26 August 2012

Scope Sunday 36

I recently came to the unbelievable, shocking realization that I haven't bought any additional scopes since I helped clean out that barn last December.  I felt that it was necessary to rectify the situation... However, despite attending the monthly MIT Swapfests this summer, several Electronic Flea Markets in California, and even the Hamvention in Dayton back in May, I haven't found anything worth dragging home.  (I've bought several plug-ins (stories for another time), but no new scopes or mainframes.)

Luckily, my friend Will reminded me that this was Boxboro weekend, so I drove up to Boxborough, Mass. Saturday morning, and looked around.  There was a dirty 564B for $200 (which is at least 10dB too high, $20 would be about right), a 7834 for $100, and several 7603s around the flea market, but the things that caught my eye were two 422 scopes (at two different sellers).

The 422 is a 15-MHz portable scope that had an optional battery pack.  The one on the left (serial number around 33,000) has the AC/DC power supply and the battery pack, but it doesn't power up.  The one on the right (SN around 12,000) works, but it has one bad channel, a broken handle, and no battery (it's AC only).  I'm hoping that they both can be fixed, but I should be able to get at least one of them working easily.

They aren't great scopes, but they remind me of a missed opportunity...  Several years ago on eBay, there was an auction for a whole pallet of broken 422 scopes.  If I recall correctly, there were 30 or 40 of them.  I thought seriously about buying them all and using them as the basis for great class project: student teams would study, troubleshoot, and fix the broken scopes.  The more scopes you fixed, the higher your grade!

I really should have done that.

05 August 2012

Scope Sunday 35

Last weekend, I finally got a chance to visit the vintageTEK Museum in Portland, Oregon.  I had a great time.  The museum is smaller than I expected; in fact, there are only a few dozen instruments on display.  Here is a picture of the whole museum taken from the front desk.

Despite being small, the museum has an impressive collection of rare instruments, including quite a few that I had never seen before in person.  First up, of course, is Tektronix's original oscilloscope from 1946, the 10-MHz-bandwidth 511. Only about 350 of these scopes were made (I have a 511A, which isn't nearly as rare).

On the other end of the frequency spectrum, they have a 519, the 1-GHz special-purpose monster from 1961. (There's also a 1-GHz 7104 in the museum, of course.)

Next up is the 945, which is the military ruggedized version of 545.  Heavy and heavy duty.

 They also have a 7704A mainframe, complete with the P7001 digitizer.

Of course, I thought the best part of the museum was the storage room and repair lab.  Here's the wall of letter-series plugins (check out the three different colors of type CA plugins in the bottom row; there's also two type O plugins and a type Q here, and a type N just out of frame).  I spent quite a bit of time poking around in the back room.

I actually spent most of the afternoon in the back, hanging around with two volunteers, who were busy sorting spare parts and fixing the horizontal sweep in a 547 (it was a busted tunnel diode, of course, part number 152-0125-00; luckily, there was a 547 parts donor on the shelf).  I don't know if I was a help or hinderance in the process, but I had fun.

After the museum closed, Ed Sinclair invited me to join the TERAC (formerly known as the Tektronix Radio Amateurs Club) for their weekly Friday night dinner at Round Table Pizza in Beaverton.  There I met another great group of (mostly former Tektronix) engineers, including Deane Kidd, and had a great time.

02 August 2012

Scope Sunday 34

OK, so it's not really Sunday, but I wanted to post a quick update. I had a great weekend in Portland, including visiting the VintageTEK Museum.

I also did a little bit of surplus shopping.  I stopped at Stuff in Happy Valley ("Nothing you need. Everything you want.") where I bought a Boss DR-110 analog drum machine (don't ask).  I then drove over to R5-D3 Electronic Surplus in Milwaukie, where I bought a manual for my Tek 585 and a couple of issues of Popular Electronics from the 1970s (which included an article about an electronic drum circuit, again, please don't ask).

I also hit Surplus Gizmos in Hillsboro, where I bought some random cables, a rebranded Tektronix video processing box, and some quad-ganged 50k potentiometers. (They were $0.10 each! How could I resist?)

More pictures and words about the museum this weekend.