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| Reviews Summary for Alpha 8410 |
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Reviews: 4
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Average rating: 5.0/5
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MSRP: $5395.00 June 2008
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Description: The Alpha 8410 utilizes an enhanced version of the bombproof RF deck, found in the Alpha 99 and Alpha 8100. On the 8410’s control board you’ll find a microprocessor that allows us to normalize amplification performance, calibrate the power and gain metering for each specific band, and increase reliability and durability. All of these functions aggregate into a single greater benefit for the user, ease of tuning. The 8410 comes standard with USB and serial ports for remote monitoring and performance data logging. The power supply stack found in the 8410 has been designed for maximum durability and reliability, while allowing for extremely easy voltage tap changes.
This amplifer is handcrafted, designed, and built in Boulder, Colorado, USA, comes with a 4-year warranty.
Tubes: 2x VTX-X118 Tetrodes
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More info: http://www.alpharadioproducts.com/8410.asp
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K7ZP
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Rating: 5/5
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Aug 3, 2009 13:05
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OUTSTANDING
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Time owned: 3 to 6 months
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I received my 8410 the end of April 2009 and wanted to wait a few months to get past the honeymoon period and see if any infant mortality issues would present themselves so that a valid and objective review could be posted.
As mentioned the amplifier arrived FedEx on a pallet... not a mark on the amp or the transformer shipping container and the best part was both units when unpacked were perfect. It is unfortunate that shippers can be so rough on delicate equipment.
After opening removing the case screws of the amplifier the very first thing you will notice is the extremely clean and well thought out design before you. As a RF Systems Engineer by trade, I really appreciate the thought that went into the design and execution of the 8410. To start with the 4CX1000A tetrodes and sockets are mounted on a tube deck that is then mounted on the main part of the RF chassis. If you have ever needed to replace the blower assembly on a amp you are painfully aware how much time it takes and how much needs to be removed. Not so on the 8410..... did I mention the thought put into their design. The RF tube deck can be removed in less than 10 minutes after opening the amp and then the axle is ready to access.
Operation and tuning is very easy and spot on. When band changing, it only takes a few seconds as the amp is returned to the numbers in tune and load ..... you are ready to go. The axle fan is very quiet in operation and has 3 speeds available dependent on tube deck temperature. After a long transmission my amp will go to it's second speed, the tube exhaust being about 145F, the deck temperature drops quickly and the fan reverts to it's low speed setting. On more normal transmissions the fan is on it's lowest setting all of the time.
Some will question that possibly the use of two 4CX1000A tetrodes might seem like overkill in a legal amp. These tubes are widely used in industry and while they have been around for a long time, they will continue to be available for many years to come. The 4CX800A/GU74B Soviet/Russian tubes used in many amps including the Alpha 91b, 99 and 8100 are excellent tubes however availability to the manufacturing folks is very questionable and as we have all seen much more expensive and more difficult to locate.
In conclusion, this amp just plain works. It is a pleasure to deal with the folks at Alpha... a great team.
Cheers... Frank, K7ZP
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K4SX
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Rating: 5/5
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Jun 7, 2009 10:24
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Excellent amplifier
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Time owned: 0 to 3 months
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I received my Alpha 8410 June 5th via FedEx. I have been an Alpha amplifier fan for many many years. I currently own the Alpha 87A and the Alpha 77sx. I have owned in the past 3 Alpha 78s and 2 Alpha 76PAs.
The amplifier was shipped via FedEx in 2 boxes strapped to a wooden pallet. Also the packing internal to the boxes was extremely good. The power transformer installed effortlessly, guided into place by 2 guide rails to ensure proper placement.
The amplifier powered up as predicted and described in the manual and was visually counted down via the RF Output meter. I initially tuned the amplifier up with 25 watts from my IC-7800 and I used a military 50 dummy load as an antenna. I used the spec sheet shipped with the amplifier and found their test measurements in line with mine. At the 25 watt drive level the amplifier put out 1000+ watts on 20 meters. I increased the drive to 40 watts and the amplifier put out 1500+ watts with very little tweeking of the tune and load controls. The amplifier tunes up in just a few seconds. (very broad-banded).
Tuning the amplifier is very easy and the spec sheet is almost spot on for setting. Also the amplifier is quiet.
Fit and finish of the amplifier is typical Alpha quality. Very nice. The internal engineering and construction is fantastic.
I will close with one negative and that is the manual. There are certainly improvements that can be made and two of them are overall quality and there is no schematic.
73,
K4SX
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W7EPA
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Rating: 5/5
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Apr 5, 2009 10:11
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The usual Alpha, expensive and worth it!!
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Time owned: 0 to 3 months
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This is the 5th Alpha amplifier I have owned.....and, by far, the best......
Starting at the beginning....my amplifier arrived in the usual Alpha fashion, 2 boxes on a pallet....one for the amp and one for the transformer.....heavy....outstandingly well packed....
Mounting the transformer is the usual job.....so many screws....bet easily accomplished.... I took time to explore the inside, finding, as I expected, it was well laid out and very neat and
orderly....even rails to guide the transformer into position.....
Enough of that
Firing the amp up for the first time was a delight...Caution...reduce the drive as suggested in the owners manual....I find the amp
works as expected with 30 watts of drive to obtain legal limit output.
The protection circuitry works well even when I attempted to load my 20 meter beam up on 80 meters.
What else to say....This exceptional amplifier will be the last one I need...wish I could afford
two of them......The wait is well worth it....
73 Joel, w7EPA
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K6AER
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Rating: 5/5
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Jan 21, 2009 10:45
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Bull dog of an amplifier
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Time owned: 0 to 3 months
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I always have a grin when someone rates a product a 5 for they have only owned the product for a few days. I will be writing a more extensive review of the amplifier and posting it in the article section but the full testing takes time. So many folks are giddy to find out about the amplifier so I thought a sort review would be nice.
Due mostly to my close location to Alpha and my RF background, I was selected to field test the first development amplifier (DEV-1) at my QTH. Gordon, Alphas Chief Engineer, has DEV-2.
First Impressions
The amplifier is extremely well built and not only do you notice the very high quality components, silver plating of the tank circuit, clean layout but the lack of cables. The layout and execution in design is A+. In a departure from typical amplifiers, Alpha has used a 2 by 6 inch 28 VDC axle fan. This is the first that know of in a non military HF amplifier design. All of the critical functions in the amplifier are controlled by a microprocessor and this includes the fan speed. The custom Alpha tube sockets for the 4CX1000A Eimac tubes are a breach lock design which includes a temperature sensor for each tube. As a result, the fan speed will increase to one of three settings depending on the cooling needed for the output duty cycle. In normal 1500 watt SSB operation the speed is low. Sound level at 18 inches in front of the amplifier is only 50 dBa. This is not much more than a whisper. Very nice.
To select the AC power in you only have to move a single jumper on the top of the relay input board from one of 5 settings for 100, 120, 200, 220 and 240 VAC. If you do run the amplifier on 120 VAC you need a dedicated 20 amp circuit and the maximum power out will be reduced.
The amplifier also has a count down timer from start to run. When you turn on the amplifier the LED on the RF power meter starts to tick down from right to left over 180 seconds until the Wait and Operate lights stop blinking and the green Operate LED glows solid green. Now you’re ready to rock and roll.
Enough of the fluff stuff and on to the hard numbers. The amplifier weighs about 70 lbs. 45 of those lbs. is the 3.5 KVA transformer. As a result the power supply is capable of serious wattage out.
With 45 watts in, the average is 1500 watts out on all bands. This has no time limit. Hard key down maximum CW wattage is 2250 watts with maximum SSB PEP wattage just below 2500 watts PEP. You don’t want to run the amplifier in this area anymore than you want to run your Ferrari at 200 MPH…but you know it can.
The reason I bring up the maximum wattage out is this gives you an idea of the head room in the amplifier. To often in an amplifier, the maximum wattage out is just that. No head room and as a result, the IMD (Inter Modulation Distortion) is very poor. On 20 meters with a two transmitters each putting out 20 watts combined, I measured 35 dB two tone IMD. One dB compression point is about 2100 watts. This means at the US maximum rated output of 1500 watts the amplifier is extremely linear as has gobs of reserve.
Heat and efficiency are also a concern to many. The amplifier efficiency was measures at 59% at 1500 watts out. Quiescent heat in standby is about 100 degrees “F” on standby with the tube exhaust temperature at 1500 watts out is 145 degrees “F”.
Operation on the air is very smooth with tuning being broad. You start with the power level at low wattage to place the Tune and Load controls and peak the output. Increase drive power and repeat the process again. Do this several times and you’re done. Write the settings down and when you return to the desired band just place the Tune and Load controls back to the recorded settings and that’s it.
The amplifier is everything you would expect in a high end amplifier and you won’t be disappointed.
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In the original posting I said the Alpha 8410 was being shipped with the Eimac 4CX1000A tubes, this is incorrect. Although you can have this tube put into your amplifier at additional cost there is a much better tube for the amplifier. Alpha has a selected tube, made for them, called the VTX-X118. It is a form, fit replacement for the Eimac 4CX1000A tube. Where it differs, is the tube the VTX-X118, is tested and selected to be a match pair in performance. The drive requirements are much lower by almost 2 dB as compared to the Eimac tube. These tubes are being run in my amplifier and I am very please with their performance.
I have had the amplifier on the air for 6 weeks and the audio and spectral reports support the bench testing that the amplifier has very low IMD (distortion) and is an extremely clean amplifier.
The amplifier currently is being shipped with soft ware version “P”.
Should any one have questions I can be contacted at K6AER@ARRL.net
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