Qs about RS DX-370

Qs about RS DX-370

Post by alex matthe » Sun, 08 Jan 1995 07:11:58

Hi all,

I picked up a Radio Shack DX-370 the other day for $40 (scratch & dent +
discontinued) the other day, the first SW I've had since I was 10 or
so (an old Phillips tube job).  Unfortunately, it didn't come
with a manual.  I have a 75ft random wire strung along the inside
walls of my apt, and reception seems pretty good -- in three days
I've picked up strong clear signals from VOAndes, VOA, VORussia,
New Zealand, Australia, China, Germany, Netherlands, BBC, Texas,
North Carolina, Tennessee, SoCal, NHK Japan, etc.

Reception during the day is pretty miserable, I suspect from
all of the television and florescent lighting in this apt complex, and
possibly just from all of the ***bouncing off the mountains
from all the weird labs here in silicon valley.
After midnight reception improves dramatically.

MW reception appears good, although I havn't tried DXing that band
yet as my being so fed up with most of the pabulum being broadcast
in this country was the main reason the little box caught my eye
in the first place.

Local FM stereo reception is very good with headphones, and plugging
the stereo headphone jack into my HI FI system makes listening
to many of the SW music broadcasts quite pleasant.

Overall, I'm quite pleased with my *very* inexpensive little radio.

However, some questions:

1.  I breezed by another radio shack and looked at two other DX-370s they
still had on the shelf.  One had a "tuning light", i.e., when the
radio decided it had a strong signal, the little red led would flash
on.  The other, like my unit says "tun" on the lcd display instead.  
Which came first, and was there any reason for this change, except
that one might cut down on battery life somewhat?

2.  It appears the only way to "scan" stations with my unit is to
hold down one of the up or down tuning buttons for about .5sec and
then let off.  Unfortunately, if another station is close to the one
I'm currently tuned to, If I don't whisk my finger off the button
within a milisecond or so of its starting the scan phase, it'll breeze
right by it.  Is there any other way to scan besides pusing the button
a gazillion times (i.e., manually tuning through the band)?  I'm also
worried that pushing the buttons so many times will wear them out as
they appear to be a bit on the flimsy side.  Hopefully they are easily
replaceable and not surface soldered to an itsy bitsy circuit board
sandwitched between 5 other itsy bitsy soldered together circuit boards.
Also, the unit that I examined with the tuning light did not appear
to scan at all like mine.  While mine seems to go through about .5Mhz
per second, that one only seemed to scan 1Khz per second (i.e., very
very slowly).  Was that unit malfunctioning?  The other difference
between the "lit" unit and mine seemed to be that it would allow for
90/60/30 minute "sleep" adjustment, while mine is fixed at (I think) 1
hour.  

3.  After reading about possible interference from RS transformers, I
purchased instead a generic made in China 3-12 volt transformer from
Fry's Electronics. (300 ma I think)
It produces no noticeable hum, however in the instruction manual for the
transformer it recommeded that unless the unit being powered has
a high current draw, I should switch it to one voltage setting lower.
I have done this, powering the unit with 4.5 volts instead of the
rated 6 volts.  I have noticed no change in receiving ability at the
lower voltage setting, however the rechargeable batteries I use seem
to expire very quickly when I unplug the unit.  Is the radio designed
to recharge rechargeable batteries and therefore when I have
the transformer plugged into it and only 4.5 volts I am actually
-draining- the batteries, or does this unit simply wear out batteries
very quickly (or maybe my batteries suck)?  Does anyone think
that switching the transformer up to 6 volts would hurt anything?

4.  With the longwire antenna attached, there is often so much broadband
interference that the scanning function becomes rather useless, as the
unit decides that it is getting reception at every 5Khz step.  One
IMO lousy workaround for this has been to unclip the antenna while
scanning, and then reclipping it when I have an actual station.
Naturally, with this method I miss many weaker stations.
Of course what I want is a little knob to adjust the sensitivity
of the circuit that decides what is and isn't a station... I guess
this really isn't a question, just a budget problem.

5.  Grounding?  What's up with this?  I heard a cute broadcast
from VAndes two days ago explaining it, and understood most of what
was said.
It appears to be half science, and half voodoo.  I would like to experiment
with gounding (earthing for those in the UK).  But I have no designated
external grounding point on the outside of my receiver.  Would soldering
a feed off a main ground trace on the circuit board inside the unit
suffice?  Perhaps there is another point on the casing of the unit
that is already connected in this fashion?  Is there some other
way of grounding the unit, or would I just be wasting a great
deal of time for a negligble reduction in interference?

TIA

Alex