I have an old 8 gernamium transistor, protable AM radio that is noisy
on weak stations when cold. It works reasonably well when set it in the
sunshine and warms up. The problem seems to be the RF section since the
noise goes away when the volume is turned down. I'm suspecting the
germanium transistors may be the problem and wondering which one might
be replaced with a silicon variety to cure the temperature problems?

I'm not sure what all 8 transistors do. Two are in the output stage,
and another is used as a audio driver that drives the audio input
transformer.There are four RF coils, the usual oscillator (red) and
mixer (yellow) and white (1st IF) and (black (second IF). But that only
requires 6 transistors, and there are eight total. The detector is a
diode, so they didn't use a transistor for that. I haven't figured out
what the other 2 transistors do.

I'm thinking of replacing the oscillator transistor with a high gain
silicon variety to try and eliminate the temperature problems?

Any other ideas?

-Bill

wrote in message
oups.com...

I have an old 8 germanium transistor, portable AM radio that is noisy
on weak stations when cold. It works reasonably well when set it in the
sunshine and warms up. The problem seems to be the RF section since the
noise goes away when the volume is turned down. I'm suspecting the
germanium transistors may be the problem and wondering which one might
be replaced with a silicon variety to cure the temperature problems?

It could be a lot of things. You need to find a way to test which.

I'm not sure what all 8 transistors do. Two are in the output stage,
and another is used as a audio driver that drives the audio input
transformer.

Usually two for output, two for audio amps = 4.

There are four RF coils, the usual oscillator (red) and
mixer (yellow) and white (1st IF) and (black (second IF). But that only
requires 6 transistors, and there are eight total.

Actually 7. Some radios had non working transistors added to bring the count
up.

The detector is a
diode, so they didn't use a transistor for that. I haven't figured out
what the other 2 transistors do.

I'm thinking of replacing the oscillator transistor with a high gain
silicon variety to try and eliminate the temperature problems?

You might need to alter the bias on each transistor you replace.

wrote in news:1163387574.804150.266160
@h54g2000cwb.googlegroups.com:

I have an old 8 gernamium transistor, protable AM radio that is noisy
on weak stations when cold....


Try over on alt.antiques.radio+phono... they'll enjoy hearing about your
germanium transistors.

Jim Land ) writes:
wrote in news:1163387574.804150.266160
@h54g2000cwb.googlegroups.com:

I have an old 8 gernamium transistor, protable AM radio that is noisy
on weak stations when cold....


Try over on alt.antiques.radio+phono... they'll enjoy hearing about your
germanium transistors.

I don't know. There has been debate in the past over there about what's
relevant to the newsgroup, and some have felt transistors aren't old
enough.

Michael

In article tGS5h.2707$_Z2.2344@edtnps89,
Homer J Simpson wrote:
I'm not sure what all 8 transistors do. Two are in the output stage,
and another is used as a audio driver that drives the audio input
transformer.

Usually two for output, two for audio amps = 4.

Perfectly easy to manage with three - one driver only.

--
*Could it be that "I do " is the longest sentence? *

Dave Plowman London SW
To e-mail, change noise into sound.

Michael Black wrote:

Jim Land ) writes:
wrote in news:1163387574.804150.266160
@h54g2000cwb.googlegroups.com:

I have an old 8 gernamium transistor, protable AM radio that is noisy
on weak stations when cold....


Try over on alt.antiques.radio+phono... they'll enjoy hearing about your
germanium transistors.

I don't know. There has been debate in the past over there about what's
relevant to the newsgroup, and some have felt transistors aren't old
enough.

Michael


Some of them think that A****er Kent radios are too new for that
group. Ignore them, there are a number of transistor radio collectors
in that group. I have most of the "Sams Transistor Radio Manuals" in my
collection: http://home.earthlink.net/~mike.terrell/HWSTm.html The Sams
index is available online.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

wrote:
I have an old 8 gernamium transistor, protable AM radio that is noisy
on weak stations when cold.

By "noisy" do you mean there is lots of background hiss, or do you mean
the sound is rough and distorted?


It works reasonably well when set it in the
sunshine and warms up.

I'm suspecting the
germanium transistors may be the problem and wondering which one might
be replaced with a silicon variety to cure the temperature problems?

No. The radio was designed to work with germanium transistors. Every
stage you change over to silicon will need to be rebiased, retuned, and
reneutralized. Not an easy job.

I'd start with replacing the electrolytics. Quite likely they're at
about 20% of their original selves. Weak electrolytics can make the
radio motorboat, or sound tinny and noisy.

On Sun, 12 Nov 2006 19:12:54 -0800, wrongaddress wrote:

I have an old 8 gernamium transistor, protable AM radio that is noisy
on weak stations when cold. It works reasonably well when set it in the
sunshine and warms up. The problem seems to be the RF section since the
noise goes away when the volume is turned down. I'm suspecting the
germanium transistors may be the problem and wondering which one might
be replaced with a silicon variety to cure the temperature problems?

I'm not sure what all 8 transistors do. Two are in the output stage,
and another is used as a audio driver that drives the audio input
transformer.There are four RF coils, the usual oscillator (red) and
mixer (yellow) and white (1st IF) and (black (second IF). But that only
requires 6 transistors, and there are eight total. The detector is a
diode, so they didn't use a transistor for that. I haven't figured out
what the other 2 transistors do.

I'm thinking of replacing the oscillator transistor with a high gain
silicon variety to try and eliminate the temperature problems?

Any other ideas?

-Bill


Since warmer=drier, I might look for paper tubular
caps. When moist, they leak badly.

"Dave Plowman (News)" wrote in message
...

Usually two for output, two for audio amps = 4.

Perfectly easy to manage with three - one driver only.

But in those days more transistors = more sales. I used to fix such things.

wrote:

I have an old 8 gernamium transistor, protable AM radio that is noisy
on weak stations when cold. It works reasonably well when set it in the
sunshine and warms up. The problem seems to be the RF section since the
noise goes away when the volume is turned down. I'm suspecting the
germanium transistors may be the problem and wondering which one might
be replaced with a silicon variety to cure the temperature problems?

I'm not sure what all 8 transistors do. Two are in the output stage,
and another is used as a audio driver that drives the audio input
transformer.There are four RF coils, the usual oscillator (red) and
mixer (yellow) and white (1st IF) and (black (second IF). But that only
requires 6 transistors, and there are eight total. The detector is a
diode, so they didn't use a transistor for that. I haven't figured out
what the other 2 transistors do.

I'm thinking of replacing the oscillator transistor with a high gain
silicon variety to try and eliminate the temperature problems?

Any other ideas?

-Bill

Replacing parts at random on electronics makes not one bit of sense.
There are hundreds of components and hundreds of connections, any one
of which may be to do with it. Trying to repair a radio by replacing
geraniums with silicon makes even less sense. Germanium trs are still
sold new as well as used.

If you dont know what youre doing, leave it alone.


NT

"J. Todd" wrote:

On Sun, 12 Nov 2006 19:12:54 -0800, wrongaddress wrote:

I have an old 8 gernamium transistor, protable AM radio that is noisy
on weak stations when cold. It works reasonably well when set it in the
sunshine and warms up. The problem seems to be the RF section since the
noise goes away when the volume is turned down. I'm suspecting the
germanium transistors may be the problem and wondering which one might
be replaced with a silicon variety to cure the temperature problems?

I'm not sure what all 8 transistors do. Two are in the output stage,
and another is used as a audio driver that drives the audio input
transformer.There are four RF coils, the usual oscillator (red) and
mixer (yellow) and white (1st IF) and (black (second IF). But that only
requires 6 transistors, and there are eight total. The detector is a
diode, so they didn't use a transistor for that. I haven't figured out
what the other 2 transistors do.

I'm thinking of replacing the oscillator transistor with a high gain
silicon variety to try and eliminate the temperature problems?

Any other ideas?

-Bill

Since warmer=drier, I might look for paper tubular
caps. When moist, they leak badly.


Paper capacitors? Transistor radios use electrolytic and mylar film
instead of paper, but the electrolytics were poor quality, and they
don't age very well. The capacitors in tuned circuits are either mica,
ceramic or polystyrene.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

Michael A. Terrell wrote:
"J. Todd" wrote:

Since warmer=drier, I might look for paper tubular
caps. When moist, they leak badly.

Paper capacitors? Transistor radios use electrolytic and mylar film
instead of paper, but the electrolytics were poor quality, and they
don't age very well. The capacitors in tuned circuits are either mica,
ceramic or polystyrene.

Lytic caps are easily tested by piggybacking. Just clip a similar value
cap on, no need for any soldering or cutting. But really its farily
pointless unless you do some fault finding first.


NT

Get a can Of "Cold Spray" when it is working good, gently spray each
transistor to find which one is causing the trouble. Then replace it with a
new germanium transistor.


wrote in message
oups.com...
I have an old 8 gernamium transistor, protable AM radio that is noisy
on weak stations when cold. It works reasonably well when set it in the
sunshine and warms up. The problem seems to be the RF section since the
noise goes away when the volume is turned down. I'm suspecting the
germanium transistors may be the problem and wondering which one might
be replaced with a silicon variety to cure the temperature problems?

I'm not sure what all 8 transistors do. Two are in the output stage,
and another is used as a audio driver that drives the audio input
transformer.There are four RF coils, the usual oscillator (red) and
mixer (yellow) and white (1st IF) and (black (second IF). But that only
requires 6 transistors, and there are eight total. The detector is a
diode, so they didn't use a transistor for that. I haven't figured out
what the other 2 transistors do.

I'm thinking of replacing the oscillator transistor with a high gain
silicon variety to try and eliminate the temperature problems?

Any other ideas?

-Bill

wrote:

Michael A. Terrell wrote:
"J. Todd" wrote:

Since warmer=drier, I might look for paper tubular
caps. When moist, they leak badly.

Paper capacitors? Transistor radios use electrolytic and mylar film
instead of paper, but the electrolytics were poor quality, and they
don't age very well. The capacitors in tuned circuits are either mica,
ceramic or polystyrene.

Lytic caps are easily tested by piggybacking. Just clip a similar value
cap on, no need for any soldering or cutting. But really its farily
pointless unless you do some fault finding first.

NT


Unless they are leaky, then "Piggybacking" is a waste of time. I
have an ESR meter, and a digital capacitor meter. On the other hand, I
would probably just replace all the old electrolytics first, then look
for other problems. It usually only takes a couple dollars worth of new
caps, and they should be replaced if you plan to actually use the radio.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

How many gangs on the tuning cap? Many of the 8 transistor radios had an
RF stage - if there are 3 gangs on the tuning cap that is a giveaway

David

wrote:

I have an old 8 gernamium transistor, protable AM radio that is noisy
on weak stations when cold. It works reasonably well when set it in the
sunshine and warms up. The problem seems to be the RF section since the
noise goes away when the volume is turned down. I'm suspecting the
germanium transistors may be the problem and wondering which one might
be replaced with a silicon variety to cure the temperature problems?

I'm not sure what all 8 transistors do. Two are in the output stage,
and another is used as a audio driver that drives the audio input
transformer.There are four RF coils, the usual oscillator (red) and
mixer (yellow) and white (1st IF) and (black (second IF). But that only
requires 6 transistors, and there are eight total. The detector is a
diode, so they didn't use a transistor for that. I haven't figured out
what the other 2 transistors do.

I'm thinking of replacing the oscillator transistor with a high gain
silicon variety to try and eliminate the temperature problems?

Any other ideas?

-Bill

Ancient_Hacker wrote:
wrote:
I have an old 8 gernamium transistor, protable AM radio that is noisy
on weak stations when cold.

By "noisy" do you mean there is lots of background hiss, or do you mean
the sound is rough and distorted?


Yes, lots of background hiss and roar at low temperature. At 80 degrees
F, it's not too bad, but at 55 degrees it whistles and squeals and the
weak stations are lost.


It works reasonably well when set it in the
sunshine and warms up.

I'm suspecting the
germanium transistors may be the problem and wondering which one might
be replaced with a silicon variety to cure the temperature problems?

No. The radio was designed to work with germanium transistors. Every
stage you change over to silicon will need to be rebiased, retuned, and
reneutralized. Not an easy job.


I'm not sure the design is the best. They used a couple resistors to
set the bias on the output stage, and when the battery voltage falls a
volt or so, the output has some crossover distortion. I fixed that
problem with a couple diodes in place of a resistor so the bias current
stays above zero as the battery voltage falls. I can now drop the
supply voltage a couple volts with no crossover distortion.

I'd start with replacing the electrolytics. Quite likely they're at
about 20% of their original selves. Weak electrolytics can make the
radio motorboat, or sound tinny and noisy.

Yes, that could be a problem, but the AGC seems to work well, so that
capacitor must be ok.

-Bill

wrote:
Ancient_Hacker wrote:
wrote:
I have an old 8 gernamium transistor, protable AM radio that is noisy
on weak stations when cold.
By "noisy" do you mean there is lots of background hiss, or do you mean
the sound is rough and distorted?


Yes, lots of background hiss and roar at low temperature. At 80 degrees
F, it's not too bad, but at 55 degrees it whistles and squeals and the
weak stations are lost.

It works reasonably well when set it in the
sunshine and warms up.
I'm suspecting the
germanium transistors may be the problem and wondering which one might
be replaced with a silicon variety to cure the temperature problems?
No. The radio was designed to work with germanium transistors. Every
stage you change over to silicon will need to be rebiased, retuned, and
reneutralized. Not an easy job.


I'm not sure the design is the best. They used a couple resistors to
set the bias on the output stage, and when the battery voltage falls a
volt or so, the output has some crossover distortion. I fixed that
problem with a couple diodes in place of a resistor so the bias current
stays above zero as the battery voltage falls. I can now drop the
supply voltage a couple volts with no crossover distortion.

I'd start with replacing the electrolytics. Quite likely they're at
about 20% of their original selves. Weak electrolytics can make the
radio motorboat, or sound tinny and noisy.

Yes, that could be a problem, but the AGC seems to work well, so that
capacitor must be ok.

Hi Bill...

I haven't read the whole thread, so if I'm repeating anyone
else please accept my apologies.

Why not consider operating it in a warmish room, and spraying
local components one at a time (with a few minutes break in between)
with "freeze in a can" (whatever they call it in your part of the world)
until you find the component that causes it to act up.

And just for the heck of it, my bet's on a resistor.

Take care.

Ken

wrote:
wrote:

I have an old 8 gernamium transistor, protable AM radio that is noisy
on weak stations when cold. It works reasonably well when set it in the
sunshine and warms up. The problem seems to be the RF section since the
noise goes away when the volume is turned down. I'm suspecting the
germanium transistors may be the problem and wondering which one might
be replaced with a silicon variety to cure the temperature problems?

I'm not sure what all 8 transistors do. Two are in the output stage,
and another is used as a audio driver that drives the audio input
transformer.There are four RF coils, the usual oscillator (red) and
mixer (yellow) and white (1st IF) and (black (second IF). But that only
requires 6 transistors, and there are eight total. The detector is a
diode, so they didn't use a transistor for that. I haven't figured out
what the other 2 transistors do.

I'm thinking of replacing the oscillator transistor with a high gain
silicon variety to try and eliminate the temperature problems?

Any other ideas?

-Bill

Replacing parts at random on electronics makes not one bit of sense.
There are hundreds of components and hundreds of connections, any one
of which may be to do with it.

There are about about 50 components. This is little portable radio
about the size of 2 packs of cigarettes (5.25 by 3 by 1.25). I like it
because it's easy to carry around and sounds better than the smaller
versions.

Trying to repair a radio by replacing geraniums with silicon makes even less sense.
Germanium trs are still sold new as well as used.

If you dont know what youre doing, leave it alone.


Well, if I leave it alone, I can only use it on hot days. I'm trying to
figure out a way I can use it on hot and COLD days?

Maybe you have a suggestion to overcome the temperature problems?

-Bill

quietguy wrote:
How many gangs on the tuning cap? Many of the 8 transistor radios had an
RF stage - if there are 3 gangs on the tuning cap that is a giveaway

David


It's just a little pocket size radio (5 X 3 X 1.5) with 2 sections for
the tuning cap.It has the usual four RF coils and input and output
audio transformers. But that only requires 6 transistors, and there are
8 used. I suppose I can trace out the connections to try and figure out
what the extra 2 transistors do.

wrote:

I have an old 8 gernamium transistor, protable AM radio that is noisy
on weak stations when cold. It works reasonably well when set it in the
sunshine and warms up. The problem seems to be the RF section since the
noise goes away when the volume is turned down. I'm suspecting the
germanium transistors may be the problem and wondering which one might
be replaced with a silicon variety to cure the temperature problems?

I'm not sure what all 8 transistors do. Two are in the output stage,
and another is used as a audio driver that drives the audio input
transformer.There are four RF coils, the usual oscillator (red) and
mixer (yellow) and white (1st IF) and (black (second IF). But that only
requires 6 transistors, and there are eight total. The detector is a
diode, so they didn't use a transistor for that. I haven't figured out
what the other 2 transistors do.

I'm thinking of replacing the oscillator transistor with a high gain
silicon variety to try and eliminate the temperature problems?

Any other ideas?

-Bill

wrote in message
oups.com...

Well, if I leave it alone, I can only use it on hot days. I'm trying to
figure out a way I can use it on hot and COLD days?

Maybe you have a suggestion to overcome the temperature problems?

The real way to fix it is with a signal tracer and signal generator. Isolate
to a section and fault find there.

wrote:

Maybe you have a suggestion to overcome the temperature problems?

As already suggested and explained, find the fault. Anything else is
just senseless.


NT

wrote:

quietguy wrote:
How many gangs on the tuning cap? Many of the 8 transistor radios had an
RF stage - if there are 3 gangs on the tuning cap that is a giveaway

David


It's just a little pocket size radio (5 X 3 X 1.5) with 2 sections for
the tuning cap.It has the usual four RF coils and input and output
audio transformers. But that only requires 6 transistors, and there are
8 used. I suppose I can trace out the connections to try and figure out
what the extra 2 transistors do.


Does your radio have a brand name and model number?


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

wrote:

It's just a little pocket size radio (5 X 3 X 1.5) with 2 sections for
the tuning cap.It has the usual four RF coils and input and output
audio transformers. But that only requires 6 transistors, and there are
8 used. I suppose I can trace out the connections to try and figure out
what the extra 2 transistors do.

They often used transistors that were weak or had one dead junction as
diodes-- either as detector and agc diodes, or as biasing diodes for
the output stage.

wrote:
wrote:


I have an old 8 gernamium transistor, protable AM radio that is noisy
on weak stations when cold. It works reasonably well when set it in the
sunshine and warms up. The problem seems to be the RF section since the
noise goes away when the volume is turned down. I'm suspecting the
germanium transistors may be the problem and wondering which one might
be replaced with a silicon variety to cure the temperature problems?

I'm not sure what all 8 transistors do. Two are in the output stage,
and another is used as a audio driver that drives the audio input
transformer.There are four RF coils, the usual oscillator (red) and
mixer (yellow) and white (1st IF) and (black (second IF). But that only
requires 6 transistors, and there are eight total. The detector is a
diode, so they didn't use a transistor for that. I haven't figured out
what the other 2 transistors do.

I'm thinking of replacing the oscillator transistor with a high gain
silicon variety to try and eliminate the temperature problems?

Any other ideas?

-Bill



Sounds like a perfect job for a can of freeze spray. Warm it up until
the problem goes away, then give suspect components a quick shot of cold.

Michael A. Terrell wrote:
wrote:

quietguy wrote:
How many gangs on the tuning cap? Many of the 8 transistor radios had an
RF stage - if there are 3 gangs on the tuning cap that is a giveaway

David


It's just a little pocket size radio (5 X 3 X 1.5) with 2 sections for
the tuning cap.It has the usual four RF coils and input and output
audio transformers. But that only requires 6 transistors, and there are
8 used. I suppose I can trace out the connections to try and figure out
what the extra 2 transistors do.


Does your radio have a brand name and model number?

Yes, it's a "Keytone" or "Kaytone" deluxe model, 8 transistor, made in
Japan. Chrome faceplate, white plastic body, red plastic back. I
searched Google but didn't find much.

-Bill


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

James Sweet wrote:
wrote:
wrote:


I have an old 8 gernamium transistor, protable AM radio that is noisy
on weak stations when cold. It works reasonably well when set it in the
sunshine and warms up. The problem seems to be the RF section since the
noise goes away when the volume is turned down. I'm suspecting the
germanium transistors may be the problem and wondering which one might
be replaced with a silicon variety to cure the temperature problems?

I'm not sure what all 8 transistors do. Two are in the output stage,
and another is used as a audio driver that drives the audio input
transformer.There are four RF coils, the usual oscillator (red) and
mixer (yellow) and white (1st IF) and (black (second IF). But that only
requires 6 transistors, and there are eight total. The detector is a
diode, so they didn't use a transistor for that. I haven't figured out
what the other 2 transistors do.

I'm thinking of replacing the oscillator transistor with a high gain
silicon variety to try and eliminate the temperature problems?

Any other ideas?

-Bill



Sounds like a perfect job for a can of freeze spray. Warm it up until
the problem goes away, then give suspect components a quick shot of cold.

Yes, good idea, but the can of freeze spray costs $10, and the radio
only cost two dollars. So I put the radio in the freezer for 30 minutes
and took it out and it didn't work at all. Then I applied a hot
sodering iron to the body of the oscillator transistor and it very
quickly started working again. Seems the oscillator doesn't run at low
temperature.

Would you guess the solution is a silicon transistor? or just adjust
the bias on the existing germanium transistor?

-Bill

wrote in message
oups.com...

Yes, it's a "Keytone" or "Kaytone" deluxe model, 8 transistor, made in
Japan. Chrome faceplate, white plastic body, red plastic back. I
searched Google but didn't find much.

Might be a collectible. If so, don't screw with it. Sell it to a
fool^H^H^H^Hcollector and use the money to buy a good set.

Homer J Simpson wrote:
wrote in message
oups.com...

Yes, it's a "Keytone" or "Kaytone" deluxe model, 8 transistor, made in
Japan. Chrome faceplate, white plastic body, red plastic back. I
searched Google but didn't find much.

Might be a collectible. If so, don't screw with it. Sell it to a
fool^H^H^H^Hcollector and use the money to buy a good set.

Yes, I'm thinking about selling it, but I want it to work well, as good
as new or better. The radio I'd really like to have is the CCRadio Plus
from ccrane company, for $134 at:

http://www.ccrane.com/radios/am-fm-r...lus/index.aspx

It's supposed to be optimized for 'talk radio' and voice frequencies,
but it's a little large to carry around. Runs on four 'D' cells for 250
hours and has a leather case and a bunch of options, solar charger,
Antenna amplifier, ect. It's supposed to be one of the best AM radios.
I see it on ebay all the time, so I might make a bid and get it for
$100 or less.

-Bill

wrote in message
ups.com...

Yes, I'm thinking about selling it, but I want it to work well, as good
as new or better. The radio I'd really like to have is the CCRadio Plus
from ccrane company, for $134 at:

http://www.ccrane.com/radios/am-fm-r...lus/index.aspx

It's supposed to be optimized for 'talk radio' and voice frequencies,
but it's a little large to carry around. Runs on four 'D' cells for 250
hours and has a leather case and a bunch of options, solar charger,
Antenna amplifier, ect. It's supposed to be one of the best AM radios.
I see it on ebay all the time, so I might make a bid and get it for
$100 or less.

I somewhat covet a Grundig all wave hand cranked, but I expect it's made in
China too.

wrote in news:1163559828.809638.315730
@e3g2000cwe.googlegroups.com:

The radio I'd really like to have is the CCRadio Plus
from ccrane company, for $134 at:

http://www.ccrane.com/radios/am-fm-r...lus/index.aspx

It's supposed to be optimized for 'talk radio' and voice frequencies...

I wonder how that is different from "lacks good bass and treble"?

Jim Land wrote:

wrote in news:1163559828.809638.315730
@e3g2000cwe.googlegroups.com:

The radio I'd really like to have is the CCRadio Plus
from ccrane company, for $134 at:

http://www.ccrane.com/radios/am-fm-r...lus/index.aspx

It's supposed to be optimized for 'talk radio' and voice frequencies...

I wonder how that is different from "lacks good bass and treble"?


Some of those CC Crane radios have a high failure rate on the LCD
displays. Ask about the model you are looking at on:
news:rec.radio.shortwave but be ready for the flaming idiots who like to
hijack almost every thread.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

wrote:

only cost two dollars. So I put the radio in the freezer for 30 minutes
and took it out and it didn't work at all. Then I applied a hot
sodering iron to the body of the oscillator transistor and it very
quickly started working again. Seems the oscillator doesn't run at low
temperature.

Would you guess the solution is a silicon transistor? or just adjust
the bias on the existing germanium transistor?

-Bill

neither, increase the stage gain. That probably means higher collector
R or similar. You may then need to adj the bias a little.

Or with an old radio like that it might just be biased way wrong, where
gain is down. Meter it and see where Vce sits when not oscillating.


NT

wrote:

only cost two dollars. So I put the radio in the freezer for 30 minutes
and took it out and it didn't work at all. Then I applied a hot
sodering iron to the body of the oscillator transistor and it very
quickly started working again. Seems the oscillator doesn't run at low
temperature.

Would you guess the solution is a silicon transistor? or just adjust
the bias on the existing germanium transistor?

-Bill

neither, increase the stage gain. That probably means higher collector
R or similar. You may then need to adj the bias a little.

Or with an old radio like that it might just be biased way wrong, where
gain is down. Meter it and see where Vce sits when not oscillating.


NT

PS keep slobbering irons off geraniums, they max out at 90C, and
slobber doesnt even melt till over 200. Just soldering Ge trs into pcbs
is prone to killing them, this is why they typically had long sleeved
leads.


NT

wrote:

wrote:

only cost two dollars. So I put the radio in the freezer for 30 minutes
and took it out and it didn't work at all. Then I applied a hot
sodering iron to the body of the oscillator transistor and it very
quickly started working again. Seems the oscillator doesn't run at low
temperature.

Would you guess the solution is a silicon transistor? or just adjust
the bias on the existing germanium transistor?

-Bill

neither, increase the stage gain. That probably means higher collector
R or similar. You may then need to adj the bias a little.

Or with an old radio like that it might just be biased way wrong, where
gain is down. Meter it and see where Vce sits when not oscillating.

NT

PS keep slobbering irons off geraniums, they max out at 90C, and
slobber doesnt even melt till over 200. Just soldering Ge trs into pcbs
is prone to killing them, this is why they typically had long sleeved
leads.

NT


Some of the early, cheap transistor radios used really poor quality
transistors. they had so much leakage that they were self biasing.
Even if you replace them with a good germanium transistor, they may need
the bias adjusted.


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

wrote in message
ups.com...

Would you guess the solution is a silicon transistor? or just adjust
the bias on the existing germanium transistor?

I did have one set only (ever) that had weak transistors. It was a minimum
count model (5 or 6) and I replaced all of them to get it to work again.

Michael A. Terrell spake thus:

Michael Black wrote:

Jim Land ) writes:

wrote in news:1163387574.804150.266160
:

I have an old 8 gernamium transistor, protable AM radio that is noisy
on weak stations when cold....

Try over on alt.antiques.radio+phono... they'll enjoy hearing about your
germanium transistors.

I don't know. There has been debate in the past over there about what's
relevant to the newsgroup, and some have felt transistors aren't old
enough.

Some of them think that A****er Kent radios are too new for that
group. Ignore them, there are a number of transistor radio collectors
in that group. I have most of the "Sams Transistor Radio Manuals" in my
collection: http://home.earthlink.net/~mike.terrell/HWSTm.html The Sams
index is available online.

Which implies that, at least sometime in the past, there were those who
repaired those radios. Did they? I remember when those things appeared
on the market, and I always thought of them as disposable items. Did
people actually take them in to be fixed?


--
Just as McDonald's is where you go when you're hungry but don't really
care about the quality of your food, Wikipedia is where you go when
you're curious but don't really care about the quality of your knowledge.

- Matthew White's WikiWatch (http://users.erols.com/mwhite28/wikiwoo.htm)

David Nebenzahl ) writes:
Michael A. Terrell spake thus:

Michael Black wrote:

Jim Land ) writes:

wrote in news:1163387574.804150.266160
:

I have an old 8 gernamium transistor, protable AM radio that is noisy
on weak stations when cold....

Try over on alt.antiques.radio+phono... they'll enjoy hearing about your
germanium transistors.

I don't know. There has been debate in the past over there about what's
relevant to the newsgroup, and some have felt transistors aren't old
enough.

Some of them think that A****er Kent radios are too new for that
group. Ignore them, there are a number of transistor radio collectors
in that group. I have most of the "Sams Transistor Radio Manuals" in my
collection: http://home.earthlink.net/~mike.terrell/HWSTm.html The Sams
index is available online.

Which implies that, at least sometime in the past, there were those who
repaired those radios. Did they? I remember when those things appeared
on the market, and I always thought of them as disposable items. Did
people actually take them in to be fixed?

Who knows. But early transistor radios, that would have used germanium
because there was no choice, were not cheap radios. They cost significant
amounts at the time. Even later, one could still get decent transistor
portables that would have cost a fair amount at the time. I once found
a Sony portable from the early sixties, and it has metal casing and is
quite heavy, complete with the large speaker. People would have been
having those repaired, there's no way they'd toss them if they stopped
working.

The cheap transistor portables came later. Likely they were less likely
to be repaired, but circuit wise they weren't that different from the
expensive portables.

Michael

wrote:
wrote:

only cost two dollars. So I put the radio in the freezer for 30 minutes
and took it out and it didn't work at all. Then I applied a hot
sodering iron to the body of the oscillator transistor and it very
quickly started working again. Seems the oscillator doesn't run at low
temperature.

Would you guess the solution is a silicon transistor? or just adjust
the bias on the existing germanium transistor?

-Bill

neither, increase the stage gain. That probably means higher collector
R or similar. You may then need to adj the bias a little.

Or with an old radio like that it might just be biased way wrong, where
gain is down. Meter it and see where Vce sits when not oscillating.



The collector appears to drive the oscillator coil and mixer coil in
series (no collector R other than maybe decoupling). There is a emitter
resistor of 2K with a drop of 0.35 volts. I figure the oscillator stage
is running at 0.35/2000 = 175 miroamps. I added a 3K resistor in
parallel with the 2K so the current is increased to 0.35/1200 = 292
microamps. This brings up the gain about 3dB, but the radio still fails
at low temperature in the refrigerator. At low temperature there is
only noise and no signal. I tried this with a more modern radio using
silicon transistors and it works well an 40 degrees or so. So, I'm
almost convinced the problem is the germanium transistors.

Will continue to investigate.

-Bill

"David Nebenzahl" wrote in message
.com...

Which implies that, at least sometime in the past, there were those who
repaired those radios. Did they? I remember when those things appeared on
the market, and I always thought of them as disposable items. Did people
actually take them in to be fixed?

The first Sony shirt pocket (just) sized one cost me more than a week's
wages - at wholesale! I repaired them for a few years until I moved on to
other things.

"Michael Black" wrote in message
...

Who knows. But early transistor radios, that would have used germanium
because there was no choice, were not cheap radios. They cost significant
amounts at the time. Even later, one could still get decent transistor
portables that would have cost a fair amount at the time. I once found
a Sony portable from the early sixties, and it has metal casing and is
quite heavy, complete with the large speaker. People would have been
having those repaired, there's no way they'd toss them if they stopped
working.

The cheap transistor portables came later. Likely they were less likely
to be repaired, but circuit wise they weren't that different from the
expensive portables.

We had a popular Philips model that had a transistor audio output stage
(OC71s and OC72s) but still had tubes for the convertor and IF. Later they
came out with the OC44 and OC45 and went fully solid state.