time, not mine.

Is it because you plan to market the design? Or that you simply don't
want anyone else to "profit" from your design?

The trend these days is to open source software, and now there's a
move to open source mechanical designs. I see the same for open
sourcing electronic designs, such as radio receivers.

Obviously, the designer of anything has the right to do with it as
they please, but I find it perplexing that you have decided not to
share your design with the rest of the world, and with posterity. But
that's your choice. When you die (as we all must), does the design die
with you?

And about the so-called "kit", I myself know that it is not a money
maker -- I'm sure you will agree with that. The goal is not to make
money (which isn't there anyway), but rather to just get something out
there for people to build and enjoy. So you would not be interested in
your design to be "kit-i-fied", and called the "Turner AM Tuner"? The
kit itself will essentially be like what diytube does: provide the PCB
boards, a schematic, parts list and directions, and the kit builder
has to wing it from there. If they don't want to even use the PCB
boards, they have the schematic and parts list to work from. In fact,
I would prefer to open source the schematic and parts list for the
AM tube tuner if you agreed with that -- that way no one will make
money from it in a proprietary sense.


Then the cabinet size for the tubed tuner will be enormous compared
to using fets, and there will be 240 tubes in there for all the
single channel tuner modules. A tubed tuner with 120 x two tubed
modules is an absurd idea.

???

Maybe I miswrote in my last reply, but that's NOT what I have in mind.
All channels will share the same tubes and RF transformers -- only the
rest of the tuned bandpass circuitry (mostly a few LC components) will
be swapped between channels. You yourself sized it out in your prior
reply, showing you understood this. [I'm just repeating this in case
someone reading this message in the distant future, who does not have
access to the other prior messages, will not be misled as to the
design I am exploring.]

For 15-20 channels, the design appears practical and doable. For 120+
channels, it's much more of a push.

Maybe reality will get in the way of doability, but for the 15-20
channel design, no one has yet offered any show stopper reasons why
it cannot work (both in a layout sense, and in an electronic sense.)
That does not mean there aren't any hidden show stoppers lurking
around the corner, but I've heard nothing yet which would make me say:
"it will never work because ..." There is, of course, a difference
between impractical and impossible -- I've not heard any reasons
which fall into the "impossible" category yet -- I have heard reasons
why it may be impractical.

The bigger issue is if anyone is interested in building and using it
for their audio system. That is the more valid question. I've
covered my thoughts on this in prior messages -- and I am looking at
this from the perspective of a tube-o-phile audio enthusiast where
audio performance is everything, and not as a vintage radio collector,
nor as a hobbyist who simply designs and builds radios as a hobby.


I think practicalities will force you to abandon tubes, and adopt
SS or go to a decent superhet. I am not sure you will figure this
out, since you just don't seem to know enough, imho.

One of the goals of this inquiry (the "channel TRF" is one side alley
of this more general thread) is to come up with a high-audio-quality
AM BCB tube tuner design suitable for building a kit, to be put
together by experienced tube amp builders who want to add an
audiophile-grade AM tuner to their setup. I've said this quite a few
times. The key word is "tube". Not that tubes are better, not that
they produce a necessarily better radio (you and I agree on this), but
that there are those who want the aesthetics of tube-based equipment.
Is anyone wishing for a tube tuner being rational? Yes and no -- it
depends upon how one looks at it.

Of course, the most obvious path to take is to investigate classic
AM tube tuner designs from the golden years (mid 30's to the 1950's)
and see if there is any particular design which is a good candidate
to base the modern design on (e.g., it must use, or be adapted to use,
tubes commonly sold today, can't be too complicated, fairly simple,
etc.) TRF, rather than superhet, is repeatedly brought up as the best
approach for the kit (even though superhets were the overwhelming
dominant design of the golden era), particularly if the prime focus is
on audio quality. But if a good superhet design comes along that
appears to meet the spirit of the various reqs, I'll seriously
consider it. Like the Turner AM Tuner.

Btw, for real heavy duty DX work (shortwave and MW), I covet the
WinRadio, so I'm not exactly out-of-step with the future of digital
radio.

Jon Noring

Patrick Turner wrote:
Jon Noring wrote:

Note again that Patrick himself said that IF is not needed when one is
building a single frequency receiver -- and from his comments he is a
very strong advocate of superhet design for a tunable receiver. That's
all the channel TRF is: a single frequency receiver, duplicated n
number of times (where n is the number of channels one wants to tune,
which are switched in and out.)

120 separate AM channels with perhaps 480 discrete LCs and two tubes
each is an entirely overcomplex and impractical idea.

Sigh.

It was a bad choice of wording on my part, since I assumed from what I
previously wrote that what I intended was obvious: that the tubes and
RF transformers remain the same, but the rest of the LC components of
the bandpass tuning stages will be swapped out from channel to
channel.

This is functionally *equivalent* to having 120+ independent and
optimized TRF circuits (one for each channel) -- that's what I
intended to say.

This is more than obvious, since in traditionally-tuned radios, nearly
all the components remain the same except the tuning capacitor (or for
a few radio designs, a variable inductor.)

Same with the channel TRF: all channels use the same common components
except those whose values/properties must change as a function of
tuning frequency, which are the bandpass filter components. Thus the
same tubes and RF transformers (as a matter of practicality) are
intended to be commonly used for all the channels.

Now, again, why use the channel approach when one can use either a
single or double tuned bandpass filter? It's a matter of the degrees
of freedom one is given in optimizing the bandpass characteristics.
In the channel TRF we should be able to, in principle at least, assure
that for each channel, from 500 khz to 1800 khz, we can have
essentially the same exact bandshape: bandwidth, shape factor, etc.
And higher order filters are definitely a possibility (if it makes
any sense to use them -- delay/linear phase is an issue.)

This degree of bandshape control cannot be accomplished by tuning one
or two capacitors (or inductors) in the bandpass tuner. In the TRF as
John Byrns is studying, simply adjusting the capacitance for tuning
has the downside of increasing bandwidth for higher frequency (in a
simple parallel RLC circuit, BW=(1/RC).) There are tricks that can be
done within the limited parameter space to keep the bandwidth more
constant, but it probably has a negative effect on the shape factor
and degree of linear phase, and still does not give the degree of
control preferred (of course, a variable inductor suggests itself.)
Thus was born the "channel TRF", taking advantage of the fact that,
for the BCB at least, all broadcasts are on pre-assigned frequencies
(channels), so why care about being able to tune in-between these
frequencies?

(Now, as I think about it, it would be possible to build a continuous
tuning system for these higher-order bandpass filters, optimally
varying each of the LC components to their best values as a function
of center frequency. It could be a "true quintuply tuned circuit" (or
higher order.) But mechanically accomplishing this would get
extraordinarily complicated: having to increase this capacitance a
certain nonlinear way, decrease that inductance by its own function,
slowly increase another capacitance, etc., all at the same time. This
is much much much more complicated than even the all-channel TRF.)

Jon

Jon Noring wrote:

Patrick Turner wrote:

Patrick, have you published the schematic for your radio? How amenable
is your design for turning it into a kit? And what are its overall
specs?

Overall specs are excellent as detailed in many previous postings.
No, I havn't posted the full schematic, and no, I am not aiming
to supply details to anyone else to make into a kit for sale. So
you'll have to do your own R&D, at your own expense, using your
time, not mine.

Is it because you plan to market the design? Or that you simply don't
want anyone else to "profit" from your design?

In today's world there *is no* market for a tubed AM radio,
and a kit would sell in such tiny numbers, that
I was led to think there is no market, and I would never profit.
Whether anyone else would make a profit is a moot point.
They wouldn't need my design though.
And if they did use my design, they'd still have to work hard at making a
prototype
free of bugs on their own.

Have you ever run a business?




The trend these days is to open source software, and now there's a
move to open source mechanical designs. I see the same for open
sourcing electronic designs, such as radio receivers.

Obviously, the designer of anything has the right to do with it as
they please, but I find it perplexing that you have decided not to
share your design with the rest of the world, and with posterity. But
that's your choice. When you die (as we all must), does the design die
with you?

I already have described my radio design in full in numerous postings.

I really couldn't care less if I die taking knowledge and experience to the
grave with me.
The living better get busy if they want to build a decent AM tuner,
and stop dithering about, if they want one by then end of next month!



And about the so-called "kit", I myself know that it is not a money
maker -- I'm sure you will agree with that.

Well then just design and build your own.

The goal is not to make
money (which isn't there anyway), but rather to just get something out
there for people to build and enjoy.

But nobody does anything for nothing.

If you want a kit for diyers then *you* better get busy.

So you would not be interested in

your design to be "kit-i-fied", and called the "Turner AM Tuner"?

I am far to busy with projects that earn money to take the time to
get a kitset prototype done for people like you who will not
work it all out for themselves.

The
kit itself will essentially be like what diytube does: provide the PCB
boards, a schematic, parts list and directions, and the kit builder
has to wing it from there. If they don't want to even use the PCB
boards, they have the schematic and parts list to work from. In fact,
I would prefer to open source the schematic and parts list for the
AM tube tuner if you agreed with that -- that way no one will make
money from it in a proprietary sense.

Then the cabinet size for the tubed tuner will be enormous compared
to using fets, and there will be 240 tubes in there for all the
single channel tuner modules. A tubed tuner with 120 x two tubed
modules is an absurd idea.

???

Maybe I miswrote in my last reply, but that's NOT what I have in mind.
All channels will share the same tubes and RF transformers -- only the
rest of the tuned bandpass circuitry (mostly a few LC components) will
be swapped between channels. You yourself sized it out in your prior
reply, showing you understood this. [I'm just repeating this in case
someone reading this message in the distant future, who does not have
access to the other prior messages, will not be misled as to the
design I am exploring.]

For 15-20 channels, the design appears practical and doable. For 120+
channels, it's much more of a push.

A 15 channel AM BCB radio is as useful as tits on a bull, imho.

switching 120 sets of LCs to allow only 2 RF amp tubes to be used presents
huge wiring problems, and is, unless *you* proove otherwise,
a complete waste of time.



Maybe reality will get in the way of doability, but for the 15-20
channel design, no one has yet offered any show stopper reasons why
it cannot work (both in a layout sense, and in an electronic sense.)
That does not mean there aren't any hidden show stoppers lurking
around the corner, but I've heard nothing yet which would make me say:
"it will never work because ..." There is, of course, a difference
between impractical and impossible -- I've not heard any reasons
which fall into the "impossible" category yet -- I have heard reasons
why it may be impractical.

The bigger issue is if anyone is interested in building and using it
for their audio system. That is the more valid question. I've
covered my thoughts on this in prior messages -- and I am looking at
this from the perspective of a tube-o-phile audio enthusiast where
audio performance is everything, and not as a vintage radio collector,
nor as a hobbyist who simply designs and builds radios as a hobby.

I think practicalities will force you to abandon tubes, and adopt
SS or go to a decent superhet. I am not sure you will figure this
out, since you just don't seem to know enough, imho.

One of the goals of this inquiry (the "channel TRF" is one side alley
of this more general thread) is to come up with a high-audio-quality
AM BCB tube tuner design suitable for building a kit, to be put
together by experienced tube amp builders who want to add an
audiophile-grade AM tuner to their setup. I've said this quite a few
times. The key word is "tube". Not that tubes are better, not that
they produce a necessarily better radio (you and I agree on this), but
that there are those who want the aesthetics of tube-based equipment.
Is anyone wishing for a tube tuner being rational? Yes and no -- it
depends upon how one looks at it.

Of course, the most obvious path to take is to investigate classic
AM tube tuner designs from the golden years (mid 30's to the 1950's)
and see if there is any particular design which is a good candidate
to base the modern design on (e.g., it must use, or be adapted to use,
tubes commonly sold today, can't be too complicated, fairly simple,
etc.) TRF, rather than superhet, is repeatedly brought up as the best
approach for the kit (even though superhets were the overwhelming
dominant design of the golden era), particularly if the prime focus is
on audio quality. But if a good superhet design comes along that
appears to meet the spirit of the various reqs, I'll seriously
consider it. Like the Turner AM Tuner.

The Turner AM tuner only exists in my kitchen.

Try to concentrate on decisions about design that *you*
will have to make, regarding the Noring Tuner.

There is enough info available for you.


Btw, for real heavy duty DX work (shortwave and MW), I covet the
WinRadio, so I'm not exactly out-of-step with the future of digital
radio.

Jon Noring

I leave you to create whatever you want to on your own.

Continuing to type at the computer and at other hobbyists won't
produce anymore fresh ideas about AM radio than the last
80 years has produced, and I suggest you spend time in your workshop
rather than clutter the airwaves with petulant requests for more info.
Nobody knows anymore than what they have said.


Patrick Turner.

Jon Noring wrote:

[Obligatory Telamon rec.radio.shortwave on-topic statement: The
following reply touches upon aspects of TRF design as they apply to MW
DXing, particularly sensitivity and selectivity of tube-based TRF
designs. MW DXing is on-topic to r.r.s. discussion. I appreciate
Telamon's efforts to keep r.r.s discussion strictly on-topic per the
written r.r.s. Charter.]

Jon (and patrick), with all due respect to the topic, getting your
thoughts together before posting and knowing when to snip goes a long way.
I don't think I'm alone in seeing that this topic just plain gets too
windy in spite of its importance or relevance. I enjoy the subject but
even I killfiled some of the initial topic titles because people were
cluttering up my screen with megaposts of ways to kill a dead horse.

If you want to avoid ****ing people off its easy enough to corral your
thoughts and not spread the topic across multiple threads while musing
at the keyboard. If you did the same at the coffee machine at the
office they'd physically pitch you out the door.

Be kind to us random readers or take it to personal email.


-Bill M

You got to know when to hold them and when to fold them. I've folded, ...

--
73
Hank WD5JFR
"Patrick Turner" wrote in message
...


Jon Noring wrote:

Patrick Turner wrote:

Patrick, have you published the schematic for your radio? How
amenable
is your design for turning it into a kit? And what are its overall
specs?

Overall specs are excellent as detailed in many previous postings.
No, I havn't posted the full schematic, and no, I am not aiming
to supply details to anyone else to make into a kit for sale. So
you'll have to do your own R&D, at your own expense, using your
time, not mine.

Is it because you plan to market the design? Or that you simply don't
want anyone else to "profit" from your design?

In today's world there *is no* market for a tubed AM radio,
and a kit would sell in such tiny numbers, that
I was led to think there is no market, and I would never profit.
Whether anyone else would make a profit is a moot point.
They wouldn't need my design though.
And if they did use my design, they'd still have to work hard at making a
prototype
free of bugs on their own.

Have you ever run a business?




The trend these days is to open source software, and now there's a
move to open source mechanical designs. I see the same for open
sourcing electronic designs, such as radio receivers.

Obviously, the designer of anything has the right to do with it as
they please, but I find it perplexing that you have decided not to
share your design with the rest of the world, and with posterity. But
that's your choice. When you die (as we all must), does the design die
with you?

I already have described my radio design in full in numerous postings.

I really couldn't care less if I die taking knowledge and experience to
the
grave with me.
The living better get busy if they want to build a decent AM tuner,
and stop dithering about, if they want one by then end of next month!



And about the so-called "kit", I myself know that it is not a money
maker -- I'm sure you will agree with that.

Well then just design and build your own.

The goal is not to make
money (which isn't there anyway), but rather to just get something out
there for people to build and enjoy.

But nobody does anything for nothing.

If you want a kit for diyers then *you* better get busy.

So you would not be interested in

your design to be "kit-i-fied", and called the "Turner AM Tuner"?

I am far to busy with projects that earn money to take the time to
get a kitset prototype done for people like you who will not
work it all out for themselves.

The
kit itself will essentially be like what diytube does: provide the PCB
boards, a schematic, parts list and directions, and the kit builder
has to wing it from there. If they don't want to even use the PCB
boards, they have the schematic and parts list to work from. In fact,
I would prefer to open source the schematic and parts list for the
AM tube tuner if you agreed with that -- that way no one will make
money from it in a proprietary sense.

Then the cabinet size for the tubed tuner will be enormous compared
to using fets, and there will be 240 tubes in there for all the
single channel tuner modules. A tubed tuner with 120 x two tubed
modules is an absurd idea.

???

Maybe I miswrote in my last reply, but that's NOT what I have in mind.
All channels will share the same tubes and RF transformers -- only the
rest of the tuned bandpass circuitry (mostly a few LC components) will
be swapped between channels. You yourself sized it out in your prior
reply, showing you understood this. [I'm just repeating this in case
someone reading this message in the distant future, who does not have
access to the other prior messages, will not be misled as to the
design I am exploring.]

For 15-20 channels, the design appears practical and doable. For 120+
channels, it's much more of a push.

A 15 channel AM BCB radio is as useful as tits on a bull, imho.

switching 120 sets of LCs to allow only 2 RF amp tubes to be used presents
huge wiring problems, and is, unless *you* proove otherwise,
a complete waste of time.



Maybe reality will get in the way of doability, but for the 15-20
channel design, no one has yet offered any show stopper reasons why
it cannot work (both in a layout sense, and in an electronic sense.)
That does not mean there aren't any hidden show stoppers lurking
around the corner, but I've heard nothing yet which would make me say:
"it will never work because ..." There is, of course, a difference
between impractical and impossible -- I've not heard any reasons
which fall into the "impossible" category yet -- I have heard reasons
why it may be impractical.

The bigger issue is if anyone is interested in building and using it
for their audio system. That is the more valid question. I've
covered my thoughts on this in prior messages -- and I am looking at
this from the perspective of a tube-o-phile audio enthusiast where
audio performance is everything, and not as a vintage radio collector,
nor as a hobbyist who simply designs and builds radios as a hobby.

I think practicalities will force you to abandon tubes, and adopt
SS or go to a decent superhet. I am not sure you will figure this
out, since you just don't seem to know enough, imho.

One of the goals of this inquiry (the "channel TRF" is one side alley
of this more general thread) is to come up with a high-audio-quality
AM BCB tube tuner design suitable for building a kit, to be put
together by experienced tube amp builders who want to add an
audiophile-grade AM tuner to their setup. I've said this quite a few
times. The key word is "tube". Not that tubes are better, not that
they produce a necessarily better radio (you and I agree on this), but
that there are those who want the aesthetics of tube-based equipment.
Is anyone wishing for a tube tuner being rational? Yes and no -- it
depends upon how one looks at it.

Of course, the most obvious path to take is to investigate classic
AM tube tuner designs from the golden years (mid 30's to the 1950's)
and see if there is any particular design which is a good candidate
to base the modern design on (e.g., it must use, or be adapted to use,
tubes commonly sold today, can't be too complicated, fairly simple,
etc.) TRF, rather than superhet, is repeatedly brought up as the best
approach for the kit (even though superhets were the overwhelming
dominant design of the golden era), particularly if the prime focus is
on audio quality. But if a good superhet design comes along that
appears to meet the spirit of the various reqs, I'll seriously
consider it. Like the Turner AM Tuner.

The Turner AM tuner only exists in my kitchen.

Try to concentrate on decisions about design that *you*
will have to make, regarding the Noring Tuner.

There is enough info available for you.


Btw, for real heavy duty DX work (shortwave and MW), I covet the
WinRadio, so I'm not exactly out-of-step with the future of digital
radio.

Jon Noring

I leave you to create whatever you want to on your own.

Continuing to type at the computer and at other hobbyists won't
produce anymore fresh ideas about AM radio than the last
80 years has produced, and I suggest you spend time in your workshop
rather than clutter the airwaves with petulant requests for more info.
Nobody knows anymore than what they have said.


Patrick Turner.

Patrick Turner wrote:
Jon Noring wrote:

Is it because you plan to market the design? Or that you simply don't
want anyone else to "profit" from your design?

In today's world there *is no* market for a tubed AM radio, and a
kit would sell in such tiny numbers, that I was led to think there
is no market, and I would never profit.

I agree with you the market is small, and not profitable. But people
do things for reasons beyond just monetary profit.


Whether anyone else would make a profit is a moot point. They
wouldn't need my design though. And if they did use my design,
they'd still have to work hard at making a prototype free of bugs on
their own.

O.k. Thanks for clarifying.


Have you ever run a business?

laugh/

I am very aware of business, thank you, having co-founded several
startup companies and non-profit ventures the last few years, plus
three sole proprieterships, one of which is still active in the ebook
publishing industry.


I already have described my radio design in full in numerous
postings.

O.k., I'll dig through Google and see what you've said on your tuner.
Love to hear it. Have you made any recordings of received stations?


The living better get busy if they want to build a decent AM tuner,
and stop dithering about, if they want one by then end of next
month!

Well, maybe I seem impatient, but... smile/


And about the so-called "kit", I myself know that it is not a money
maker -- I'm sure you will agree with that.

Well then just design and build your own.

I just might, or as part of a team of like-minded individuals.

Even though the current focus I am taking is the channel TRF, I am not
wedded to it even though it appears that way. John Byrns approach for
an improved TRF is *very* intriguing. Maybe it's the rebel in me...


But nobody does anything for nothing.

This is very true, but there are rewards that go beyond strictly
monetary.


If you want a kit for diyers then *you* better get busy.

Definitely!


I am far to busy with projects that earn money to take the time to
get a kitset prototype done for people like you who will not work it
all out for themselves.

So I should not embrace a classic design from the past, but to
design it all from scratch?


A 15 channel AM BCB radio is as useful as tits on a bull, imho.

Your comment is noted. You definitely will not be interested in a
15 channel TRF kit, then, if it ever came out. smile/


switching 120 sets of LCs to allow only 2 RF amp tubes to be used
presents huge wiring problems, and is, unless *you* prove otherwise,
a complete waste of time.

Agreed about the huge wiring problems, and agreed about having to
prove it, or someone having to prove it. One reason for mentioning it
as I have is to engage the collective creativity of the many people
here in the newsgroups -- to think positive, and to think of a clever
way to make it work. Or, it may catalyze some other idea leading to
some improvement somewhere.

Before going into the workshop, it is good to maybe run thoughts and
ideas off of other experts. One doesn't build a bridge by going out to
the site and start building. Rather, it is carefully planned to meet
the specific requirements. Experts in bridge design are consulted,
etc. And this includes for new bridge designs which have not ever been
built before (there are new bridges now being built which push the
limits, and doing it in unorthodox ways.)

(I'm of the view that all ideas, even silly ones, may have value in
unforeseen and unpredictable ways. I'm also of the view that one can
think of a hundred ways why something will not work, while all one
has to do is to think of one way to make it work. That's why I have
no difficulty in proposing what may end up being silly ideas.)

Of course, contingent on the whole channel TRF concept is that the RF
bandpass filters can exactly be tailored for each frequency. One thing
which has not been established is how important is this really? Will
accomplishing this result in a noticeable improvement in audio and
general performance over the better superhet or tunable TRF designs
(and maybe allow a simplification of the rest of the circuitry)? Or,
will it only result in a marginal improvement, maybe only measurable
with equipment? If the latter is the case, then the channel TRF
concept becomes less attractive, except maybe for some unusual
circumstances.


The Turner AM tuner only exists in my kitchen.

Ah, the kitchen radio. smile/ I'm sure it is a great performer.


Continuing to type at the computer and at other hobbyists won't
produce anymore fresh ideas about AM radio than the last
80 years has produced, and I suggest you spend time in your workshop
rather than clutter the airwaves with petulant requests for more info.
Nobody knows anymore than what they have said.

I am wondering if something like the channel TRF for BCB reception
was ever proposed in times past, or used in some unusual application
where it was called for? Anyone?

Thanks, Patrick, for your frank feedback. It is welcome.

Jon Noring

Henry Kolesnik wrote:

You got to know when to hold them and when to fold them. I've folded, ...


I wish that Jon could actually experience this and see that his
thinking 'outside the box' isn't going to be an automatic revelation
that 80 years of radio has simply overlooked.
Thirty minutes on the bench could save 'light-hours' of ramblings.

-BM

"Jon Noring" wrote in message
...

[snip]


This is functionally *equivalent* to having 120+ independent and
optimized TRF circuits (one for each channel) -- that's what I
intended to say.

[snip]

How would each of the 120+ independent TRF circuits get optimized? With a
scope and a sweep and marker generator? Any one of the channels might be
easy enough, but 120 is asking alot. Even moreso, with the complication of
Wide/DX option. And it's not like there a wonderful victory after the
struggle. Wideband AM sometimes sounds very good, and sometimes not.

Have you heard wideband AM?

Frank Dresser