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