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Author Topic: Used 'Scopes  (Read 587 times)
KG6OMK
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Posts: 107




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« on: May 03, 2007, 03:03:27 PM »

I've decided I want a "new" scope.  I see quite a few used scopes on eBay.  The prices seem almost to good to be true.  High end Tectronix 7904 scopes (that's a 500Mhz 4 bay mainframe scope,  Maybe sold for $15k new) are going for under $200.  The "basic" dual trace Tek 454 is selling for about $100.  

Are there any models of Tek scopes to stay away from or for look for?  Any advice about these older (1970's to 1990's) scopes is welcome.  The 7000 series seems interresting.  
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KE4DRN
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Posts: 3734




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« Reply #1 on: May 03, 2007, 03:16:25 PM »

Hi Chris,

You're right, too good to be true, most are scams,
they copy legit auctions and list them at low prices
and ask for wire transfers.

Here is a link for you,

http://tech.groups.yahoo.com/group/TekScopes/

Over 3,000 members and wealth of information,
many also swap/sell scopes.

73 james
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WB2WIK
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Posts: 20672




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« Reply #2 on: May 04, 2007, 02:18:19 PM »

A lot of folks have been lucky and not scammed, but I wouldn't buy test equipment via eBay unless it was from:

-A legitimate dealer who is a registered corporation I can research

-or-

-A seller local enough to me that I could go visit him to inspect the goods prior to completing the transaction.

Modern scopes are complicated enough that only one of 40,000 components can fail and take the whole scope down forever.  I'd rather start with one that works perfectly and has a recent cal tag on it.

Around here, they're everywhere.  I've bought 'scopes from local (literally neighbors) garage sales that were like new and worked perfectly -- and every inexpensively.  These are mostly from TRW, Litton, Hughes, Northrop-Grumman, Rockwell, Boeing et al. and somehow found their way out the doors of those labs and into engineers' homes.  I don't ask how, I just like the goods and the prices...

WB2WIK/6
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KC0WOX
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Posts: 1




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« Reply #3 on: May 06, 2007, 02:24:55 PM »

I bought a tektronix 7904 from a friend and I love it!  I was able to verify operation first. If you can find one on ebay that will allow returns if not operational, you might be able to get a good deal. I've seen them go pretty cheap. A great way to do it is to search using the closest first. If you find one locally, you can verify the operation and also save the freight, which could be considerable due to size and weight.

I've bought about 10 plugins on ebay and have had good luck with them. I even got one that was brand new in the original box and packing. The slides and plug in connector on the back look like they have never been installed in a scope.

I like to work homebrew and it's great to be able to look at the signal anywhere in the rig.

Leonard
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K8AG
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Posts: 352




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« Reply #4 on: May 24, 2007, 10:21:45 AM »

I agree with WIK.  If the dealer has 99.6+ with 100+ sales transactions and the scope actually shows all of the traces showing an active waveform, I might bite if the price was right.  Also make sure that all of the plug-ins displayed come with the unit.  Plug-ins are frequently not tested when sold and you have no clue if they will work.

If you are very very careful you can get a deal.  $200 does not sound like too ridiculous.  After all, service on  these scopes is expensive.  They are 30 year old scopes.

73, JP, K8AG
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KG6OMK
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Posts: 107




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« Reply #5 on: May 24, 2007, 11:53:28 AM »

To reply to my own question:  Just bought a used Tek 465b from eBay.  Paid $97 plus $24 shipping. I waited for one that was shown with a live trace in the photo and described as "working" from a dealer with good feedback.

What I got was an old but working 100Mhz dual trace scope.  Works fine except there is some intermittent instability in the lower end of the horizontal timebase.  But the display is rock solid when looking at signals that are 1Mhz and up.  Was able to look inside a 32Mhz crystal oscillator ad see clear waveforms. I could compare traces in a TTL logic board and see gate delays and sme "ringing" on the signals.  I'd say well worth the $97 paid.

Next I'll look for a non-functional same model scope for parts just in case I ever need them

I suspect the instability issue is that a cap needs to be replaced. Or if I'm lucky it's just dirt on the switch contacts.  If major service is ever required, I'm sure it will be cheaper to simply buy a replacement scope off ebay.  The way I see it now is the with prices this low there is little risk.  Just don't get into a bidding war
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AI4NS
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« Reply #6 on: May 27, 2007, 08:55:52 PM »

I think I would wait until you have a problem. Most scopes fail with similar bad parts, so you may be buying one that has the same bad part you will have eventually.

Mike
AI4NS
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