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

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

Reply to
Ancient_Hacker
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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.

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 Thanks,
    - Win
Reply to
Winfield Hill

Link?

-Dave

Reply to
David Ashley

formatting link

Barry Lennox

Reply to
Barry Lennox

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.

--
 Thanks,
    - Win
Reply to
Winfield Hill

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.

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

Reply to
Rich Grise

In message , dated Sat, 26 Aug 2006, Rich Grise writes

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

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Reply to
John Woodgate

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

Reply to
Homer J Simpson

My father called that a "profit center".

...Jim Thompson

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|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

In message , dated Sat, 26 Aug 2006, Homer J Simpson writes

Before WWII? Not after, I think.

Probably.

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OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk
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Reply to
John Woodgate

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

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.

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

--
 Thanks,
    - Win
Reply to
Winfield Hill

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!

Reply to
mc

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.

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 Thanks,
    - Win
Reply to
Winfield Hill

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.

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 JosephKK
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Reply to
joseph2k

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.

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Reply to
Michael A. Terrell

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