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Re: 524D RCA customized scope on the big sales platform
On Fri, 22 Apr 2022, Jeff Dutky wrote:
I'm not interested in this specific scope, but I grabbed the pictures for both the RCA affiliation, and the visible graticule, which I don't see mentioned on the TekWiki. I am almost completely ignorant of NTSC waveform monitoring; does anybody else know what that graticule represents, how it's used, and what it's called?It is the standard graticle used to read a NTSC video waveform: the zero is, well, zero - the transition between video and sync the sync pulses are displayed below the line - ideally down to 40 the video is above the line with white levels reaching a peak of 100 at the top of the graticle and the black level dropping down to the dotted line but not down to zero. The display was usually used at line rate (1750kHz) and not at frame rate (60Hz) but both displays had their uses. You would use this to setup a camera for example so the whites are white, the blacks are black, and the checks are checks etc. Too much white and the video gets into the audio on a transmitted television signal and you would hear it as a buzz on you black and white 21 inch Admiral. Naturally you want the right amount of black and white to give you a decent picture. When colour was added, the chrominances information was added as a varying 3.58MHz subcarrier riding on the luminance waveform. A separate vector scope was used to setup the chrominance so the reds were red and not green etc. but the level of the colourburst at the front of each line and level of the chrominance riding the luminance waveform could be monitored with this display. -- Richard Loken VE6BSV : "...underneath those tuques we wear, Athabasca, Alberta Canada : our heads are naked!" ** rlloken@... ** : - Arthur Black |
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Re: 524D RCA customized scope on the big sales platform
On Fri, Apr 22, 2022 at 09:47 AM, Jeff Dutky wrote:
Video signal is coded as black ~ 10% (dashed line is at 7.5%, probably black level spec) white is 100%, sync pulses are at -40% (bottom half graticule). The reason for 0 to 100% and -40 to 0% ranges, with a dashed line at 7.5%. Ozan |
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Re: 524D RCA customized scope on the big sales platform
On 2022-04-22 12:47 p.m., Jeff Dutky wrote:
I'm not interested in this specific scope, but I grabbed the pictures for both the RCA affiliation, and the visible graticule, which I don't see mentioned on the TekWiki. I am almost completely ignorant of NTSC waveform monitoring; does anybody else know what that graticule represents, how it's used, and what it's called?I couldn't find the listing. Can you make the pics available somewhere? Is it an ordinary vectorscope graticule? e.g. Tek 1720, etc. --Toby |
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Re: Tektronix P6021Current Probe Termination
The probe and its termination (passive, 134, or 7A14) are designed as a system. As you can see in the P6021 manual, the Passive Termination box is a complex RLC network with several calibration adjustments. If the probe worked decently with a plain 50-ohm resistor, Tek would have used it.
Dave Wise From: [email protected] <[email protected]> On Behalf Of jimbert4 via groups.io Sent: Friday, April 22, 2022 8:53 AM To: [email protected] Subject: Re: [TekScopes] Tektronix P6021Current Probe Termination Will it work better with no termination box if I use a 50 ohm oscope input? What termination is it looking for? |
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Re: 524D RCA customized scope on the big sales platform
I'm not interested in this specific scope, but I grabbed the pictures for both the RCA affiliation, and the visible graticule, which I don't see mentioned on the TekWiki. I am almost completely ignorant of NTSC waveform monitoring; does anybody else know what that graticule represents, how it's used, and what it's called?
-- Jeff Dutky |
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Re: Tektronix P6021Current Probe Termination
You can also use a 7A14 plugin, IIRC.? It switches between probe types based on a ring, which is in a small adaptor that you attach to the probe.
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Compensation for both probe types is different. Harvey On 4/22/2022 11:18 AM, Dave Wise wrote:
The P6019/P6020/P6021/P6022 current probes MUST use either the appropriate termination box, or a Type 134 Current Probe Amplifier. Otherwise the frequency response will be poor since the probe portion was designed to be terminated in a low impedance not the typical 1Meg of a scope. |
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Re: Tektronix P6021Current Probe Termination
The P6019/P6020/P6021/P6022 current probes MUST use either the appropriate termination box, or a Type 134 Current Probe Amplifier. Otherwise the frequency response will be poor since the probe portion was designed to be terminated in a low impedance not the typical 1Meg of a scope.
Dave Wise From: [email protected] <[email protected]> On Behalf Of jimbert4 via groups.io Sent: Friday, April 22, 2022 7:17 AM To: [email protected] Subject: [TekScopes] Tektronix P6021Current Probe Termination I have a P6021 current probe but no termination box for it. Is the termination box necessary to use it and what are the consequences of not using it? What is the impedance of the probe output without the termination box? |
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Re: Need help diagnosing and repairing a Tektronix 491 Spectrum Analyzer
See if you have a LO feedthrough signal on band B near the left end of the scale. The A and B band use the same number pencil triode oscillator tube and you can swap the b tube in to get the a band working if necessary
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On Apr 19, 2022, at 3:37 PM, Jim W3FAW <okrobie13@...> wrote: |
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Re: 2432 calibration battery?
Hi,
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Yes, cal data is stored in the nvram. But I wouldn't worry much about it, as the 2432 is very simple to calibrate. By the time you solve the problem of saving and transferring the calibration data from the old nvram or during the battery change, you can do the calibration. Most of the calibration steps are automatic with self calibration and you only need an external power supply to provide a couple of voltage levels for the external calibration steps. Self cal and extcal will set the scope back to specifications. Szabolcs Bert Haskins <bhaskins@...> ezt ¨ªrta (id?pont: 2022. ¨¢pr. 21., Cs, 17:32): Does this scope have calibration data stored in battery backed ram? |
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Re: Dogbone Capacitors
I think Erie made some of them. For those who enjoy restoring boat anchor transmitters such as the Johnson Ranger and Valiant, a temperature compensating version is used in the VFO. They were made with both + and - temp coefficients, finding the correct one to stabilize a vintage VFO can be a challenge. I don't think they have been made for? well over 50 years, so finding them takes time. My friend Bob Harrison, W2ICQ, now SK,? well known in the HF AM groups, had? a knack for choosing the correct one to keep ancient VFOs on frequency. For years he made do? with a basic EICO scope, until I gave him a 453. It quickly became indispensable.
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??? Bruce Gentry, KA2IVY On 4/21/22 21:46, Richard Knoppow wrote:
Fairly common. I have seen them in Collins 51J receivers and in my RCA AR-88 receiver. They are ceramic caps often temperature compensating type. I am drawing a blank on the name of the well known maker of capacitors who made them. I don't know the history or the mechanical construction. They are high quality caps which seldom fail. You are probably aware that the characteristics of "low K" ceramic and "high K" ceramics are quite different. Low K, AKA NPO or CG0 are very reliable and do not change with age while Hi-K ceramics do age and have some undesirable characteristics like high dielectric storage and variation of capacitance with voltage and temperature. The Lo-K type are made in various grades of temperature characteristic for compensation. I just tried to find the name of the company who made a lot of these things but could not. Some ceramics were made in the dog-bone style and some as ceramic or bakelite case axial types. |
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Re: Dogbone Capacitors
So.eone mentioned Erie,? I am pretty sure that was rhe brand name?Sent from my Galaxy
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-------- Original message --------From: ¸é±ð²Ô¨¦±ð <k6fsb.1@...> Date: 4/21/22 7:52 PM (GMT-08:00) To: [email protected] Subject: Re: [TekScopes] Dogbone Capacitors I have seen them in stuff as early as early 1930s, never found a bad one, effectively ceramic with silver on either side of the tube. dif temp coefs.....dawgbone¸é±ð²Ô¨¦±ðOn 4/21/22 5:42 PM, Jeff Dutky wrote:> Were the tubular "dogbone" capacitors unique to Tek, or were they a commonly available third-party component in the 60s and 70s? Does anybody have any information on how these were made? Was there a "correct" jargon for them?>> -- Jeff Dutky>>> >>> .
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Re: 2445 EPROMs
Unless his posts have gone missing, there should be a record of previous posts on the subject by any number of people.? From what I understand, in the conversion, there are parts left out, so while the scope reports a higher bandwidth, certain compensation networks are not included, so the resultant response is not the same from the "upgrade" to the proper model.? Further than that I will not say, but there were other issues with the transaction.
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Harvey On 4/21/2022 10:27 PM, Bob Headrick wrote:
I do not think Chuck is back - message #163375 was years ago. I see him occasionally in the HP/Agilent group. IMHO it was a great loss for this group. |
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Re: Dogbone Capacitors
I have seen them in stuff as early as early 1930s, never found a bad one, effectively ceramic with silver on either side of the tube. dif temp coefs.....dawgbone
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¸é±ð²Ô¨¦±ð On 4/21/22 5:42 PM, Jeff Dutky wrote:
Were the tubular "dogbone" capacitors unique to Tek, or were they a commonly available third-party component in the 60s and 70s? Does anybody have any information on how these were made? Was there a "correct" jargon for them? |
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