I don't know why people think, or are told, that a 30 foot vertical is an all band antenna. Especially one with a thin wire element.

The entire "vertical longwire" concept is strange to me.

The AL12 Ameritron series amplifiers does that. Bias goes to near class B on CW switch position.

I'm sorry threads get this way, but it is impossible to have reasonable, logical, factual, conversations in some instances.

Certainly everyone knows MFJ needs to do better with QC, but the claim they don't care at all or don't test anything is false. Everything is tested and inspected.

There are also different lines, in different buildings, with entirely different people, as well as externally manufactured products. 

The issue comes down to missing things the final tester, and people on the line, should not miss. They do take this issue seriously, even though there are some people that cannot offer anything except useless vitriol.

We have a national problem in that our pollutions are generally very wealthy and out of touch, and are funded by corporations and wealthy people. Most of the hot button claims they make that determine who we vote for are less than half true.

That's why we continue for 30-40 years with things that don't work for the middle class, reduce poverty, improve public health, or improve education.

When I voted, an issue that takes public funds and sends them to private schools, or even home schools, was worded "This amendment improves eduction in Georgia by allowing choice". What it really means is my tax money will be taken away from public schools to fund Joe Rich as he sends his kids to a $15,000 a year private school, or some religious school choice where science says the world is 3000 years old, or to some home schooler parent.

73 Tom

Bill,

The reason I respond like I do is because I don't think you (or KE5JPP, or NN4X) can have a logical, factual, rational conversation about quality control or manufacturing issues.

I think most people understand, or have the capacity to understand, that there will always be some percentage of problems unless cost becomes unreasonable.

Further, I think most people understand or have the capacity to understand that looking at reviews, or one point in the field, does not tell what percentage of problems exist. If 10,000 of something complex requiring knowledgeable or skilled user interface are out in the field that are PERFECT in every way, there will be problems.

The matter is made worse by things that get by the testers, and by workers who don't do a diligent job 100% of the time, and by parts that are troublesome.

There is no question at all, and I said this several times, the tester was getting too slack on the 811 line. I also said I drove up there months ago, and they made some changes. There is no doubt they had a problem, and no one denies that, but the problem is not at all what you represent it to be.

The real problem I have is your irrational approach to statistics.

When I was there, we unboxed dozens of units. We found about the same percentage of units that had potential issues as field reports showed. Mostly they dealt with stranded transformer wires that were not tinned before insertion into the board, so they looked ugly. There were occasionally other connections that did look good, and we went over all of that.

One of the changes was I reworked the rear panel board to be more compatible with lead free solder. This will make it easier to solder parts with lead free solder, which does not flow through holes or out on the trace anything like leaded solder does. The new board has thermally isolated pads that will heat to full temperature faster, and while the lead free will never look as good as leaded solder, it should flow through the new pads good enough to fill both sides.

What really annoys me is how a few people, not many, get on a campaign where they actually make things up and present it like they know what they are talking about. An example is the false claim that things are not tested. They certainly are tested, but multiple things work in concert to cause more problems than there should have been.

Some of those problems are not 100% curable, and will never be curable, because the market will not bear the cost of a 100% cure. The margin already is 20% or so, and no one is going to tolerate a doubling of labor cost. Even if the QC was taken to a level where there were near zero issues, field failures would only decrease to about 3-5% because of component issues, and the most problematic components have a single source.

It's more than a little annoying to do all this work, and try to come here to help people, and to much of this extra work (including a four hour one-way drive, there and back, at my donation)  just to constantly have two or three people making things up.

Now you can pretend you understand QC, but anyone who knows how this works also understands it is impossible to use just a percentage of units from one of the smallest volume stores, or select a few bad eHam reviews out of dozens of good ones (most things you complain so much about are over 4.5 in review), and indite an overall system as terrible. You can't even, from your vantage point of seeing a percentage of units from a dealer with a small percentage of volume, have any idea what the actual percentage of problems are.

I'm sure you are 100% convinced you know everything about what goes on without visiting, or without seeing actual data. But I think most people are wise enough to realize if things were as bad as you and a few others claim, there would be a  dissatisfaction rate much higher than 1 in 10. Anyone with any common sense knows more people complain about things than keep quiet.

Read back through this, and think about this a while. If there is anything that doesn't sense, ask. Someone will explain it.

Does anyone have Vinnie's phone number?

I doubt you will find a detailed article on capacitor design, unless someone did their doctorate thesis on the topic. It is probably like RF inductor design, although there was one good inductor design paper many years ago. 

Bill,

You should just drive over and beat Martin up directly, or drive over here and beat me up in person. Then you will be a happy man. Your mission in life as a savior for all bad things in QC will be complete.



At least some people on here, apparently the majority, have some common sense.

What I don't understand is why any time an amplifier thread or question pops up, you and your buddy down there have to turn it into a "MFJ sucks" thread. By now, everyone knows that is your position in life.

A 44 ft dipole covers 30 - 10, but a 90 ft dipole has a pretty high SWR on 80 meters. With a feedline SWR of 100:1 or more, some really weird things happen.

I'd never go shorter than 100-105 feet on 80 meters.

 

I actually measured one.

A "bazooka" has about the same bandwidth with the coax connected as a stub as it does with the coax connected just as a regular fat wire (center not used). It also has about the about the same field strength.

The bandwidth comes a little bit from outside conductor and dielectric loss (braided conductor with vinyl jacket), a little bit from being thick, and a little bit from stub loss.

If you just use a thick conductor, bandwidth gets better.

If you fan the conductors apart and use two conductors on each side, it can cover the whole band with coax feed with reasonable SWR and no extra loss.

If it gets hot, a foil has been damaged on the top or bottom or the washer is high resistance (perhaps anodized or perhaps corroded from humidity or heat).

The spacer connects both on the top foil and bottom foil, which are wide for RF current.

Unfortunately you have to drop the front panel forward and slide the tank assembly out to redo much more. If it gets hot that fast, there is still a connection issue there.

Another faster fix might be to install a wide copper or brass strip from the outside stator connection stud of the loading capacitor to the band switch common terminal. That would divert some current to another path.

I would do something, because there obviously is still a problem there.

We cannot infer anything at all from reviews....unless we live in Florida and the review is negative. I'm sure if was rated by statistics at a repair center, almost 100% would be defective.  

Look at the AL1200:
http://www.eham.net/reviews/detail/22

It is 4.9 out of 5. It is also built and tested in Mississippi.

The AL1500, built and tested in Mississippi, is 4.8 out of 5:
http://www.eham.net/reviews/detail/21

The AL811 and other tube amps (except 572, which has more tube problems) are 4.5 or higher.

Amplifiers that have high initial component problems, or are sensitive to SWR, have lower ratings.

For other examples, look at antennas. There are a number of antennas that do not work at all like the manufacturer claims, and cannot be made to work as claimed, that get 5 out of 5.

If I come on here and say the assembly lines are different, some fool from FL questions my integrity. I really don't know what to do, because the two people south of me are far more in touch with how things work and what percentage of total production generate some type of service issue.

A person really can't stick to facts here. If they don't say what N4ATS or NN4X want them to say, it means they have no integrity.  

The resistance stabilitly occurs because the capacitor is compact and has the same path length through the component, and nearly the same current distribution and density in conductors, regardless of capacitor setting.

However, the capacitor Q changes. :-)

It would take a good sized book to cover this stuff.

:-)

73 Tom

NO. Don't let anyone convince you that "hearing better" means you transmit better.

A single sharp null in the direction of noise or QRM can make an antenna "hear better", but the same antenna can have much less gain for transmitting in the desired directions. Many other things can cause this same effect, also.

As a rule if the ABSOLUTE signal strength level over is better on receive, an antenna will transmit better. That is entirely different than "hearing better".

Let me give you an example....

I live in a quiet rural location, and I can consistently night-after-night hear and copy Europeans on 160 meters better on a five foot whip antenna than on my 200-foot tall vertical.

Signals not even audible or detectable in the noise on the tall vertical, which makes it impossible to know the absolute levels, are clearly heard on a short whip in the woods. There is probably over 30 dB more transmit signal level on the tall vertical.

For receiving below VHF (sometimes higher), antenna pattern and response to noise sources generally dominate ability to copy. For transmitting, only absolute gain at the particular angle, polarization, and in the correct direction matter.

Those two cases (receive quality and transmit quality) can be, and often are, vastly different.

Here's another thing to consider....

When a system has loss, it is not always bilateral. A tuner that transforms 50 ohms to 500 ohms, if it has loss, does NOT transform 500 ohms to 50 ohms.

On receiving, the receiver end sets feedline SWR and feedline loss.  When transmitting, the antenna end sets feedline SWR and feedline loss.

I can match a 50 transmitter to a 10 ohm antenna with a series 40 ohm resistor. The transmitter will see a 1:1 SWR. If I put a 50 ohm receiver on the system, the 10 ohm antenna sees a 90 ohm load and would have a  9:1 SWR.   

What happened to reciprocity? Think about that a while. Reciprocity does not always exist in systems with loss.

73 Tom

This is old and stale, but I see someone else reactivated it, so I wanted to comment on the advice above......


NEVER EVER give more than they ask for, and especially NEVER point out things that might be problems. NEVER.

Always supply exactly what they need, and the VERY MINIMUM they ask for. The only thing to ever fight is what they decide is a problem. Offering things not asked for will often create problems they never even thought of.