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Author Topic: Is Elecraft KPA500 Linear Amplifier Worth Waiting For....  (Read 12976 times)
WA6MJE
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« on: October 31, 2010, 07:30:44 PM »

I have been licensed since 1959, and have lost and found interest in hamming several times over the years.  Here I am again building up a modest station. I have a rig (IC 7000) and a very functional antenna system in my HOA restricted home using BuddiPole parts, a Hi-Q screwdriver, elevated radials and prayer. Next step, a modest, solid state, small footprint linear in the 500-600 watt range for those moments when others struggle to read me on PSK, SSB or CW. I more or less am ready to hit the buy button on the Ameritron ALS-500M for various reasons, including bang for the buck, ability to go portable on 12V, remote so I can leave it on the floor when home, etc. The only unknown in my decision equation is the announced, but not available Elecraft KPA500.  The ALS-500M including a 90 amp PS will set me back about $1050.  I would pay more if I got substantially more quality (but not necessarily for just more power).  Elecraft has an exceptional reputation.  I have my eye on a K3 down the road that would match their linear.  But I am impatient and want to get on with this station build. Anyone know anything about the Elecraft KPA500?  Anyone see it at Dayton?  Anyone know any rumors?  I know it will have a built in power supply from the pictures, and a smaller footprint than Ameritron which is worth some extra bucks to me. The Ameritron is older technology having been in production for a long time, and Ameritron sometimes has MFJ QC moments.  I would wait maybe a couple of months, and spend maybe 50% more for a quality Elecraft linear.  Unless someone knows something, waiting seems like a crap shoot to me. Just my luck to buy the Ameritron, and have the Elecraft show up for a cheap price with outstanding features just as my Ameritron shows up the door with loose screws falling out of the box, and others rattling inside the amp.

Rene - WA6MJE
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W6GF
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« Reply #1 on: October 31, 2010, 10:22:09 PM »

Well I have 2 K3s and an ALS500. I love Elecraft products, but the ALS500 puts out a solid 450-500 watts. It seems to reliable and forgiving.  My watt meter does care where the power is coming from.  In a nut shell, I have some pretty fancy liners and several Ameritrons. As I said the watt meter can not tell the difference.

George W3GF
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AD5X
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« Reply #2 on: November 01, 2010, 04:02:14 AM »

For about $1250 you can get the ALS-600.  Much better than an ALS-500 for a home station (50VDC FETs, a little more power, probably better IMD).  The ALS-600 50V power supply is included in the price.  I've had an ALS-600 for about 4 years and it has performed flawlessly (see the "Reviews" section at www.ad5x.com).  For me, the only advantage of the KPA500 would be the addition of 6-meters.

Phil - AD5X
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WX7G
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« Reply #3 on: November 01, 2010, 05:29:30 AM »

I don't know what the KPA500 would provide that the ALS-600 does not. I have an ALS-600 in the house and an ALS-500 in the car. They are both good amps with the ALS-600 running 500 watts on CW and the ALS-500 running 400 watts.
« Last Edit: November 03, 2010, 01:35:19 AM by DAVE CUTHBERT » Logged
NI0C
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« Reply #4 on: November 01, 2010, 05:58:11 AM »

Except possibly for aesthetic reasons, there is no reason to "match" a transceiver with an amplifier.  I would expect (but don't know for sure) that the Elecraft amplifier would have good QSK performance on CW, as Elecraft has made that a priority in its K3.  So, if QSK is a consideration for you, that would be something to compare with the Ameritron amplifiers. 

73,
Chuck  NI0C
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W6CD
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« Reply #5 on: November 01, 2010, 05:31:31 PM »

I really like my SGC-500 solid state amp - quality unit, works great - 12v for mobile capability.  Auto band switching feature makes my setup a 500 watt transceiver.
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WA6MJE
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« Reply #6 on: November 01, 2010, 08:14:54 PM »

Great comments from everyone.  Thanks for the input. I got email back from Elecraft today about the KPA500 that is in development. They say they "hope" it will be available in early 2011.  Well, you know how that goes.  They also say it will sell in the $2200 "range".  This more or less answers my question about is it "worth waiting for".  Not for me. Everyone here seems to be happy with the other 500-600 amps on the market.  I have gone ahead and hit the buy button on the Ameritron ALS 500M.  The input I got here helped make my mind up. My station build is very close to the finish line. Thanks and 73s. 

Rene - WA6MJE
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W7NNN
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« Reply #7 on: November 02, 2010, 08:22:42 AM »

WARNING:Don't use an amp with the Buddipole
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WA6MJE
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« Reply #8 on: November 03, 2010, 05:46:32 PM »

WARNING:Don't use an amp with the Buddipole

I think I have fairly well worked my way around the power limits of the Buddipole.  I mounted a Hi-Q 4-160 RT screwdriver as the vertical element coil.  It has a full legal limit power rating with 4 inch coil wound with 12AWG wire.  No Buddipole coils will be used anywhere. I replaced the 26 AWG wire radials that come on the Buddipole kite winders with 12AWG wire as elevated radials for the vertical.  I replaced the Buddipole TRSB balun with a high end 1:2 balun from BalunDesigns that has a rating of full legal limit. I replaced the BuddiPole coax with high quality Belkin RG8 from DX Engineering. The only thing left of the original Buddipole is the VersaTee and the tripod, the 22" arm(s) and 9.5 foot whip.  I do not know what rating the whip has, but I have seen mobile operators run high power on much smaller diameter whips.  12AWG wire can handle the load in a dipole, and the BP whips should exceed the current capacity of 12AWG wire. If necessary I will hunt out a better whip, but the BP whip seems up to the job of 400 watts.

I replaced all of the above essentially to maximize efficiency, squeeze out every thing I can from the Buddipole vertical, and secondarily to increase power limit. I have HOA limitations and have to take down the antenna when not used. However, to make the best out of a bad situation, I modified the Buddipole idea with the highest rated components I could find.  I cannot think of anything else to do with a portable vertical.

If anyone thinks anything else needs attention I would appreciate feedback.  Thanks for the cautionary warning, but I hope I have covered all the bases on this.

Rene - WA6MJE
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ZENKI
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« Reply #9 on: November 09, 2010, 11:48:57 PM »

The solid state amplifier market is very crowded. There are many good products out there. Most hams will look at the dollars per watt ratio.
The leaders in this category for solid state amplifiers are the Ameritron ALS600 and 1300. In the homebrew arena you have the venerable EB104 AMP. There are other products like the SPE which have  very good performance.


If Elecraft cant offer some competitive  advantage in technical performance, features or economy on the dollar per watt ratio, its going to be hard to know how successful the KPA500 will be. If its priced more than the ALS1300 its going to be hard to justify its  high asking price.

I would consider the KPA500 if it  had excellent IMD performance, high continuous duty cycle and the ability to be remotely controlled via a ethernet port.  The AMP should also be able to be operated into a VSWR of say 3:1. If it is YASA(yet another solid amplifier) with poor IMD and a high price I will take my dollars elsewhere. Elecraft does not have a proven record in solid state amplifier design and  all its transmitter products have relative cheap poor performing 100 watt PA's especially on the higher bands and 6 meters.

Why I might consider buying the KPA500 is Elecraft excellent product support, excellent reflector of users, good documentation  and company openness towards implementing new ideas and listening to its users. Its not like the JA companies who bottle up under criticism and whom run their companies more along the lines of  some sort of secret intelligence service. I have yet to find any JA company admitting that it screwed up or made  a mistake. The JA companies never admit their failings! So from this perspective buying a solid state amp that you can fix, upgrade and discuss openly with its designers is something worthwhile as part of the purchase price.

I will  wait and see what the list price and the specification  is for the new Elecraft AMP before casting judgment. Personally I would be more interested in a 200 watt PA upgrade for the K3. This upgrade would include decent FETS  with excellent IMD performance like the FT5000. I dont  think this will ever happen because it would require the redesign of the whole radio. I will just have too wait for the future K4.
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VK4FD
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« Reply #10 on: April 08, 2011, 12:24:35 AM »

 Grin

Well I ain't never!....No actual test results given and from your "Code Name" I can have to question your technical knowledge.

If you are going to comment on an amateur product it would be real helpful to others if you back your comments with a technical discussion showing test results that support your theory and comments.

Well, maybe it's better you not make rash statements at all in the future!

my 2 cents worth....yep, keep the change
 Cool
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K8AC
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« Reply #11 on: April 09, 2011, 05:42:35 PM »

The best guys to ask your question to are those who are still waiting for the other two solid state amps they were showing at hamfests a few years ago and promising they'd be available soon.  It's been so long, I can't recall the model numbers.
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K3GM
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« Reply #12 on: April 09, 2011, 09:54:39 PM »

...........Personally I would be more interested in a 200 watt PA upgrade for the K3.........

What kind of performance increase would you expect to see over the currrent 100 watt PA that's currently available?
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ZENKI
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« Reply #13 on: April 22, 2011, 07:05:48 PM »

...........Personally I would be more interested in a 200 watt PA upgrade for the K3.........

What kind of performance increase would you expect to see over the current 100 watt PA that's currently available?

Well 3db is not a lot however 99% of the time I would not have to turn on my linear. This has been my experience using 200 watts. On numerous times I would switch between 200 watts and 1kilowatt during a QSO and nobody comments that my signal has dropped.  I would not even bother buying the KPA500 if I was already running 200 watts of output.

The other reason is that I need 200 watts of drive is  for my linear.  I  need   200 watts of clean power. Any 200 watt PA would need 3rd order IMD figures of at least -40db below PEP. The K3 has a lousy PA that produces unacceptable levels of IMD at full output.

The IMD figures for the KPA500 hardly looks spectacular.  I will wait and see  what the final IMD figures are like for the KPA500 at reduced power output. However, the problem of K3's poor IMD wont be solved driving a KPA500 since the K3's IMD is already inherently poor. Its just unfortunate that Elecraft  chose such poor IMD performing transistors for the K3's PA.

Now that the FT5000 is available, I am not surprised that its selling so well. The same could be said for the IC7700, while it might not have the worlds best receiver in the world, 200 watts is high up on the priority list of many.

While I do understand that the K3 was designed as portable radio, the majority who buy the K3 use it for home station use and nothing else. If  I wanted a portable radio I would use my K2.

I would be happy to throw away my KPA100 and KPA10 away and install proper FET PA boards running at high voltage even if it meant using an external high voltage power supply. This is not going to happen directly from Elecraft,  so I will just wait for the K4 whenever that is released. Hopefully the K4 will have 200 watts of output power with brilliant IMD performance. It would even be better if the K4 used adaptive pre-distortion IMD cancellation techniques like the ADAT transceiver.

I see that the Hilberling radios is being advertised in QST, that might make a good choice. The Hilberling has 200 watts of output  and also has some impressive TX IMD performance.




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KB9CRY
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« Reply #14 on: April 27, 2011, 06:46:02 PM »

I have an old SB-220 and I bet my 1000 watts sounds the same as yours.
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