[flipper]

On Tue, 13 Dec 2011 18:08:49 -0800 (PST), NT
wrote:

On Dec 3, 3:06*am, flipper wrote:
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'.

Dead tvs with boards to take out are relatively cheap.

Not back then and even if there was one there wasn't an Internet,
Craigslist, and Ebay to find it. And even if you get past all that a
hurricane was on the way and even in this day and age things don't
instantaneously appear on your doorstep.


The last of those tvs i played with had dire soldering, and I
suspected the modularisation was necessary to make such bad soldering
produce a useful percentage of ok boards.

I was being a bit flippant but I think you've hit the target. It's a
lot more likely the reason for modularity was for in house test and
manufacture than a noble notion of home repairability. Someone might
have thrown it in as an additional 'feature' but I doubt it was the
primary factor.


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.

I suspect lack of joined up thinking. Designers think it makes the
sets repairable and reduce the pile of dead boards, so implement it.
Then later the parts dept realise they can chanrge a pretty penny for
these little boards, so do. It kills the original idea of course.

No company I've been in has been that 'disjointed' and departments
don't get to charge whatever they think a good idea. It's usually a
well planned, from all angles, cost/profit margin analysis including
expected warranty and after sales service revenues.

That doesn't mean they necessarily get it 'right' but if that were
'the plan' they sure wouldn't let some yahoo in the parts department
arbitrarily screw it up.


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

The interface question is fairly easy, pick your interface standards
and award use of your system logo to any product that complies with
these standards. You can probably get away with only one standard, and
make match current practice of around 0.1-0.2v 10k at af.

Computers cost around 10x as much as a radio. So the extra cost of
modularising is low in percentage terms for pcs, but high for radios.
And the savings of modularisation for pcs are medium to high, but for
radios are mostly low.

Yeah, I just don't see it but, hey, if someone has the guts and
capital then that's what free enterprise is all about.

NT