US ham and Manufacturer on a far away continent

Here is the e-mail of the US ham:

Mark,

1. The manufacturer's series of amplifiers are experiencing a breakdown where the plate current swings all the way to max and the 600 volt line fuses blow and there are no spare parts to fix them, or reasons why
this happens.

2. There are ten amplifiers that have recently failed this way waiting for repair in xxx, and they are going to be returned to their owners when the ex-manufacturer repair person receives money to ship them back without being repaired.

3. The nomenclature on small electronic devices in the amplifiers has been systematically erased and sanded off to prevent duplication of the boards or non-authorized repairs or redesigns from being done.

4. The schematic diagram appearing in the owners manuals is tacitally incorrect.

5. The American Repair facility has been waiting for over one year for spare parts.

6. The Russian doorknob capacitors are KVI-3 and are not rated for RF Power service and may heat up, short circuit and explode with no warning.

7. The exhaust pulling fan is half the CFM capacity of the pusher fan and the buildup of residual air pressure in the final tube plenum means a drastic loss of tube cooling air flow at best and a destroyed output tube at worst.

8. The tube sockets are manufactured in the mid 1960's. The tube itself in my test amplifier was manufactured in 1990. The manufacturer does not state that the amplifiers are "used" or "recycled" at any point and this is a misrepresentation.

9. If the vacuum relay burns out it will be necessary to remove the controller board. No spare controller boards are available if the board is damaged.

10. The GU-78b tube is no longer being manufactured and when stock is depleted the amplifiers will not have any source of substitute devices.

Please contact me if you require further facts about the 3 kW amp of this manufacturer.

US ham.

Here is the manufacturer's reply which was in this format refused to be published by the amp reflector:

Gentleman, I have no intention to enter into any polemics with this particular message addressed to anybody concerned with our amplifiers. My aim is to provide factual information, as well as some technical and engineering aspects with which some members of this reflector have been ill informed. You may have read the " MUD SLINGING" exercise, written by the US ham on this reflector, for one and only one reason, to degrade the good name and reputation, our amplifiers enjoy. This was definitely not a review, reviews are usually written by people who actually use an amplifier, use it over a period under heavy contest condition, and observe its cons and pros. A respectable reviewer is usually an experienced person with technical as well as practical knowledge, intelligent and totally unbiased. The US ham's statements about our 3 kW amplifier are totally untrue, false, and show great lack of technical knowledge.

I believe, that, as a manufacturer as well as an active member of the design team, I'm competent enough to make corrections to his assumptions. My response is as follows.

According to the above statement, all our amplifiers are experiencing a breakdown as described above!
Now here is the truth: Recently our representative for North America had an unusual problem with two 3 kW amplifiers, where after a three minutes of warm up period or due to slight vibration, a considerable jump in plate current blew the fuse. Luckily at the same time we had the same problem with a 3 kW amp here on the far away continent. We investigated the problem, and found, that after turning the amplifier on and after a certain but inconsistent time period, the control grid to cathode resistance was dropping as the temperature of the tube was rising. RESULT: FAULTY GU-78B tube. However, after doing some further research and investigations, we have found the primary reason for tube failure. We believe, that a little 2.2nF capacitor in the EBS conducted, considerably reduced the bias, plate current increased and the fuse blew. As we have never paid much attention to the little in our opinion unimportant coupling capacitor, which job is only to deliver some RF to generate EBS voltage, we did not realize that some transceivers generate a considerable high voltage spike, which could damage this capacitor, or even the input coupling capacitor, and a loss of bias would occur. Hence, high plate current and a blown fuse.
We had a second but exactly the same problem with a 2 kW amp which we brought back from Texas. Here the GU-84B tube was faulty and presented the same symptoms as the GU-78B in the 3 kW amp. I immediately advised our representative of the possible problem.
Out of several hundred amplifiers operating on all six continents, we have so far replaced five tubes, three GU-78b, and two GU-84B. I'm still waiting to see what our representative will tell me about the two amps he is servicing. Gentleman, with a record like this, any manufacturer would be extremely proud. And the reason for this fine record is not only the high quality of the tubes used in our amplifiers, it is also the design and the sophisticated protection circuitry used in all our amplifiers. An operator using an amplifier of ours, can be blind, stupid and dumb, and will not be able to destroy the amp, unless using a hammer!

2. There are ten amplifiers that have recently failed this way waiting for repair in Virginia, and they are going to be returned to their owners when the ex-manufacturer's repair person receives money to ship them back without being repaired.

Well Mr. US ham, if you can give me not ten, but only five serial numbers of the faulty, fuse blowing 3 kW amplifiers, I'm willing to give you a brand new one or equivalent in cash! I have no problem putting my money where my mouth is!! Are you???

You are again talking in plural! There is one and only one electronic device, where we have erased the nomenclature, and I give no apologies to anyone! All manufacturers do it in one way or the other. We have spent many thousands of dollars on R&D, and we have full right to protect our work, our ideas and our designs. We are actually talking here about the little "ramp function driven soft start module"! Yes, our soft start unit is really unique. As we all know, there are three different methods of soft starting an Amplifier.
a.) The very old and relatively effective resistor / relay method, used by many amplifier manufacturers. This method is good, but usually does not allow using one single transformer if one wants to prolong the life of the tube filament. The switching time is in many cases too short. However, this depends on many factors, such as: the size of the transformer, tubes used, filtering system, etc.
b.) The second and most ineffective soft start method certainly is the so called solid state zero crossing method. That means, that the power is turned on when voltage across the load is zero, but in a 50Hz system, it takes only 5miliseconds for the voltage or current to reach its maximum. 5 milliseconds is practically as good as a short circuit, and in most European homes fuses blow! At 60Hz it's even worse.
c.) Now let's look at our method. In short, an IC ramp function generator drives a 40Amp triac, connected in series with the load. The circuit can be factory adjusted over a time span of say 1 to 5 sec. I can not in this small space talk about many advantages of this system, for more info, see our WEB site. However, I feel quite comfortable claiming that this is the best system under the sun. If I'm wrong, please accept my apology.

4. The schematic diagram appearing in the owners manuals is tacitally incorrect.

Yes, this I do believe. We do not just turn the handle, we are continuously searching for better ideas, better designs and improved performance. Just look at one of our amplifiers build some three years ago and one build today. You will see the difference! It is therefore very hard to continuously upgrade the literature, specially if there is only a small not very important modification. I know of manufacturers who for 15 years or more have not made any improvements on their current models. Could be, that their products designed so many years ago were so advanced, that no upgrading was ever necessary, or they love turning the handle of their sausage machine! I would certainly think of the latter.

5. The American Repair facility has been waiting for over one year for spare parts.

Please give me some more details. I'm not aware of anybody whose amplifier is waiting a whole year for service. Would appreciate your help. I admit that sometimes I was perhaps a bit slag, or I have forgotten, after all we are all humans. We do have a couple of the very original 2 kW amps with the 4CX1600B, where the tubes are faulty, new tubes are not available and we have designed a new RF tube module with two GU-74B tubes which directly replaces the 4CX1600B module. At least we are doing something, we try to look after our customers in the best possible way.

6. The Russian doorknob capacitors are KVI-3 and are not rated for RF Power service and may heat up, short circuit and explode with no warning.

A very interesting statement, partially correct but not in this context. There are two types of Russian ceramic transmitting capacitors available. The K15U-1 M1500 and the KVI-3!
The K15U are designed for all kinds of RF applications and very suitable for tuned circuits as well, and if the voltage rating is right, they are just perfect. There is nothing better!!
Now let's see the KVI-3. This capacitor has been designed for several RF and pulse applications, but they are not suitable for high power, in high Q tuning circuits. However, they are very suitable for RF coupling, de-coupling and pulse work. We must remember that a capacitor used in pulse circuitry, would usually for short pulse durations handle at least ten times the current it was originally designed for. I'm talking here currents not voltages. This capacitors are usually 10 or 20 kV devices.
We are utilizing these fine capacitors as a plate coupling capacitor, where due to relatively high impedance, and not being part of the plate tuned circuit (some people might argue about this), the RF plate current is relatively low. We have tested this capacitor in an amp with 5KW PEP, and it wouldn't even blink. Not once has this capacitor let us down.

This statement is absolutely wrong. Let's have a good look at the 3 kW/2 kW amp cooling system. We use a 72CFM turbine blower as the main unit to pressurize the sub-chassis and push the air through the tube. Due to the air resistance in the tube, the output pressure has been considerably reduced. It has been found that due to the relatively small air inlet area of the tube socked and the cooling area of the tube anode, under very heavy duty cycle, the amplifiers sensitive temperature control would bypass the amp when it gets too hot. By adding an additional exhaust pulling fan, which does not have to have the capacity of the pusher blower was added. During our tests, it has been shown that the actual anode body temperature was reduced by about 35degrees Celsius. If the author of the "mud slinging statements" would just do a simple test, to place the hand over the exhaust outlet with the engaged or disengaged (and removed) pulling fan, he would never make a totally stupid statement #7 above. As far as I know, Alpha has been providing an optional puling fan system for years, did anybody complain??

I have E.F. JOHNSON CAT. NO 122-0275, 3-500Z tube sockets also manufactured in the 60's and have been selling them to an amplifier manufacturer, may I ask what is wrong with sockets made in the 60's ? Tubes manufactured in the 90's are new tubes, never been used before (also called New Old Stock - NOS). Some Eimac tubes, manufactured some twenty years ago, are still sold as brand new by some outlet. What would you call an amplifier using a brand new tube which was manufactured some ten years ago a "RECYCLED AMPLIFIER"???

9. If the vacuum relay burns out it will be necessary to remove the controller board. No spare controller boards are available if the board is damaged.

You obviously are not very observant! The vacuum relay or the QSK module is one of the easiest modules to remove. It is held in position with one only M4 screw! By un- soldering the output coax and removing the screw, the module can be removed with two fingers.
Re control boards, another total nonsense! We have at the moment 50 control boards in stock, and 200pcs on the way. In the early stages we had two components which failed some times. Now the control board no longer fails, and is the most reliable module in the amplifier. We do not sell spare control boards, but they are available as a replacement, that means, you send us the old or damaged board, and we will replace it with a new one. The same goes for all our amplifier modules.

10. The GU-78b tube is no longer being manufactured and when stock is depleted the amplifiers will not have any source of substitute devices.

When corresponding with the factory in the mid 90's, the tubes were manufactured periodically (every two / three years) in batches, according to demand. There are still many military installations which require new tubes, this is the reason, why GU-74B, GU-78B, GU-84B and many others are available. All these tubes are minimum five years old, but brand new.

N.B. Please contact me for any further info. I sincerely believe, that our 3 kW amplifier is the one and only one in the world, and that there is no better amp, that could meet our 3 kW amp in craftsmanship, features, design, performance and price. There is world wide a silent majority of very happy of our 3 kW amp users, who wouldn't even think of using any other amplifier.

73, the manufacturer

Please note, I will not enter any further discussions about this subject on this reflector