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Author Topic: QST Magazine Technical Articles  (Read 21487 times)
K3AN
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Posts: 787




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« on: December 20, 2011, 08:33:15 PM »

In the 50 years I've been a ham I've seen them go from cutting edge to useless and now to downright dangerous. I'm of course referring to the article on setting the filament voltage in an Ameritron amplifier. The Ameritron web site has a rather blistering rebuttal. It's worth the read if just to understand the safety issues involved.

www.ameritron.com

If for some strange reason you DO decide to build or modify something per a QST article I suggest you wait until you receive the two following issues to be sure they've identified and pointed out all the errors and omissions in the original article. The recent article on the two-tone audio generator is a great example. Most of the errors were pointed out in the following month's issue but an additional error was pointed out a month after that. I really don't think they have a technical editor any more, despite what the masthead says.

But they just added another employee to their fund raising staff!
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G3RZP
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Posts: 8123




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« Reply #1 on: December 21, 2011, 05:46:10 AM »

I find QST to be far less technical than it once was - maybe because the level of interest in 'radio' as such, rather than the digital side, has diminished. The RSGB Radcom isn't quite as bad, and does have the merit that most (but not all) articles are subject to peer review. This hasn't stopped one or two goofs, though, and regular columnists don't get their material reviewed.

So before slavishly copying anything from a magazine - even QEX - it is wise, as 'AN says, to wait a month or two. Although it's often more fun to try rolling your own from scratch....or at elast using somehting from the Handbook, which usually has less in the way of errors.
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W4VR
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Posts: 1214


WWW

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« Reply #2 on: December 21, 2011, 08:24:05 AM »

I buy QST, not for the articles or ads, but to help support the organization in representing the amateur community at domestic and international levels.  I spend about 10 minutes looking at the magazine, and very often find very little of interest.  Decades ago hams enjoyed building equipment and peripherals, but I don't believe there is much interest in doing that anymore.  I wonder how many hams or hobbyists actually build the projects in QST.  As for mistakes, omissions, etc., I think that is a common practice in just about everything you read nowadays, whether it be technical or news articles.  But, I have to agree with one of the commenters in this thread that the technical editors appear to be sleeping on the job at HQ to let so many errors go unnoticed.
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N4NYY
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Posts: 4941




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« Reply #3 on: December 21, 2011, 08:34:23 AM »

I read on QRZ that W8JI ripped QST a new bunghole. Even for the amplifier novice that I am, the warnings are scary and concerning, being that I read QST quite often. I have no experience with amps (I run 100W and QRP). I came into possession of an SB-200 for restoration. It is on the shelf, and I am seriously contemplating just ridding myself of it. I do not need to touch touch voltage and kill myself, trying to do nothing more than a restoration.

Articles like these are often referenced by people like me, that have little experience. Many times, if the expertise is beyond my knowledge, I would just assume they know what they are talking about. In this case, it would have been fatal. So I am glad Tom called their mistake and I was able to find his rebuttal before I stuck my hands int the amp.

I heard a retraction is coming in Jan. But I think I may still pass on the amp.
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K8AXW
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Posts: 6312




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« Reply #4 on: December 21, 2011, 08:52:37 AM »

I've been a ham for 55 years and an ARRL member for over 40 years.  I am always excited to get my new QST for the month and do a quick run-through to see if there are any new construction articles.  During my 55 year ham career I've spent most of my time and energy building instead of operating.  

While I too go through the ham ads without fail, I only do it to torture myself because my days of buying these nice offerings have long been gone.

The latest and biggest ARRL boondoggle in my opinion has been the ARRL Homebrew Challenge.  Fantastic idea but poorly executed.

No doubt the HBC has created a new interest in homebrewing (based on my personal involvement) but it has also created a tremendous amount of discouragement because of the complexity and difficulty replicating the entries.  Nothing discourages a homebrewer quicker than have a project fail to work as advertised!

Whenever an HBC winner requires a shop full of troubleshooting equipment then, in my opinion, the original goal has been lost.



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K8AXW
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Posts: 6312




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« Reply #5 on: December 21, 2011, 09:31:55 AM »

NYY:

Quote
I heard a retraction is coming in Jan. But I think I may still pass on the amp. 
 

I read the Amplifier Forum here on eHam.com daily and well as several others like the Elmers Forum where we are now.

I understand and appreciate what you think now about the SB-200 and the fear generated by the guys on some of these forums.... like the Amplifier Forum.

Please consider some advice.  Get the SB-200 down off the shelf, do what you want with it to restore it.  If the power supply capacitors are original, I'd replace them.  Not sure what to use, ask and you will be told.  As for the rest of it, remember this.  The SB-200 design is a good design and thousands of them were sold and most of those are still on line even though they are over 30 years old.  No filament voltage adjustments and other silly modifications need be made. 

Power it up and if the HV is where it should be, you don't even HAVE to replace the filter caps.  The reason I even suggested that one thing is because mine started to bulge on the tops and since the amp had other obvious signs of abuse (probably by a CB'r) I changed mine out. 

Now about the HV.  There's nothing to concern yourself here IF you follow basic rules.  Memorize them or write them down but NEVER fail to follow these basic rules.

1 - Look at the panel voltmeter and verify that the HV is zero.
2 - ALWAYS unplug the amp before taking it out of the case or working on it.
3 - ALWAYS use a "chicken stick" to discharge the HV capacitors.
4 - Never work on the amp while tired, drinking alcohol or using medication that impairs
     your thinking.
5 - Never work on an amp when you have distractions in the work area.  This includes
     your wife, kids or even pets. 
6 - Never work on the amp with the tube/HV cage is off.
7 - ALWAYS take your time!

There you are.  Seven basic safety steps to follow.  No big hairy deal!
Keep your SB-200 and enjoy it.  If you still want to get rid of it, you won't have any problem there!

Oh yes, one more thing.  The case is designed to contain any shrapnel!  (Just kidding)
     

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WW3QB
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Posts: 810




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« Reply #6 on: December 21, 2011, 10:10:19 AM »

I cannot think of any reason to open a powered up amplifier. They have the simplest circuits of most ham equipment. I replaced the bandswitch in a FL-2100B (similar to SB-200, but not as well made) with no problem. The only other common repair is to replace the caps and tubes. No reason to ever expose yourself to high voltage.
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G3TXQ
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Posts: 1790




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« Reply #7 on: December 21, 2011, 11:09:32 AM »

Over the past couple of years I've eMailed QST several times to point out technical errors. In every case the author eMailed back acknowledging the error. In no case was there a follow-up retraction or amendment in the magazine!

Steve G3TXQ
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WB2WIK
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Posts: 21753




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« Reply #8 on: December 21, 2011, 01:38:23 PM »

Over the past couple of years I've eMailed QST several times to point out technical errors. In every case the author eMailed back acknowledging the error. In no case was there a follow-up retraction or amendment in the magazine!

Steve G3TXQ

At least we can say they're consistent. Smiley
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TANAKASAN
Member

Posts: 933




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« Reply #9 on: December 22, 2011, 01:56:10 AM »

Rather than remember seven safety steps you only need to remember one

S I D E

Switch off

Isolate the amp by pulling all the plugs out

Dump the HV to ground using the mentioned chicken stick

Earth the HV line to get rid of any residual charge.


Work safe, cooking in your own fat is a nasty way to go.


Tanakasan
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KD1I
Member

Posts: 396




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« Reply #10 on: December 22, 2011, 10:40:48 AM »

A note to N4NYY,   no reason to fear the SB200 or any other amp or piece of equipment as long as you follow what K8AXW said.   Great rules to live by. I have worked in medical x-ray for almost 40 years now (someday I'll get an honest job) and have worked with 480 volt 3 phase inputs to 150 KV to the x-ray tube...a bit more than you are likely to encounter in the SB 200.   Just make a pact with yourself that you will never ever touch the HT and never ever tough two objects at the same time....ever.
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AD6KA
Member

Posts: 2243




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« Reply #11 on: December 22, 2011, 10:18:38 PM »

I heard a retraction is coming in Jan
But I think I may still pass on the amp.
You missed the whole point of the article.
Has nothing to do with the merits of the AL-80B.

It's about a ridiculous "MOD" to the amp that
is supposed to increase 3-500z tube life by an order
of magnitude
(ROFL) via a filament voltage change.
None of the authors conclusions are based on
hard data...and the dweeb can't even operate his
DVM properly.
Quote
I read on QRZ that W8JI ripped QST a new bunghole
Go back and actually read the article it this time.

There is nothing at all wrong with the AL-80B amp.
I reckon the only reason it was mentioned at all is because
it was one the author had access to that used the 3-500Z.

Quote
K8AXW:
The latest and biggest ARRL boondoggle in my opinion has been the ARRL Homebrew Challenge.  Fantastic idea but poorly executed.

Double amen to that statement!
As reflected in the fact that only ONE of all those
transceivers and amps have actually been kitted and sold.
The MMR-40. I bought one out of curiosity and
was not impressed. A brass screw inside a coil
for a permeability tuned oscillator in the VFO.
What year is this? PITA to build & align AND poor performance.
And this was the winner of the competition?  Cheesy
73, Ken  AD6KA
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W6RMK
Member

Posts: 680




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« Reply #12 on: December 23, 2011, 07:36:29 AM »

So, suggest (to the QST editors) an alternate contest and scoring system.
Coming up with this stuff is harder than it looks, and then you have to actually write it all up.

1) It has to have broad appeal (not necessarily that it has to have millions of would-be users, but the several hundred thousand readers of QST shouldn't be going, "meh?  another paddle made from beer can scraps?")

2) It has to be a technical challenge (i.e. building yet another Velleman kit or programming an Arduino to send CW isn't going to do it) for the entrants, yet be simple enough for the would-be builders to actually execute in a couple week-end's spare time.  (no fabricating diodes starting with sand)

3) It has to be cheap (and NOT relying on surplus or junkbox to be cheap, nor relying on hours of machining and fabrication)

4) It has to be a hardware project, using parts that are readily available (no "I happened to have a 4CX15000 in my junkbox, so I whipped up a quick power supply with one of my spare pole pigs")

5) It has to be RF (Audio processors, Keyers, Parrots, and DC power supply type projects need not apply)


There just aren't many projects that fit this set of criteria:  Medium power RF amplifiers, simple receivers, and that sort of thing.

There are lots of one-off experiment ideas out there, but not that lend themselves to a design contest for ARRL.  For instance, there's a video out there showing how to turn a multi-feed DBS LNB into a radar.. very clever, but doesn't meet many of the criteria above..Likewise, you could have a contest to build a better modulator/demodulator for some digital mode, but that's software only these days, and doesn't lend itself to photos of prototype hardware.
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W8JI
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Posts: 9749


WWW

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« Reply #13 on: December 23, 2011, 07:53:59 AM »

The function of any large organization is always to preserve the jobs of the people in the organization. This is because the people controling how the orginzation acts are the people who work there. The good of the general  population, or those they serve, are far distant to the goal of keeping their own job.

This is true across the board, from politics to QST. This is why we are getting dumber and things are unraveling.

In 1950, we would have revolted over a foreign nation actually stealing our technology through hacking, and stealing our jobs. We would have had fits about shifting all the burden to the middle class, until it started to evaporate. Now we take those who do that to dinner, make them our heros, and call them our partners. It is a different world.

73 Tom
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K1ZJH
Member

Posts: 3301




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« Reply #14 on: December 23, 2011, 08:01:25 AM »

Over the past couple of years I've eMailed QST several times to point out technical errors. In every case the author eMailed back acknowledging the error. In no case was there a follow-up retraction or amendment in the magazine!

Steve G3TXQ

I've pointed out a few errors in QST articles, and they have at least on one occassion ran a clarification.

I've stopped pointing out errors to magazine editors because they (editors) usually aren't technically inclined or
even interested in technical accuracy, and it usually ends up with the editors dragging the author and reader
into a confrontational debate with bad feelings all the way around.  One magazine, that just arrived in the mail,
shows a vertical antenna where the author uses a raised feedline a couple of feet above the radials to "avoid"
common mode pickup on the coax. These days it is all about filling pages between ads with light reading
material for the home "library."

Pete
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