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Re: Used TDS520D Price?
For appraisals, my go-to is eBay completed items.
You’ll see what stuff actually sold for. There have been no recent sales on the -D model, but a -C sold for $270. Seller was asking $300. Put it on eBay at $325. Wait a month, reduce it then to $299. The flea market will bring $100-200, if you have a buyer with strong interest. Not my first choice. Via iPhone; cel is 617 283 8263 |
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Re: 492 has no 110 MHz IF
if I understand correctly (big if!), that intermediate frequency is produced by mixing the 2nd LO 2182 MHz output with the 2072 MHz input signal from the 1st converter. I'm trying to understand why the 110 MHz IF is dead, even though the LO signal is present at approximately the right level.
Very small “if”, I’d say.” -;( You may look at those two ~2GHz signals with your 7T11/7S11, if you have a suitable sampling head, like e. g. an S2 or S4 and probing setup. Same for the 110MHz mixing result, if even to see if any of it is there. Not sure what Dave P. means about signal levels. Operating input level <= 1Vpp or 350mV RMS. Safe PP 5Vmax. Recommended input level between say 50mV RMS and a few 100mV RMS at most, ISTR. You’ll need a faster counter plug in than either a 7D14 or 7D15 to measure their frequency. Take the impedances of the signals you look at and your test setup into account but I guess you know all that. Raymond |
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Re: Like to say hello and ask a question about my Tektronix 465 ocsilloscope
Rebonjour Wilfred
Bravo for the new 465. Since the 1970s the successors were improved, so 465B has better control, LED not incandescent etc. Nowadays the last of the analog CRT scopes from Tektronix are great buys, 2465,2465B, 2475B, etc. A 1990s scope has much better reliability than the 1970s you have. Just my experience Jon |
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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: '[email protected]' <[email protected]> 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: [email protected] <[email protected]> On Behalf Of Adam R. Maxwell via groups.io Sent: 13 March 2025 06:01 To: [email protected] 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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Show quoted text
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: [email protected] <[email protected]> On Behalf Of Adam R. Maxwell via groups.io Sent: 13 March 2025 06:01 To: [email protected] 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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