sctvguy1 wrote:

On Fri, 15 Apr 2016 07:47:44 -0700, karabas2001 wrote:

On Friday, April 15, 2016 at 3:06:45 AM UTC-4, wrote:
Hi I have a Kenwood R 1000 , love it . . it developed power problems .
i have since stripped the power board . .unfortunately I cant get most
of the important parts . do you know of any second hand or new boards
available I really want this radio to work again. Regards Peter ZS5
PX

What parts do you need ? Nearly anything inside a radio of this vintage
should not be a problem .

Too bad it does not have tubes that can just be replaced.




Tubes last alot longer than paper and electrolytic capacitors.

On 04/16/2016 04:00 AM, analogdial wrote:
Tubes last alot longer than paper and electrolytic capacitors.

Now there's a blanket statement if I ever heard one.

My experience with the tube era was that a power supply
would commonly have problems with either the rectifier
tube or the electrolytics.

Back then - as a teen, that is - I was a lot better at replacing
tubes and swapping out electrolytics than I was at anything
else, so take this with a grain of salt, but there did seem to
be a lot of tube failures. The tubes that ran hot in the
miniature tube versions of the All American Five radio - the
50C5 output tube and the 35W4 (?) rectifier - were the usual
suspects.

Nowadays tube radios, etc., seem to be showpieces and not
actually used, with those ancient capacitors continuing to
age while the tube filaments remain intact; so, today at
least, the old tubes last way longer than those ancient
capacitors!

George

P.S. The All American Five in my garage is still plugged in
and still works fine at almost 50 years of age. Likely had
a tube or two replaced over the years and little else.

On Sunday, April 17, 2016 at 1:48:00 PM UTC-5, G Cornelius wrote:
On 04/16/2016 04:00 AM, analogdial wrote:
Tubes last alot longer than paper and electrolytic capacitors.

Now there's a blanket statement if I ever heard one.

My experience with the tube era was that a power supply
would commonly have problems with either the rectifier
tube or the electrolytics.

Back then - as a teen, that is - I was a lot better at replacing
tubes and swapping out electrolytics than I was at anything
else, so take this with a grain of salt, but there did seem to
be a lot of tube failures. The tubes that ran hot in the
miniature tube versions of the All American Five radio - the
50C5 output tube and the 35W4 (?) rectifier - were the usual
suspects.

Nowadays tube radios, etc., seem to be showpieces and not
actually used, with those ancient capacitors continuing to
age while the tube filaments remain intact; so, today at
least, the old tubes last way longer than those ancient
capacitors!

George

P.S. The All American Five in my garage is still plugged in
and still works fine at almost 50 years of age. Likely had
a tube or two replaced over the years and little else.

Do you remember that many stores had tube testers and some of those stores sold tubes too? I reckymember them.

On 4/17/2016 4:33 PM, DhiaDuit wrote:
On Sunday, April 17, 2016 at 1:48:00 PM UTC-5, G Cornelius wrote:
On 04/16/2016 04:00 AM, analogdial wrote:
Tubes last alot longer than paper and electrolytic capacitors.

Now there's a blanket statement if I ever heard one.

My experience with the tube era was that a power supply
would commonly have problems with either the rectifier
tube or the electrolytics.

Back then - as a teen, that is - I was a lot better at replacing
tubes and swapping out electrolytics than I was at anything
else, so take this with a grain of salt, but there did seem to
be a lot of tube failures. The tubes that ran hot in the
miniature tube versions of the All American Five radio - the
50C5 output tube and the 35W4 (?) rectifier - were the usual
suspects.

Nowadays tube radios, etc., seem to be showpieces and not
actually used, with those ancient capacitors continuing to
age while the tube filaments remain intact; so, today at
least, the old tubes last way longer than those ancient
capacitors!

George

P.S. The All American Five in my garage is still plugged in
and still works fine at almost 50 years of age. Likely had
a tube or two replaced over the years and little else.

Do you remember that many stores had tube testers and some of those stores sold tubes too? I reckymember them.

I'm old enough to remember those well. I had a beast Hallicrafters short
wave tube radio that I'd stay up much to late listening to. Good memories.

On 4/17/2016 4:33 PM, DhiaDuit wrote:
On Sunday, April 17, 2016 at 1:48:00 PM UTC-5, G Cornelius wrote:
On 04/16/2016 04:00 AM, analogdial wrote:
Tubes last alot longer than paper and electrolytic capacitors.

Now there's a blanket statement if I ever heard one.

My experience with the tube era was that a power supply
would commonly have problems with either the rectifier
tube or the electrolytics.

Back then - as a teen, that is - I was a lot better at replacing
tubes and swapping out electrolytics than I was at anything
else, so take this with a grain of salt, but there did seem to
be a lot of tube failures. The tubes that ran hot in the
miniature tube versions of the All American Five radio - the
50C5 output tube and the 35W4 (?) rectifier - were the usual
suspects.

Nowadays tube radios, etc., seem to be showpieces and not
actually used, with those ancient capacitors continuing to
age while the tube filaments remain intact; so, today at
least, the old tubes last way longer than those ancient
capacitors!

George

P.S. The All American Five in my garage is still plugged in
and still works fine at almost 50 years of age. Likely had
a tube or two replaced over the years and little else.

Do you remember that many stores had tube testers and some of those stores sold tubes too? I reckymember them.

I'm old enough to remember those well. I had a beast Hallicrafters short
wave tube radio that I'd stay up much too late listening to. Good memories.

On Monday, April 18, 2016 at 1:50:57 AM UTC-5, Mike S wrote:
On 4/17/2016 4:33 PM, DhiaDuit wrote:
On Sunday, April 17, 2016 at 1:48:00 PM UTC-5, G Cornelius wrote:
On 04/16/2016 04:00 AM, analogdial wrote:
Tubes last alot longer than paper and electrolytic capacitors.

Now there's a blanket statement if I ever heard one.

My experience with the tube era was that a power supply
would commonly have problems with either the rectifier
tube or the electrolytics.

Back then - as a teen, that is - I was a lot better at replacing
tubes and swapping out electrolytics than I was at anything
else, so take this with a grain of salt, but there did seem to
be a lot of tube failures. The tubes that ran hot in the
miniature tube versions of the All American Five radio - the
50C5 output tube and the 35W4 (?) rectifier - were the usual
suspects.

Nowadays tube radios, etc., seem to be showpieces and not
actually used, with those ancient capacitors continuing to
age while the tube filaments remain intact; so, today at
least, the old tubes last way longer than those ancient
capacitors!

George

P.S. The All American Five in my garage is still plugged in
and still works fine at almost 50 years of age. Likely had
a tube or two replaced over the years and little else.

Do you remember that many stores had tube testers and some of those stores sold tubes too? I reckymember them.

I'm old enough to remember those well. I had a beast Hallicrafters short
wave tube radio that I'd stay up much too late listening to. Good memories.

Vacuum Tube Testers Youtube

G Cornelius wrote:

On 04/16/2016 04:00 AM, analogdial wrote:
Tubes last alot longer than paper and electrolytic capacitors.

Now there's a blanket statement if I ever heard one.

My experience with the tube era was that a power supply
would commonly have problems with either the rectifier
tube or the electrolytics.


Series string sets are harder on tubes than transformer sets. Open
heaters and HK shorts are the usual failures. A thermistor used as an
inrush current limiter helps.

The failure rate for paper caps must be close to 100% by now. That
doesn't mean that the circuit no longer works but that the leakage is
now out of spec and they will only get worse in the future. I doubt
there's been a decent paper wrapped elecrolytic seen for at least 20
years.

I seem to recall reading that some small signal tubes are rated for a
life of 20,000 hours. Or was it 50,000 hours? Anyway, 20,000 hours at
4 hours a day is about 14 years. Maybe twice that long before the radio
actually goes deaf. I like to fix up old radios and I very rarely find
tubes with low gain. As I mentioned, the occasional common failure
modes are open heaters and HK shorts.

I have a strong suspicion that most of the tubes replaced in the past
were still useable. A gently aging tube might work quite well at normal
voltages but be an underperformer in a circuit in which a leaky screen
bypass cap is pulling down the voltage. A new tube might perk up the
circuit but the real problem is the leaky cap.

And it was common repair shop practice to knowingly replace good parts
such as tubes.

Shocking, I know! And I understand why. I was a new tech at a shop,
and a customer called in about her microphone preamp all of the sudden
having distorted sound. I asked the obvious question "Did you put new
batteries in?" "Yesssss! Of course I put new batteries in!!!!!!!! Do
"you think I am an idiot??!!!"

Needless to say, her "new" batteries were just as dead as the first set.

Stupid me, I thought she'd be pleased that new batteries that actually
worked brought the preamp back to perfect operation.

"YOU CHARGED ME THAT MUCH (our minimum charge, actually pretty cheap)
JUST TO REPLACE THE BATTERIES!! YOU'RE A DAMN CROOK!!!!"

No, if I was a crook, I could have charged her five times as much for
replacing good parts and we both would have been so much happier that
day.

Long story short, tubes get an largely undeserved bad rap for
unreliability.

On Fri, 22 Apr 2016, analogdial wrote:

G Cornelius wrote:

On 04/16/2016 04:00 AM, analogdial wrote:
Tubes last alot longer than paper and electrolytic capacitors.

Now there's a blanket statement if I ever heard one.

My experience with the tube era was that a power supply
would commonly have problems with either the rectifier
tube or the electrolytics.


Series string sets are harder on tubes than transformer sets. Open
heaters and HK shorts are the usual failures. A thermistor used as an
inrush current limiter helps.

The failure rate for paper caps must be close to 100% by now. That
doesn't mean that the circuit no longer works but that the leakage is
now out of spec and they will only get worse in the future. I doubt
there's been a decent paper wrapped elecrolytic seen for at least 20
years.

And the stuff wasn't intended for perpetual use. It was "average stuff"
intended to be used, and then eventually fade away. Indeed, it was
tossed. SSB came along, making a lot of stuff "obsolete", transistors
came along and people wanted that. So in the late sixtes and early
seventies, the old AM and tube equipment was relatively cheap. There was
a period when I was getting stuff, playing with it a bit, then trading it
for something else. Not many were thinking of "collecting", and nostalgia
hadn't set in. So that generally caused the stuff to be relegated to the
garbage, or the top shelf.

It's only in more recent times that the stuff was seen as valuable. So
those capacitors that weren't so great to begin with are now decades
older. The tubes sitting around didn't age (though I finally stripped
some old RCA Carfones, mobile equipment for the trunk of the car, and when
I pulled the tubes, a fair number had been broken, even though I don't
remember them being in a situation for that, they just sat there for
decades), while the capacitors probably kept on aging even when not in
use.

As I said, it's the way they made capacitors up to a certain point,
equipment made after that point didn't use paper capacitors but did use
ceramic, so their life is likely in good shape now.

Michael

Michael Black wrote:


And the stuff wasn't intended for perpetual use. It was "average stuff"
intended to be used, and then eventually fade away. Indeed, it was
tossed. SSB came along, making a lot of stuff "obsolete", transistors
came along and people wanted that. So in the late sixtes and early
seventies, the old AM and tube equipment was relatively cheap. There was
a period when I was getting stuff, playing with it a bit, then trading it
for something else. Not many were thinking of "collecting", and nostalgia
hadn't set in. So that generally caused the stuff to be relegated to the
garbage, or the top shelf.

It's only in more recent times that the stuff was seen as valuable. So
those capacitors that weren't so great to begin with are now decades
older. The tubes sitting around didn't age (though I finally stripped
some old RCA Carfones, mobile equipment for the trunk of the car, and when
I pulled the tubes, a fair number had been broken, even though I don't
remember them being in a situation for that, they just sat there for
decades), while the capacitors probably kept on aging even when not in
use.

As I said, it's the way they made capacitors up to a certain point,
equipment made after that point didn't use paper capacitors but did use
ceramic, so their life is likely in good shape now.

Michael

The caps probably did age even when not in use. I had some old NOS wax
dipped paper caps and they all were leaky. Somewhere in Terman's Radio
Engineer's handbook, he says paper caps can be expected to work as new
for only a few years or so. He had an example for leakage sensitive
circuits in which the usual coupling cap is replaced by two much
larger caps in series with a grounded bleeder in between which,
presumably, would forestall the capacitor aging problem.

Back in the 50s, the higher quality, less disposable electronics, used
those newfangled Sprague Black Beauty capacitors in place of the run
of the mill wax dipped paper caps. I suppose that toxic, short circuit
mess hadn't fully devloped by the mid 60s, when Sprague retained the
name "Black Beauty" for their axial lead mylar film caps. The "Orange
Drop" name for radial lead caps is still around, of course.

Mylar caps replaced paper caps at about time electronics started going
solid state so it's understandable why people associate the unrelibility
problems with tubes.