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.
snip
Any other comments?

Here's a somewhat related discussion:

http://www.survivalblog.com/2011/06/...r_prepper.html

On Nov 28, 3:15*am, 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.

*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.

Regens and distortion... if the regen stage doesnt demodulate, there
is no significant distortion. Distortion comes from the prewar
approach of using a nonlinear regen stage to demodulate as well.


NT

On Dec 19, 10:26*pm, Mike S 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.
snip
Any other comments?

Here's a somewhat related discussion:

http://www.survivalblog.com/2011/06/...r_prepper.html

The author here is definitely an eccentric but he has some good
ideas. Like the late Mel Tappan, whom I knew as a kid and whom he
references frequently, he simply has no idea that 90% of even the
small minority perceptive and future-oriented enough to be interested
in what he has to say does not have the unlimited funds that would be
required to implement some of what he discusses.

On Dec 24, 10:33*am, NT wrote:
On Nov 28, 3:15*am, 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.

*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.

Regens and distortion... if the regen stage doesnt demodulate, there
is no significant distortion. Distortion comes from the prewar
approach of using a nonlinear regen stage to demodulate as well.

NT

Hmmmm, never thought about that.