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John Smith[_7_] · November 11th 11, 06:07 PM posted to rec.audio.tubes,rec.radio.shortwave

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.

That means no regens, no DC bull****, and no plug in coils. It must
have production grade RF and IF coils, a bandswitch, and require
alignment. If sold as a kit the builder will need a RF generator and a
scope (or a spec an or CSM with a track gen).

It should use off the shelf parts even if those shelves are bare, as
it is better to copy an existing item than design from scratch. I
would clone the Eddystone dial mechanism and the bandswitch and coils
from some Hallicrafters or Hammarlund set, they could be sold as
desperately needed replacement spares for the old sets too. I would
use a seeing eye tube mounted in a hole in the dial as opposed to a
meter movement, again, getting a run of new tubes made is possible if
you are buying several thousand. There are some surplus that could be
used if really needed too.

I would use a separate power supply and speaker for several reasons.

I would have the radio take in B+ and heater voltage and put out 600
ohm +4 audio. A regular supply could be used at home or car battery
and a switchmode brick for B+. A headphone jack would be supplied off
this tube.

The set should cover 500 kHz to 30 MHz, AM, SSB and CW, with a
product detector of course. A 455 kHz IF is needed so as to use common
mechanical or crystal filters, which are optional. There should also
be a 455 kHz IF out for an external synchronous detector.

Any other comments?

Yeah, why would anyone build a survival set whose filaments would burn
much more power than a VERY high end transistor set? You plan on
hauling around sq yards of solar cells to power that rig?

Regards,
JS