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Used TDS520D Price?
I have a TDS520D ( 2 channel, 500Mhz, 2GS/sec) that I am planning to bring to a local flea market to sell. I'm trying to figure out a reasonable asking price. Doing a Google search returns a very wide range of asking prices. It boots up fine and the self-test is good. Everything on it seems to work fine but haven't verified the floppy drive or printer port are working, but I have no reason to believe that they aren't.
Looking for recommendation on a reasonable asking price. Thanks, Dale |
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Re: 492 has no 110 MHz IF
Could the problem be something as simple as the oscillator being off frequency? My microwave counter has a power supply problem that I'm also trying to fix, and I doubt a 7S11/7T11 combo is precise enough to adjust it.If you want to finely adjust a 110MHz signal, a 7T11 time base would be useless with its very limited frequency accuracy and resolution. Raymond |
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Re: 492 has no 110 MHz IF
If you want to measure frequency, then the 7D14 is probably the tool choice
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(to get in the ball-park anyway), but GPS locked counter will be better. David -----Original Message-----
From: David C. Partridge <david.partridge@...> Sent: 13 March 2025 11:03 To: 'TekScopes@groups.io' <TekScopes@groups.io> Subject: RE: [TekScopes] 492 has no 110 MHz IF Actually, a 7S11/7T11 combo will give you pretty accurate measurements of RF signals (typically better than a power meter). The signal needs to be large enough though, if you talking 0dBm that's fine (0.224Vrms), but if the signal level is smaller than that, you will have problems and below about -7dBm (100mV rms), you'll probably be out luck. David -----Original Message----- From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Adam R. Maxwell via groups.io Sent: 13 March 2025 06:01 To: TekScopes@groups.io Subject: [TekScopes] 492 has no 110 MHz IF Hi all, I've been trying to troubleshoot an amplitude problem on my new 492, which has had multiple other little problems along the way. At this point, I can get a stable display and frequency is OK, but amplitude is 20-30 dBm lower than it should be. Attenuator and first mixer seem good, but I'm missing the 110 MHz output from the 2nd converter (should be -37 dBm or -39 dBm depending on band), measuring with HP 8484A. The front panel 2nd LO output is ~17.6 dBm on the first band, and I measure +9 dBM and -1.5 dBm directly on the 2nd LO cavity oscillator, which all seems in the ballpark (and at least verifies the oscillator is not dead). Could the problem be something as simple as the oscillator being off frequency? My microwave counter has a power supply problem that I'm also trying to fix, and I doubt a 7S11/7T11 combo is precise enough to adjust it. I'm mildly tempted to just try turning the adjustment screw on the cavity oscillator and see if the display responds. Any other ideas? I'm not enthusiastic about opening up the 2072 MHz 2nd converter, but that looks like the only thing in the signal path that would lose the 110 MHz IF on all bands. thanks, Adam |
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Re: 492 has no 110 MHz IF
Actually, a 7S11/7T11 combo will give you pretty accurate measurements of RF
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signals (typically better than a power meter). The signal needs to be large enough though, if you talking 0dBm that's fine (0.224Vrms), but if the signal level is smaller than that, you will have problems and below about -7dBm (100mV rms), you'll probably be out luck. David -----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Adam R. Maxwell via groups.io Sent: 13 March 2025 06:01 To: TekScopes@groups.io Subject: [TekScopes] 492 has no 110 MHz IF Hi all, I've been trying to troubleshoot an amplitude problem on my new 492, which has had multiple other little problems along the way. At this point, I can get a stable display and frequency is OK, but amplitude is 20-30 dBm lower than it should be. Attenuator and first mixer seem good, but I'm missing the 110 MHz output from the 2nd converter (should be -37 dBm or -39 dBm depending on band), measuring with HP 8484A. The front panel 2nd LO output is ~17.6 dBm on the first band, and I measure +9 dBM and -1.5 dBm directly on the 2nd LO cavity oscillator, which all seems in the ballpark (and at least verifies the oscillator is not dead). Could the problem be something as simple as the oscillator being off frequency? My microwave counter has a power supply problem that I'm also trying to fix, and I doubt a 7S11/7T11 combo is precise enough to adjust it. I'm mildly tempted to just try turning the adjustment screw on the cavity oscillator and see if the display responds. Any other ideas? I'm not enthusiastic about opening up the 2072 MHz 2nd converter, but that looks like the only thing in the signal path that would lose the 110 MHz IF on all bands. thanks, Adam |
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Re: Tek 492 Y axis failure?
Hi Mark,
thanks for the link. I'll have a good read through it. As for further failed tantalums, that could well be the case as the video amplifier is still not running correctly. Fortunately the 'parts-donor' unit still had this module and that one does seems to be working. I've removed the Yig and have been looking for clearer disassembly images or videos but without luck as of yet. Before I attempt to open it, when I get some time, I'll look through the manual and see if the lack of vertical deflection might be on one of the plug-in boards. There are 11 of the bolt-connected modules, from the underside, which I had intended to test, but I'm not prepared to risk any further damage. Thanks James |
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Re: Like to say hello and ask a question about my Tektronix 465 ocsilloscope
Hello Mike,
Thanks for your reply. I did some checks on some regulated voltages indeed in terms of voltage level and ripple or other nasty oscillation issues and all looked clean. However, not really structured and I can't remember the values at this moment to be honest, I only know I didn't see any unexpected things. (I've got a second scope as well fortunately) But, I will have a look again. It is a very nice piece of quality equipment, must have cost a serious amount of money when it was new. Usually my interest is low frequency spectrum like audio and video, sweeps on LPF and HPF filters, but with 100 MHz I can do a lot more I reckon. Thanks, Wilfred |
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Re: Salvage yard rescue: Tektronix TU-50. Some questions from a non-tech
I prefer to use vintage equipment to calibrate my oscilloscopes, mainly because I enjoy the challenge.
I just hate to see these golden age of electronics jewels going to the scrap and being destroyed. And at this time I have room for the larger 500 series stuff. A TU-50 has been a want for quite a while now. I don’t need it, but I’d like a nice one to preserve. So I sent you a PM Ricky. |
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Re: Identify TDS640A 'hackable' options via serial number?
In the aforementioned link to enable options, follow the process as usual, but instead of sending the command 'WORDCONSTANT:ATPUT 327690, 1'. send 'WORDCONSTANT:ATPUT 327690, 0' (without quotation marks) instead.
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That should turn the floppy drive option off. Or you could install a floppy, or even a Gotek Slim Floppy Emulator to provide USB for convenient screenshot transfers etc. :) (I used this exact one and they work perfectly). Jared On Wed, Mar 12, 2025 at 07:16 PM, walkerru3 wrote:
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Re: Like to say hello and ask a question about my Tektronix 465 ocsilloscope
Wilfred:
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All of the capacitors that you mention are part of the power supply, and their ripple is not specified, as they are part of pre-regulator circuitry.? Can you check the regulated DC voltages and determine if the ripple on the DC voltage buses are within limits?? These limits should be specified somewhere in the service manual(s) (refer to w140.com).? If the service-manual-specified limits for ripple on the various regulated DC buses are within limits, you should be fine. If I am missing something here, that others are aware of, please let me/us know! Mike N4MWP On 3/12/25 15:36, Wilfred via groups.io wrote:
Hello again, |
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Re: Like to say hello and ask a question about my Tektronix 465 ocsilloscope
Hello again,
It's been a while since I wrote and had to say goodbye to my 465 oscilloscope, but I managed to find another one and luckily without any issues. The serial number is 109003, which is I understood one of the latest. (Not sure though) Anyway, I did a check on the power supply voltages and the big capacitor's ripples between the plus and minus on the Elco itself: C1512 (550uF) 79V and 300mV ripple, C1513 (1200uF) 74V and 1V ripple, C1542 (5500uF) 23V and 1.5V ripple, C1552 (50009uF) .2V and 700mV ripple, C1562 (3000uF) 12V and 1V ripple. Any idea if this is acceptable ? It might be wise to replace them in the future, but for now I just leave it as it is and use the oscilloscope it was made for. Thanks again and have a lovely evening, Wilfred |
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Tek 492 Y axis failure?
Hi.
I have this 492 which was working. Last week a friend donated a largely stripped 492 whose remaining parts I thought could be tested in the working unit. First thing to test was the crt. Unfortunately, nothing appeared on the display and the distinct smell of toasted component filled the air so quickly turned the 492 off. Following my nose, led me to the video amplifier board, where a shorted tantalum was quickly found. With that replaced, the 492 came back to life, all the lights, traces, display readings etc. However, there appears to be no vertical readings. Before I dive into the manual when I next get time, does anyone have any idea as to where to look? For example, could the video board have damaged an adjacent board? I've seen people replacing the diode and tantalum in the Yig filter, so I should just check there first... Once this is fixed, I'll give it a miss testing the remaining parts and just sell them 'as is - for parts' James |
Dale Drake
Raymond Domp Frank
David C. Partridge
James55
Wilfred
Eric Boyle
Jared Cabot
Mike Dinolfo