OK, so sometimes I search craigslist for:
Oscilloscope
Tektronix
Heathkit

Well this weekend I got lucky, and found someone selling some unbuilt heathkits for a great price.  He also had a few Archer 5V power supply kits for sale, which I’d never seen before, appeared complete, and were reasonably priced.  I bought two, here’s the one that I’m going to build.

In it’s original box:

Unboxing:

Well, it’s clear how the manual was folded in the box.

The enclosure and (stick-on) front panel was in flawless shape.

The circuit board showed some signs of age.  One or two pads lifted a little while soldering, but nothing tragic.

Components neatly packed within the chassis

Box-O-Parts

The Build

The screw heads were proud of the surface, which would have compromised the front panel application.

And then I remembered I had a drill press and a countersink bit.

The manual suggests soldering the transformer and rectifier together on the bench based on a rough drawing, but given the rigidity of the wire and the tight dimensions, it seemed a better plan was to at least tack-solder the two together while temporarily in situ.

Transformer & rectifier permanently mounted.

All other elements mounted.

 Testing

Brought it up on the variac with no troubles.  I was able to trim the voltage to 5.46V, and it held across a wide range of line voltages, without a load.

I was unable to calibrate the unit to 5.0V with the stock parts, so first I re-installed the circuit board with the bottom screws in the top holes, so it was easier to access.

Then I soldered in some jumpers in place of R2 and hooked up a decade box.

Then I soldered in some jumpers in place of R2 and hooked up a decade box.  1.8k would have put 5.0v directly in the middle of the trimpot range, but I didn’t have any so I got away with 2k.  I was able calibrate it to 5.0v, and so far it’s been performing without trouble.

You’ll notice that there are actually 4 terminals on this supply.  That’s because this is a ‘sensing power supply’, which allows it to compensate for losses in the wires from the power supply to the load.  The two sense lines can be of a much lower gauge then the supply wires, since they’re not passing any appreciable current.  They sense the voltage at the load, and are part of the regulation feedback circuit.  The regulator’s target is 5v at the load so if it’s gotta output 6.3v to overcome 1.3v of drop, then it happily obliges.

In addition to being fused both at the line side and low voltage side, it also has short circuit protection.

Oh, and here’s the schematic.

I think this is going to be a nice supply for LED tape experimentation.

My 7000 series collection got a bit boost yesterday when I went to pick up my Ebay winnings.  What started as a pickup for a Tek 551 dual beam scope ended as a trunk full of Tektronix booty.

7834 Mainframe
I picked this up about a year ago (coincidentally from the same same guy).  It was host to my only plugin, a 7D01 Logic analyzer + DF1 display formatter.  The 7834 is a great 400Mhz mainframe, but completely wasted on the 7Dxx plugins.  In fact, the higher bandwidth is in part possible due to it’s rather diminutive screen, making it pretty much the worst host for these plugins.  I decided it was time to give this frame the plugins it deserved, so I picked up a 7A26 200Mhz vertical and a 7B80 timebase, which is triggerable to 400Mhz, and sweeps down to 10ns.  Both work flawlessly in the 7834.
Here it is running the 7D01 a few weeks ago.  I’m using an EPROM reading arduino program to generate the counting pattern.

7603 Mainframe
I actually owned one of these about 24 years ago and ended up selling it.  I ended up buying a 7603, along with the above mentioned analog plugins, plus a 7D20 for a totally reasonable price.  He even threw in a few 7D01’s for parts.  Sweet.

7D20
This 40 Mega-sample per second digitizing scope, like all of Tek’s ventures into new territory, was a groundbreaking piece of hardware for 1980.  It works amazingly well for a 35 year old piece of gear, with the exception of an Error 54 which shows up on self test.  The service manual identified this as a waveform RAM error (specifically U410), which explains the few missing samples on captured traces that always show up in the same place.  Fortunately, I have a stash of the venerable 4116 RAM chips.  Unfortunately, they’re not socketed on the 7D20, and I’ve yet to
Unsurprisingly, the documentation is superb, and the theory of operation makes for an interesting read.  The RAM error is easily overlooked for now, but figuring out how to test 4116 RAM chips seems like it could make for an interesting project.  Another worthwhile project might be a fan-base for the 7603, as the 7D20 really cooks in this passively cooled frame.
Here’s the offending RAM chip.  No glaring physical maladies, but it does look like this board has seen a service bench before

Here it is showing the output of my Precision E-75 signal generator, which I fired up for the first time ever today (after checking the caps & rectifier of course).  Obviously it needs some work (the E-75) , but the measured frequencies are within a few % of what’s shown on the dial.  Note the pixel hanging below the lower trace at the 6th division, that’s due to the RAM error.

It’s a fairly capable machine.  Of course a $300 cheap Chinese POS would blow it out of the water, but this is way more satisfying & fun to operate.  I really enjoy helping keeping the history of these pieces alive in whatever way I can.  Beats TV, and it keeps me off the streets.

7D01
My adventures with this old dinosaur are chronicled here