NT
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More options Nov 27, 10:08 am
On Nov 26, 5:54 am, wrote:

- Show quoted text -

If I were designing such a product, I'd do everything in my power to
avoid end user alignment with testgear, for one very simple reason: it
wipes out 99.9% of your potential customers, its business suicide.

Perhaps one could use resonators instead of LCs, if you dont like the
interstation garbage of agced reaction.

NT

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NT
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More options Nov 27, 10:18 am
On Nov 27, 4:08 pm, NT wrote:

- Show quoted text -

Of course a valve radio is business suicide to begin with, performance
per dollar has come a long way since the valve era. Number of valve
radios currently on the market is zero, so no-one has managed to make
them compete with 30cent ICs and 2cent transistors.



I intend to set the expectation that you must have a bench with a
certain amount of basic test equipment and a proper soldering station
to do this. If you will or can not do this a different hobby is for
you.

Large numbers of Heathkits were built by people with NO skills, but
larger numbers got half finished and thrown in the dumpster or taken
to a shop and a large sum was paid to have them pro built to save
face. I knew a TV shop owner who had a policy: He'd fix ANY Heathkit
but he charged a one time fee equal to the kit price. Otherwise he
would not even look at them. Heathkits did a poor job of teaching
technicianship precisely because they were secretaryworthy.

Bauer built radio broadcasting gear the same way. A secretary could
build them and at NAB one year one did.

I am not looking at a BIG market.

* Valves have a place in audio, for the truly faithful. But then,
audio only requires a few valve types, frequencies are easily
managed, and circuitry remains stable for much longer periods of
use. *Whereas radio applications require more sophisticated valve
construction, and significantly different valve types for given
applications, to accomodate frequencies that stretch from 10X to
100000X audio frequencies.

* What's comforting in radio with valve technology, is the general
sense that the technology itself is accessible. And widely
understood to be more forgiving. That valves may be removed, tested,
and replaced by the techologically limited, and operated under
conditions that would destroy solid state. Whereas, SS receivers,
self service requires a much higher level of skill, with a much
lower threshold of abuse. For those with limited technological
experience, this can be daunting. Especially, as in the case of this
receiver, during an emergency, where supply lines are uncertain, and
technical support is nonexistent.

* I can see where the OP is coming from. Build an accessible
receiver that's fairly forgiving to extremes in noise, signal
levels, voltage, and hostile events, and you'd have a generally
useful rig for the general population in an emergency. It's a nice
thought.

* But as has been pointed out here multiple times, SS technology in
a proper design has proven more resistant to EMP than generally
believed, operating voltages are easier to generate, and manage,
power requirements are lower, and performace of the technology is
dramatically improved since the days of valve receivers. All at a
fraction of the cost. And in an emergency, valve supplies will be
just as short as SS components.

* All of which points to the fact that a well designed kit radio for
use in emergencies would be more like the Ten-Tec 1254, than it
would be like a Hallicrafters S-40. And the Ten-Tec 1254 is a kit,
costs $200, and requires no user alignment, but offers significant
performance across the spectrum from LF through HF.

* In a package that's available now.

No regen offers simplicity of use and selectivity, nor is the demod
audio very good in most cases.

A real SW-3 with a transformer in place of the watchcase headset was
tested by a friend in a screen room with HP test gear for SINAD and
audio quality. The rig consisted of HP, 8640B and 339A as I recall and
minimum AM distortion was six or seven percent, but that was only at
something like -20 dBm input and 60% modulation. I can't remember what
SINAD was.....it was dismal.

Passive TRF sets, i.e., "crystal radios" were capable of very good
fidelity OTOH. The old Millen was capable of equaling the test set's
own performance. Again you had to drive the hell out of it though.

On Nov 27, 11:16*am, Michael Black wrote:
On Sun, 27 Nov 2011, NT wrote:
If I were designing such a product, I'd do everything in my power to
avoid end user alignment with testgear, for one very simple reason: it
wipes out 99.9% of your potential customers, its business suicide.

Perhaps one could use resonators instead of LCs, if you dont like the
interstation garbage of agced reaction.

And Heathkit is the model for that. *They'd prealign tuned circuits,
they'd have certain stages as preassembled modules, they'd build some
relevant test equipment into the equipment (like those tv sets with some
sort of metering in the back). One I always liked was a scanner, they
included some parts to make up a 10.7MHz oscillator and mixer. *The
oscillator would provide the signal to align the IF strip, and then you'd
mix the local oscillator with this outboard oscillator/mixer to get a
signal on the signal frequency, to align the front end.

Heathkit of course did design for the beginner, I gather once they had the
instructions together they found people who had never put a kit together
to follow the instructions so they could make sure they made sense (and if
followed properly, would result in a working piece of equipment).
Despite the fuss about Heathkit being for the hobbyist, they always had
taht color tv set, that musical organ, that boonie bike, that were
aimed at people who just wanted something cheaper, and were willing to
put some time into it. *But that's why Heathkit shut down the kits, with
time the sorts of things their was interest in got so complicated (and
parts so small) that it was no longer cheap to come up with the
instructions, pack the kit compared to just building it at the factory.

Heathkit offered factory wired as well as kit equipment in many
cases. But even the kits were more expensive than good used
competitive equipment and sometimes more than respectable factory
built.

The Japanese were part of the problem because they made it their
business to acquire market share at the expense of profit. The
Japanese in their salad days were content to take losses no American
competitor would for market share, because they thought long term.
American companies quit thinking long term in the mid-70s because MBA
thinking and stock market valuation was everything to the CEO. The
Japanese were racially conscious, nationalistic, and group future
driven and have always had a "co-opetitive" rather than dog-eat-dog
mentality. What has sidelined Japan is the acceptance of American
business theory.

In Amateur Radio products, Japanese companies sold equipment at cost
or lower until there was no more American competition. In fact, they
still sell them at prices amazingly low for their feature sets and
costs of development. That is because they figure the American ham who
is appliance operating instead of building is not learning and being
the competitive future.

Conspiracy theory? No, experience. My father worked for a Motorola
plant in the Midwest for decades. When a certain board member died,
Mother M sold the plant and product line to Matsu****a _for less than
the real estate was worth_. I don't blame Matsu****a for buying it and
shutting it down, even though they swore they would not do so. It was
a competitor they didn't need. But the people of the town, although
many are very stupid, still needed those jobs. I don't blame them:
they were acting rationally. It is we who acted irrationally in
allowing such a deal to go through. Ford or GM would have been happy
to buy up Japanese car plants in the 70s and do likewise, but the
Japanese would not allow it. No sane nation would.

Sorry to get into politics.

Another fault with Heathkit equipment was often that mechanically
they weren't very good. Their audio amps in the tube era were fine,
because no mechanicals are needed there. In ham equipment they needed
that and didn't have it. Collins and Drake were much much better. Yes,
they cost more, but by the time I was in high school there were good
buys in older Collins and Drake equipment because the first S/Line and
4 line buyers were going /SK already.

Another reason American companies abandoned ham and shortwave radio
was that government defense contracts spoiled most companies that got
them. Once spoiled they were like fat lazy schoolkids, and discipline
was not forthcoming. Collins was always an avionics company, and into
commercial broadcast as well. Art Collins kept them in the ham
business but when he died they ditched it as fast as possible.

My next receiver will be an SDR. Eliminating all but one conversion
stage (since the SDR goes straight from RF to I/Q baseband) and
doing all the filtering and demodulation with perfect mathematical
accuracy in software not only gives you tremendous dynamic range and
filtering capability, but it makes the recovered audio almost
supernaturally clean-sounding.

Listening to a good SDR into a high-fidelity sound system for the
first time is like discovering that pillows had been strapped to
your speakers, and gravel had been stuck to your voice coil, for all
these years -- and finally removing them.

The SDRs I have seen have been mickey mouse affairs that used sound
cards for demod. But when a good standalone unit is offered at a
reasonable price I will give it a try.

On 11/27/11 21:15 , wrote:


Valves have a place in audio, for the truly faithful. But then,
audio only requires a few valve types, frequencies are easily
managed, and circuitry remains stable for much longer periods of
use. Whereas radio applications require more sophisticated valve
construction, and significantly different valve types for given
applications, to accomodate frequencies that stretch from 10X to
100000X audio frequencies.

What's comforting in radio with valve technology, is the general
sense that the technology itself is accessible. And widely
understood to be more forgiving. That valves may be removed, tested,
and replaced by the techologically limited, and operated under
conditions that would destroy solid state. Whereas, SS receivers,
self service requires a much higher level of skill, with a much
lower threshold of abuse. For those with limited technological
experience, this can be daunting. Especially, as in the case of this
receiver, during an emergency, where supply lines are uncertain, and
technical support is nonexistent.

I can see where the OP is coming from. Build an accessible
receiver that's fairly forgiving to extremes in noise, signal
levels, voltage, and hostile events, and you'd have a generally
useful rig for the general population in an emergency. It's a nice
thought.

But as has been pointed out here multiple times, SS technology in
a proper design has proven more resistant to EMP than generally
believed, operating voltages are easier to generate, and manage,
power requirements are lower, and performace of the technology is
dramatically improved since the days of valve receivers. All at a
fraction of the cost. And in an emergency, valve supplies will be
just as short as SS components.

All of which points to the fact that a well designed kit radio for
use in emergencies would be more like the Ten-Tec 1254, than it
would be like a Hallicrafters S-40. And the Ten-Tec 1254 is a kit,
costs $200, and requires no user alignment, but offers significant
performance across the spectrum from LF through HF.

In a package that's available now.

No regen offers simplicity of use and selectivity, nor is the demod
audio very good in most cases.



Ten-Tec 1254 is a superhet.


A real SW-3 with a transformer in place of the watchcase headset was
tested by a friend in a screen room with HP test gear for SINAD and
audio quality. The rig consisted of HP, 8640B and 339A as I recall and
minimum AM distortion was six or seven percent, but that was only at
something like -20 dBm input and 60% modulation. I can't remember what
SINAD was.....it was dismal.

Passive TRF sets, i.e., "crystal radios" were capable of very good
fidelity OTOH. The old Millen was capable of equaling the test set's
own performance. Again you had to drive the hell out of it though.

On Nov 27, 10:39*pm, wrote:
On Nov 27, 11:16*am, Michael Black wrote:





On Sun, 27 Nov 2011, NT wrote:
If I were designing such a product, I'd do everything in my power to
avoid end user alignment with testgear, for one very simple reason: it
wipes out 99.9% of your potential customers, its business suicide.

Perhaps one could use resonators instead of LCs, if you dont like the
interstation garbage of agced reaction.

And Heathkit is the model for that. *They'd prealign tuned circuits,
they'd have certain stages as preassembled modules, they'd build some
relevant test equipment into the equipment (like those tv sets with some
sort of metering in the back). One I always liked was a scanner, they
included some parts to make up a 10.7MHz oscillator and mixer. *The
oscillator would provide the signal to align the IF strip, and then you'd
mix the local oscillator with this outboard oscillator/mixer to get a
signal on the signal frequency, to align the front end.

Heathkit of course did design for the beginner, I gather once they had the
instructions together they found people who had never put a kit together
to follow the instructions so they could make sure they made sense (and if
followed properly, would result in a working piece of equipment).
Despite the fuss about Heathkit being for the hobbyist, they always had
taht color tv set, that musical organ, that boonie bike, that were
aimed at people who just wanted something cheaper, and were willing to
put some time into it. *But that's why Heathkit shut down the kits, with
time the sorts of things their was interest in got so complicated (and
parts so small) that it was no longer cheap to come up with the
instructions, pack the kit compared to just building it at the factory.

*Heathkit offered factory wired as well as kit equipment in many
cases. But even the kits were more expensive than good used
competitive equipment and sometimes more than respectable factory
built.

*The Japanese were part of the problem because they made it their
business to acquire market share at the expense of profit. The
Japanese in their salad days were content to take losses no American
competitor would for market share, because they thought long term.
American companies quit thinking long term in the mid-70s because MBA
thinking and stock market valuation was everything to the CEO. The
Japanese were racially conscious, nationalistic, and group future
driven and have always had a "co-opetitive" rather than dog-eat-dog
mentality. What has sidelined Japan is the acceptance of American
business theory.

*In Amateur Radio products, Japanese companies sold equipment at cost
or lower until there was no more American competition. In fact, they
still sell them at prices amazingly low for their feature sets and
costs of development. That is because they figure the American ham who
is appliance operating instead of building is not learning and being
the competitive future.

*Conspiracy theory? No, experience. My father worked for a Motorola
plant in the Midwest for decades. When a certain board member died,
Mother M sold the plant and product line to Matsu****a _for less than
the real estate was worth_. I don't blame Matsu****a for buying it and
shutting it down, even though they swore they would not do so. It was
a competitor they didn't need. But the people of the town, although
many are very stupid, still needed those jobs. I don't blame them:
they were acting rationally. It is we who acted irrationally in
allowing such a deal to go through. Ford or GM would have been happy
to buy up Japanese car plants in the 70s and do likewise, but the
Japanese would not allow it. No sane nation would.

*Sorry to get into politics.

*Another fault with Heathkit equipment was often that mechanically
they weren't very good. Their audio amps in the tube era were fine,
because no mechanicals are needed there. In ham equipment they needed
that and didn't have it. Collins and Drake were much much better. Yes,
they cost more, but by the time I was in high school there were good
buys in older Collins and Drake equipment because the first S/Line and
4 line buyers were going /SK already.

*Another reason American companies abandoned ham and shortwave radio
was that government defense contracts spoiled most companies that got
them. Once spoiled they were like fat lazy schoolkids, and discipline
was not forthcoming. Collins was always an avionics company, and into
commercial broadcast as well. Art Collins kept them in the ham
business but when he died they ditched it as fast as possible.- Hide quoted text -

- Show quoted text -

Japan barely manufactures any electronics today . ROK seems to be the
new leader lately.

On 11/27/2011 7:41 PM, wrote:

My next receiver will be an SDR. Eliminating all but one conversion
stage (since the SDR goes straight from RF to I/Q baseband) and
doing all the filtering and demodulation with perfect mathematical
accuracy in software not only gives you tremendous dynamic range and
filtering capability, but it makes the recovered audio almost
supernaturally clean-sounding.

Listening to a good SDR into a high-fidelity sound system for the
first time is like discovering that pillows had been strapped to
your speakers, and gravel had been stuck to your voice coil, for all
these years -- and finally removing them.

The SDRs I have seen have been mickey mouse affairs that used sound
cards for demod. But when a good standalone unit is offered at a
reasonable price I will give it a try.

Yeah, I suffer along with my HD Audio card ... but hey, as soon as
something better than concert hall audio comes along, I will consider it!

ROFLOL

Regards,
JS
The calendar says 2011, the heart says 1776!

On Nov 27, 7:27*pm, John Smith wrote:
On 11/10/2011 9:52 PM, wrote:

* With the survivalist market as well as the DIYers who would build a
kit I have given thought to the idea of building a new tube shortwave
receiver as a usable, practical set.

...

Any other comments?

As I once pointed out, long ago, now, in an amateur group, what needs to
be done is to build a radio equiv to how PCs are now done.

First you would have a generic case, these could be made by anyone, in
any design. *The would provide the user with an abundance of choice in
the looks of the rig.

Next, each section of the radio would simply be a plug in card, to a
"mother board." *You would have an rf section, which could cover any and
all bands, depending on construction, it would simple plug into one of
the slots on the motherboard. *Audio, rf, filter, conversion, etc., etc..
could be done this way.

You would have a basic set of all sections, and could expand, or upgrade
as you would have -- or as becomes available.

It would change the face of radio, SW radios would become as numerous as
PCs -- well, almost.

Most any small manufacturer could enter the market, and provide a case,
rf section, audio section, etc. -- and expand from there, if they choose.

I simply can't get enough interest ... but the radio could be just am,
am fm, am-fm-sw, am-fm-sw-vhf, am-fm-sw-vhf-uhf, am-fm-sw-vhf-uhf-shf,
or any possible combination wanted ... this is an idea whose obvious
advantage, for consumers, is simply screaming out for production!

Later, if one wished, he could just buy a larger standard case, move his
receiver components over, buy a larger power supply, and drop in the
appropriate transmitting section(s.)

We simply wait for the radio to leave the age of the horse and buggy ...

Regards,
JS


But.... 99% of radio buyers have little idea what features they want,
and the very slow change in feature sets of each module are in most
cases of close to zero interest to end users. Plus radios seldom
become obsolete - even 1920s sets are still usable, for the few of us
that wish to.

Unit radio did of course exist in the early 20s, when radio technology
really was changing fast, and it made a significant difference. Come
the 30s it was gone though, even though the technology was still
changing fast. End users didn't vote for it.

A slightly similar approach was also tried in tv in the 70s, with lots
of small pcbs that could each be replaced affordably if it ever
failed. But ultimately buyers just wanted the cheapest, not to pay for
later repairability.

Does anyone other than John think there's commercial mileage in
modular radio now?


NT

On Fri, 2 Dec 2011 17:48:46 -0800 (PST), NT
wrote:

On Nov 27, 7:27*pm, John Smith wrote:
On 11/10/2011 9:52 PM, wrote:

* With the survivalist market as well as the DIYers who would build a
kit I have given thought to the idea of building a new tube shortwave
receiver as a usable, practical set.

...

Any other comments?

As I once pointed out, long ago, now, in an amateur group, what needs to
be done is to build a radio equiv to how PCs are now done.

First you would have a generic case, these could be made by anyone, in
any design. *The would provide the user with an abundance of choice in
the looks of the rig.

Next, each section of the radio would simply be a plug in card, to a
"mother board." *You would have an rf section, which could cover any and
all bands, depending on construction, it would simple plug into one of
the slots on the motherboard. *Audio, rf, filter, conversion, etc., etc.
could be done this way.

You would have a basic set of all sections, and could expand, or upgrade
as you would have -- or as becomes available.

It would change the face of radio, SW radios would become as numerous as
PCs -- well, almost.

Most any small manufacturer could enter the market, and provide a case,
rf section, audio section, etc. -- and expand from there, if they choose.

I simply can't get enough interest ... but the radio could be just am,
am fm, am-fm-sw, am-fm-sw-vhf, am-fm-sw-vhf-uhf, am-fm-sw-vhf-uhf-shf,
or any possible combination wanted ... this is an idea whose obvious
advantage, for consumers, is simply screaming out for production!

Later, if one wished, he could just buy a larger standard case, move his
receiver components over, buy a larger power supply, and drop in the
appropriate transmitting section(s.)

We simply wait for the radio to leave the age of the horse and buggy ...

Regards,
JS


But.... 99% of radio buyers have little idea what features they want,
and the very slow change in feature sets of each module are in most
cases of close to zero interest to end users. Plus radios seldom
become obsolete - even 1920s sets are still usable, for the few of us
that wish to.

Unit radio did of course exist in the early 20s, when radio technology
really was changing fast, and it made a significant difference. Come
the 30s it was gone though, even though the technology was still
changing fast. End users didn't vote for it.

A slightly similar approach was also tried in tv in the 70s, with lots
of small pcbs that could each be replaced affordably if it ever
failed. But ultimately buyers just wanted the cheapest, not to pay for
later repairability.

I had one of those and when there was a failure discovered that just
one board cost half what the entire TV set had, and that was with me
doing the diagnosis, meaning I didn't have the cost of a 'TV service
man' plowed on top of it. That doesn't strike me as a terribly good
deal on 'repairability'.

It would, of course, go dead with a hurricane coming so I didn't have
much time and used the "hold in breaker, see what smokes" test. A
quick check of the schematic to see why and what else might have gone
with it and I fixed the thing with a couple of zeners and a resistor.

I often wonder if the 'modular PCB' idea was so 'tube test and
replace' repairmen could use the same technique on the solid state
stuff but a $250 PCB isn't a 3 buck tube. The economics just don't
work.

Does anyone other than John think there's commercial mileage in
modular radio now?

I don't because, for one, the 'computer' analogy is flawed. Computer
peripherals operate parallel on a common bus and they're not dependent
on the others. You can have 'no extras' and still have a computer, or
pick and chose whatever 'extra' things you want, like a TV tuner card.
It's the common, well defined, bus that makes this work but, even
then, it isn't 'free', which is why you see low cost PCs with all the
'typical' things stuffed onto the motherboard and maybe one or two
'expansion slot(s)', if any.

A radio, on the other hand, is essentially serial in operation with
signal coming in one end and out the other. Remove any part and you no
longer have a radio so you 'need them all' to begin with and there's
little reason to later change it even if you could (unlikely) figure
out how to enforce some common 'interface' at every stage through the
whole thing. And then there's the added cost at every single interface
break.

Bottom line, for the performance/cost ratio you can't beat solid state
and a robot assembling the stuff at warp speed. And it can be done so
cheaply you're better off to chuck it and buy another one assembled at
warp speed.




NT

On Fri, 2 Dec 2011, NT wrote:



Does anyone other than John think there's commercial mileage in
modular radio now?

Not as portrayed, and certainly not as a general radio.

There have been articles about building in modular form and even some kits
that were modular, and of course it's a great form for experimenting, why
remake the whole radio if you want to try a new IF strip or add a new
detector? Or buy the modules you want to build up something, rather than
be stuck with what the complete radio the company sells.

But there can't be a general bus, one module takes its input from the
antenna or a previous module, and its output goes to the next module,
those have to be well isolated. The power supply is standard to each
module, the whole point of three terminal regulators was to make
regulation specific to boards rather than one big power supply feeding
everything. But control lines will be different depending on the function
of the module, some requiring lots of lines, others requiring few or none
at all.

And there's no way it would be for everyone. The average radio user
doesn't care, they just want AM/FM radio, nowadays not even AM and a radio
is a radio, once you have one for average use there's no need for
improvement.

A modular radio might be interesting to the hobbyist, which of course is
where the concept has travelled. It's there in all the VHF converters
described in the hobby magazines, getting extra coverage with a shortwave
radio at the cost of a "module", ie converter, rather than having to build
a whole new radio. It's the hobbyist that wants to try things, it's the
hobbyist that is interested in the radio in itself. They are the ones who
might want to do better on longwave, or listen to the police band (even
then, or a lot of that type of hobbyist, existing scanners are more than
enough).

For a small company aimed at the hobbyist, modules make sense. They dont'
ahve to offer multiple receivers, just enough modules for someone to put
together what they want. I long ago argued with a friend that if he was
going to go into a small electronic business, just selling boards made
sense, since then he's not involved in dealing with cabinetry. The
hobbyist can buy the modules and then take care of putting it in a case.

It's a fairly limited market, yet at one point was one that might do okay.
You can have a successful business without making loads of profit, and
indeed doing away with things like UL approval by using an existing AC
adapter or having the buyer come up with one keeps overhead down, as does
the lack of cabinetry. Find a market that really exists, and cater to it,
you may not be rich but the business may keep going.

I have no idea if the market is there anymore. I've been going through
old magazines lately, and it reminds me how much time and even money I
spent on magazines, the hobby electronic ones and the ham magazines, and I
feel detached to it as the magazines disappeared, virtually no hobby
electronic magazines in North America, and the ham magazines dwindling but
more important less available on newsstands than in the old days. The
magazines were pretty important, and I'm not sure they really have been
replaced with other things. If nothing else, they were way to keep track
of the companies that sold kits and parts.

A different way to look at it is to think about commercial shortwave
receivers. They have become really cheap, and fairly good. I paid
somewhere around $80 for a Hallicrafters S-120A (the transistorized one)
in the summer of 1971, the most I could afford, the cheapest receiver
I could find locally. It was junk, the only good thing about it was I had
no experience so I didn't know how bad it was for a bit. You can get a
Grundig Yacht Boy 400 (or whatever the same model in a different cabinet
is) for a hundred dollars, some of the other Etons for the same complete
with synchronous detector. For that matter, I am finding sw receivers
at rummage and garage sales now for pretty low amounts. That Grundig
Satellite 700 for 2.00 at the Rotary Club sale, that Sony ICF-SW1 at a
garage sale in September for 10.00 (and then about half an hour later an
Eton Mini 300 for 2.00 at another garage sale, though that is junk).

They are infinitely better than the old low end analog receivers.
People talk about buying all kinds of models, but nobody seems to think
that if a hundred dollars is seen as "disposable" then why not buy a radio
to modify extensively?

Buy one and put it into a bigger cabinet. Make it a desktop physically,
complete with a good tuning knob on the front panel. Even receivers with
up/down buttons can be tuned with a tuning knob. All those people who
judge a radio by "sound", they can put a nice big speaker in the cabinet,
though better to use an external speaker. Add better lighting to the LCD
display. Add that Q-multiplier. Add some filters if you can get some at
the proper IF frequency. The radio becomes the foundation to customize.
Add an FM IF strip and then feed the radio with converters to hear those
higher bands. Put some more front end selectivity in the box, yes
suddenly you'd have to tune it in addition to the tuning knob, but that's
the way it used to be on the good receivers anyway. It doesn't have
fine enough tuning? Then add a variable capacitor across the second
conversion oscillator (either directory or via a varicap), and you can get
a fine tuning knob that isn't linked to the BFO. For that matter, one
could splurge and add crystal controlled BFO, getting the frequencies to
be in the right place in relation to the IF filter.

What's wrong with current receivers that can be improved with a little bit
of work? Some things can't be fixed, but a lot of these new receivers
offer a pretty good foundation compared to what there was in the old days.

YOu start with a reasonably good receiver, you see the low cost so you
aren't afraid to hurt it, and you make it the receiver you want, just like
someone would want those modules for.

Michael