Wednesday, November 11, 2015

For Mr Carlson

There's a guy on You Tube who is possible THE SMARTEST, MOST INTERESTING ham/electronics whiz I know. O.K., there are several - like W2AEW, etc.,  but I am absolutely aghast at Paul Carlson's range of knowledge, the projects he undertakes, his incredibly useful repair videos, and the absolutely Gothic work shop he has made for himself.

And, of course, I mean that last point in the nicest, most envious way. His regard for old-timey electronics and the care that he puts into his repair videos teaches one both respect for the heritage as well as traits and skills not apparent in the usual slap-dash, stumble-tongued how-to productions. (That would include, of course, those crippled, one-minute silent movie specials your truly puts up.)

Anyway, that said and in order to give you an idea what I am talking about, here's Paul on a venerable Tek scope:

..and for good measure, here's a tour of his lab:

(I can just hear the struts and cables groaning under the weight of those lovely, old instruments.)

So, one day I wandered over to Paul's You Tube site to a transistor classification video he put up and made an off-hand comment suggesting he do a piece on curve tracers. As you might expect, he did so using a standalone tracer and that magnificent Tek treasure!

I was not mindful that his B&K curve tracer had a provision for comparing two devices -- essential when matching transistors -- but called attention to the gimmick I built to do same. Of course, mine is rather limited to TO-92 and similar packages; one of those massive power supply pass transistors or an RF power amp device would need shoe-horning in. What hell, waddya want for a SUnday afternoon at the bench and idle hands!

It was designed for my Tek 7704A 7CT1N curve trace plugin and it's pretty straight forward asthe pictures below will show:

It should be explained that the machined 8-pin DIP socket is mounted on a little board by the QRP-ME folks. (They make an extensive assortment of these useful little gadgets for Manhattan construction. Click here to see their basic squares and then walk back to see their other products.) Aside from that, Hoovering up the 2x3 pole switch might be an issue but easily had off eBay or a local electronics supply house.

If you view Paul's transistor designation tutorial (recommended), then you might think that the EBC versus ECB might be a problem.

Not so, anchovy breath!

Here I ripped off the socketing from those cheap DMMs where they have four holes marked EBCE. You will note that it's only a matter of slipping a 2S TO-92 package down one notch to get the correct connections. Also note that I color-coded the connector wires and the E wires are green. Note that both go to the last pole on the switch.

(I guess that's colour-coded for those in the Great White North. Paul is Canadian and I want him to feel at home.)

I'd post A/B pics of the curves but that'd get redundant.

Oh, and one final comment: Paul is the spitting image of my middle son, Erich. And that's a compliment as both are handsome and both smart as a tack.

-Seven Turds-

Sunday, November 1, 2015

Keys to the Kingdom

The other day I had the distinct pleasure of attending the Orange County Amateur Radio Club auction and it was no ends of fun. Aside from benefiting the club with some shelf detritus ("One man's trash is another man's treasure"), I was able to repopulate the empty space with some stuff that i could not possibly exist without.

Chief among them -- and truly a treasure -- was this J-38 Morse code key. It is identical to the one I used back in the days of yore when I was pounding brass under the call sign WV6KJK. It cleaned up real nice and is like new. Enjoy:

I have a couple of "kits" I have compiled that are the old Novice crystal controlled transmitter and regen receiver and I have it in mind to build up an authentic 60s Novice station as a kick. Hell, maybe even use it to work SKN a year or so from now.

-Seven Turds-

Tuesday, September 29, 2015


I am going to indulge in some wanton and probably unjustified ranting here and, with it, cast slime and aspersions on two guys who post You Tube videos that drive me to drink. But before I go any further, I will post them here and at least give you all a chance to crack a bottle of Jack as well:

The first is by Dave Jones over at EEVBLOG:

..and the second is by M. J. Lorton:

So, a caveat and then my complaint: I am a complete ninny when it comes to electronics and these two gentlemen can run rings around me in terms of knowledge and experience. That said, both are off-putting because they do not construct too many videos that help the average twit like myself. In fact these two are nothing more than 45-minute brag tapes about how Dave Jones scored his voltage reference for a song from some poor, unsuspecting clod at an Aussie swap. Don't even get me started on Lorton who manages almost one hour lisping his way through minute-by-minute temperature changes in his workshop. (And this is the last of six similar videos on the subject. Get. A. Life.)

Paint, drying, etc.

So, that's this got to do with anything? Well, I scored an HP 3468A off eBay for a modest price and was looking forward to incorporating it onto the bench as a reference because it was more accurate than all of my other instruments. Or, as Juvenal once famously said:

Quis custodiet ipsos custodes?

In doing research on my scored treasure I cottoned to the fact that this unit uses parameters stored in CMOS memory to effect its accuracy. Basically, the instrument measures what it measures and then offsets or digital differentials are applied to the measurements to show up on the display. Again, these are stored in CMOS memory circa 1980s and that was volatile. If it lost power, the RAM contents vanished. In order to retain the memory, HP designed a 3V Lithium battery backup that lasted about 10 years.

Well, that's all well and good an idjits like myself open their treasures up, slap a DMM on the backup battery, read 3.12V and think all is well. Sadly, a Lithium battery has a life profile that looks like a ball rolling off a table. After ten years, you're living on borrowed time.

(This was the deal with my old Icom IC-745. When it lost its mind, Mother Icom had you by the short hairs to reprogram the radio. Fortunately, the Piexx folks came along with their non-volatile RAM and saved the day.)

So, casting about, I found a tremendous gentleman -- Mr Modem Head -- who did a treatise on restoring a 3468A and replacing the CMOS backup battery. Fearing a day of reckoning, I studied both posts assiduously, got a replacement battery form DigiKey, and last Sunday afternoon I did the surgery.

Well, the operation was a success but the patient died!  When I powered the unit up after the solder cooled, up came the infamous ERROR 1 message on start-up:

I swear by all that is holy, the backup battery was strapped with 3.25V at all times. I followed the procedure to the letter. But, alas, I crapped out, rolled snake eyes, busted, came up with three peach pits, etc. So now my treasure was only as good as the other DMMs I had lying around and I was off searching for how to calibrate it myself using a Voltage Standard DMM Check, the HP service manual, and my wits.

..well, the DMM Check and service manual at any rate.

By the way, Mr Modem Head's blog is everything that Wanker and Motor-Mouth Jones is not. It is artfully done, contains useful information; true wit and wisdom. Sadly, current events (life, responsibilities, etc.)  conspire to keep Mr Modem Head from to many recent posts but he is a roll-up-your-sleeves electronics hobbyist who shares his project efforts in a stunningly beautiful style superbly laid out on his blog. (See links above.)

..all for the common man without benefit of $20,000 instruments or being knee-deep in prime Fluke or HP surplus.

Anyway, the outfall here is that a calibration shop was located who would redo the parms for $65 and my HP is headed for Medford, Oregon as we speak. I will keep you apprised.


Monday, September 7, 2015

The Wreck of the old '485..

My Tek 485 had been sleeping on the shelf and I needed to take it to a friend's house to help him debug a problem. Checking it out before I left, I found it did not light up -- no power, to pilot light, no trace, nothing.

So, with the help of my friend, Dick, WB6JDH, I took it apart and did a preliminary visual on the back plane, the line board, the switcher board and the PS board. The two 430-ohm resistors (R1812 and R8113) were burnt out so I replaced them with two 2-watt 470-ohm resistors on the line board.

All else looked fine. After cleaning out some carbon and dust, pulling the "start" transistor and then the "stop" transistor on the PS board and bringing the unit up on a variac with each, we got the power supply to work -- but experienced some smoking and burning during the process.

Cleaning out further carbon and burned areas revealed no seemingly bad components so we brought the unit fully up under power and it seemed stable. However, attempting to view a trace on the scope revealed that the vertical position controls did not work and I was unable to get a dual trace. I was pretty careful with the setup and triggering so I do not thin thee was a cockpit error. Another anomaly was a distinct PS snapping when the "ADD" button was pressed.

Here's the video:

A tantalum cap on the A7 board (near U650 and the 15V test point) shorted and took out the associated RF choke. We swapped the A7 board with one from a donor 485. Turns out that one was bad as well. Q374 and Q384 were both bad and were replaced with matched 2N3904s. Was easy to do because most semiconductors are socketed on that board. But that was karma because removing and replacing the A7 board WAS a bitch! The delay line was soldered on and a semiconductor on the board was bolted on a heat sink to the frame below. Getting its leads through the two holes in the sub-chassis was a delicate operation -- especially on a 100-degree day with 90% humidity.

I deserve NONE of the credit for solving this problem! Dick, WB6JDH, [literally] sweated through the debugging process and suggested we swap boards from the old donor unit. I just dd the donkey work and took copious notes.

I also treated us to burgers and dogs afterwards.

Resolution Resolved
Actually, the resolution was a false positive and the malady returned. (And, truth be told, who's to say it won't return in the future?) But, in tracing the origin of the horizontal position controls back to their source on the power supply board, I found all of the components in each of the position controls to be within spec and performing correctly. However, it was noted that the cable plugs along the top of the PS board were unseated and, after re-seating them, the scope seemed to function correctly. So, as I said, the problem might re-occur but at least I'll know how to troubleshoot it.

Stay tuned..or don't!


Clearing out the shack and the bench..

I decided that I got too much stuff and need to "clear the bench" as they say in baseball. So below are pictures offered up in aide of a couple of scopes I have that I want to get rid of. They are a pair of Tek T9XX student scopes that have fallen into dis-use. Both are essentially in good working order. Here goes:

Tek T935 35 MHz Dual Trace
Immaculate inside and out. The trace is modestly bright and it generally seems to function o.k. although it may need some attention in the Dual mode.

Tek T922 15 MHz Dual Trace
Tektronix T922 Student Oscilloscope, every bit as clean and immaculate as the T935 above and it has a really bright trace. This scope is dual trace with a 15 MHz bandwidth and a bright trace and all seems to work o.k.

I discovered the on/off detent switch sometimes does no catch but hit it with a little contact cleaner and worked it a few times and it has returned to proper form. Other than that, it's a good unit. there they are. Now, I'd be in great shape if I could get my 485 to work! (See next post up the road.)


Monday, August 24, 2015

Stay tuned..

..I am about to rip a new asshole for LDG, the LDG Yahoo Group, and the IC-7200 Yahoo Group. Hint: You buy 4-5 of LDG's tuners and kits over the years and you'd think you would get a little more that shrugged shoulders and "Dunno, our LDG Z11 PRO II works on our IC-7200."

And the IC-7200 Yahoo Group ain't much better; just appliance operators.


Well, maybe I am just having a bad hair day!

RETRACTION: I need to apologize for the harsh remarks made about LDG. Dwayne offered advice that I did not heed because, basically, my head was up my ass. He told me to plug the Z11 in BEFORE I actuated the tuner and things should be all right. I did so and -- viola! -- everything worked as it should!

I should explain that I was in typical "Chicken Little, the-sky-is-falling-mode" when attempting to discern the problem but that's no excuse for my contempt. So, I am sorry, Dwayne! Your products -- from the original LDG kit I built (and still use with my FT-817) to the two Z-11s I use around the shack and the other two or three tuners I have had pass through my hands -- are the tops!

Thanks again!


Tuesday, July 7, 2015

A Triplett Amongst the Simpsons

I stumbled on a decent Triplett 630 NA the outer day on eBay and scooped it up. Was in great cosmetic shape but had a few range inaccuracies and the needle stuck. So, after looking at it and considering the dirt price I paid and factoring in the skill required to remove debris from the meter movement, I packed it up and sent it off to my favorite meter repair people: Instrument Meter Services..notably Ike and Jason. It was accompanied by a symptoms report and instructions to give unto the tender mercies of their tech, John.

After a reasonable amount of time and for a very reasonable price, the unit was received back into the shack where it nuzzles up to my two Simpsons. One of 'em was a 260 I inherited from my late father and the other, a 270 I found at a swap meet -- also for dirt. Its performance is well within a satisfactory 3% of full scale at the most variant but when it counts, is dead on the money -- as are my Simpsons, by the way. John up at IMS sure knows his stuff and does good work.

But let's face it, these folks units are collectors that I value higher than what I could actually turn 'em for on eBay or at a swap, but then that's the point of collecting, innit?

Anyway, here's some shots of the Triplett and its innards. It's immaculate and one of my pride and joys: