WB6JDH's Scope Emporium

"Would you buy a used scope from this man?"

My Tek 7704A lives! It was revived by the gentlemen who provided me with it originally. Read here the colorful background on just how this came to be.

One has few true friends in his lifetime. Some become friends at work or in a sport that one indulges in or as a fellow member of a club or organization or by way of a hobby or pastime.

Dick, WB6JDH, is a true friend and a person who I crossed paths with because of our mutual love of Amateur Radio. I'd say "electronics" but that's not really the truth in my case; I am still one of those wriggling things, clambering up onto the sand, trying to extricate myself from the primordial ooze. Dick has long since deposited himself well inland, evolved through the lizard, early mammal, Neanderthal and Cro-Magnon stages, and walks erect into the sunny uplands of electronic theory.

I stand in awe of him -- not only because he knows shit but because he does shit. He crafts radios, test equipment, devices, restores the old and preserves it for the rest of us -- the largely great unwashed -- who have little or no appreciation for this art, its attendant skills, or the worth of beautiful things from the days gone by.

During his career, he was a chemist -- a graduate of San Jose State back in the early 60s -- who stood many hours at vats of printer's ink formulating the ingredients of one color or another. Somewhere along the line he took up flying model airplanes (held a control-line speed record I am told) and gardening (he and his lovely wife, Ann, are constantly pruning, weeding, manicuring the vegetation that surrounds their ancestral manse, The Groveside Arms). He also dove into ham radio. Maybe the intellect that allowed him to master the arcane art of chemistry also gave him the talent to understand electronics but I more think it is his temperament and tenaciousness. When faced with a problem, He is like a terrier, unrelenting until he understands the underlying concepts and principles and then doggedly pursuing the resolution.

Simply put, Dick is one of my best friends -- no, a hero to me -- because of his ceaseless curiosity and the fact that he can make things work. He also is a wonderful pedagogue. (In case you are wondering, it's not something that you can get arrested for.)

His domain, his kingdom is the workshop in his garage. Of course, it long ago lost the capability to house both of his cars. Rather, it became a magic repository of the miraculous electronic detritus; radios and instruments and fragments from the stone age to the near-past. He probably has two of everything except for those items he has three or more of.

Over the last decade, Dick has ventured into the arcane world of repairing old oscilloscopes, specializing in old 70s and 80s Tektronix and Hewlett Packards. As the picture above shows, he has a stack of Tek 7704s and 7904s, a quintillion plug-ins, and various and sundry other related gear. In addition to that, he has a storehouse in the backyard housing even more treasures as well as what I call his "knob farm" -- dead Tek 465s and 7704s that he cannibalizes parts from and uses to plant geraniums.

To me it's all like that wonderful scene in the 50s move "King Solomon's Mines" where Steward Granger stumbles into the cavern strewn with jewels and gold and silver and any trinket imaginable.

But this treasure trove grows with each two-per-month visit to the Southern California swap meets, gracious attendance to fellow ham's estate sales, local salvage emporiums, and general ham-to-ham barter. And, as I said above, he often finds his inventory augmented by repair drop-offs.

And now to the reason for this post: About two years ago, I had been visiting Dick on a regular basis only to realize I had been subjected to a constant mantra by Dick to the effect that I really needed to upgrade my bench scope to something like a 7704. He was semi-kidding, of course, but it became more intense during late one rainy February when I had made several trips to his Mecca in a vain attempt to repair my wavering Tek 2465. (I thought I did a post on that but cannot find it.) In any event, I was troubleshooting the beast and located a bad resistor which breathed life into it again. But, alas, the 2465 was crippled and maimed and actually no longer serviceable. It was at that point I succumbed. Dick and I chatted and negotiated and -- in return for the remains of the 2465 and a very reasonable amount of spare cash, I was "lent" one of the 7704s from his stack and four very useful plug-ins.

Of course, I got it back home and, for the life of me, could not figure out where to put it on the bench. But setting it up and operating it got me hooked and I never looked back. Eventually, I hollowed out a spot for it (see picture above and some previous posts with pictures of my bench) and revel in its complexity, accuracy, and beauty. It has performed reasonably faithfully barring a couple of incidents with a misbehaving 7CT1N curve racer and a 7D15 frequency counter.

Dick and I pored over the curve tracer and sort of mutually solved. Well, Dick did most of the brain work and I did the donkey tasks. But I felt pretty good just to have taken a part. The counter was a more formidable problem and I am justifiably proud that I solved this one myself. (If you do not count the advice I got from the guys on the Tek Scope Yahoo group. From thence, I thought, I was off and running.

Or so I thought.

During my effort to get the UW VFO working, my Tek 7704 lost the trace and no amount of pushing buttons replacing plug-ins or hurling invectives would restore it. So, in a frenzy, Dick got a call and a desciption of the situation. He graciously set aside some of his Friday afternoon for me to visit. He also said that he had a couple of 7904s ripening on the vine and maybe I would be interested. I owned that I would (thinking that Dick would countenance a swap) and made arrangements to take Friday afternoon off from work.

Long story even longer, I showed up and we poked and prodded and measured and scratched our heads to no avail. Dick verified that the mainframe power supply voltages were present and correct and we pressed on. After a bit more of this confusion, Dick blithely reached over and turned the left side mainframe intensity control clockwise and -- BAM! -- let there be light!

Now didn't I feel the fool? It was one of those humbling experiences that embarrassed me but not that much because I got to spend the afternoon with a good and dear friend.

The trade for the 7904? Well, truthfully, I was so glad to have my old 7704A back with me. It had served me well over the past couple of years and I would have felt like I was selling one of my children into slavery had I parted with it. So, I loaded it up into the back of the Jeep and joyously returned to the shack on another rainy February day..

..just like the first time I brought her home with me.

-72-

Making progress on the UW VFO..

I diddled with the KayPro some over the weekend and have been led to believe that re-capping the Micrex video board might solve my problem. I will do a more lengthy post on that as  reference in the event anyone's searching. But, honestly, my impression of the knowledge out thee on the various Retro Computing boards is miles wide and millimeters thick. I sure as hell ain't no double-E but some of the folk lore is just absolute fantasy land presided over by witch doctors. I'll dig up some of the incredible excerpts when I do my post. One of them is a real side-splitter.

Anyway, I had a few moments this evening and wanted to engage in some idiocy of my own, so I turned back to the Ugly Weekender VFO. What follows is something that outstrips the stupidity of the KayPro posts and leaves them panting in the dust!

You are warned!

I put it in the form of an e-mail to WB6JDH:

Dick,

Per your advice, I rewound the coil: 42 turns tapped about 10 turns up from ground. It measured out at 8.45 uH and, when strapped in alone without the variable cap, hummed along at about 4.810 MHz. Adding the variable cap dropped it to 4.700-4.780 MHz (swinging the cap). Here are some pictures:

Source of Q1

From there:

Collector of Q3

No wonder we use a transformer after Q3. How does it eliminate all of that hash?

Output of T1

Note that I swapped the 10K resistor for a 5K and that only gave me the 650 mV above. When the 10K was swapped back in, it rose a bit. I still don't understand why that stage is in there unless it's to buffer the VFO from the next stages.

Anyway, I lashed in the variable cap and just for grins measured the total capacitance across C2 (i.e., the entire L/C circuit) and got a 180-270 pF swing across the range of C1.

Probably not kosher; tracing that out on the nomograph yields about 3.200 MHz.

If I do some rough calculations, the two caps in parallel yield 100+10 pF to 100+120 pF or a range of 33-39 pF. That in parallel with the 100 adjacent to C2 (which is not in the circuit) yields 133-139 pF, I guess. Probably wrong; maybe not. Look what it does on the nomograph:

Using the nomograph again, I gotta wind a toroid a little less that 4 uH to get the VFO in the 7.000-7.070 MHz range. That's about half of what the coil is no (42 turns) -- or 21 turns.

Not really sure what will happen if I don't land on 7.000 MHz going up -- So I am going take a deep a breath and probably add a padder at C1 and see what that that does and *then* rewind the toroid. That way I can zero he VFO in.

So that's my story and I am sticking to it.

Am I crazy?

~Bill

-72-

Coulda, woulda, shoulda..another tangential rant leading nowhere.

I am going to take a break (actually several breaks) from the UW work to rant -- about good things and bad. First the good things:

Slake your thirst
My good friend and fellow CAP squadron member, Dave Martin, and I had a mini-adventure at the long-legendary TRW swap meet up in the South Bay of SoCal last weekend. Dave is a brilliant guy fro whom I have a deep admiration for. He is an MIT graduate (as was my dad) who is in a continual contest with his own intellectual curiosity and the result is an upwelling of knowledge for all within proximity or earshot. 

 O.K., stick with me now, because this is hyper-tangential Tinkers-to-evers-to-Chance Rube Goldberg. Dave and I stopped by an electronics store after our meanderings (and a truly fine Mexican meal) whereupon he saw a Raspberry Pi offered for around $40. When he fully satisfied my thirst for knowledge on what the devil this was, he simultaneously awakened in me memories of an old KayPro 2X I have lovingly stored away and a desire to delve more into the nascent trend of "RetroComputing"

So then there's that..

Get your MITs on one of these
So, never content to stick to the subject, I stumbled upon a You Tube video by Jeff Tranter discussing the Briel Altair 8800 kit he recently purchased. Now Jeff is also an amazing guy. He publishes a fantastic series of videos of largely vintage Heath equipment but has done a series of the Altair Briel sells. Here is the last in the series where he brings up CP/M on his newly-assembled kit:

I commend the entire four videos to you -- and subscribing to Jeff's works on You Tube for a thoroughly fascinating tour through the Heathkit past as well.

Anyway, to unwind the loops, I need to revive my KayPro so I can see if my talent at C programming -- that I learned somewhat after my "Darth Vader's Lunch Box" started gathering dust. "And why revive," you ask? Well, it saves me about $350 over getting the Briel kits for one. It's an act of love and regard for a wonderful piece of machinery that essentially helped me break away form the world of Big Blue IBM and mainframes and get into the rebellious of C code-slingers who wrote stuff more for love rather than money.

Could I do it on that platform? Could I go back and conquer or master? Well, with inspiration from Dave and Mr Tranter, I sure got the energy to try it again.

Now, the bad things.

These reminiscences stir some enmity in me to tell the truth. First, my long-ago dislike of the IBM mainframe world and their coercion of we serfs into their way of life. Sure, it was a living but only that. It was soulless, unemotional, and uninspiring. When PCs came along in the late 70s and early 80s, it was the Wild West, the frontier. The machines resided in your home and not in some air-conditioned, raised-floor, isolated vault attended by the high priests in operations and systems programming. Your only access was by means of punched cards or a remote green-eyed 3270 running TSO. You had to beg to have drives mounted and tapes hung and jobs scheduled.

But when I got my first Vic 20 and then the KayPro, I was master of all I surveyed. I could write what the hell I wanted and run it when I wanted. As I mastered the KayPro (first a II and then the 2X), I grew to understand Unix and C and got myself work outside of the Big Blue realm. Sure, it was only 64K and two floppies (that really did flop) and about 400-600K of storage and an 80x25 character display with limited graphics -- but it was all mine! Do you hear? All mine!

Well, I could (and probably will) go on and on with the remembrances, but I will spare that for the series I contemplate documenting the revival. So, I guess that's a good thing after all.

Dawn of time as we know it..
The pioneers of this revolution were kind of like the guys who preceded George Washington, the first president elected after our Constitution was ordained. There were a number of them -- largely forgotten -- who saw us through the tumultuous years between the Revolution and the Constitution. They deserve some credit for the role they played in making this country what it is now -- or at least what it was before the incompetent boob who is running the show has is attempting to make it.

Similarly, there were giants who pioneered what we blithely take for granted now. When they stopped walking the land, it was subsumed by a few nutless Nancy Boys whom the popular media and the whole slew of fruity tutu-wearing Apple-using faggots deem as the forefathers of the industry.

Among my heroes -- most unsung -- are folks who carved this niche out of the granite unknown of technical mystery. They invented stuff like operating systems, they created hand-crafted products that operated on thin air alone, and they were so wrapped up, so obsessed with their creativity that the preening, boy-men walked in and plundered.

I will not re-fight the battles that have raged for several decades. Rather, I would say that they were the pioneers who were my true heroes and not the ones who came after the redskins were subdued.

For example, go all over the internet and you will see the battle raging about how the panty-wearing Harvard dropout stole the OS market from the guy who wrote the first run-everywhere micro OS.

Consider Gary Kildall, CP/M creator..

..versus Billy the Kid Gates.

Or, consider, consider the guy who every Apple-using fairy swoons over versus the guy who was the "R" in K&R C:

Makes you want to throw up, don't it. In fact, I am taking a break to go get a vomit bag. Be back in a sec.

-72-

Ugly Weekender VFO Board Trials and Travails..

It's FINALLY up on on the bench again and under scrutiny. As I surmised, my careless slapping of components into holes and soldering them together led to a non-working VFO board. Here is a blow-by-blow of what I know.

The difficulty in assembling this kit from collected parts and the FAR boards is that the original transmitter article was done in typical ARRL QST slap-dash fashion: no corresponding part numbers for the labelled components and no means to relate the silkscreen markings on FAR's boards to the original schematics.

But, no one promised you a rose garden, eh?

Firstly, here is the schematic I have been working from:

Here is the whole board on the test bed. The quality is not the greatest but it gives you the view from 20,000 feet.

Here is the lower left hand corner of the FAR board where the keying and spot switches are located. I noted from the original transmitter article, it was keyed from the VFO so I chose to close the circuit there. Those are the yellow and black lines heading off board.

Here is the first problem area I encountered. D1 is the diode next to the 1 megohm R17. Careful inspection will reveal that the little bastage was wired in backwards. See the diode cathode band on the North side of the PCB while the actual component's cathode band is facing South. If you look closely, you can see the silk screened diode band peekign up fromt he gold tolerance band on the 1 megohm resistor.

I reversed the diode and got nothing radically changed, so I trucked on. Basically, there are two points of curiosity in debugging this board: What actually does one short to test the board (key versus "spot" switch?) I voted for the key jack. This is sort of outlined below in the picture.

And one final mystery remains. How are the holes below populated? They are marked as C46 and C14. The latter is easy enough to dispose of as the circuit indicates it to be a 0.01 uFd cap. However I am all at sea when it comes to C46. It is not called out in the schematic so far as I can see and yet it is strapped across to D2 to ground. I suspect it is a 0.01 uFd as well but will check with Alan and the QRP Tech Yahoo crew for their opinions and insights.

Here are the voltages I measured:

-73-

Resuming the Resumption of the Ugly Weekender..Part Deux

Well, unfortunately a spot of work and other responsibilities had gotten in my way (reviving an HTX-100, helping out with the restoration of the LBYC ARC station, CAP, etc.) but finally this little beast has re-emerged on the work bench and I mean to put the coal to it and push on through to the end -- and all that. Below are some catch-up photos. Sorry for the gauzy-bright appearance. It's a desk lamp I pressed into service to aid my ailing eyes.

The Battleground..

PA Board

VFO Board

Receiver Board

Unlike N8WQ's fine effort, mine lacks discipline. I grabbed all of the parts I had and stuffed them into all three boards without any interim testing. Sure hope I do not live to regret it. My reasoning, however, aside from the fact that I wanted to eliminate the possibility of having the cache of ingredients scattered to the four winds and /or cannibalized for some intervening project, was that the three boards were elemental enough. I will hit the VFO first and breathe life into that. Thence to the PA board and thence to the receiver.

The big challenge -- well not a challenge really -- will be to find a suitable, snazzy container for the units. I have not decided on whether to miniaturize it as the original authors or to go full OHR-100/OHR-500 and build a copper-clad box. I am thinking the latter because I am not a back-packer and have an abundance of copper clad material and they can come out quite handsomely if finished correctly.

I think I should need the extra room because I might want to add an internal keyer and an S-/RF-out meter. I also have one of those vernier dials and they need a broader (taller) cabinet face to accommodate them. I'll probably try to make the resulting unit look like my "twins". These are a pair of Dave Benson's SW-## kits (an SW-20 and SW-40) that I built into a couple of very special boxes along with the RIT boards and TIC keyers. Special Boxes, you ask? Well, they were a pair of really nice clam shell boxes that Chuck Adams made with a newly purchased break (brake?) and brought to a Pacificon NorCal convention once many years ago. Here are the radios:

SW-20+ Built into K7QO's box

SW-40+ built into K7QO's box

The boxes painted up nicely thanks to the fact that Chuck's work on the metal was his usual "flawless meticulousness". I'll do a another post on all of the pictures I have of these for anyone stopping by. But needless to say, they are among my more treasured collections of QRP kits I have built. And, yes, I know that the SW-40's RIT board is upside down.

*sigh*

 As long as I am in full disclaimer mode, let me say I am unapologetic about using the Far boards versus full-on ugly building. You want ugly construction? Let me do it and you'll end up with something looking like the QRP rig that The Elephant Man would use.


Anyway, on to the Ugly Weekender.

-72-

My Icom IC-745 is being offered for sale

UPDATE! Old Betsy has been sold and is going to a great home. The gentleman who purchased it has probably one of the more extensive radio collections going and a fantastic QTH in the mountains somewhere. (Since I have not asked nor have been given his o.k. to pass along pictures he sent me, I prefer to maintain his anonymity.) He said he was going to upgrade her with a keyer board and some other Piexx accoutrements. Nonetheless, I loved my old IC-745 as it reminded me of one my dad had. But it was time to move on and the IC-7200 looks promising. Although -- truth be told -- I realized when I was packing it up, that the IC-745 was almost the excact same size as the IC-7200.

Had I known that, would I have kept Old Betsy? Probably not. The IC-7200 is easier to interface for digital modes and has that marvelous filtering system on board.

Anyway, she'll enjoy her time in the mountains, I am sure.

. . .
Here's the poop:

(1) It's immaculate.
(2) It has he Piexx board installed so there's no worries of it losing its mind.
(3) It was just up to MTS Ham Radio Repair in Washington last month. More below.
(4) It puts out 60-100 watts on 160-10 meters. See pictures below.
(5) Includes a power cord, the original operator manual, and a CD with a service manual on it.
(6) It does NOT come with a power supply but runs fine with a SAMLEX switcher or a 12 VDC gel cell.
(7) Did I mention it's immaculate?

Scott Malcom of MTS went through this radio stem-to-stern in November, tweaked it up, and certified it was up to spec. It pus out power as follows on all the bands:

(1) 160 Meters at 90 watts
(2) 80 meters at 95 watts
(3) 40 meters at 85 watts
(4) 30 meters at 80 watts
(5) 20 meters at 80 watts
(6) 17 meters at 60 watts
(7) 15 meters at 70 watts
(8) 12 meters at 70 watts
(9) 10 meters at 80 watts

..and this was using a gel cell with a charge of 12.7 VDC ~~ NOT 13.8 VDC.

I am asking a starting bid of $425. I figure the packing and shipping costs will be about $40. I don't have to tell you that the Bird 43, dummy load, and the cables are NOT included in the sale, do I?

Here are the pictures with the power readings:

Front view of rig set up for test.

160 Meters at 90 watts

80 meters at 95 watts

40 meters at 85 watts

30 meters at 80 watts

20 meters at 80 watts

17 meters at 60 watts

15 meters at 70 watts

12 meters at 70 watts

10 meters at 80 watts

..and a clean bottom..

..and a clean top..

..left side is clean..

..and the right side..

..and the face is clean..

..on the left side..

..and the right.

Overall view of the face.

With cord and manual.

..and the back.