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Re: Dumont knock off of Tek
Stephen Hanselman
So did Knight-Kit,
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Regards, Stephen Hanselman Datagate Systems, LLC
On Jun 22, 2019, at 11:20, ken chalfant <kpchalfant@msn.com> wrote:
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Re: Hello to the group, and a WTB
Dave Seiter
Welcome!By "everything missing", do you mean that the metal channel that runs the length of the scope is missing also, or just the two handles? Seems that I recall someone making leather handle replacements about 10 years ago, but it might have been a limited run. You'd think that a good leather worker on Etsy would see the market for the handles!
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-Dave
On Saturday, June 22, 2019, 5:02:06 PM PDT, greenboxmaven via Groups.Io <ka2ivy=verizon.net@groups.io> wrote:
Hello, I'm Bruce, KA2IVY, Syracuse New York . I found this group while searching for information on a 555 scope. I got one from an estate sale for a very good price. I powered it up carefully, and all the basics work. The jug is in good shape too, on both guns. However, the entire scope , power supply, and cart are grungy and boy does it stink when it's on! There is NO question why the owner is SK! I have read other posts on this group, there are people here that know Tektronix and know the craft very well. It's a pleasure to find a group like this. I have a couple other Tektronix projects I bought at the Rochester and Cortland hamfests, more about them later. The first thing the 555 needs is a bath, I was somewhat surprised to see Tektronix did it at the factory, and considering the "atmosphere" I barely survived in TV ststions, they needed it. For the "WTB" part, the carrying handles on the 555 display unit are completely missing, not just the strap you grab, but everything. The handle on the power supply is rotten down to the steel strap inside, even with a glove on picking it up by the handle is not fun . Does anyone have these handles to spare? Also, the aluminum mesh filter screens are missing from the display and power supply, does anyone have them to spare? Thanks, 73, Bruce
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Re: Dumont knock off of Tek
Leon Robinson
Ken,
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I had a Jettronix 535 equivalent 50 years ago. I have a Lavoie La-265 and the CA equivalent. It hasn't been powered up in probably 15 or 20 years. Sent from K5JLR
-------- Original message --------
From: ken chalfant <kpchalfant@msn.com> Date: 06/22/2019 1:20 PM (GMT-06:00) To: TekScopes@groups.io Subject: Re: [TekScopes] Dumont knock off of Tek Greetings, I’m not sure it is fair to call a Dumont scope a Tek knock-off. Allen B. Dumont opened his company in the 1930’s and was producing an oscilloscope around 1943. Tektronix was founded in 1946. HP, founded in 1939 produced its first scope, the HP-130A, on or about 1956. Initially Dumont was probably the leader in oscilloscope technology for a few years, but Tektronix quickly took the lead. The competition between Tek and HP was good for the industry in general and Tek and HP specifically. Dumont was unable to keep pace. Perhaps because Mr. Dumont was not as open to new ideas as was Tektronix and Hewlett Packard leaders. I believe Dumont was eventually acquired by Fairchild. I actually owned a dual beam, four channel Fairchild/Dumont scope. I also owned a number of other Dumont scopes. They really weren’t knock-offs. Interestingly, a company named Lavoie made “exact” (well sort-of) Tek knock-offs of the 53x and maybe the 54x scopes. The story I heard told that this opportunity came about because the military was pressured to open bid for scopes meeting the Tektronix specifications. I have used some Lavoie scopes a long time ago. From the outside they looked almost exactly like the Tek scope they copied, but the knobs were different. However, they were not the same level of quality construction on the inside as the Tek scopes. That’s my two cents, FWIW. Regards, Ken On 21Jun, 2019, at 8:54 PM, Dave Seiter <d.seiter@att.net> wrote:
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Re: HP 547a Current Tracer probe useful in finding shorted Capacitors ... was ... Most common capacitor spot failure in 7K scopes?
Jelcke de Boer
An other handy tool for finding shorts is the ToneOhm.
Many models available I use the 550A. https://www.polarinstruments.com/products/toneohm/toneohm_950.html Jelcke
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Hello to the group, and a WTB
greenboxmaven
Hello, I'm Bruce, KA2IVY, Syracuse New York . I found this group while searching for information on a 555 scope. I got one from an estate sale for a very good price. I powered it up carefully, and all the basics work. The jug is in good shape too, on both guns. However, the entire scope , power supply, and cart are grungy and boy does it stink when it's on! There is NO question why the owner is SK! I have read other posts on this group, there are people here that know Tektronix and know the craft very well. It's a pleasure to find a group like this. I have a couple other Tektronix projects I bought at the Rochester and Cortland hamfests, more about them later. The first thing the 555 needs is a bath, I was somewhat surprised to see Tektronix did it at the factory, and considering the "atmosphere" I barely survived in TV ststions, they needed it. For the "WTB" part, the carrying handles on the 555 display unit are completely missing, not just the strap you grab, but everything. The handle on the power supply is rotten down to the steel strap inside, even with a glove on picking it up by the handle is not fun . Does anyone have these handles to spare? Also, the aluminum mesh filter screens are missing from the display and power supply, does anyone have them to spare? Thanks, 73, Bruce
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Re: GPIB using Win98 and a NI GPIB-PCII/IIA ISA card to talk to my TDS540B?
craig.belcher@...
I'm just about to head down the ISA path and I'm reading this, got a recommendation on a USB interface?
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Calibration of the Measure Function on a TDS220
Steve Hendrix
I'm new to the group, so please forgive any faux pas on my part!
I have long used a TDS220 and still like it a lot. I note that the Measure function, specifically displaying a DC voltage numerically, has always had a nontrivial offset that seems larger than it should be. I even sent it out to a Tek cal lab, and it seemed to be unchanged afterward. Here are examples of the offset from ideal (zero) with the ground clip clamped directly on the probe tip, standard x10 probe: V/Div VDC 50 2.96 20 1.14 10 0.377 5 -0.012 2 0.111 1 0.055 0.5 0.021 0.2 0.001 0.1 -0.007 0.05 -0.005 0.02 0.005 Are these numbers reasonable for the instrument, or is there some adjustment I can make? Steve Hendrix
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Re: Dumont knock off of Tek
greenboxmaven
On 6/22/19 2:20 PM, ken chalfant wrote:
Greetings,By the mid 1960s, Dumonts were easy to find and not expensive for high school kids with "pump gas-cut grass-throw papers" money. The low frequency response made them less than ideal for TV shop work, and useless for repairing the color circuits in TVs. A Heathkit, Eico, or perhaps RCA might be within reach, but a Tektronix was a dream most of us had to wait some time for. I was given a monsterous Dumont dual beam scope that did not work. I restored it and used it mostly for audio. I think it might have made it to 500KC. I used them in the Air Force. The ones we had were "clones" of the 524. They worked ok, but just were not the "real thing". There was indeed an effort to avoid relying on one maker for a while. One of the most interesting was the Eldeco copy of the Collins KWM-2 transceiver Bruce Gentry, KA2IVY
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Problomatic (broken) 464 storage scope.
mark@...
Ok,.. I am looking for some pointers if you would be so kind,... I have a broken 464 scope... the symptoms are as follows:-
1) The scope powers up,.. but the beam is not running correctly,.. ie as it was failing the beam was going back in time in a curly pattern,... 2) Beam finder does bring the beam in though 3) Fan does not make a continuous tone/noise... ie speed changes. A) So far I have checked for magic smoke and burnt etc,.. so far nothing! B) Have measure main voltages,.. And this is where things start going to pot: 5 volts DC measures 5.58v,.. with more ripple than I can measure -8 Volts DC measures in at -8.4v again with loads of ripple. +15 Volts DC measures in at 15.8v,. with loads of ripple +65 Volts measures in at 68v and loads of ripple 140 Volts measures in at 134v with loads of ripple. So clearly, ( I assume ) the power supply looks suspect,... I sort of suspected failed input electrolytics.... but reading further forum stuff this seems unlikely as they are essentially Mil. grade components,.. so probably not the source of my problem. I have also seen other utube video where the voltages are measured ,.. and mine are no where near close or as stable as these.... My other thoughts then go of to the Tant caps... are there are lots of them,.. the ones in the supply do not appear as short,.. as the is measurable resistance...(less than 10 ohms,.. is this normal?). Now I'm thinking there may be issues on another board which is dragging the main supply down,.. causing the massive ripple and cycling,.. ( do not have a second scope,.. which makes life more difficult for sure ), But I think the supply may be in a cycle of dipping in and out,.. and failing to get to normal operation ,.. because of some down stream fault. As the failing supply with also give the timebase scans trouble as there is nothing stable,.. I also noted prior to complete failure was that vertical calibration had gone to pot,.. simple DC signals of 5v did not show as 5v on the scope... so everything seemed to be in a cascade failure,.. but all leading be back to the power supply,.. but is this correct. Before I start jumping in a stripping things apart,... isolating boards etc,... does anyone on have any pointers for me,.. as I am hoping someone may be able to offer some more informed paths to tread and try ,.. before I jump in with a soldering iron and spanners many thanks
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Re: Dumont knock off of Tek
cksamsung.ck@...
I'm new to this tekscope group. I was referred by someone at QRZ forum and
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I hope I'm not being out of line. Does anyone know Dan Shores in Portland. Chris K
On Fri, Jun 21, 2019, 7:54 PM Dave Seiter <d.seiter@att.net> wrote:
Funny how things come in groups; I've never seen a transistorized Dumont
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Re: still trying to track down 2216 manuals
n7bfs
I have one of the 2216's and the original owners manual (in poor condition) and would love to find a service manual (electronic preferred).
If there are any updates on this thread it would be appreciated. Also I have the rack mount 'ears' but the 'inserts' that go into the side 'holes' that hold the scope into the brackets are missing. Does anyone have pictures or source of these little guys? Looks like there are four per bracket. Thanks for any tidbits on this nice 'digitizing' analog scope :) Doug C
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Re: Dumont knock off of Tek
Jim Potter
I'm guessing that scope didn't have any amplifiers or sweep. That meant you had to have big enough voltage signals to deflect the beam directly. It would be interesting to see more detailed specifications.
Jim At 05:45 PM 6/22/2019, Brad Thompson wrote: Bob Albert via Groups.Io wrote:James M. Potter, PhD, President JP Accelerator Works, Inc. 2245 47th Street Los Alamos, NM 87544 TEL: 505-690-8701
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Re: Dumont knock off of Tek
Brad Thompson
Bob Albert via Groups.Io wrote:
Hello-- And before that, in 1934 General Radio offered an oscilloscope (the model 687) with "useful" response to 130 MHz: https://www.ietlabs.com/genrad_history/genrad_museum Quoting from the museum site: "...GR decided not to make more oscilloscopes deciding that they were not precise enough for laboratory use and only useful in the radio service shop. Needless to say, that was a lost opportunity. However in 1938 they did make an advanced oscilloscope, the type 770, known as “Big Bertha”, but it was only used internally and never sold...." ...Which begs an obvious question: given GR's reputation for building precision instruments, why didn't someone on the staff tackle the "precision problem" and make a good oscilloscope? 73-- Brad AA1IP
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Re: 7CT1N
Harvey White
On 6/22/2019 6:45 PM, Dave Brown wrote:
Been some time (several years, now retired) since I used mine and loaned itNot so much a problem, but that the traces are running at about a 60 hz rate, so 10 traces refreshes about 6 times a second (or less, since it's a half cycle). That's where the flicker/refresh rate comes in. On a 7904, I have not seen an objection from my point of view, but that's just me. The refresh rate is inherent in the collector supply voltage. Harvey DaveB, NZ
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Re: Dumont knock off of Tek
Bob Albert
The story I heard was that Dumont himself said that his company would always be the leader in oscilloscpes, somewhat akin to the president of Ford saying the Japanese could never erase the 20 year lead that Ford had.
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Mr. Dumont didn't face reality. Then we see that his company made a Tek clone. I recall LaVoie for one doing that. Or was that LeCroy? Then Fairchild did it but they were the same as Dumont I think. I owned one and it was a good performer. This corporate ball of snakes really puts so many at a disadvantage. Greed certainly turns out to be an enemy, but it's human nature apparently.
On Saturday, June 22, 2019, 02:46:19 PM PDT, Richard Knoppow <dickburk@ix.netcom.com> wrote:
A strange decision for DuMont since they were deeply involved with television. On 6/22/2019 2:28 PM, Richard Solomon wrote: --From what I was told back in the 60's,it was a Marketing decision. Richard Knoppow dickburk@ix.netcom.com WB6KBL
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7CT1N
Dave Brown
Been some time (several years, now retired) since I used mine and loaned it
to a friend a few days back to check out-he thought he might buy it- but he reckons it's got too low a refresh rate-something I don't recall. Yet to get it back-could be a week or so- but wondered if there may be something wrong with it that could cause this complaint? Any thoughts? DaveB, NZ
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Re: Dumont knock off of Tek
Richard Knoppow
A strange decision for DuMont since they were deeply involved with television.
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On 6/22/2019 2:28 PM, Richard Solomon wrote:
From what I was told back in the 60's,it was a Marketing decision. --
Richard Knoppow dickburk@ix.netcom.com WB6KBL
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Re: Dumont knock off of Tek
Richard Solomon <dickw1ksz@...>
From what I was told back in the 60's,
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it was a Marketing decision. Dumont believed there was no market for high frequency scopes so they concentrated on low frequency (500 Kc max) high sensitivity (microvolts in some cases) scopes. Tektronix held the opposite belief (high frequency). We all know who made the right decision. 73, Dick, W1KSZ
On Sat, Jun 22, 2019 at 11:20 AM ken chalfant <kpchalfant@msn.com> wrote:
Greetings,
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Tdr cable 015-1023-00
NigelP
I have just acquired one of the above 1ns cables for the s-6 & s-52 & 7s12. Does anybody have info about how to use this cable..... Specifically about bending (or not !) ?
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Re: Dumont knock off of Tek
Dave Brown
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