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Re: RG174?
Just a word of caution, a lot of stuff from China is ok, especially for non-critical parts and I've had good things from 'China RF' for instance but some is junk, I've had BNC patch cables listed as RG58/CU with such sparse shielding braid as to be useless - about 15% coverage max I would say and really badly terminated too - so depending what you want the cable for you might do better to buy a known brand or, for a few bucks I guess - take a gamble!
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Adrian On 5/23/2018 8:08 PM, Cliff Carrie wrote:
What's a good source of 12 feet of RG174? |
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Re: RG174?
I buy from The RF Connection as well. Great service and great prices.
On Wed, May 23, 2018 at 12:08 PM, Cliff Carrie <cliffcarrie@...> wrote: What's a good source of 12 feet of RG174? |
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Re: RG174?
What's a good source of 12 feet of RG174?
Search eBay for item number 112471540709. It's described as 5M RP SMA WIFI Antenna WAN Router Female to Men Connector Extension Cable Black US $3.35 with free shipping from Shenzhen China delivered between June 14 and July 19. My recent experience with Far East purchases is that delivery is generally on or before the earlier date. 5M is 16.4 feet. At this price, cut off the connectors and throw them away, or get clever and save a 2 foot pigtail with connector from each end to use on other projects. I have purchased similar items, but possibly not from this seller. The ones showing a black jacket are normally RG174 which is more flexible than the beige RG316 ones, so better for an extender. I have no connection to the seller, nor any specific experience with them. Regards, Cliff Carrie ________________________________ From: [email protected] <[email protected]> on behalf of Pete Lancashire <xyzzypdx@...> Sent: Thursday, May 17, 2018 6:09:54 AM To: [email protected] Subject: Re: [TekScopes] RG174? Pity your not looking for RG316 On Wed, May 16, 2018, 8:37 AM John Griessen <john@...> wrote: What's a good source of 12 feet of RG174? A customer wants to make an |
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Re: Tek 577 sells for $256 on eBay
OK. I am exchanging email with the seller in an effort to determine it's operational state. Just want to double check on that because I have such a pile of things that need fixing that if I bring another thing in that needs fixing, my better half is going to relegate me to the dog house.
@dennisT ... how much are you charging for your attachment and are their any other requirements I should know of? |
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Re: Tek 577 sells for $256 on eBay
Good Day,
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I'd agree here. Valuetronics is still asking 3,000 USD for a *576*, see Cheers, Magnus On 23/05/2018 07:16, Craig Sawyers wrote:
I believe I may have an opportunity to acquire a 577 D2 for $200 if anyone has an opinion on that.Bargain |
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Re: using scope channel 1 and channel 2 invert and add functions vs floating DUT
In the data acquisition world this might be called "pseudo-differential".? The DUT has to be able to tolerate the probes impeadance to ground at the measurement (probe) points.
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It does allow you to directly measure the voltage "across" something such as a current sense resistor and it does allow you to measure stuff without introducing a "ground loop". It's NOT an "isolated measurement" and it's NOT a "true differential measurement". Both "isolated" and "pseudo-differential" have their limitations.? You generally have up to a given isolated voltage and a DC+peak AC requirement to meet. I think it's bad to think of the measurement as subtraction.? It's (A-G)-(B-G) = A-G-B+G = A-B with limitations. On Monday, May 21, 2018, 3:43:08 PM EDT, Fabio Trevisan <fabio.tr3visan@...> wrote:
Hello Nielsen See my comments right after your points (upon which Harvey already answered... this is just my 2 cents). On Sun, May 20, 2018 at 10:40 am, nielsentelecom@... wrote: Your mention of using a voltmeter, to measure voltages between 2 points captures the essence of taking a differential measurement (because in a "sorf-of" way, this is what your voltmeter is doing, measuring the voltage of the red lead "in relation" to the voltage in the black lead). However, that usage you mentioned of a voltmeter is only possible because you're talking about a portable voltmeter that's isolated from the mains, isolated from earths ground and also isolated of your D.U.T. in other words, the voltmeter is floating, and then it fits exactly in the same bill as using a floated scope (i.e.: a battery operated one). Should you be using a bench voltmeter, which is powered from the mains and therefore grounded and you would need to make that same measurement between two nodes of the circuit where neither of them is ground on the D.U.T., you would face exactly the same problem as when trying to make that measurement with the scope. Your high voltage idea in respect to exceeding limits; would it be possible toThe high voltage idea... I suppose you're talking about this part of Harvey's answer: Harvey wrote...Well, in that answer, he's only referring to an alternative to floating the oscilloscope, which is to float the D.U.T. Since the signals you're measuring are hypothetically riding on top of a voltage (e.g. 500V) that would be forbidden to the scope, if you float the device and connect the scope's ground lead to that hypothetical 500V of the D.U.T. you would be bringing that 500V to the oscilloscope ground lead's potential (0V), turning any voltage on the D.U.T. that are around that ballpark of 500V closer to ground and measurable by the scope. However, since the scope's ground lead is at 0V, and now you turned the DUT's 500V voltage into 0V, all voltages on the D.U.T that would be near 0V, will be now in the -500V ballpark (read... possibly ever y exposed metal part of the D.U.T. is now probably at -500V). This "strategy is as much hazardous as "floating" a scope that's not meant to be operated floated (i.e. any non-battery operated scope, including your Tek or your Hitachi). This strategy also, doesn't have any thing to do with the impedances seen by the D.U.T. as you suggested. Indeed, what you suggest makes sense, but the rational is flawed because one normally cannot disregard the ground leads of each channel input. The scope's inputs' impedance from the tip of the channel 1 probe to the tip of the channel 2 probe would be the sum of each channel's impedance (i.e. 2MOhm) if the ground leads would remain disconnected (from the U.U.T.s), and also disconnected from ground (which would take - again - the scope to be floating because, if it isn't floating, both channels' ground leads are grounded, via the scope's grounding wire to your facility ground). So, academically... 1. if you use a floated oscilloscope (for safety's sake, a battery operated one) 2. If you don't connect EITHER of the inputs' ground leads to the D.U.T., but only connect both ground leads one to each other (I`m assuming here that, a battery operated scope can also be one where the two inputs' ground leads are isolated from each other, such as some Tek scopes meant for this kind of floated operation). Then, academically, 1. The resultant input impedance would be 2MOhms 2. Possibly (depending on how the oscilloscope is wired internally, as this is an academic reasoning), it **could** withstand twice the maximum input voltage from the tip of CH1's probe to the tip of CH2's probe. Rgrds, Fabio |
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7a42 Issues
Hi,
I've been a long time lurker is this group, recently I had some time to look at a 7A42 that bought a few years ago. Like others I have the leaky NiCd issue. I've neutralised the leakage with vinegar, cleaned up the board, fixed some tracks, and replaced two corroded diodes associated with the battery circuit. Running the 7A42 without a new battery, it completed the self-test but then I started to see some erratic operation in front panel LEDs, relays and on screen text. Has anyone seen this? My first thought was one of the EPROMS my be faulty. Some of the time however the self-test starts again, and prior to installing a new battery I found that the battery negative connection is not connected to ground so I suspect there is some corrosion at this point on the board and possibly there is intermittent shorting between the internal +5V and ground layers. Does anyone have any thoughts on this? Regards, Peter |
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Re: Help needed with no trace no beamfinder on 465 (not b)
Hello Keith,
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you can also disconnect the ground strap of the HV multiplier, which pokes out from between the main board and the vertical amplifier board underneath the HV cover on the main board. Tt is soldered to the main board ground plane. Desolder it, and put it out of the way so it won't spark or anything.... wrap heat shrink on it or so. If the HV multiplier is toast, you should see a trace with it disconnected. I have replaced the HV multiplier on my 465. Removal of the vertical amplifier board is required to do this. The procedure is in the service manual and is fairly straightforward. I can't offer much help beyond this, because this is the only repair I know on Tek scopes ;-) My repair thread is here: /g/TekScopes/topic/7654225#107633 Hope this helps, Ian. On Wed, May 23, 2018 at 12:45 AM, Keith Ostertag <stuff@...> wrote:
I had been working on this 465 (SN B175976) for a few days. I had replaced --
One man's "magic" is another man's engineering. "Supernatural" is a null word. -- Excerpt from the notebooks of Lazarus Long, from Robert Heinlein's "Time Enough for Love" |
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Re: Tek 7904 CRT
Craig Sawyers
The one 7K CRT that does not ship well inside it frame is the 7104. I've bought two that the rearI collected mine in person, but it also came with a custom rigid and foam padded flight case, which certainly would be a safe way to ship. Craig |
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Re: Tek 577 sells for $256 on eBay
get it!
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¸é±ð²Ô¨¦±ð On 2018-05-22 05:39 PM, David Berlind wrote:
I believe I may have an opportunity to acquire a 577 D2 for $200 if anyone has an opinion on that. |
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Re: Tek 577 sells for $256 on eBay
tom jobe
My opinion is you should buy it if you have any interest in owning a curve tracer, as that is a very good deal!
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tom jobe... On 5/22/2018 5:39 PM, David Berlind wrote:
I believe I may have an opportunity to acquire a 577 D2 for $200 if anyone has an opinion on that. |
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Re: Tek 7904 CRT
The one 7K CRT that does not ship well inside it frame is the 7104. I've
bought two that the rear was hit hard enough to shatter the CRT. Got full credit but still sucks On Tue, May 22, 2018, 8:38 AM oliver johnson via Groups.Io <nojjamaica= [email protected]> wrote: Hi I would like to help you out in this scope project you have there , but |
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Help needed with no trace no beamfinder on 465 (not b)
I had been working on this 465 (SN B175976) for a few days. I had replaced a burned out input resistor on one channel and tightened a shaft coupling. After that it was more or less working, but I was checking something else (can't recall) when I noticed that suddenly I had no trace, and pressing the beamfinder shows nothing. So I suspect that I accidentally shorted something. A visual inspection shows nothing obviously burned or open.
My trouble shooting and electronic skills are pretty minimal, so I could really use some help fixing this. I do have another scope, a recently acquired 2213A. I'm using a 465 manual that is close but not exactly for my scope- the manual's Tek number is tek-070-1330-00 (some other manuals seem to cover a later model- B200000 and up). I can't find a trouble shooting chart in this manual that I read other people referring to. I have been reading through a past thread that seems related: /g/TekScopes/topic/7656979#126934, and using that as a starting point I have checked the following: All low voltage supplies are within tolerance, and ripple on each seems close to within tolerance. Fuse F1419 is good. Tantalum C1419 seemed fine, but I went ahead and replaced it with a 100uF 50v electrolytic. I do have a high voltage probe, so I checked TP1423, it measures only -82V (should be -2450V) Q1418 seems good. Following a comment by David Hess in the previous thread, I looked at the collector with my 2213A- it shows a slightly distorted wave approx 1.5 volts p-p (Horiz on my 2213A set to 10uS). It's base voltage measures about .47vdc using a VOM. David's comment was: "If you have a secondary working oscilloscope, the collector of Q1418 on schematic 10 will show if the high voltage inverter is operating." Albert suggested to check C1416- mine measures .48vdc, way off from what it should be. Alberts past comment was: "The best indication for output of the oscillator circuit is the voltage at C1416, shown as -4.5 V in the schematic. Roughly speaking the AC peak-peak voltage across the base winding in T1420 is twice this voltage. Since the average voltage across that winding is zero (neglecting the small resistive loss) you should also measure about -4.5 V at the base of Q1418. But a measurement load at the base might influence the oscillation." The collector of Q1404 measures about 3.3v, should be around 4.4v? I don't know what the above indicates, or what to do next. tmillerdems had said: "First thing I would do is lift the input lead from the HV multiplier that connects to T1420 transformer. That will isolate the HV multiplier that is known to cause HV problems. The regulation comes from sampling the -2450 volt cathode supply. You should still get some display if you get the cathode supply going sans PDA supply. " I don't see where/how to locate the "input lead from the HV multiplier that connects to T1420 transformer" - can I access that from the main board? Both T1420 and the HV multiplier are located beneath (and hidden by) the main board, correct? I also cannot locate CR1421 (using the image on page 160 of the manual). If either the T1420 or the HV multiplier are toast then that probably makes the scope unrepairable (at least by me, I'm guessing). Oddly enough, I also have 464 that I recently acquired with the same problem (no beam)- at least I didn't cause that one! Thanks if you can help, Keith Ostertag |
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Re: Wanted 067-0681-01 Tunnel Diode Pulser by new member
If the signal isn't the right amplitude to fit on the dotted line
markers, the temptation is to change the vertical gain using the VAR gain control. Unfortunately in many scopes that will also change the scope's bandwidth and hence risetime. (Essentially a BJT's Ft is a function of Ic). With regard to the PG506 signal, I'm pretty sure now that you did use the level adjustment as I suspected in my earlier post. It's the only way to get the screen amplitude in your picture, with the 'scope on 10 mV/div and a 10x feed through attenuator. It explains the slow rise time. Very good information. I just checked it out and you are more than correct. 50ohm input seems far less effected by the variable gain adjustment for whatever reason. Using the variable gain adjustment in 1Mohm though reduced the RT from 1.3ns to 3ns. I'm wondering if there is something wrong with my pg506 because I get a good amount of ringing until I get very close to full amplitude,when using the fast rise. |
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Re: Strange Tek part Numbers in an AM503B. Can anyone identify them
Hi
160-9569 is the whole processor, including OTP ROM. I was able to read mine, i posted the bin on www.ko4bb.com. You can find it as Tektronix_AM503B_current_probe_amplifier_EPROM.zip The processor is labeled 160-9569-02 W5. Regards, Guido |
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Re: Tek 7904 CRT
Hi?I would like to help you out in this scope project you have there , but i do not have the time to part out scope as you would like me to . In addition shipping the crt like that can be problematic, breakage is possible even if double boxed or internal damage . That has happened to me with a scope that was shipped , broken crt and also another with open heater . If your friends are going to be around at a later date its best to just ship as is .
Sent from Yahoo Mail on Android On Tue, May 22, 2018 at 8:54 AM, gerar2182<gerardo_novillo@...> wrote: Hi Oliver What do you think if i buy the scope, and you part out it? My friends are outside of US now for work reasons. The equipment is very big and very heavy for delivery. So, if you accept, i will be very very grateful for your cooperation. Please let me know? your decision when possible. I will need the CRT, boards , knobs, plug ins and power supply. I understand you are sure that CRT is OK. Thank you so much. Gerardo Novillo ________________________________ De: [email protected] <[email protected]> en nombre de gerar2182 <gerardo_novillo@...> Enviado: lunes, 21 de mayo de 2018 16:55 Para: [email protected] Asunto: Re: [TekScopes] Tek 7904 CRT Let me check with my friens and i will contact you soon. Thank you so so much. Gerardo Novillo ________________________________ De: [email protected] <[email protected]> en nombre de oliver johnson via Groups.Io <nojjamaica@...> Enviado: lunes, 21 de mayo de 2018 16:43 Para: [email protected] Asunto: Re: [TekScopes] Tek 7904 CRT I would like to have $125 for scope and plugins Sent from Yahoo Mail on Android ? On Mon, May 21, 2018 at 2:37 PM, gerar2182<gerardo_novillo@...> wrote:? Thank you for your soon reply Oliver. I understand your point of view. So, let me know the cost of scope. I have a couple of friends in Texas and Palm Bay. If i buy the scope, may be possible to send to one of them?. Then will be disassembled by them and send me the parts i need. Thanks. Gerardo Novillo ________________________________ De: [email protected] <[email protected]> en nombre de oliver johnson via Groups.Io <nojjamaica@...> Enviado: lunes, 21 de mayo de 2018 15:06 Para: [email protected] Asunto: Re: [TekScopes] Tek 7904 CRT Hi Gerardo I dont want to rip apart the scope and part out ,if you would like to buy the scope that has a few plugins thats fine , the only thing is it might too costly to ship to you as most things ar outside of the US . Sent from Yahoo Mail on Android ? On Mon, May 21, 2018 at 1:52 PM, gerar2182<gerardo_novillo@...> wrote:? Hi Oliver Im new in this group and i dont know if is? possible to speak about transactions here. Im very interested. I live in Argentina. Here is not possible to get this part . Please let me know how much you want for the CRT and how much for shipping to Argentina , using USPS. Also let me know how much for the Power Supply. May be i will in need of the Readout Board and some knobs. Im trying to come back to life a completely dead equipment. Thank you very much. Gerardo Novillo ________________________________ De: [email protected] <[email protected]> en nombre de oliver johnson via Groups.Io <nojjamaica@...> Enviado: lunes, 21 de mayo de 2018 13:57 Para: [email protected] Asunto: Re: [TekScopes] Tek 7904 CRT Where are you locates i have a spare 7904 with ps out that i started to repair , crt is fine , i am in ny if you are interested. |
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Re: Wanted 067-0681-01 Tunnel Diode Pulser by new member
On Tue, May 22, 2018 at 05:58 am, lop pol wrote:
Thanks lop pol for correcting me. I didn't think about the link to the video. It's not one of Alan's best videos I have to say: You can see the edge shape change (causing rise time to change with it) when he uses the variable attenuation which he just ignores, he ignores the fact that the 100 % level isn't set correctly when he uses the cursors and the 10% and 90 % markings on the 2467B and he ignores the (waveforms/second) duty-cycle reduction by using the B-trace, which of course only has the repetition rate of the A-trace. Does the resulting loss of brightness compensate for the lower intensity at the start of the A-trace because of limited unblanking speed? From my experience, scopes like the 485 don't benefit from using the delayed (B-)trace for this. Maybe other or slower 'scopes do. Raymond |
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Re: Wanted 067-0681-01 Tunnel Diode Pulser by new member
On Tue, May 22, 2018 at 05:25 am, Raymond Domp Frank wrote:
I'm not going to spend 13 minutes off my remaining life to see exactly what was done in that video, but there is a trap in this area. I think he was referring to to video siggi linked. Which indeed does tell you to adjust the VAR gain control to fit the rise time markers. |
Peter ONeill
Raymond Domp Frank
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