John,
I was wondering about the 7D20 whether it was any good or not, and if I should
sell my digital scopes. I have two Panasonic digital storage scopes with the
cursors and all the neat stuff. They are 100 and a 50 MHz dual trace, delayed
sweep, with storage. The 50 MHz I'm thinking about selling if anyone on the
mailer is interested. I also have a Tek 453, 50 MHz, dual trace for sale in
very good condition. Actually, a 50 MHz, you can do a lot with especially if
they have an expander on the horizontal section like X5 or X10. I have a
Heathkit also which is a 15 MHz but usable to 30 MHz according to the book.
That was the first scope I bought when I went into the TV repair business years
back off my cousin. It's in A+ condition for its age. It's not one of those
plastic scopes but the blue metal cabinet ones with the white face. All of
these are soild state.
The 7633 I bought has two 7A18's in it and one 7B53A. One of the 7A18's was
damaged (knobs was messed up), so I bought a 7A26 to replace it and get the
full 100 MHz functionality. I may replace the other 7A18 with the 7A13 like you
mentioned and have the 7A18's as spares.
If you still have the junker, let me know as I'd be interested in it just for
parts. I'm thinking about buying a junker off ebay for that reason, especially
for the CRT. There's some shows up on there with no sweep with just a bright
green screen, and you can get these cheap. The CRT is worth it. I'm thinking
about getting into repairing these and the 400 line of scopes buy buying up
junkers for parts.
Best,
Will
*********** REPLY SEPARATOR ***********
On 3/27/06 at 10:51 AM John T. M. Lyles wrote:
>The 7633 is a fine piece as long as it is working. If you live in a
>humid area, try to either keep it working in an airconditioned or
>dehumidified area, or use it frequently to keep the HV section from
>getting too damp. Also, keep that area clean inside. I killed my
>first one and it was not repairable, so if you need parts I may still
>have the carcass out in the shed unless I unloaded it at a hamfest
>for parts already. One thing I like about vintage old Tek scopes is
>that they hardly drift, compared to what old HP scopes did. I am
>talking solid state here, not the big tube scopes. They were in a
>different league.
>
>Since killing my 7633, I now have a 7623 which is slightly less
>capable for storage and a 7603, as I mentioned before. I use the 7603
>with Tek S/A plug-ins, as it has a bigger/nicer screen that the
>plastic dB graticle cards fit, and you don't need the analog storage
>if you are using one of the better S/A units that had digital
>storage, like the 7L14 instead of 7L12, and the 7L18 and 7L5. I use
>the -5 and -14 in my shop at home. Last week i hauled 7L14 in my 7603
>mainframe out to a local AM radio station to help realign their STL
>(950 MHz) from their studio. What a monster to move, but it really
>worked well. I could easily see their signal (6 watts, other side of
>a ridge a few miles distant) from a yagi on the tower, and it was in
>the prescence of CDMA cellular transmitters on the same tower at 850
>MHz range. They were booming in, so I was worried about damaging the
>front end of the S/A, but it survived and picked out the -70 dBm
>signal while these big carriers were just 100 Mhz or less away -
>without using a bandpass or notch filter. By the way, don't buy a
>7L12 S/A plug-in as you will be disappointed, as it has poor phase
>lock, 300 Hz min resolution BW, and you need analog storage screen to
>really make use of it. I sold my after I got it at an auction,
>realizing that digital storage is the only way to go for useful
>spectrum analysis where you need to move markers, study the trace for
>a while, and compare tuning (before and after adjustments).
>
>My 7623 is used with the 7B53A horizontal and 7A26 veritcal plug ins.
>You don't need faster plug ins as the mainframe (deflection
>bandwidth) for 7623 or 7633 will limit your vertical response to 100
>MHz. With their P6106 10 x fast probe, you could get 95 MHz freq
>response if you had the 7A26 and 70 MHz with the 7A18. For timebase,
>the 7B53A dual/delayed sweep plug in is the only way to go with these
>scopes.
>
>I still use the analog storage on that 7623 scope, but it takes some
>care to remember how to make it work well. You have all those strange
>options, and you can really make an ugly trace if you don't practice
>setting it up. I used it a lot a year ago testing the built-in flash
>on digital cameras (the red eye and autofocus are preflash before the
>main flash). I needed to modify some slave units so that the slave
>flash would only respond to the main and not the preflash. The 7623
>did admirable job, although i have to admit to being spoiled having
>access to TDS scopes at work now - we got rid of nearly all of the
>analog scopes except for 2467. Last year at work I bought and
>installed TDS3034B scopes in rack mount in all of the 200 MHz RF
>system racks, to be able to track changes in the waveforms as well as
>send them over ethernet to my computer in the office. I can now
>detect minor changes in cathode current for big 3 MW triodes in
>operation, and know when we will have to change tubes, by using the
>stored waveforms compared to active trace.
>
>I have seen the old 7D20 digitizing plug-in used at work, and in my
>estimation it was a POS. It is so old that the technology was very
>primitive for what you have to haul around. The 7D20 would do 40 MS/s
>with 1K record length. If i were going for a DSO, I would look hard
>at the Tek TDS 2000 or TDS 3000 series of lunchbox scopes. They are
>quite incredible what they can do, up to 500 MHz (2 Gs/S). When I
>ever find one of those cheap, I will be done with my 7623 scope
>altogether and only keep the 7603 with the S/A plug-ins.
>
>If you can find one working, the 7A13 differential comparator
>vertical plug-in is real handy. It allows you to dial in a huge DC
>offset voltage, and continue to measure low DC changes, all DC
>coupled. Also, it has a calibrated read out of this offset. It also
>can be used as a differential set of probes and have the offset
>function working. You could look at the ripple voltage across a 50 mV
>shunt, for example, while in the presence of 400 VDC - if your probe
>tips were rated for it. It has a 20,000:1 Common mode rejection ratio.
>
>Good luck, those were great scopes, if you can keep them going. There
>are much better ones now, but I believe that those mainframe versions
>were more versatile and reliable than the venerable 454, 465, 466,
>468 'portables'.
>
>
>>Message: 9
>>Date: Sat, 25 Mar 2006 23:35:39 -0500
>>From: "Will Matney" <craxd1@verizon.net>
>>Subject: [Amps] Tek Scope
>>To: amps@contesting.com
>>Message-ID: <200603252335390140.07F52B01@outgoing.verizon.net>
>>Content-Type: text/plain; charset=ISO-8859-1
>>
>>All,
>>
>>I finally broke down and bought a Tek 7633 ( 100 MHz DSO ) with the
>>plug-ins. I bought a 200 Mhz dual trace vertical amp plug-in to
>>replace one 80 MHz one that's in it. I'm wondering if any have used
>>the digital plug-in which makes it a digital scope? This is the
>>plug-in that takes up all three bays, and is a one plug-in deal. I
>>primarly bought it with the intention of buying a spectrum analyzer
>>and tracking generator plugin later on. Now though, I'm wondering
>>about the digital plug-in. The plugins in it are a delayed time
>>base, and two dual trace vertical plugins, both 80 MHz. The one
>>vertical was damaged, mostly a couple of knobs so I bought a 200 MHz
>>to get the full use out of the scope. It will still have the one 80
>>MHz in it which is good. Any comments on the 7633 scope would be
>>appreciated.
>>
>>Best,
>>
>>Will
>>
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