Re: [PLUG] [OT] SW radio question

[Steve Litt via plug <plug@lists.phillylinux.org>]

Eric Lucas via plug said on Wed, 19 Oct 2022 14:23:36 -0400

>I know this is off topic however there are quite a few ham radio folks
>here and I need some knowledgeable advice.
>
>I'm planning on buying a portable AM/FM/SW radio and I'm down to these
>two Sangean ATS-909X2:

[snip the two Sangeans]

In my metal garbage can, which serves as the best Faraday cage I can
muster, sits my MFJ-8100k, which I built as a kit. See
https://mfjenterprises.com/products/mfj-8100k . It can be
bought for more money fully assembled:
https://mfjenterprises.com/products/mfj-8100w . It's about 7 inches by
6 inches by 2 inches, approximately. It's powered by a 9 volt battery,
so for SHTF you'll need several 9 volt batteries.

Here's the manual:
https://static.dxengineering.com/global/images/instructions/mfj-8100k_mm.pdf

This is a regenerative radio, just like from the 1930's but
transistorized for longer life (if your metal garbage can can keep out
the EMP). As people have stated, you'll need a good antenna (50-100 feet
of stranded bell wire thrown up into a tree would be good enough).

This radio won't pull in stations as well as good Sangeans and
Grundigs, etc. You need some skill operating the regeneratation and
frequency dials, almost simultaneously. There is definitely some
hand-capacitance. With a 30 foot indoor wire antenna I can only pull in
strong stations because there's so much electrical noise in our house,
but that's true of all my shortwaves. If the neighborhood power goes
off, all that electrical noise goes away. The MFJ-8100 is best listened
to through headphones.  The dial is marked for
frequencies, but the dial is small, the frequencies are approximate,
and are subject to adjustment.

So you're probably asking yourself why my metal garbage can contains
this radio...

It's a simple circuit on a single layer, one sided board. No digital
stuff to go bad. None of these endless rotate/click controls, which
inevitably go bad after a few years. Only one integrated circuit in the
whole thing: A LM386 op amp for audio amplification. A *real* air
gapped tuning capacitor that you can blow dust out of, instead of these
wax-separated tuning capacitors or PLL circuits. No dial string,
it's a geared Vernier variable capacitor. If you could scavenge
transistors, resistors, and diodes you could probably repair this
thing; don't try this with a modern Sangean. Like all regenerative
radios, it can do CW and SSB natively, although it will probably sound
a little donald-ducky unless you're better with frequency/regen
adjustment than I am, but it's understandable. It covers a heck of a
lot of frequencies, though it's not continuous frequency coverage.

For a run-of-the-mill local disaster like a hurricane or earthquake,
what you need is a battery operated FM radio. But for bigger, longer
lasting stuff like financial collapse, EMP, civil war, asteroid strike
or Yellowstone mega-eruption, a nice, simple, small regenerative
receiver might be just what you need to hear what people 1000 miles
away have to say. Be aware that MFJ sells transmitters too, although if
you transmit you're letting others know where you are. I think a set of
FRS walkie-talkies might be appropriate too, if not used frequently.
I'd get the ones that work with real batteries, not rechargeables.

Like I said, my MFJ-8100k is kind of a recommendation out of left
field, but that's what I have in my metal garbage can, along with my
backup disks and some batteries and a very nice AM-FM radio.

SteveT

Steve Litt 
Summer 2022 featured book: Thriving in Tough Times
http://www.troubleshooters.com/bookstore/thrive.htm
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