| K2GAV |
Rating:  |
2024-09-28 | |
| Rugged, sophisticated, not quite bulletproof |
Time Owned: more than 12 months. |
I've owned this amplifier for almost four years and have logged over 12,000 contacts with it.
The split design allows the power supply to be placed away from the shack bench and the RF deck is as small as any small HF rig. It's about half the size of my TS-990.
The unit is well built and provides a compact full legal limit amplifer with an internal antenna tuner.
I had two infantile failures due to a poor design. Fortnately, I was able to obtain the modification parts from Elecraft and install them myself. That saved me about $250 in shipping costs.
Sadly, the amplifer suddenly failed with a Low Gain - 0 message. It was out of warranty so it had to go back to Elecraft for repair. After a ~$1,000 repair bill and ~$220 in shipping costs - plus 2-1/2 months repair time it's back home and working again. Since the amplifier keeps an error log, which I examined before it went back for repair, there was nothing I could see that indicated this was my fault. Elecraft agreed that they could see nothing in the log to indicate why it failed. Both LDMOS FETs were replaced. Uggh! I've owned two Elecraft rigs and both have had to go back for out of warranty repairs. The other is a KX-3.
BTW, Elecraft will not provide a schematic or a service manual for this product. So, for out of warranty repairs you're at their mercy and expect a hefty bill and a long wait time without it.
In summary, I've enjoyed using the KPA-1500 for many, many QSOs. But, this strange failure and high cost (in time and money) has taken some of the joy away.
It would have earned a GREAT! review if it weren't for the costly failure and lack of service information. |
|
| N6XI |
Rating: |
2024-08-09 | |
| Outstanding Full Power Solid State HF+6 Amp |
Time Owned: more than 12 months. |
[Updated Aug 2024 from original posted in 2018]
Like many others, I had waited a long time for Elecraft to introduce a full power HF+6 amp. I loved the KPA500 as a Rig 2 amp in my SO2R station but occasionally wanted just a little more "oomph." I loved my trusty Alpha 87a but felt that its auto-tune motors moaning and groaning in the background were a bit dated and the 3-minute warmup at turn-on was ... well, a turn-off. Also, the tiny, pixel-based remote control app from Alpha was hard to see on a modern, high-resolution monitor so I was uncomfortable operating that amp remotely. As a result, I did most of my remote operating with the KPA500 and really missed full power in DX pileups. I had just about given up hope - and in fact had a back-order in place for an almost-full power solid state amp from another manufacturer - when I got a call from Elecraft offering me the opportunity to field test their upcoming KPA1500. I was delighted but cautious, understanding from personal experience that the last 20% of an engineering project can take 80% of the schedule time. I gave them an enthusiastic "Yes!" but waited for a few progress reports before canceling my pending order with the other company. I'm glad I hung in there with Elecraft.
The KPA1500 became a reality and it was well worth the wait. It is exactly what I had hoped for, a full power version of the KPA500, seamlessly integrated with my K3 transceiver, and later K4, which now operates as if it were a 1500W radio. Of course, an amplifier is a pretty easy thing to integrate, and the KPA1500 will work fine with any transceiver - just connect to the near universal SO-239 RF input, RCA phono plug key line, and SO-239 coax antenna and you're good to go. With the K3 and K4, there is a special 15-pin cable that connects to its ACC connector to provide not only a key line but also BCD band data, Auxbus frequency data, a power-up signal, a tx-inhibit signal, and ALC. With some Icom radios, the same 15-pin connector accepts their unique voltage-level band identification in place of the Elecraft/Kenwood/Yaesu BCD. There are also Ethernet, USB, RS232, and AH4 interfaces for use when needed.
There are some interesting and beneficial differences between KPA1500 and the earlier KPA500 amp. While the KPA500 had an internal, linear power supply and an optional KAT500 external antenna tuner, the KPA1500 has an external, switching power supply and a built-in, internal antenna tuner. I like this arrangement for several reasons: The KPA1500 RF deck is nicely compact, only slightly larger than a K3 or KPA500, fitting easily into either of my two stations. It is light weight and much easier to handle than typical tube amplifiers like my Alpha 87a or the ACOM 1000 I'm still using at my valley station. (When will I trade it in for a second KPA1500??) The power supply is the same size as but lighter weight than the RF deck, contains its own cooling fans, and fits unobtrusively behind or under the operating desk. (You could certainly locate it on the desk if you have room.) You'll love the DC power cable with its 75 amp Anderson Power Poles and #4 conductors! It's quite flexible, considering its size. Unlike the smaller APP connectors, the 75 amp units have a robust, detented locking mechanism that produces a healthy “snap!” when you fully insert the plug. They're big and beefy, befitting the high current being passed. I also like having the ATU built-in and included. Even though most of my antennas are well-behaved, the ATU gives me full-band flexibility and an added measure of confidence that my amp is safe. Like its little bro, the KPA1500 has instant-reading LED bar graphs for RF Out and SWR, but its LCD display is larger and more informative. You can cycle through pages displaying just about any operating parameter you would care to monitor, much like the ACOM 1000 that has been my favorite manually-tuned, tube amp. The power graph has more than 30 LEDs, but the logarithmic scale results in only six of them being active between 1000 and 1500 watts where most users will spend most of their time. The engineer in me understands but my inner pedant wishes the scale were somewhat expanded, with more precision where it's most useful.
What about switching noise from that power supply? There doesn't seem to be any. After six years, I've never encountered a noise attributable to the KPA1500 PS. I've also been unable to detect any increase in noise floor. In fact, the noise floor dropped on some bands when the amp and its ATU were inline, surprising me until I realized that the ATU was filtering out-of-band noise. Elecraft says they did much more thorough and scientific searching for such noise and also found none. I think both Elecraft and their OEM PS vendor did a good job of filtering out switching noise. By the way, the PS can be placed on the desk or floor. It has three LEDs but you really don't have to look at them unless you're diagnosing a problem.
Operators of other Elecraft rigs have been asking me on the air about the ATU: Is it the same as the other excellent Elecraft auto-tuners? Well, yes and better! Like its predecessors in the K3, KX3, KX2, KAT500, and its successor K4, it uses relay-switched inductors and capacitors in an L-network. The tuner can put the caps on either side of the toroids to increase flexibility in finding tuning solutions. Unlike the earlier tuners, though, this one has gobs of memory for tuning solutions. For every 20- or 50-KHz segment of every band, the tuner can retain up to 31 separate tune settings, certainly more than ample! When it finds itself wanting to re-tune, it first checks all known settings for the current segment. In less than a second (mere milliseconds in many cases) it can adapt to a change from one antenna to another that it has seen before. Only for previously untried antenna/frequency combinations does it have to seek a tuning solution. Even that is pretty fast, as with other Elecraft tuners. The amp puts itself into Standby automatically when the ATU is tuning. It also has slightly different operating modes than KAT500. The default mode, which I've used almost exclusively, tunes only when requested by a TUNE button. It follows the band segment in which the transceiver says it's operating or it determines frequency by sampling incoming RF from a non-integrated transceiver. You get one-touch tuning with Elecraft exciters - tap TUNE and you're done in seconds ... or less.
Like the KPA500, this amp operates full QSK with silent PIN diode switching. It's good, clean QSK, not quite as easily interrupted as a barefoot K3 or K4, but everything I could ask for. Compare that to amps like the Alpha 9500 whose loud vacuum relay competes with the transceiver's audio output to drive your ears into distortion! Speaking of noise, the fans in the RF deck are temperature-driven, quite quiet at idle but they qualify as loud when the amp heats up. It's not as loud as the blower in a 9500, but certainly noticeable.
On the air, the amp has generated 100% enthusiastic comments. "Great audio," "perfect keying," and "LOUD!" are the things I hear. I've operated it for six years now, making thousands of casual CW, SSB, and RTTY contacts and some serious and casual contesting on all modes with nary a hiccup. RTTY can be a real challenge for amplifiers, but KPA1500 handles it well at full power for extended key-down periods. The amp self-limits at 1800W but the two solid-state devices could each generate full power themselves, so the pair is loafing along at 1.5 KW. I'm a stickler for avoiding the red LEDs, that light up over 1500W but I understand that headroom is a good thing. K6NV offered the following unsolicited report after a RTTY Roundup: "Friendly neighbor report - That amp is a 10+. No phase noise, no clicks, no spurs, nothing but a nice sig, did not know you were on except for the vertical spike on the P3 with red around it. Very clean, really nice to listen to from a mile away."
I often operate my mountain station remotely from Silicon Valley. I enjoy using the excellent KPA1500 Remote app which has a client/server mode that gives me an attractive remote control panel running on the control site computer. Additionally, KPA1500 Utility provides an interface for firmware updates, configuration parameter settings, and firmware command communication. It runs locally but can be accessed remotely via a remote desktop app. That RTTY RU contest I mentioned above was done remotely, my first attempt at remote RTTY, and it was almost as good as being there.
The KPA1500 PS comes with a built-in AC power cable with a common US NEMA 235V plug. If your socket is different, you can build an adapter or cut off the factory plug and install your own. The package also included the 15-pin D-sub control cable that connects the PS and the RF deck, a USB cable to connect the amp to your computer, and a high quality but rather short RCA-to-RCA cable in case you choose to use it as a dedicated amplifier keyline connection. It was too short for all but the most compact station layouts and I hope that by now they have upgraded to a longer one. But it doesn't really matter for me because I key the amp through an optional KPAKnAUX cable (K3 or K4 ACC to KPA1500 AUX) which is long enough for most purposes and provides the additional integration signals mentioned above. The manual, which I have reviewed in draft form, is quite good, as we have come to expect from Elecraft.
All in all, KPA1500 exceeded my high expectations. It is a noble addition to the Elecraft line of transceivers, amplifiers, and accessories. I look forward to many more years of faithful service.
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|
| W2NER |
Rating: |
2023-08-28 | |
| Better than expected! |
Time Owned: 0 to 3 months. |
I have had many many amplifiers and my goto amp was a Acom 2000A which I sold recently. I have been a Acom guy for years. If you thing is tube amps, Acom is the one to go to. I'm getting old and I wanted to get something that would be easy to move around in the event my wife had to. At one time I had a Elecraft KPA500 which was bulletproof and was a great amp. So, I gave a KPA1500 a try, and I'm glad I did. It's wonderful, and the auto tuner is fantastic bar none! I have been so impressed by the workmanship I have gone all Elecraft! I purchased a KPA1500 a few weeks ago and it's been flawless. I can run it with 20w and see, 1300 watts with no problem. So, if you can swing the cost, get it, you wont be sorry. Yes they had some issues with the firmware early on but, that's been all ironed out. A++++. Sorry Acom, I've been converted, hihi! Oh, I have seen many say the fans are noisy, well I can agree with that to a point. But, I fixed that by replacing the fans and changing the mounting system. The mounting is done with rubber standoff's now, like many fans are done. Between the fan replacement and mounting system change, you can hardly hear them. Now if your into contesting and the fans run at high speed to cool the very high temps, yes, you're going to hear them. No getting around that, but, it is a massive improvement now with my mods.
As far as the power supply making any noise, that has to be an anomaly because you do not know it's even powered on in my shack. If you do a lot of digital work and push the amp it limits, you have to keep an eye on your temps. I don't do much digital work at all so, no data on performance with this mod.
Mod installation:
I don’t have instructions but I have some pics. It’s not that hard, the hardest thing was drilling out the holes where the pressed in nuts are. Getting them out is easy, put one of the fan screws back in part way and tap it with a hammer, come right off. Then after all of them re out, you need to drill out the holes large enough for the rubber fan mounts (not to big, step one size at a time till the rubber mount goes in snug). I think mine ended up being a .197 dia drill but, I’m not positive. Mount all the rubber mounts on the fans, then install the fans on the 1500. You have to cut and splice in each fan, you can trace each wire back to where it’s soldered on the power supply but, for ease of installation, I decided not to do that. Below are the parts and legal stuff.
I take no responsibility for any damage you or this modification may cause.
Fans
https://www.ebay.com/itm/303103688139
Mounts
https://www.amazon.com/gp/product/B01M4LVBY2/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
install Videos
https://www.youtube.com/watch?v=wykqVTTvrUI
https://www.youtube.com/shorts/DNwfdbBOW1c |
|
| NR9V |
Rating: |
2023-08-07 | |
| Great amp but not perfect |
Time Owned: 6 to 12 months. |
Great amp, very nice front-panel layout & UI, easy to set up, small footprint. I ended up trading 'down' to an SPE Expert 1.5K-FA however which I like better yet cost ~$1500 less. Both work flawlessly with my TS-890.
The SPE is lighter, quieter, less fan noise and supports 2 ins 4 outs and SO2R. I used to have the 1K-FA about 5 years ago which was not as nice, the 1.5K-FA is a definite step up.
I should also note a small issue - the KPA power supply makes a quiet buzzing noise when the amp is off which is annoying and requires both the amp and the power supply to be separately turned on & off if you don't want a constant quiet buzz in the shack. |
|
| N4APG |
Rating: |
2023-06-04 | |
| Excellent Performance on MARS/GOV Frequencies |
Time Owned: 3 to 6 months. |
I am very pleased with my new Elecraft KPA1500 amplifier. The amp has abundant overhead, even on MARS/Government frequencies. Once trained to the frequency of use, the tuner is extremely fast and capable. This amp can easily meet government standards for ALE operation and tuning.
The connection to my Yaesu FTDX101MP is straightforward with the Elecraft interface cable.
This is not an inexpensive amplifier, but worth every penny if you need an amp for MARS and Amateur Radio use. Elecraft has gone beyond in making this amp useful in MARS. |
|
| W2LEW |
Rating: |
2023-04-02 | |
| Very Pleased |
Time Owned: 0 to 3 months. |
| Well I have owned my KPA 1500 s/n 01257 for just about one Month, and I am here to share my opinion. The KPA replaced an Acom 2100 Tuber which has been 100% reliable. I decided to go 100% Solid State with the Elecraft. I have the KPA 1500 coupled to a Kenwood TS 890 via a Serial Cable to enable auto band switching which it does very well. I usually keep my power levels at a KW or less, but it's nice to have the Horsepower if needed. I believe the KPA is running dual BLF188XR finals which have plenty of headroom in the RF department. Even at sub Kilowatt levels the Fan kicks in shortly at stage 1 and is somewhat noisy, but at stage 4 it is deafening. The built in auto tuner works so well and fast that I sold my HF Auto as it was no longer needed. I noticed that most competitive Legal Limit amps are foreign built and I wanted a USA manufactured one to avoid shipping over the Pond if repairs or parts are needed. It was a big $$ investment, but I'm happy with the product. |
|
| K3MD |
Rating: |
2022-11-18 | |
| Great when working |
Time Owned: more than 12 months. |
After delaying purchasing one of these amplifiers 4 plus years, I found one for a very good price used. The seller had had the unit updated and tested before selling it. The unit puts out 1500 W effortlessly. I interfaced my unit with an IC-7610, and the amplifier tracks the exciter flawlessly. This is remarkable given my lack of IT skills. The fan is a bit noisy, but at least it prevents the power out from destroying the transistors on board. The built-in antenna tuner is totally remarkable... it will match 3/1 very easily. I have never seen an automatic antenna tuner with such an extensive matching range. It performs well in the CWT... the CQWW SSB is this weekend... we will see (unless it gets totally wiped out by the solar flare). This unit is a joy to operate, after using manually-tuned full-power linears for 50 years. On DXpeditions I used an Ameritron 500W transistor amp with an external manual tuner. No need for that... the KPA1500 tunes your 80/40 antenna very easily. I plan on sending in another review after pounding the unit in many HF/VHF contests later. At least I have no need to pay $750 to $1500 for a new old stock Eimac 4CX1000A tube for my Alpha 8410 linear. Good Eimac pulls are $900 at RF parts... I got my good pulls for $150 a few years ago.
I had a single final failure after about 5 months. It took 3 months to get repaired. The repaired unit worked, but the ci-v did not work. Reset my IC-7610 in the chance that it was at fault. Excited with 100w, both finals blew. Lost temper, sent it back. It was repaired on warranty, but only the RF unit was sent back. I guess this is my fault for describing the problem in a detailed letter included with the unit rather than going thru product service. Got power supply back, so far it has been working FB. I still keep my no-problem used KPA500 and Alpha 8410 for backup. I do not like losing a final in mid-contest, which often happens. Like losing your hospital's CT scanner and having to send cases out. |
|
| AA6VB |
Rating: |
2022-11-17 | |
| An Excellent Amplifier Despite Some Shortcomings. |
Time Owned: 6 to 12 months. |
When my main amplifier needed repair I finally put my KPA1500 into service. The raft of DXpeditions presented an excellent opportunity to run the KPA through its paces. Performance has been outstanding.
A simple 1/8” (3 mm) mono or stereo cable connection was all that was necessary to allow the amplifier to track band changes on my Icom exciter. Operation is smooth and seamless. It’s like having a 1.5 KW Transceiver.
The menu system is clear and very easy to navigate. You can access certain menus items (e.g. fan settings) even when the amp is transmitting. The build quality, fit and finish and ergonomics are all excellent. The RF deck is small and separate from the power supply so it takes up less space on the operating desk than many other amplifiers.
I have only used it a few weeks but it has been flawless on CW and SSB up to the legal limit and FT8 up to 800 watts (don’t feel the need to run more power even when conditions aren’t great).
Elecraft uses two BLF188XR LDMOS transistors each capable of between 1200 and 1400 watts (depending on frequency) at 50 volts so running the amp at 1500 watts leaves plenty of headroom. The use of two devices is, in my opinion, an advantage over some other amplifiers.
The amplifier remembers the antennas “per band”. The tuner, after being properly configured, remembers the tune required for each band segment and automatically switches to that match (without retuning).
In the interest of providing a meaningful review for those who are trying to choose between one amplifier or another I feel compelled to share the following comments:
The fans can be loud at setting “3” and above and positively deafening at the highest setting - “5”. The fan noise is much higher than any other solid state or tube amplifier I’ve ever owned and it’s not a close contest. Don’t take my word for it. Just listen to the YouTube videos posted by WX0V. I use a RadioSport Headset which is pretty effective at eliminating most ambient noise but the fan noise still comes through at the higher settings.
I also wish Elecraft had seen fit to (a) allow two inputs (like SPE, Flex, and Icom); and, (b) provide at least 3 and preferably 4 outputs. Sure, one could use outboard coaxial switches for the inputs and outputs but these external devices should not be required on a high end amplifier. In my opinion this is a major shortcoming of the amplifier and my reason (along with the fan noise) for rating the amplifier a “4” instead of a “5”. Otherwise, it’s a fabulous amplifier.
For anyone using one radio and only two antennas, or for someone who doesn’t mind extra devices (antenna and rig switches) in the shack this is a truly great amplifier (if fan noise is not a concern). The amplifier should meet or exceed expectations.
73,
Bob/AA6VB |
|
| AE6PP |
Rating: |
2022-06-09 | |
| Excellent |
Time Owned: more than 12 months. |
| How to describe my KPA1500 Amplifier? I would like to say: BEST EVER. I have been QRV since 1960 as OH1VR and owned few home made, Dentron, Kenwood, Acom etc. amp's. My KPA1500 arrived to Finland over a year ago and since it has used mainly remote. The tuner of the amplifier is incredible. For remote user the amplifier is easy and secure. I'm not a technical guy - I love to operate and finally I have something that runs smoothly with my Elecraft twins. Yes, one problem: the price. The government of Finland wanted me to pay extra 24 % as VAT. |
|
| KP4AA |
Rating: |
2022-02-11 | |
| Best Amplifier I’ve owned to date. |
Time Owned: more than 12 months. |
I bought my KPA1500 over a year ago as the second owner. My previous amp was the KPA500/ KAT500 which I bought new in around 2015 and never had any issues with.
The KPA1500 has been through numerous 48 hour contests and hasn’t hiccuped. I keep the RF deck and Power Supply right next to each other and intentionally have the fans set to level 1 for everyday operating and level 2 during contests via the menu options. Why even allow the amp to get warm enough for the fans to kick in? Heat is the enemy! I do not find the fan noise objectionable whatsoever but I also use headphones when operating.
I have no complaints at all about this amp. One thing I have found is that the protection circuitry is extremely good at finding intermittent antenna, cable and connector problems that I was unaware I even had. Every single time I’ve noticed intermittent high SWR (yellow or red) on the amp or it intermittently faulted out it wound up being either an elevated vertical radial on the ground or shorting out to a fence in the wind or a poorly installed connector or a bad cable. I wouldn’t have noticed many of these quick intermittent problems with a tube amp. The auto tuner is also very easy to train and is as good at matching as any auto tuner I have used.
I have the amp mated with the Elecraft K3S, Array Solutions remote antenna switching and the OM Band pass filters. All instantly switch during a band change. There is no option for operator error at KP4AA and it’s nice to chase new mults on other bands with a single push of a button and not worry about blowing something up. I will never get rid of my KPA1500 and I will never go back to a tube amp.
If I could add one improvement it would be to have the power supply on/off switch moved to the front of the power supply from the rear. It’s very important for me to isolate the power supply from the mains here on the island where voltage spikes often occur. Turning it off from the front instead of reaching behind the power supply would be nice. |
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