For my personal reference..

I inherited (for a pile of greenbacks) a really mint Tek 485 and wanted to check it out so I came up with these videos courtesy of this really nice guy (who sounds eerily like Gomer Pyle).

He does a pretty job of explaining and demoing this feature. I post it here as a convenience for myself. There's also this video on how to check one of these beasts:

..and some more:

Enjoy; I shall.

-73-

Idiom Press SCAF-1 Wars: My own fresh hell continues..

Well folks, I was forced to capitulate. The guy at Idiom Press still yet again continues to ignore my pleas for information. I was lucky to have scooped up one from my good friend and mentor, Dick, WB6JDH, and "opportunities abound. (See below.)

But to close off this little chapter of my own fresh hell, I cancelled my order with Idiom Press and told them that I was not going to be joining their fan club anytime soon. Closing the loop, I published the following review on eHam.net:

I am compelled to weigh in with a less-than-sunny evaluation of this product. I had written a previous review (removed by eham.net) based upon my experiences with the Idiom Press people and their failure to not only not deliver their product BUT TO REFUSE TO ACKNOWLEDGE MY ORDER AND RESPOND TO E-MAILS AND PHONE CALLS OVER A SIX-WEEK PERIOD. (I was not alone in travails like these; another ham had similar contemporaneous problems and likewise cancelled his order.) I can understand the previous review being removed because it was not about the product per se.

Anyway, aside from the fact that I did not have my order honored and ultimately cancelled with them, I bore the actual product no malice. In fact, because I was able to pick up one at a swap meet -- one requiring repair work, by the way -- I want to now write of my experiences and offer caveats to anyone contemplating purchasing the product or the kit. Here goes:

Firstly, the unit I got at the swap did not work. Attempts to find a manual were fruitless until a fellow ham graciously sent me a copy of his. Upon commencing the repair work I noted that there were radical differences between the manual and the actual unit I had on hand. While the board may have been accurate per the manual, the front switch was not. My unit had a DPDT with six tabs and the manual had nine tabs. The wiring on the unit I had bore only the remotest resemblance to the wiring in the documentation.

Please note that the instructions were published in 2006 and there was an addendum of corrections outlining a means of modifying the LM386 circuitry so it would perform better. (I think circa 2008) It was a very complex series of "four instructions up from the bottom change x to y" steps and occurred to me that perhaps the owner should have REWRITTEN the original to reflect the changes and tied them more tightly to board/kit revisions.

When I finally got my unit working, I was pleased -- BUT ONLY MILDLY IMPRESSED -- with its performance. The circuit is merely a low pass filter comprised of the two SCAF chips driven by a 555 timer. It ain't rocket science. Frankly, the NEScaf kit by the New England QRP club (http://newenglandqrp.org/nescaf) and the HI-PER-MITE (http://www.4sqrp.com/HiPerMite.php) offer products with as much promise, are very well supported, and are much more reasonably priced than the Idiom Press SCAF-1 unit.

Finally, previous "I bought mine several years ago, built it, and love it" reviews might be nice and fuzzy and heartwarming but you will be spending anywhere from $95 to $130 for one of these things and, if so, you had better be prepared for

(1) At least six weeks of being ignored after your order is taken.
(2) The prospect of a kit whose instructions are ambiguous and possibly out-of-date.
(3) A pathetic record when it comes to support and service.

The 2 is for the performance of the unit. Were I to rate the overall experience with Idiom Press with respect to the SCAF-1, it would be zero.

Color me unimpressed.

The Adventure Continues
That said, Dick's unit -- that he graciously sold to me and that was working when he did so -- went South when I began to operate it around the shack. It performed (as I said in the review) adequately but I was not screaming and the Earth did not move for me. I would rate it a so-so and look more eagerly to buttoning up my Hi-Per-Mite and NeSCAFe filters since they are documented better and seem to perform AS WELL AS the SCAF-1. Actually, truth be told, I am casting about for a really, really sexy container for the Ramsey AF-1 -- it performs very well but cries out for a better looking home.

Though my "Filter Days" are coming to an end (I have learned a lot and have several units that will make the various receives sound good), I will get Dick's SCAF-1 working (with Dick's help of course) since there are the following unexplainable anomalies:

(1) The two Zener diodes to derive the +5V and -5V display run hot (very hot!) when a phone jack is plugged in the back and 12.5 VDC is applied.

(2) The unit does not work (i.e., complete silence) when powered by 12.5 VDC and switched on. See above regarding hot Zeners.

(3) The unit will not work with the right rear PCB mounting screw put in place and tightened down. It's intermittent. Again, see #1 and #2 above. This also happens when the box lid is mounted.

Now, I have no Earthly idea why all of this happens (which is why I am going to WB6JDH's QTH Saturday) but, when I find WB6JDH finds out, I will write it down here.

Breaking News!
I have discovered why the Zeners heat up and it'll surprise you. It is a fundamentally BAD DESIGN. I write the followign to Joe, K3JLS, and let it serve as a warning to you if you are contemplating the purchase of one of these units:

Joe:

Just a word to let you know that there is a potentially serious bug (thank you for the schematic and manual) on the SCAF-1. It will not affect 99% of the people who use it, but it bit me in the fanny.

As you know there are two grounds in the unit. One is the power supply common ground and the other is the "artificial ground" in the circuit to derive the +5 VDC and -5VDC voltages for the chips. Turns out, if you have a common power supply for your SCAF-1 and your HF rig, then the two grounds on the SCAF-1 touch pee-pees and cause the voltages to get all hosed up and the Zeners to get hotter than blazes.

It affects my station because I use an Astron RS-20M to drive my IC-745 *and* the SCAF-1.

First noticed it when I was researching why the board seemed to have "microphonics" when I buttoned up the board and put on the cover. At the risk of boring you to distraction, I kept the cover off when I was testing it in the station and noticed every time I plugged in the station PS,that the unit stopped working and the Zeners began to sizzle. I then powered it with a separate gel cell and everything worked fine.

Also, my unit was one built by one of my SK friends and it had 4-40 screws from the chassis to the board which -- after a little abrasion -- shorted the two grounds together. So I replaced them with nylon screws to avoid any problems.

Probably obsessing over this, but would not feel right if I did not inform you. Oh, and I am NOT a EE but I got a friend who is [one and is the smartest ham I know when it comes to fixing things: WB6JDH] and he confirms [my analysis].

So, the bottom line is that common ground problem exists for anyone who buys the SCAF-1. Also, here's a tidbit: the SCAF-1 circuit was ripped off a 1995 QST article (reference upon request) that has a Far circuit board made for it. I was gonna get that but, now that I know the dual-ground problem, I think I'll live with my other swap meet treasure -- the Ramsey AF-1 -- and that should be fine.

Besides, I have to build the upscale version of Lou's noise bridge.

..so many kits/projects, so little time.

-72-

The wonderful thing about amateur radio..

I spent the last post gassing about what was wrong with my order from the Idiom Press people. Turns out, I was a decade late and $95 short. Seems this is part of the Idiom Press culture; those folks have been doing that since at least 2004 so far as I can determine. There are a number of threads abroad on the internet -- some dating from as long ago as 2004 -- complaining about their lackadaisical, cavalier business mien.

Most threads start with the interrogatory, "Is Idiom Press still in business; I just placed an order and.." followed by several respondents relating similar anecdotes and subsequent replies strangely savaging the original messages for not having enough patience or relating how the son has taken over the business and "needs time to catch up".

Give them a break? Give me a break!

A very representative thread of this discourse can be found on, strangely enough, an Elecraft e-mail forum -- it includes a verbose lecture from W7AQK that just screams of "no, I have not done business with Idiom Press":

What a lot of folks don't realize is that a great many of the amateur radio suppliers, and especially the QRP type suppliers, are "one man operations"! As such, they don't have a particularly organized and sophisticated ordering and shipping process. Accordingly, if you are in a particular hurry, or need something quickly from one of these very small companies, you should talk to them personally and make sure you are going to receive your order in the timeframe you are expecting. There are a thousand reasons why it might take longer than you expect to fill your order. Most of these little companies are operating out of their garages, or similarly small space, and parts coming in versus things going out can be an issue. I'm not making excuses for bad service, but so many of these operations are reliant on their receiving the necessary parts, which they really can't control. They can't afford to maintain large inventories of parts, so a sudden rush of orders probably means a lag time that would normally be considered unacceptable.
...
Bottom line, if you are in a big hurry, call them and talk to them personally to find out what delay might be in the offing! I know, some of
these operations promise more than they can handle, but most of them, I think, try to be reasonably forthright in their advertising. In any event,
if time is of the essence, I'd be verifying things them personally.

You go in business, advertize a product and you either deliver or you respond to e-mail inquiries as to timeliness of the order-filling process or an explanation re parts shortages, etc. I would just salivate to see W7AQK order something form those folks and then try to phone them up for a status. That's the point, dummy! They do not respond.

Well, I was able to get a SCAF-1 from my very good friend, Dick, WB6JDH, last weekend. I took it home and hooked it up and heard..

..Zero..zip..nada!

Turns out somewhere int he handling of the unit, the two 5.1V zeners that comprise the -5VDC supply took a dirt nap. And for the sake of honesty, it probably wasn't Dick who did the dirty but rather yours truly, Mr Heavy Hands. So I still have a ways to go to test this unit and give a competent review. Although I will say this: it's a low-pass filter and i am prepared to not be as impressed with it's performance as I was. (But, I am prepared to be surprised.)

Enough sucking lemons. I want to hand a out a mighty kudos to folks like Dick and to those hams you seem to bump into all over. Another soldier in the Idiom Press Wars is Joe, K3JLS, who has come to be a very fine acquaintance. Seems he scored a manual for the SCAF-1 and is generously sending me a copy in the mail. I will be scheming and plotting how I can get even with such a fine gentleman. But, to me, guys like Joe and Lou (the progenitor of the two noise bridges I wrote so much about earlier) and Dick are what make this hobby worthwhile.

Also, here's a little tidbit to look for if you are traipsing around a swap meet or see it pop up on eBay: The Ramsey AF-1 CW filter kit. It is out of production, I believe, but is a rare exception to the old saw about Ramsey kits being trash. If you can score one, then my advice is to pounce! The manual for the kit is here.

More on this and gentlemen like Joe and Dick and how really great ham radio is.

-72-

I would love to review the Idiom Press SCAF-1 but..

..I placed an order a little over two weeks ago and have not received it nor have I heard a peep out of this guy. Moreover, three e-mails and a phone call have gone unreturned. All I am looking for, fer crissakes, is some acknowledgement that the tool has received my money and will be shipping the kit -- whenever.

I mean, Midway, U.S.A. back ordered my turret-press reloader but at least have the courtesy to inform me of the status, etc.

The Idiom Press K-3 keyer is the best around but I don't remember there being any such delay with that. Oh yeah, that's because I bought it off-the-shelf at Ham Radio Outlet in Orange County, California.

You'd do well to heed this and read the eHam Net reviews on this product, particularly ones like this:

 
Caveat emptor, as they like to say.

UPDATE: Still nothing on this front. However, I put up a "me too" review on eHam.net echoing that K3JLS's experiences were my own. Basically one month after K3JLS came up dry, I was too.

I went over to eHam.net today (04-17-2013) and found that both our reviews had been scrubbed. Another review was leading the list by some guy who bought the kit several years ago and experienced a delay in receiving his order but got an e-mail from Idiom Press saying that he was getting the built product for the kit price.

With respect to eHam.net pulling K3JLS's and my reviews and, at the risk of sounding like I do not have a life, I cry BULLSHIT! Firstly, the eHam review editor may be on firm ground in redacting our reviews because, technically, neither of us had the product delivered and -- by some tortured logic -- relating our experiences to POTENTIAL CUSTOMERS of Idiom Press might be misleading.

Whatevs.

But, were I a potential customer (who else reads reviews?), I would want to know if there was problems with the supply and availability of a product. Since -- at latest inspection -- there are no caveats on the Idiom Press site about delays or "we're running behind" then the guy is setting up customers for a big disappointment and certainly not creating any good will.

All this said, I want to be clear on one point: I am not one of those piss-and-moan types who gets mad and demands legal recourse because a kit maker has my precious $80-100. Some time ago, Steve, K1EL, was producing a follow-on edition to his K-40 CW keyboard device -- the K-42 -- and my order was not filled for a longish time. I e-mailed Steve and he said he was running behind because he had been in a terrible car crash and was recovering but I could have my money back if I wanted.

I would hear nothing of the sort! I told him not to sweat the small stuff, get better, and when the K-42 was ready to ship, it was ready to ship. PERIOD. I even offered to help him test/debug some of the firmware and/or a prototype device. Point here was that the man was honest and responsive and was in a real bind. Having the unit on the market was far more important to me that having my grubby loot returned. It is even the case with Idiom Press. I am looking forward -- someday -- to receiving and building the kit.

And, as for Idiom Press, I have spoken with the gentleman before several years ago when I was contemplating the purchase of a new version of his K-3 keyer. He was pleasant and accommodating and, I believe, he is still so.

It's just that we -- K3JLS and I -- would appreciate hearing something -- anything -- about our orders.

As for eHam.net, well, I am buying a built SCAF-1 from my good bud, Dick, WB6JDH. (He has two of everything.) After I get it, I will post a review of it on Eham.net and relate that the reason I bought a unit because I got bupkis out of Idiom Press.

Let's see if that review sticks. 

-72-

Revisiting N6TWW's Calculations..

In a preceding post, Mike, N6TWW, discussed the calculations he made in order to develop a phasing harness for a couple of VHF antennas. I borrowed on his numbers to further ingrain this poor boy's TDR technique.

(1) Speed of light = 186,000 miles per second.

(2) 186,000 x 5,280 = 982,080,000 feet per second.

(3) 982,080,000 / 1,000,000,00 = 0.98208 feet per nanosecond.

(4) 0.98208 feet = 11.78 inches.

(5) Light travels 100% in free space but travels only as fast as the velocity factor along a cable.

(6) The velocity factors of popular cables are:

      CABLE    -  VF
      RG-8     - .66
      LMR-400  - .85
      RG-8X    - .84
      RG-11    - .75
      RG-58    - .66
      LMR-195  - .83
      RG-59    - .82
      RG-62    - .84
      RG-174   - .66
      RG-213   - .66
      RG-214   - .66
      RG-217   - .66
      RG-218   - .66
      RG-316   - .79
      RG-400   - .695
      LMR-500  - .85
      LMR-600  - .86
      1/2 HARD - .81
      7/8 HARD - .81

(7) I got 2 hunks of cable I want to determine the length of. One is a long piece of RG-8X and the other is a shorter piece of RG-58. I have another hunk of coax that I want to verify the velocity factor of.

(8) For the longer hunk of RG-8X, I assume that the velocity factor in 84% so that means that when an electron travels through it it's only going 84% as fast as its cousin in free space. Consequently, it is traveling 84% of 11.78 is 9.98952 inches. So let's say 10 inches for grins.

(9) I lashed up the scope and the function generator like these two lads did and found that the RG-8X cable's out-and-back trip was 2.4 divisions at 100 nanoseconds per division. So 100 x 2.4 = 240 and half of that (only want one-way) is 120 nanoseconds. Thus, the cable is 120 x 10 inches or 1,200 inches long. Obviously, 1,200 inches is 100 feet. (Do I really have to?) And, guess what, that's what the guy at the swap meet sold to me: 100 feet of RG-8X.

(10) The shorter hunk was 1.6 divisions at 100 nanoseconds which works out to 160 nanoseconds. The one-way time, of course, is 80 nanoseconds and, since it's RG-58, the distance traveled in a nanosecond is 11.78 x 0.66 or 7.78 inches. So electrons traveling 80 x 7.78 inches or 51.8 feet.Let me get a tape measure and check that number.

(11) Not for the third hunk of coax, I know it's 22.75 inches long and I know that it "scopes out" to 0.7 divisions and 100 nanoseconds. Half of this (one-way trip) is 0.35 x 100 or 35 nanoseconds and 35 x 11.78 or 412.3 inches or 34.36 feet.

But that's the distance in free space, and I know that the coax is 22.75 feet long. So the velocity factor would be
34.36 / 22.75 or 0.662107 or 66% -- which is what they say RG-58 should be.

Funny thing, that!

-72-

Probing the mysteries of 'scopes..

Here's the deal-e-o on scope probes:

..remember, this blog is for me and not for heavy duty PhD EE types. Sorry for my pedestrian pace.

-72-

Time Domain Reflectometry for the poverty stricken..

Munching my tuna fish sammich today at work and came across this:

..thought I'd store it away here for reference. Here's a practical application of this method:

Let's face it, I'm like a kid in a candy store. I am smitten with this application. Here's a variation on the same theme:

..graphic explanation for characteristic impedance and possible entre into the phenomenon of SWR? Lord, is this fun or what? I feel like one of those freaking apes at the monolith in 2001.

Ain't life grand?

-73-