Keyboard Shortcuts
Likes
- TekScopes
- Messages
Search
|
Re: Blade Runner
开云体育That is the terminology used for servers which consist of a rack into which one can plug different types of server blades, for instance .Cheers, Dave On 1/4/2013 4:42 AM, donblack1au wrote:
? |
|
Re: Rear feet for 475
John Griessen
On 01/03/2013 10:46 PM, Rob wrote:
the fins receive the cord as it wraps around very well. Also releases well when needed, etc. I am not sure what resist wellSounds like ABS -- it has some flex and does not shatter easily, (maybe if in Alaska winter). |
|
Re: 2465B auto measurment error
Thanksfor all of your input.
toggle quoted message
Show quoted text
I redid the cal 2 and 3. Vertical and triggers. Error is still there. Looks like at low frequencies-below .5 MHZ it works, above that the error occurs. I am thinking there is a problem with the U500 trigger. I see a few on Ebay. Anyone here have one for sale? B --- In TekScopes@..., "Tom Miller" wrote:
|
|
Re: 7A19 vs. 7A29 Noise
Anyway, I haven't noticed a difference in trace noise betweenThanks! There is no fundamental connection between amplifier input impedance and noise. I've design preamplifiers with sub-300 pV/rtHz, and they could easily have GOhm input resistance. That's because the noise of the input bias resistor is shunted by the (much lower) source impedance. The relatively high noise of some of the high-Z plugins seems to be mostly a function of their active parts. I've also noted differences between some time bases (e.g. between two 7B80 I have). Apparently one has higher trigger jitter. Best, Samuel |
|
2246 Mod A main board overloading the SMPS
Alas - if only it were that simple ...
I finally fixed my SMPS and put it back into the chassis with only the main board. It runs in chirp mode - about every 1 sec there is a clicking sound - the secondary voltages rise and then something gets overloaded and the SMPS shuts down and then cycles again. I quickly disconnected power, isolated the SMPS and again verified that the SMPS is fine on its own with just the cooling fan load with a steady internal 44 VDC. No new or collateral damage thankfully. There are no obvious shorts on any of the supply lines on the main board. The issue may still very well be with the SMPS being unable to handle load even though the fan runs fine and the other voltages are fine. I assume that chirp mode is a common issue with these SMPS supplies. What have others done to (1) find whether the issue is with the SMPS or with the main board and if the latter, (2) which supply line or lines is drawing too much current and how to isolate the problem further? Thanks in advance. Priya. |
|
Re: Rear feet for 475
Jim
Tim has a number of plastics he can print with, as well as colors. ?We exchanged a few emails; he said he re-engineered the shape of the foot a little because all his plastics are of a harder durometer than the original. ?So the re-engineering was necessar to allow the cord to snap in correctly. ? The mechanics/physics of his process also resulted in a slightly different finish than the original (and somewhat crude, IMHO) injection molding process. But overall, I think his are
nicer looking than the originals. ?Time will tell whether they are more durable too, but in 20 years, will it matter? Contact Tim to order. ?I'll let the group know when I've got my cast repros available. 73 Jim N6OTQ
|
|
Re: Rear feet for 475
I think he is?referring?whether?they are durable, as in quality made. Ship, ship, when time ? From: Rob To: TekScopes@... Sent: Friday, January 4, 2013 6:46 AM Subject: RE: [TekScopes] Re: Rear feet for 475
?
I cannot answer any questions on the manufacturing, direct output, etc. ? I can however attest that what is received is indeed strong enough to stand the scope on (don’t know if a 7834 is heavier than the original application). ?In addition (and most important for me) the fins receive the cord as it wraps around very well. Also releases well when needed, etc. ?I am not sure what resist well question is but they work exactly as I hoped they would in all applications I have used them in. They are not inelastic but as well not to elastic. I suppose they could be made to fail but it would take something well outside normal use to do so. ? Hopefully answers a bit and is helpful Rob ? From: TekScopes@... [mailto:TekScopes@...] On Behalf Of Alex Sent: Thursday, January 03, 2013 9:25 PM To: TekScopes@... Subject: [TekScopes] Re: Rear feet for 475 ? ? They look good. Is this the direct output of the printer or is there an intermediate step to getting the final part? I remember that stereolithography output was far too fragile to use directly so it was used to make a mold. Do the 3D parts resist well? Can you stand the scope on end? --- In TekScopes@..., "Rob" wrote: > > I as well can attest that the feet turned out great. I bought and put them > in service on a 7834 and TM-503 both of which benefited greatly as I like > this cord wrap design far and above the originals they came with. > > > > From: TekScopes@... [mailto:TekScopes@...] On Behalf > Of George Lydecker > Sent: Thursday, January 03, 2013 5:48 PM > To: TekScopes@... > Subject: [TekScopes] Re: Rear feet for 475 > > > > > > Gang, > > Here are some pictures of the 3D printed feet Tim created; > > http://groups.yahoo.com/group/TekScopes/photos/album/1580745225/pic/list > > I am very happy with the results. > > Goerge > > --- In TekScopes@... , Jim > wrote: > > > > I would add -- Tim was kind enough to send me one of his prototypes so I > could use it to make a mold, and compare my castings from his prototype vs. > an original foot that Tom Jobe sent me. > > > > I owe both of them some preliminary samples as soon as I find the time to > make molds and cast something. > > > > Fortunately, I'll have a whole lot more time in my shop during the next > two weeks. A bunch of unplanned projects finally concluded in the last > couple of days. > > > > 73 > > Jim N6OTQ > > > > > > > > >________________________________ > > > From: Glydeck > > >To: "TekScopes@... " > > >Sent: Thursday, January 3, 2013 5:13 PM > > >Subject: Re: [TekScopes] Rear feet for 475 > > > > > > > > > > > >I bought some and they work great. I plan on posting some pictures, but > have not got around to it. Tim's Email address is; > > > > > > > > >lemonscentedmoisttowelette@ > > > > > >George > > > > > >On Jan 3, 2013, at 2:14 PM, Paul Amaranth wrote: > > > > > > > > > > > >>I saw him offering those on ebay along with the handle endcaps. > > >> > > >>they look very nice. Search for tektronix feet and it should > > >>come up. > > >> > > >>On Thu, Jan 03, 2013 at 07:56:09PM -0000, Gerald Krizek wrote: > > >>> Does anyone know if the fellow that was trying to 3D print rear feet > for the Tek 475 has had any success? I seem to have lost his e-mail address. > > >>> Thanks, > > >>> Jerry > > >>> > > >> > > >>-- > > >>Paul Amaranth, GCIH | Rochester MI, USA > > >>Aurora Group, Inc. | Security, Systems & Software > > >>paul@ | Unix & Windows > > >> > > >> > > > > > > > > > > > > > > > > > > |
|
Re: Blade Runner
Don Lewis
Some young server-room whipper-snapper.? These kids! ? ? ? ? From: donblack1au
To: TekScopes@... Sent: Friday, January 4, 2013 5:42 AM Subject: [TekScopes] Blade Runner
?
I know selling used Tektronix equipment can be a cut throat business sometimes but I've never heard them called "Blades" before, eBay item 221171607705 ;) .
Don Black. |
|
Re: 7A19 vs. 7A29 Noise
Craig Sawyers
For a 7A26, with 20,000 times input resistance (if it was purelyresistive), and 2/5 the bandwidth, the thermal noise would be 1.8mV which would be soit would occupy more than 1/3 division of the CRT. So why don't you see it?On full bandwidth in my 7904 workhorse, one of my 7A26's on DC coupling measures 1/3 of a *minor* division at 5mV/div (needed a magnifying glass for that) - so about 0.1mV tangential noise, and it looks just like fuzzy noise. With the 20MHz bandwidth limit switched in the trace is so narrow it is impossible to measure the noise. Craig |
|
Re: Rear feet for 475
Rob
开云体育I cannot answer any questions on the manufacturing, direct output, etc. ? I can however attest that what is received is indeed strong enough to stand the scope on (don’t know if a 7834 is heavier than the original application). ?In addition (and most important for me) the fins receive the cord as it wraps around very well. Also releases well when needed, etc. ?I am not sure what resist well question is but they work exactly as I hoped they would in all applications I have used them in. They are not inelastic but as well not to elastic. I suppose they could be made to fail but it would take something well outside normal use to do so. ? Hopefully answers a bit and is helpful Rob ? From: TekScopes@... [mailto:TekScopes@...] On Behalf Of Alex
Sent: Thursday, January 03, 2013 9:25 PM To: TekScopes@... Subject: [TekScopes] Re: Rear feet for 475 ? ?
|
|
Re: 7k extenders
Neganur
toggle quoted message
Show quoted text
On 4.1.2013, at 5.33, Sergey Kubushyn <ksi@...> wrote:
|
|
Re: 7k extenders
On Thu, 3 Jan 2013, Mark Pilant wrote:
I would also take 3 or 4 sets if possible. Like Jim, I would be interested in 3 sets (6 connectors) to make--- * * KSI@home KOI8 Net < > The impossible we do immediately. * * Las Vegas NV, USA < > Miracles require 24-hour notice. * * |
|
Re: Rear feet for 475
Alex
They look good. Is this the direct output of the printer or is there an intermediate step to getting the final part?
toggle quoted message
Show quoted text
I remember that stereolithography output was far too fragile to use directly so it was used to make a mold. Do the 3D parts resist well? Can you stand the scope on end? --- In TekScopes@..., "Rob" wrote:
|
|
Re: 7k extenders
Mark Pilant
Like Jim, I would be interested in 3 sets (6 connectors) to make
up 3 7000 extenders. I already have a Tek flexible extender, but need to have at least another for some of my plugins and making two of the same kind would probably work better than trying to make another flexible extender. - Mark |
|
Re: Rear feet for 475
Rob
开云体育I as well can attest that the feet turned out great. I bought and put them in service on a 7834 and TM-503 both of which benefited greatly as I like this cord wrap design far and above the originals they came with. ? ? From: TekScopes@... [mailto:TekScopes@...] On Behalf Of George Lydecker
Sent: Thursday, January 03, 2013 5:48 PM To: TekScopes@... Subject: [TekScopes] Re: Rear feet for 475 ? ? Gang, |
|
Re: 7A19 vs. 7A29 Noise
The real question is why DON'T you see the 7A26 noise?
toggle quoted message
Show quoted text
IF (and that's a big if!) the input impedance of an amplifier were purely resistive then the thermal noise contributed by the resistor (Vn)is Vn(RMS)= sqrt(4*KB*T*R*(F2-F1)) in Volts, where T is the temperature of the resistor (in degrees Kelvin). (70F = 294K) K is Boltsmann's constant (1.38 x 10^-23) R is the resistance in ohms F2-F1 is the bandwidth you are measuring the noise across. In the case of a Tektronix 7A19 amplifier it would be DC to the full bandwidth of the plugin (500,000,000Hz - 0Hz) = 500,000,000 So, if a 7A19 had a purely resistive 50 ohm input its thermal noise at room temperature would be 20uV which is far too small to see on the scope even at the most sensitive setting of the 7A19. For a 7A26, with 20,000 times input resistance (if it was purely resistive), and 2/5 the bandwidth, the thermal noise would be 1.8mV which would be so great you couldn't help but notice it on the most sensitive scale because it would occupy more than 1/3 division of the CRT. So why don't you see it? The answer to my question is simple: the input isn't purely resistive. The amplifier specs say there is resistance and capacitance at the input. With 1Mohm input impedance the effect of even a small capacitance becomes significant as the frequency of the signal goes up. Another way of looking at this is that with a lower 50ohm input impedance, a capacitor will have little effect until you reach very high frequencies. For high frequency work 1MOhm amplifiers are not a good choice, 50 ohm inputs are better. The capacitance at the input of the 7A26 kills a lot of the noise and keeps the trace sharp. The 7A19 will have no visible noise. Dennis -----Original Message-----
From: micpreamp, Sent: Thursday, January 03, 2013 12:58 PM Hi all, I have a 7904A with a 7A19 plugin (plus lots of slower ones, e.g. 7A24 and 7A26). I'd love to have two channels of > 500 MHz, and I'm contemplating if I should chase another 7A19 or get two 7A29 (and sell the 7A19). The 7A29 will make better use of the mainframe bandwidth and has a variable vertical deflection feature. What I wonder: how do things look noise wise? I hate blurry traces, and I'm rather surprised how sharp the 7A19 is (much better than the 7A26!). Anyone who could compare them side-by-side? Any other difference I should know about? Thanks a lot, Samuel |
|
Re: 2246 Mod A - Is it OK to replace just one SMPS switching transistor?
Francis
--- In TekScopes@..., "Tom Jobe" wrote:
Thank you to all that have contributed to this interesting discussion!Hiya Tom ! Wish you a wonderful New Year ! I have now 7 Teks working flawlessly, plus a dozen of plug-ins for my 7904's. (I have some Philips too...). The only which will be out of rescue is a 2213 which has dropped from a desk and has a defective CRT. Sad... |
Sergey Kubushyn