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Re: TLA700 - Logic Analyzer - PCMCIA->CD-ROM interface ...
...And the RTC Dallas DS12887 was - as could be expected - dead.
"Disappointment" Will make an attempt to use an external battery as shown in several Y-T videos. If unsuccessful... Will put it away and see if there are some mainframe versions available that uses a separate PC. Ulf |
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Re: 10Mhz under frequency in 184 Time-Mark Generator
If its cycling, its probably good. Mine wasn't heating, nor cycling
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till I repaired it. Just a thought, oh well.... On Tue, Dec 7, 2021 at 8:55 AM n4buq <n4buq@...> wrote:
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Re: 10Mhz under frequency in 184 Time-Mark Generator
I can hear the thermostat cycling and see the lamp cycling as well. I'll check whether it's actually warm to the touch in a bit just to make sure.
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Thanks, Barry - N4BUQ ----- Original Message -----
From: "David Holland" <david.w.holland@...> Is the heater in the octal plug actually working? -- Mine was not. |
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Re: 10Mhz under frequency in 184 Time-Mark Generator
Is the heater in the octal plug actually working? -- Mine was not.
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(The thermostat was stuck open IIRC). They don't run cool, so you can definitely tell... David On Tue, Dec 7, 2021 at 8:45 AM n4buq <n4buq@...> wrote:
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Re: 10Mhz under frequency in 184 Time-Mark Generator
Hi Eric,
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I probably did not perform a suitable warmup as I had considered that was more of a drift issue than anything. I presumed that if I can't get a +/- swing cold, then something may be wrong but that may not be correct. I'm letting it do a proper warmup and will recheck. I'm pretty sure I was checking that via the output connector (per the manual) so that shouldn't have offset the oscillator with unnecessary capacitance (but thanks for the reminder about that). Thanks, Barry - N4BUQ ----- Original Message -----
From: "Eric" <ericsp@...> How long a warmup time are you giving the crystal before trying to cal. |
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Re: 10Mhz under frequency in 184 Time-Mark Generator
Hi Jeff,
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Y11 is mounted in an an octal plug along with its heater so I can unplug that if need be. I have disassembled a trimmer similar to the one used for C11 and, as I recall, it did need some cleanup (I seem to recall the silver had migrated but that's a distant memory) so I was considering a cleanup for this on as well. Thanks, Barry - N4BUQ ----- Original Message -----
From: "Jeff Dutky" <jeff.dutky@...> The advertised spec is +/- 0.001%, so (if my math is right) you are will within |
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Re: 10Mhz under frequency in 184 Time-Mark Generator
Oh, I forgot to say: the trim cap looks like the same kind that was used in some 500-series scopes. With great care they can be disassembled and cleaned.
Here is a video showing the process If you watch the video (it's a bit slow going) the video creator notes that one of the metallized disks is corroded which limits the upper range of the capacitor. You may have a similar problem. -- Jeff Dutky |
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Re: 10Mhz under frequency in 184 Time-Mark Generator
How long a warmup time are you giving the crystal before trying to cal.
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Also how is your probing set up? This circuit is incredably sensitive to capacitance. Not enough heat in the crystal and or too much capacitance in the probing set up will drag the crystal off to the low side of things. Eric On Tue, Dec 7, 2021, 12:41 AM Jeff Dutky <jeff.dutky@...> wrote:
The advertised spec is +/- 0.001%, so (if my math is right) you are will |
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Re: 10Mhz under frequency in 184 Time-Mark Generator
The advertised spec is +/- 0.001%, so (if my math is right) you are will within the advertised precision.
The circuit in which Y11 operates looks pretty simple, the only components around it are C11, R11, L18, and V10. I'd have a look at R11 to be sure it hadn't drifted (the parts list seems to indicate that it's an unremarkable carbon comp resistor, with 10% accuracy). You could also remove the Nuvistor and the crystal in order to check C11 in place. I expect that both V10 and Y11 are socketed, but I can't really tell about the crystal oven from the pictures in the service manual, so it might be easier to unsolder C11 than to remove Y11. -- Jeff Dutky |
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Re: Recommended ventilation clearance around a 2465 scope
My 2465B, ex-military, has the original plastic accessories envelope secured on the top of the scope, so that is essentially a "blanket".
I've never given a second thought to the thermal insulating properties of the envelope, being that it is original equipment. As I understand it, the bottom panel with the ventilation holes is critical. Under the scope, I have about 2.5cm (1") clearance with the bail handle positioned underneath the scope, and I spray compressed air through those holes every so often to keep them clear of dust build-up. At the rear, the original long black legs provide sufficient clearance from the wall, for the fan exhaust. |
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Recommended ventilation clearance around a 2465 scope
All of the feet - both front and rear - on my 2465 have crumbled b/c of age. While I'm waiting for replacement feet, can anyone tell me the recommended clearance around the case? I couldn't find anything specific in the operator's manual other than it should "have good ventilation".
I have limited space on the shelf and want to place the rear of the 2465 case about 1in to 2in from the wall. I'm also going to temporarily put something underneath to raise it off the shelf for the bottom ventilation holes. Thanks, J |
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10Mhz under frequency in 184 Time-Mark Generator
Try as I might, the 10Mhz crystal oscillator will not quite make it to 10MHz. The trimmer will get it to about 9.99987 (or something close to that) but I can't quite get 10MHz. I presume the crystal just can't be "pulled" enough and not sure if C11 is closer to 3pF or 12pF but I presume it's 3pF. Is there anything else that might be preventing the circuit from being set to either + or - with the cap? Is it possible the cap really isn't doing 3pF to 12pF anymore and, perhaps, needs to be disassembled and cleaned?
9.999x is really close enough but it's annoying to not be able to put it spot on (or, at least, closer to it). Thanks, Barry - N4BUQ |
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Tek 2225 Channel 1 Help Request + possible parts request
Hello All,
I have an ebay purchased Tek 2225 and have issues with Channel 1. It seems to get a proper looking sin wave however the amplitude varies between 1/2 and 1/5 of what it should be based on the setting. Also occasionally hops left or right and back but maintains shape. Any ideas where to look? R145 appears to work appropriately but cannot adjust amplitude anywhere near where it needs to be. I plan on recapping shortly. If the Channel needs to be replaced, does anyone have a parts model that I could purchase from? Also looking for a probe adjust fitting for the front panel, which is strangely gone. Thank you all for your time! Very Respectfully, J G |
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Re: What is a 5B10 with Mod 711C?
I found just this on page 78 in Tektronix_Catalog_1991.pdf?
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710R? -? XY/YT switching of center compartment signal711C? -? add control on 5B10N for switch in MOD 710R Petru On Tuesday, December 7, 2021, 01:19:06 AM GMT+2, Jeff Dutky <jeff.dutky@...> wrote:
I just bought a 5B10N on the auction site that looked unusual. It has a toggle switch in the upper right corner of the front panel labeled "L vs R (BLANKING)" and it appears (from the images included in the listing) to have a factory mod called "Mod 711C", but I can't seem to find any documentation about such a modification on TekWiki. Does anybody know anything about this modification and what it does? I have posted two images of the item (images from the listing, since I have not received the item yet) in the album /g/TekScopes/album?id=270601 -- Jeff Dutky |
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What is a 5B10 with Mod 711C?
I just bought a 5B10N on the auction site that looked unusual. It has a toggle switch in the upper right corner of the front panel labeled "L vs R (BLANKING)" and it appears (from the images included in the listing) to have a factory mod called "Mod 711C", but I can't seem to find any documentation about such a modification on TekWiki. Does anybody know anything about this modification and what it does?
I have posted two images of the item (images from the listing, since I have not received the item yet) in the album /g/TekScopes/album?id=270601 -- Jeff Dutky |
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7S14/5S14N bias supplies: something to build on
#photo-notice
Hi all,
I've picked up a 5S14N. <insert childish bouncing & vocalizations> Not surprisingly, it has dead bias cells in one channel. (Or: surprisingly, it has good bias cells in one channel.) Replacement remains a work in progress but I thought this might be generally useful. The four through-holes for the two cells align to a 0.1" grid and have enough space around then to fit a bit of PTH perfboard to build on. /g/TekScopes/album?id=270597 |
Michael W. Lynch
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