wrote in message
ups.com...

wrote:
My wife and son are both E.E.'s and their explanation is that IC's
begin to degrade slowly as a result of impurituies in the wafer.
Simple components like capacitors dry out and resistors begin to
open
up. Wish I knew more, but I can hear what they tell me in the
radios
I've owned. I owned one of the comparison radios, the Panasonic
RF5000b. Big beast of a 24 pound radio with four antennas. It
was
pretty insensitive by any measure. Sure it would catch the big
nighttime SW's but that was about it. Other radios, such as a
Radio
Shack DX150b were still pretty sensitive (and still raspy
sounding)
after 25 years, so the rate of degradation isn't a constant.

Do a net search on "eletro-migration".
Over time the electrons carry some of the ions that make
junctions either P or N. Electro-migration increases with heat,
I think it doubles for every 3C degree increase. This is why
overclocking CPUs cn lead to unexpected failures.

So, does that mean it might not be a bad idea to
do some restoration work (or have it done) on
the newer radios when they reach 20 years or so,
sort of like the older tube radios?? I imagine that
the caps last longer than the old paper caps or black
beauties, but fixing up an R-70 or an FRG-7700 (if
in otherwise decent shape) hadn't occured to me before.

--Mike L.

wrote in message
ups.com...

wrote:
My wife and son are both E.E.'s and their explanation is that IC's
begin to degrade slowly as a result of impurituies in the wafer.
Simple components like capacitors dry out and resistors begin to open
up. Wish I knew more, but I can hear what they tell me in the radios
I've owned. I owned one of the comparison radios, the Panasonic
RF5000b. Big beast of a 24 pound radio with four antennas. It was
pretty insensitive by any measure. Sure it would catch the big
nighttime SW's but that was about it. Other radios, such as a Radio
Shack DX150b were still pretty sensitive (and still raspy sounding)
after 25 years, so the rate of degradation isn't a constant.


I'm not an EE, but I do fix electronics as a hobby. In my experience,
degraded (but not totally dead) ICs or transistors are among the least
likely failures and failed semiconductors are almost always caused by
exposure to excess voltage such as static discharge or funky power supplies,
reversed voltage or drawing excess current through them. Spilled liquids
can be a menace.

Bigger problems are poor solder joints, dried up electrolytics, cracked
circuit boards, drifted carbon composition resistors and home handyman
alignments.

If you're looking for esoteric failure modes, don't forget tin whiskers.
Tin plated conductors, such as the leads on most IC packs, can grow fine
whiskers from the tin plated leads which might short out adjacent pins.

The most likely parts to fail on tube radios are paper capacitors,
electrolytic capacitors and carbon comp resistors. Tubes age as well, but
they're usually OK.

Frank Dresser

For a well designed integrated circuit, the most likely thing to fail
is the package, which in turn leads to failure in the bonding. Consumer
grade electronics use porous plastic packages, while the military forks
out for ceramic.

It is possible to get ion contaminator from how the wafers were handled
(such as a moron touching the edge), but the associated threshold
shifts show up very soon. I'm not sure if you can find this on the net,
but all the IC companies do some sort of die seal to reduce this
problem.

I'd blame the capacitors, especially tantalum. Resistors should be
stable.

Regarding electromigration, this is also well understood and
compensated for in the design process.

I can tell you that most chips coming to a failure analysis lab are
damaged by electrical overstress. Often a power surge will shoot right
through the power supply and zap some chip. [Some radios are "always
on" if hooked up to the AC mains, so a radio that is off can get
zapped.] Second comes latch-up related problems, not exactly the fault
of the chip, i.e. all chips using reverse biased diode isolation will
latch under some external conditions.

wrote:

Collectors have a whole different set of reasons for buying a radio
than users. Compare the price for that radio with the $600.00 for an
FRG-7, $800.00 for a Sony 6800, $3,000 for a SonyCRF320 or $800.00 for
a Zenith TO. Prices no user would contemplate, but several collectors
would not blink twice at.

The Sony you mentioned was one of many luggable radios in it's time.
It probably priced out lower than but was meant to compete as a
reasonably priced alternative to the Panasonic Rf-5000a, Zenith TO,
Nordmende & Grundig offerings. All were reasonable performing radios
in their time with notably pleasant audio - much mellower than anything
found today. In all cases time will have taken a toll on their
electronics and there's a good chance controls will be noisy, dial
accuracy will be frustrating, plastic started to fade, etc. For my
purposes the Sony would be fun to use for a while, but that's about it.
That there have been 32 bids to date tells me there's more than one
collector that have a different view.


wrote:

http://cgi.ebay.com/ws/eBayISAPI.dll...5895 535&rd=1


Don't forget the GE World Monitor, another competitor in the TO type
radio derby of the 60s. I have an early version of the World Monitor, a
P990C that my grandfather bought new in 1964. He bought it for the FM
band, this at a time when most small transistor radios were MW only. He
paid $100 for it, which was a lot of money in 1964. It still works well,
and has the original AC adaptor (he used it in his auto repair shop). I
could probably get $800 for it on ebay, not that I would risk the wrath
of my grandfather by doing so.

Note that the seller has amended his auction to argue that the Sony is
worth $400. He originally put it up for $19.95.


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In article .com,
says...
http://cgi.ebay.com/ws/eBayISAPI.dll...5895 535&rd=1




A friend's dad had a huge collection of receivers from the late 50's
until he died in 1981, and this was one of the portables. The Sony
wasn't great when it was new, let alone now...



Here's something that went for a sane price...not bad.

http://cgi.ebay.com/ws/eBayISAPI.dll...tem=5756638102
&ssPageName=STRK:MEWA:IT


BDK

I've had two Sony CRF-5100s in my time. The first I bought was from a school
rummage sale about 15 years ago for $8. Another was from a hamfest a few
years ago for $85. Neither was terribly impressive and I sold them for
roughly what I had in them.

"BDK" wrote in message
...

A friend's dad had a huge collection of receivers from the late 50's
until he died in 1981, and this was one of the portables. The Sony
wasn't great when it was new, let alone now...

In article ,
says...
I've had two Sony CRF-5100s in my time. The first I bought was from a school
rummage sale about 15 years ago for $8. Another was from a hamfest a few
years ago for $85. Neither was terribly impressive and I sold them for
roughly what I had in them.

"BDK" wrote in message
...

A friend's dad had a huge collection of receivers from the late 50's
until he died in 1981, and this was one of the portables. The Sony
wasn't great when it was new, let alone now...




When my friend's dad died, he auctioned off almost all his stuff,
keeping the nicer R390A of two his dad had, and a nearly new looking
Hammarlund HQ180. The rest went, along with a seemingly endless supply
of parts he built up over the years. Half the attic was stocked with NOS
receiving tubes, and a large number of high power linear amp tubes and
other transmitter tubes. His dad's so called "friends" attempted to
steal all his stuff after he died, and were really upset when my friend
didn't give them the stuff for a tenth it's real worth.


I think the CRF-5100 went for 90 or 100 bucks, but it wasn't one of the
ones I wanted, so I really didn't pay attention to the bids on it. I
wanted the Drake R7, but was outbid almost instantly. It ended up nearly
what a new one cost..

BDK

I have a will,it is all legal and binding too.In fact,years ago I went
to one of those crooked lawyers (all lawyers are crooks,but of course
y'all already knew that) and got it all did up legal.When I
croak,anything my sister and brother in law doesn't want of mine,(and I
doubt if they would want to have any of my old junk) an old buddy of
mine can have what he wants.
cuhulin

wrote in message
oups.com...

http://cgi.ebay.com/ws/eBayISAPI.dll...5895 535&rd=1


Why yes Capt. I would love to explain this to you. This is what we on Earth
call a radio. It is designed to receive radio signals. Radio signals bring
news and entertainment to all corners of the planet and are transmitted by
radio stations. Hope this helps. Take care.

B.H.

In article .com,
says...
http://cgi.ebay.com/ws/eBayISAPI.dll...5895 535&rd=1


Interesting price. Remember ?? a couple of months back I posted
an inquiry saying I found one of these in working conditon on a back
shelf in the stock room at work...did anyone have any doc's to assist my
restoration ??

The radio is currently in service in our undergrad analog circuits
lab so the students can listen to something more interesting than top
40's when they're in there after hours trying to finish up.

It still needs an unkludged bandswitch knob, and I'd love to have
a copy of the alinement data.