KPA1500

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  • Updated 1 year ago
Photo of Richard McClelland, AA5S

Richard McClelland, AA5S

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Posted 2 years ago

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Kari Gustafsson SM0HRP, Elmer

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Wov quite impressive with an internal ATU as well. And it is specified for Flex radios also. Looks it will handle SO2R as well. Better than new ACOM 1200S. So there is a real solid-state 1 kW+ amplifier war out there now.  
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Richard McClelland, AA5S

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I just posted this to get the information out there.  Maybe another PG XL vs KPA1500 thread is in order.
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Al / NN4ZZ

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The doc says to use DDUtil for enhanced mode....but seems like it could use the Flex USB output also for a "no local PC" configuration.  And it has an ethernet connection so that may be an option too. 


(note: I already have a nice solid state legal limit amp but it's good to see more options coming available)

Regards, Al / NN4ZZ  
al (at) nn4zz (dot) com
SSDR / DAX / CAT/ 6700 -  V 1.10.16
Win10
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Bill W2PKY

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The 2 box build is very nice for a lot of reasons and built in ATU is also wonderful. They will sell a lot of these amps!
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Paul Christensen, W9AC, Elmer

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On the plus side, it appears to have native Ethernet connectivity, distributed weight and cabinet size across two separate units, RF sample for use with transceivers that support adaptive predistortion, and a PIN diode T/R system. 

Not sure if the PG XL will have PIN switching or not.  Done right in design, PIN diode switching can be very reliable even into high SWR terminations.  I'll be looking to see how much bias voltage is applied to the Rx diodes in Elecraft's scheme.  If reverse bias approaches 1KV DC, then there's little chance of diode destruction at the 1500W level.

Paul, W9AC
(Edited)
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Ria - N2RJ, Elmer

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Two LDMOS
No single amp SO2R (one input only)
ATU is 3:1 but can go to 10:1 with derating
Two antenna outputs
$6000 MSRP
APD
6 meters included

Seems like a modestly good amp, but I'm not sure I would want one as a flex 6700 owner.
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k0eoo

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I couldn't find reference to the LDMOS's but I like the price and built in tuner, BUT, not much head room for a full power amp.

I don't like the two box design and they don't say anything about the power output per mode or anything about duty cycle, at least not so far...  No SO2R...

Whereas, the PGXL has the MEffA high efficiency feature and 100% duty cycle in all modes, which other SS amps cannot match.  I find this very compelling...  Normally SS amps don't do well on RTTY compared to tube amps but the PGXL delivers.

I would have thought the prelim info for the KPA1500 would have been more forthcoming with performance date, a bit surprised, unless, the performance data isn't...

I had a KPA500 and liked it but don't think there will be a KPA1500 in my future.
(Edited)
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Ria - N2RJ, Elmer

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The pic from Visalia shows the RF deck being not very big, which was probably their intent anyway as they wanted to retain the K-line concept. PS sits below your desk, rf deck up top.
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k0eoo

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I get why they might design two boxes, I have done that myself in the past.  But these days I already have too many wires/cables running around that's why I didn't like the two box approach, especially with the high DC currents that will be flowing in the power cable.
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Clay Autery

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Two boxes is more flexible, especially for folks who want to power the amp with a different power supply.
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Larry - WA7LZO

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The best part about the KPA1500 is its 2 box design. Makes it soooo convenient for transport, etc. Looks very nice, but we'll need more info and specs, like IMD performance, duty cycle by mode, etc. The price seems low, by comparison to other amps with tuners. Still, unless it has outstanding specs, I'm sold on PG XL, as I want to have 100% integration with one vendor, stem to stern.

Br,

Larry
WA7LZO
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km9r.mike

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Interesting but I am grateful that PGXL has incorporated SO2R. Even if not contesting, I like the option of cruising the hf bands at full legal limit and also have 1500w in the same box ready to go while monitoring 6m. I also like the flexibility of a remote tuner. My tuner in my 6700 is always in bypass mode because my KAT 500 is remote in the attic and if I could have purchased the 6700 w/o an antenna tuner I would have.  The 100% duty cycle of the PGXL is bonus as well because I do enjoy an occasional rtty contest.

I have not pulled the trigger yet and PGXL will be my first amplifier ever, but I feel very confident with everything I have seen so far. I also feel comfortable since Ranko is no stranger to contesting and he understands what is required from equipment while contesting. Elecraft understands contesting as well, but for me PGXL is the better fit.

BTW I also like the led lighting. Too bad that the amp will be remote.
(Edited)
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Norm - W7CK

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Hey Mike,
You said your KAT500 is remote in the attic.  Can you describe how far away it is and how you control it?  Maybe a very long USB cable?  How hot does it get in your attic?

Norm
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km9r.mike

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Hi Norm,

Soory for delay in reply currently in HKG. I just moved into my new qth last Oct so I have not seen summer temps yet in the attic. I have however had the kat 500 for over 2 years now and have used it remote since new. It has been wx proofed and has operated 100% from temps ranging from 10.0 F to 105.0 F without issue, but that was at only 100w max. A laptop cooling pad at the base of the tuner might be prudent for higher tx power. It can utilize usb cat control, but I have only relied on freq sensing control to date. That has worked well, however, in the two years of using it I have had perhaps 4 events total that resulted in a fault in the tuner which required me accessing it's front panel controls to reset the fault. I am guessing here, but the new qth is at approx 5000 ft msl and Reno only gets above 100 F about 7 days a year. With that in mind, I do not see attic temps getting much above what the tuner has already operated in ,however, there may be more of them than previous.

This does give me pause though with the idea of remoting the amp to there as well. Thinking things through, it would probably be better to keep the amp in an environmentally controlled area vice subjecting it to the wide range of temps. Probably well within it's capabilities, however, the lengths of my coax runs from shack to antennas is only 75 feet and will need only two of them to reach antenna genius in the attic and shorter runs from there. So in the long run, probably better to keep the amp in the shack for now and only think about remoting it if the environment can be controlled in that area.

Hopes this helps Norm,
Mike
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G8ZPX

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so if they can do a full legal SSD amp WITH and internal ATU at this price then what is costing so much more in the PGXL making it far higher price yet without an ATU?
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km9r.mike

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Math is your friend Steve.

Cost kpa 1500 = 6k duty cycle unknown
Cost PGXL = 7k full duty cycle at legal limit all modes

Cost SO2R w/ kpa 1500 = 2 x 6k = 12k
Cost SO2R w/ PGXL = 7k. i.e. 5k in savings and a nice feature

Internal tuners are not value added to me. If I utilize a turner, I prefer to remote them as close as possible to feed point of antenna increasing their efficiency and transfer of power to the antenna .

 If SO2R is not value added then PGXL still allows an op to monitor a completely separate band say 6m while working the hf bands at the same time w/o the need to purchase a separate 6m amp.

Finally, although I do not have money to burn I do not see 1000 dollars as a far higher price in the big scheme of things. 5k on the other hand for two ATUs that I will not use seems to be wasteful to me though.
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G8ZPX

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Mike, more than capable of doing basic maths, thanks. What you've done is to try and justify the cost via a features and benefit analysis, like a good salesman would. That is not my concern as I am neither interested in SO2R or an internal ATU for that matter.

I can however easily envisage the likely cost impact of components (2k rated ATU components are not cheap). So, what I was asking is what is costing so much inside the PGXL to cost so much more?   For example, If I took out the ATU parts from the Elecraft product there would be a $2k+ difference, so where is that $2k reflected in the actual material cost?

With many nice amps coming out like the Elecraft, the new Ameritron S/S, and the Jumo amp to name a few, unless you really need SO2R why should we be spending more?
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Ria - N2RJ, Elmer

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You're looking at this strictly from the cost of materials perspective.

In that case you should ask why the 1.3K-FA is $1000 less than the KPA1500 for only one less transistor ( I was told the KPA1500 uses two).

A transistor in bulk will be about $150-$175.

But there is R&D cost and frankly these things are priced at what the market will bear. It's still cheaper than most tube amps and still cheaper than what full legal limit solid state amps (e.g. 2K-FA, dishtronix Prometheus) have been for now.
(Edited)
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Gordon, ve7on

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I think the biggest reason for the added cost is the PGXL has 2 companies marking up one product whereas the KPA1500 has only one level of markup. 
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Paul Christensen, W9AC, Elmer

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"Cost kpa 1500 = 6k duty cycle unknown
Cost PGXL = 7k full duty cycle at legal limit all modes"

We still need more information concerning the true duty-cycle of both amps.  CCS v. ICAS tells us nothing about the total key down duration at 100% duty-cycle at rated power.  A CW test carrier is a 100% duty cycle mode.  How long can we keep the key closed with both amps while producing maximum rated power?   

Some of us will recall the argument made by Dick Ehrhorn of ETO (Alpha amplifiers).  In the early '70s, he decided against rating his amplifiers using these terms and instead rated them at 100% duty cycle with No Time Limit. 

The ads he created showed a brick placed on a key.  In at least two instances, the company held a contest that gave a lucky entrant a new amplifier if s/he could best guess how long the brick was placed on the key at full power.  In the case of the Alpha 86, the winner guessed close to one month.

We should dispense with the CCS and ICAS terms as they can be manipulated to produce misleading results -- and this was exploited by several amplifier manufacturers going back many decades.

http://www.ab4oj.com/quadra/icas.html

Paul, W9AC
(Edited)
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Dave - W6OVP

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>The ads he created showed a brick placed on a key.  In at least two instances, the company held a contest that gave a lucky entrant a new amplifier if s/he could best guess how long the brick was placed on the key at full power.

That's great marketing!
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KY6LA - Howard, Elmer

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NOSTALGIA. I bought SERIAL NO 1 ALPHA 374 directly from Dick Ernhorn at Dayton Hamvention 1974. It was the 3 tube 3KW DX version that he could not sell in the USA to an American and had been used for the brick on the key MARKETING DEmo at the show. Since I was a DX station, I saved him the cost of shipping it back to Colorado and of course got a great price.
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Ria - N2RJ, Elmer

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Recently, the brick on key has been brought back but for the holidays they put a fruitcake instead. Clever.

The company is under new ownership and Dishop is supposedly working on a new solid state amplifier.
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Craig - KØCF

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The duty cycle on the KPA1500 is clearly spelled out in the FAQ:
Q: What is the expected duty cycle for the KPA1500?
A: Duty cycle at 1500 Watts output is rated as 100% ICAS (Intermittent Commercial and Amateur
Service). For 100% duty cycle modulation modes (RTTY, JT-65, FT-8, etc):
• 1.8-30MHz: Maximum 5 minutes key down / Minimum 5 minutes standby
• 50 MHz: Maximum 50 sec key down / 50 sec standby with Min Fan Speed set = 2

It will obviously handle a RTTY contest for the whole 48 hours with its 50% duty cycle. It may be illuminating to read the reviews, which are linked through the Elecraft web page. One of the reviewers is a RTTY contester (WØYK) and raves about its effortless handling of a contest.

The KPA1500 uses two LDMOS devices rated at 1400 watts each, in a push-pull arrangement for excellent IMD numbers.

Just saying...  (disclaimer: I have a KPA1500 on order)

73,
Craig, KØCF