Hey Win, did you ever use that WWII 715 pulser tube?

[Ancient_Hacker]

Looking thru my junkbox, I again spotted a few 715C tubes, which
reminded me of Win's high speed HV ramp project, of which I havent
heard anyhing about recently.

Just wondering, how'd it turn out? Did you use the solid-state
totem-pole arrangement or the good old vacuum toob?

Regards,

George

 

[Winfield Hill]

Ancient_Hacker wrote...

Looking thru my junkbox, I again spotted a few 715C tubes,
which reminded me of Win's high speed HV ramp project, of
which I havent heard anyhing about recently.

Just wondering, how'd it turn out? Did you use the solid-
state totem-pole arrangement or the good old vacuum toob?

I appreciated the vacuum-tube suggestion, and procured a
few 5D21 types on eBay. I also read about these tubes in
a few fascinating WWII submarine patrol reports, e.g.,
the USS Tang, submitted May 15, 1944, and the USS Bergall,
dated Dec 7, 1944. I suggest you look those up on the web.

As for the project, my summer students made a preliminary
prototype of a precision high-voltage current source for
1us long current pulses, which worked quite well, after I
added a pair of ferrite beads to stop the HV MOSFETs from
oscillating strongly at 50MHz during the pulse! They got
it running in the final hour of their summer job here, or
I should say in the final post hour, since they decided to
stay an extra hour to get it going. We observed a linear
1us ramp, exchanged high fives and shut everything down.

 

[David Ashley]

I appreciated the vacuum-tube suggestion, and procured a
few 5D21 types on eBay. I also read about these tubes in
a few fascinating WWII submarine patrol reports, e.g.,
the USS Tang, submitted May 15, 1944, and the USS Bergall,
dated Dec 7, 1944. I suggest you look those up on the web.

Link?

-Dave

 

[Barry Lennox]

link?

http://www.warfish.com/tang/report2_t.html

Barry Lennox

 

[Winfield Hill]

Barry Lennox wrote...

http://www.warfish.com/tang/report2_t.html

Thanks, Barry. Although the patrol report details are fascinating,
I enjoyed the radar repair paragraph. In reading the patrol report
it becomes clear how important the radar was to their survival and
success (remember, the enemy didn't have radar), and despite the dry
language, how serious it was when it failed and was being repaired,
talk about working under pressure!

(M) RADAR

The performance of the SJ radar was very satisfactory when it was in
operation. Fortunately its off periods in general coincided with bright
nights when shipping could be sighted and to the return trip. The trouble
was generally in the new type transmitter and among other things entailed
the failure of the original modulator unit, the spare, and finally a third
one obtained from the USS TRIGGER. Around the clock repairs by our "long
course" radar officer, a first class radio technician, and a first class
radioman could only temporarily overcome the rate of breakdown. A thousand
man hours were devoted exclusively to its overhaul with only temporary
results and the knowledge that "they hadn't said uncle" as a reward. The
details of the failures are listed below:

Item Number of Reason for
Number Description failures failure

135 VR-150/30 Tube 2 Lost gas
120 6L6 (metal) Tube 4 shorted and weak
121 6L6 (glass) Tube 1 poor emission
134 VR-105/30 Tube 1 lost gas
140 919 LP Lamps 4 Poor regulation
117 6AC7 Tube 4 shorting and poor emission
122 6SN7 Tube 2 poor emission
118 6AG7 Tube 1 shorting
127 705A Tube 3 not known
116 504G Tube 5 shorting and poor emission
129 717A Tube 2 soft
119 6H6 (glass) Tube 1 shorted
114 2X2 Tube 1 lost emission
135A 5D21 Tube 1 gasious

--- rest of long list redacted. I note the 5D21 25kV 10A pulse
tube was a minor nuisance, compared to the rest of the stuff.
The USS Bergall patrol report was similar, only one failure.

 

[Rich Grise]

.

Item Number of Reason for
Number Description failures failure

135 VR-150/30 Tube 2 Lost gas
120 6L6 (metal) Tube 4 shorted and weak
121 6L6 (glass) Tube 1 poor emission
134 VR-105/30 Tube 1 lost gas
140 919 LP Lamps 4 Poor regulation
117 6AC7 Tube 4 shorting and poor emission
122 6SN7 Tube 2 poor emission
118 6AG7 Tube 1 shorting
127 705A Tube 3 not known
116 504G Tube 5 shorting and poor emission
129 717A Tube 2 soft
119 6H6 (glass) Tube 1 shorted
114 2X2 Tube 1 lost emission
135A 5D21 Tube 1 gasious

--- rest of long list redacted. I note the 5D21 25kV 10A pulse
tube was a minor nuisance, compared to the rest of the stuff.
The USS Bergall patrol report was similar, only one failure.

Oy, what a trip down nostalgia lane! Anybody remember those
dime-store tube testers, where when the TeeVee started going bad,
you'd pull out all of the tubes (remembering where they go back in,
of course) and take them down to the store and test them all - throw
away the bad ones, and buy a replacement right there on the spot.

Of course, it's a little hard to do this on a submarine, although,
they must have had a tube tester on board - how else could you diagnose
"poor emission", of all things? ;-)

Thanks!
Rich

 

[John Woodgate]

Anybody remember those dime-store tube testers, where when the TeeVee
started going bad, you'd pull out all of the tubes (remembering where
they go back in, of course) and take them down to the store and test
them all - throw away the bad ones, and buy a replacement right there
on the spot.

In UK, the number of TV dealers who had an emission tester AND knew how
to use it, was minimal. They only tested heaters.

 

[Homer J Simpson]

In UK, the number of TV dealers who had an emission tester AND knew how to
use it, was minimal. They only tested heaters.

ISTR that Boots had these way back when? Or was it only US drugstores?

 

[Jim Thompson]

In UK, the number of TV dealers who had an emission tester AND knew how
to use it, was minimal. They only tested heaters.

My father called that a "profit center".

...Jim Thompson

 

[John Woodgate]

ISTR that Boots had these way back when?

Before WWII? Not after, I think.

Or was it only US drugstores?

Probably.

 

[Winfield Hill]

Rich Grise wrote...

Oy, what a trip down nostalgia lane!

I hope you retreived asnd read the entire patrol report, that's
a trip down nostalgia lane before our time, but worth taking.

Anybody remember those
dime-store tube testers, where when the TeeVee started going bad,
you'd pull out all of the tubes (remembering where they go back in,
of course) and take them down to the store and test them all - throw
away the bad ones, and buy a replacement right there on the spot.

I remember them in the supermarket or something like that, rather
late in the scene; before that you needed to visit your local TV
service guy with his tube tester. My memory is they didn't have
much impact. Perhaps that's because I was more interested in the
tearing the sets apart for parts.

Of course, it's a little hard to do this on a submarine, although,
they must have had a tube tester on board - how else could you diagnose
"poor emission", of all things? ;-)

It seems they had a complete store of parts and test equipment.

 

[mc]

I remember them in the supermarket or something like that, rather
late in the scene; before that you needed to visit your local TV
service guy with his tube tester. My memory is they didn't have
much impact. Perhaps that's because I was more interested in the
tearing the sets apart for parts.

There was a self-service tube tester in Marvac Dow Electronics (formerly Dow
Radio) in Pasadena as recently as, I think, 1997. Is it still there?

Also, I've heard people complain that TVs used to be *much* easier to fix --
all you had to do was change a tube. That misses the point; nowadays most
TVs run for >5 years without needing any repairs at all!

 

[Winfield Hill]

mc wrote...

Also, I've heard people complain that TVs used to be *much* easier to
fix -- all you had to do was change a tube. That misses the point;
nowadays most TVs run for >5 years without needing any repairs at all!

My wife's 23" Panasonic has been running flawlessly for nearly
20 years, and is used almost every day for the evening news.
A 27" model we got for the living room went 13 years before its
first failure, which was a failed solder joint on the flyback
transformer primary. After resoldering the joint, it went four
more years before we exchanged it for a HDTV LCD-screen model.

 

[joseph2k]

On Wed, 23 Aug 2006 14:25:18 -0700, Winfield Hill wrote:


Oy, what a trip down nostalgia lane! Anybody remember those
dime-store tube testers, where when the TeeVee started going bad,
you'd pull out all of the tubes (remembering where they go back in,
of course) and take them down to the store and test them all - throw
away the bad ones, and buy a replacement right there on the spot.

Memory lane. It ran a little different for me, if the TV got funky, my dad
pulled from 1 to 3 tubes and took them to the shopping center and tested
them. Later he had me ride my bicycle off to test them, i was around 7 or
8 at the time. I had to write down the test results. Then he gave me the
money to go but the new tube (though occasionally he had one "in stock").

Later about when i was 12 or so, i took the cover off the back of the set
and rarely pulled more than one tube. Since the new set was mostly
miniature tubes, a toothpick with a flag attached was stuck into one of the
socket pins with the tube type printed on it. Soon i was fixing
electronics on the block for spending money.

BTW, my dad was an electrical engineer, and i was an observant child.

Of course, it's a little hard to do this on a submarine, although,
they must have had a tube tester on board - how else could you diagnose
"poor emission", of all things? ;-)

An emission tester was easy enough to build in the day (1950's). Some of
the radio stores had transconductance (gm) testers.

 

[Michael A. Terrell]

Memory lane. It ran a little different for me, if the TV got funky, my dad
pulled from 1 to 3 tubes and took them to the shopping center and tested
them. Later he had me ride my bicycle off to test them, i was around 7 or
8 at the time. I had to write down the test results. Then he gave me the
money to go but the new tube (though occasionally he had one "in stock").

Later about when i was 12 or so, i took the cover off the back of the set
and rarely pulled more than one tube. Since the new set was mostly
miniature tubes, a toothpick with a flag attached was stuck into one of the
socket pins with the tube type printed on it. Soon i was fixing
electronics on the block for spending money.

BTW, my dad was an electrical engineer, and i was an observant child.


An emission tester was easy enough to build in the day (1950's). Some of
the radio stores had transconductance (gm) testers.

At 13 I was working part time in a TV shop. Not only did I get paid,
but I got all the B&W trade ins for free. I made more money in the used
TV business than from my job.


--
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