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Re: Correction re:Re: [TekScopes] 1L10 crystal needed (Newbie)
Harvey White
Or was that more words?
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You can get one, but mouser doesn't have any, for less than two dollars. You could likely spend a bit of time doing the divide by 10, or just find one with a 900 Khz output and stuff a resistor/capacitor low pass filter across the output. No idea, though, on what the original circuit wants. Harvey
On 1/24/2021 8:16 PM, Harvey White wrote:
Yep, covered that in less words..... <grin>
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Re: 2445B 2465B 2467B A5 board
Chuck Harris <cfharris@...>
Through hole electrolytics, B010001 thru B049999
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SMD electrolytics B050000 till the end. Tantalum, AFAIK never. -Chuck Harris Ondrej Pavelka wrote:
Hi folks,
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Re: 1L10 crystal needed (Newbie)
Tom Lee
Hi Harvey,
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Yes, those are among the multiple ways to generate a good square wave at 900kHz. The stock 900kHz oscillator to be replaced produces a sinewave to heterodyne with an 800kHz signal, so what is yet to be determined is whether the harmonic content of a square wave is acceptable here, or whether some filtering will have to be added. --Cheers, Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 http://www-smirc.stanford.edu
On 1/24/2021 17:00, Harvey White wrote:
Use a 74LS90, which is a divide by 2, and a separate divide by 10. (This assumes a 9 Mhz can oscillator, and that it's 5.0 volts supply, and that the rest of the circuit needs a 5 volt signal.
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Re: Correction re:Re: [TekScopes] 1L10 crystal needed (Newbie)
Harvey White
Yep, covered that in less words..... <grin>
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Harvey
On 1/24/2021 8:10 PM, Brad Thompson wrote:
Harvey White wrote on 1/24/2021 8:00 PM:Use a 74LS90, which is a divide by 2, and a separate divide by 10. <snip>Hello--
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Correction re:Re: [TekScopes] 1L10 crystal needed (Newbie)
Brad Thompson
Harvey White wrote on 1/24/2021 8:00 PM:
Use a 74LS90, which is a divide by 2, and a separate divide by 10. <snip>Hello-- IIRC, the 74LS90 has divide-by-2 and divide-by 5 sections. If you need a divide-by-10 square wave, feed the divide-by-5's output to the divide-by-2's input. 73-- Brad AA1IP
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Re: 1L10 crystal needed (Newbie)
Harvey White
Use a 74LS90, which is a divide by 2, and a separate divide by 10. (This assumes a 9 Mhz can oscillator, and that it's 5.0 volts supply, and that the rest of the circuit needs a 5 volt signal.
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Note that some oscillators put out a sine wave, and some put out a square wave. This only works with a square wave output oscillator. If you use a 74LS192 (also a divide by 10), the only output is either the Q4 (divide by 8, but high for two clock cycles), or carry (one clock pulse). These aren't symmetric. Most crystal oscillators are 50% duty cycle, spending the same amount of time as a 1 as a zero. These implementations don't do that. Simple fix. Connect the 74LS92 divide by 5 to the 9 Mhz. This gives you a 1.8 Mhz asymmetric clock. Big deal. Then connect the 1.8 Mhz output of the divide by 5 to the input of the divide by 2 section, which gives you a guaranteed 50% duty cycle 900 Khz clock. If the rest of the circuit expects that 50% duty cycle, you have it now. Harvey
On 1/24/2021 6:01 PM, Ed Breya via groups.io wrote:
The 1L10's 900 kHz crystal appears to be for an oscillator, so you could make a 9 MHz - a very common crystal frequency - oscillator and divide it by 10, if you can't find a 900 kHz one.
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2445B 2465B 2467B A5 board
Ondrej Pavelka
Hi folks,
Is there a way to tell (for example by serial number) which scopes had which version of the A5 board? I am aware of 3 variants 1) leaky surface mount electrolytics 2) through hole electrolytics 3) solid tantalum I guess this is how it went chronologically. Through hole Surface mount Tantalum Anyone on here please knows more about the subject?
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7904: odd readout issue + vertical gain issue
Sean Turner
Hey folks,
Wondering if there is someone here who is a readout system whisperer. I have me a 7904 that wasn't working when I got it. It's a rather interesting one, with all available options equipped. This includes the fast write crt with P11 phosphor. A bunch of shorted tantalum capacitors replaced later, and I have a mostly-working scope. I did rob some parts (including the crt and vertical amp) from a similarly optioned parts unit 7903 I have. Unfortunately someone burned the original tube very badly. Lucky to have a drop in replacement! At any rate, there's a trace and it's even reasonably calibrated fir vertical gain, as long as the trace doesn't stray too far from center. Essentially, there seems to be no happy medium between setting the vertical centering and the readout center on the vertical amp. The readout essentially is stuck low on the crt...what should be at the top of the graticule is in the center and squishes up if you move it any higher. Additionally, the vertical gain drops, the lower down the trace goes. This all was observed on both tubes so I doubt it's the tube. So far I've tried curve tracing all the transistors in the network on the vert amp formed by Q694, Q698, Q710, Q716, Q723, and Q728. They are all fine. I *also* tested the transistors in the output of the readout X and Y signals on the readout board. They are also fine. Additionally, I swapped some ICs from the 7903's readout board. This actually helped a little, but the readout still squishes up if you try to move it (and the trimmer pot tops out before it gets anywhere near the top of the graticule anyway). I'm running out of ideas on what to try, so was wondering if anyone on the list has encountered similar issues or knows what might cause them. Thanks! Sean
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Re: 1L10 crystal needed (Newbie)
Tom Lee
Ed has an excellent idea (as always). There could be a small issue related to the additional mixing products you would get from the harmonics of the square wave output typical of such oscillators, so you might end up wanting to add a filter between any such oscillator and where it plugs in (P218? I was looking at the schematic earlier, but may be mis-remembering the plug/socket identifier). I haven't looked at the circuit closely enough to see if this is truly a big enough problem to worry about, though.
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--Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 http://www-smirc.stanford.edu
On 1/24/2021 15:01, Ed Breya via groups.io wrote:
The 1L10's 900 kHz crystal appears to be for an oscillator, so you could make a 9 MHz - a very common crystal frequency - oscillator and divide it by 10, if you can't find a 900 kHz one.
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Re: 1L10 crystal needed (Newbie)
tgerbic
Could also get a programmable oscillator from someone like Digikey and request it be programmed for 900Khz. I think they have oscillators down to +/-15ppm for ~$5. Might need a buffer/driver. Would replace the entire oscillator circuit.
Tony
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Re: 1L10 crystal needed (Newbie)
Ed Breya
The 1L10's 900 kHz crystal appears to be for an oscillator, so you could make a 9 MHz - a very common crystal frequency - oscillator and divide it by 10, if you can't find a 900 kHz one.
Ed
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Re: Mystery Probe Accessory Grab Bag 'o Fun
On Sun, Jan 24, 2021 at 09:46 PM, Jeff Dutky wrote:
Hi Jeff, You're right, it's absolutely meant for / suited to the P6008. I couldn't imagine, because of the relatively small BW (still 100 MHz) of the P6008, so some series inductance wouldn't harm so much and Tek didn't provide low-inductance clips as standard for many 100 MHz and even higher BW probes, and it perfectly fits the P6201 as well: I have 4 as-new P6201's, in original cassette, complete with accessories and - yes - I had to add the low-inductance thingy myself... Also, the (screw-on) accessories in the sealed plastic bag in your photograph all suit the P6008, not the P6201. So, you were right, although <A> fits the P6201 as well. A possible clue: The pin <D> in your picture is longer than the pin in <A>. The probe input pin on the P6201 extends less far than the screw-on sharp pin of the P6008 in your sealed accessories bag. Interesting! <C> may be the "official" low-inductance ground clip for the P6201. Raymond
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Re: 1L10 crystal needed (Newbie)
snapdiode <snapdiode@...>
Pictures on TekWiki
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Re: 1L10 crystal needed (Newbie)
Joel,
I have a working mint condition 1L10 that I'm not planning to ever use. Would trade it for a working 1A4 or 1S2. Regards, John
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Re: 1L10 crystal needed (Newbie)
Joel,
Maybe a source here: http://www.quartslab.com/ Regards, Dick Sent from a Virus Free Bunker deep within The Utopian State of California Bibimus Ergo Sumus, En Vino Veritas, Quaerite et Invenietis, Illegitimi non Carborundum
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Re: 1L10 crystal needed (Newbie)
Tom Lee
Now, THAT's a museum piece! Please take some pics of its innards and outards when you get a chance. I'll rummage through my Mystery Box of Crystals (a cousin of Jeff's probe box) and see if by some miracle I have a 900kHz crystal. What package is it in?
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Cheers, Tom -- Prof. Thomas H. Lee Allen Ctr., Rm. 205 350 Jane Stanford Way Stanford University Stanford, CA 94305-4070 http://www-smirc.stanford.edu
On 1/23/2021 15:16, Joel B Walker wrote:
Hello All,
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Re: 2235 Horizontal Calibration Issue
Stephen
Thank you Ozan.
It’s been a long day, but I’ll make those measurements later on or tomorrow. (I’m 9h ahead of you). Il report back as soon as it’s done. Thanks again for your help.
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Re: New Member Introduction
Stephen
Welcome!
I’m also somewhat new. I’ve been here less than a year I think. Nice, great and extremely knowledgeable people. They always go out of their way to help mere mortals like me. You’ve come to the right place.
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Re: New Member Introduction
Glad you are here. You will be amazed what you can learn from this group.
-- Michael Lynch Dardanelle, AR
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Re: New Member Introduction
Jim Ford
Welcome, Joe! You're in the right place. Jim Ford Sent from my Verizon, Samsung Galaxy smartphone
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-------- Original message --------From: Joe <The-Lohrbach-Family@...> Date: 1/24/21 11:21 AM (GMT-08:00) To: TekScopes@groups.io Subject: [TekScopes] New Member Introduction Hi,recently I have become aware of this group and the interesting topics discussed here. For more than 40 years I have been fixing almost anything as a hobby - from 1930s radios and all kind of TV sets to automotive automatic gearboxes, engines and body repairs. So meanwhile there is a lot of tools and instruments around. On the threshold to retiring I plan to better maintain and restore some of my gear. I have got the following Tektronix equipment: 516 ( got it 1983 from Siemens Munich Germany. They were so kind to calibrate it before handing it over. Still in use, almost trouble-free)545 B (got it 1990 from University of Aachen Germany for free with crt screen smashed. Brand new crt was about $ 20 from NATO surplus then. In occasional use, I have about 8 or 10 plug-ins for this one including the calibration fixture, again brand new from NATO warehouse)565 (not complete, waiting for restoration, no plug-ins)585 A (in restoration, needs some new capacitors. Just now collecting all these 6922s, has the 82 plug-in)575 (being prepared for recalibration, from a Siemens engineer who had this one stored in the attic since 1990)7603 with two 7A26 plug-ins (has not been powered up for ten years at least)I am looking forward to reading many interesting stories.
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