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Reviews For: Hardrock-50 HF+6M Solid State Amplifier Kit

Category: Amplifiers: RF Power - HF & HF+6M

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Review Summary For : Hardrock-50 HF+6M Solid State Amplifier Kit
Reviews: 59MSRP: 260.00
Based on Jim Veatch's winning ARRL Home Brew Challenge II amplifier design, it's been improved and functionality has been expanded to include a new aluminum enclosure with built in heat sink, an LCD display, pre-soldered SMT components, computer control options, software upgradeable, easier to use connectors, and MORE. All software is open source and the unit hackable, including an accessible I2C header to add your own peripherals.

Kit includes 4 PCBs (3 without .5W driver) with all surface mount components professionally installed using a reflow process. Builder only needs to install through hole components; toroidal inductors, relays, transistors, connectors, etc. Also includes professionally machined case with integral heat-sink, all chassis mount components, interconnects and instruction/assembly manual. Supports auto band select (depending on transceiver) and can be driven with 0.5 watts.
Product is in production
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# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
W4RQ Rating: 2014-11-11
5 Stars! Amp & ATU Time Owned: 0 to 3 months.
I concur with other builders, this is everything that the reviewers here claim it to be. It is a 5 Star addition to my KX-3 station. I want to say Jim Veatch provides the best Customer Service and Tech Support that I have ever experienced!
I haven't built a real kit in many years and I thoroughly enjoyed the build, including winding my own Toroids and Transformers,
Jim was very responsive and helpful. His guarantee of a working build is golden!

Earlier 5-star review posted by W4RQ on 2014-09-26

Recently I found it easy to build this amp kit.
Winding the transformers was easy, it just took a little time, and the rest of the build was a piece of cake. The amp follows band changes of the KX-3 and gives 50 watts out with about 3 watts input.
In October the new internal ATU Kit will be shipping and my preorder is placed at the introductory price, a savings of $40.
At half the price of a KXA100, I am a Happy Camper. Jim's customer service is far above any I have ever seen, and the amp works flawlessly with my KX-3.
KK4ZP Rating: 2014-10-05
Using the Hardrock-50 amp and new ATU with my KX3 Time Owned: 0 to 3 months.
I just wanted to comment on how effortless it is to operate digital modes with the HR50 following DXLab Commander via the secondary CAT port, or following the KX3 via its ACC1

In both cases the HR50 ATU tunes my OCFD in a snap upon band changes and I can run my KX3 at .4 or .5 watts and get 10 -15 watts out of the amp. that is usually more than I need.

Even though I probably worry too much about it, I carefully watch the temperature of the HR50 when using the key-down mode like JT65.

I am having a blast with this set up, and highly recommend it. The ATU tunes my OCFD to SWR of 1.6 or less on 80-10m. Even when I want to use my KX3 without the amp, the QRP mode allows the ATU to tune the antenna.

I usually work QRP but it is nice to have the amp when I want to operate with a few more watts without heating up the KX3.


AG6QR Rating: 2014-09-09
Good amp, great support, sturdy mechanical construction Time Owned: 0 to 3 months.
The mechanics of this kit have changed a little bit since earlier versions (reviewed here). There is no longer any need to drill holes; the heat sink comes pre-drilled and tapped, which makes the mechanical construction easy. The case is rugged, solid bare aluminum, sturdy and nice looking. The heat sink is nicely over-engineered.

All of the SMT devices are pre-installed, and that includes nearly all the resistors and capacitors. What's left for you to do is mostly inductors, connectors, and relays, along with the power transistors. There are quite a few toroids to wind, and a handful of binocular transformers to wind and mount.

I did have one glitch when I went to check out the amp. Jim provided quick help on the support forum. One of the pre-installed SMT chips wasn't soldered perfectly, and I had to touch up a solder joint with my soldering iron. If I had been unable or unwilling to do that, I could have mailed the amp back and he would have gotten it working, but it wasn't hard to do myself. Judging by the support forum traffic, I don't think my problem was typical, but the good support is typical, regardless of whether the problem was caused by the purchaser/builder or the kit maker.

I now have an amp that puts out 50+ Watts on all HF bands, plus about 35-40W on 6m, and it requires only about 1.8W of input drive. I got the optional QSK board for CW, which works very well (my CW speeds are moderate). I've set it up to automatically switch bands, following my KX3 as it's tuned.

For a KX3 owner especially, there's an inevitable comparison with the Elecraft KXPA100. I'm sure that is a very fine product, well-integrated with the KX3. The Hardrock is about half of the KXPA100 in many ways: half the power, half the weight, half the physical volume, and half the cost (if you get both in kit form with QSK and no tuner these days). It offers a kit building experience that lets you get your soldering iron hot, if you like that sort of thing. I do enjoy kit building, and this is a good value, with excellent support and a solid finished product.
N5RWK Rating: 2014-08-19
Great Little Amp for KX3 Time Owned: 3 to 6 months.
I purchased this kit in order to get a bit more power for my Elecraft KX3 transceiver, but did not want to spend the money to get a KXPA100. While I'm sure the KXPA100 is an excellent amp, the Hardrock-50 is less than half the price, and the idea of building it from a kit was appealing.

This was my first build of an amp, but was not difficult. My build went smoothly, except I managed to over-wind a couple of coils by not paying close enough attention to the instructions. I initially had low power output on 80m and 160m, so I checked the coils and sure enough I had wound too many loops. Fortunately removing coil loops is easy to fix, and now the amp works perfectly.

I made a couple of minor mods to the kit to make it easier to connect it to the KX3, substituting 50-ohm BNC connectors for the SO-239's. I also swapped the location of the input and output jacks to ease cable management.

I'm having a blast using the Hardrock-50 with my KX3...running barefoot with the KX3 on SSB required patience, but with amp at 50W making contacts is easy. Using a resonant antenna makes tuning unnecessary, and the auto-bandswitch functionality works well with the KX3. The band coverage matches the KX3 nicely (160-6m).

Overall, this is a great product!
N0MEU Rating: 2014-08-07
Great! Time Owned: 3 to 6 months.
I am not an experienced builder...last kit I built was 30ish years ago. I found the HR-50 kit
to be a straight forward and very enjoyable project with great instructions and fantastic support available from
Jim WA2EUJ. I did opt to purchase the prewound toroids from The Toroid Guy.

I'm using the HR-50 with my KX3 was my main station. I built the cable which connects serial comms and PTT from
the KX3 to the HR-50 accessory port. The HR-50 automatically follows the KX3 band changes!

Overall I'm extremely pleased and definitley recommend the HR-50!
N0AAH Rating: 2014-07-29
Fun again Kit! Time Owned: 0 to 3 months.
Long cry from old heathkits...great little amp that does what it is suppose to do...intermediate build, no surface mounts! Simple to follow directions...and service from Jim!!!! Well, it is the best on the market..Put some fun back in your life and build one!!
W8OQ Rating: 2014-07-13
Excellent Amplifier Time Owned: 3 to 6 months.
I bought this amplifier in Dayton after comparing its features and pricing with the Elecraft KXPA100. The HR50 seemed to be the better value. Building it was easy, but stripping the #30 Kynar wire for the SWR circuit was a challenge. (Easy way from an Internet search: find a nail clipper that has a lever for closing. Clamp down on a straight pin and then use the indents for stripping – works very well!) The amp worked the first time with my KX3, producing 50W with 2-3W drive. The display is quite informative, showing the PEP power, SWR, input DC voltage, heatsink temperature and band. I also purchased the QSK board and it works well at my maximum speed of 28WPM. I have not tried auto band change from the KX3, but as I have to change bands on both the KX3 and SteppIR, it becomes automatic to hit the band switch on the HR50 as well. The only criticism is that the input is not well impedance-matched to 50 Ohms and the SWR is rather high, but the KX3 doesn’t seem to mind and I can use its antenna tuner if needed. With 50W I can’t tell the difference in signal reports from my 100W rig – the difference only amounts to a fraction of an S unit. In my home station I find myself using the KX3/HR50 most of the time rather than a much more expensive 100W rig. In summary the HR50 is an excellent value, very well designed, and a pleasure the use. Highly recommended.
VE7NI Rating: 2014-05-29
Nice amp! Time Owned: 0 to 3 months.
I like running CW QRP and building my own gear. The desire for 25 to 50 watts RF o/p power caused me to do some shopping around for an HF amplifier I could use with my QRP gear.
I also wanted an amp that I could build.
The Hardrock 50 meets all the requirements for my operating. When I wound the toroids, I was too tired and put an extra winding on a couple of them. Once the error was discovered (with a couple of suggestions from Jim), the amp worked perfectly!
I am very pleased with the amp and would recommend it to other QRP operators who want the capability of running a bit more output power from time to time using their favourite QRP rig.
AI5RB Rating: 2014-04-19
Great Amplifier for the KX3 Time Owned: 0 to 3 months.
Assembly was a snap. The fit and finish is solid and beautiful.
Easy and perfect setup/alignment.
Works perfectly with my KX3 cabled to the ACC1. The QSK option is just right for CW!
Full output with 2W in.
The HR50 team was great support during the build - quickly sending a replacement part that I had ruined.
This is a very affordable amplifier for a QRP rig for use as a base station.
KI4EZC Rating: 2014-01-21
Hardrock 50 serial #1180 outstanding Time Owned: 0 to 3 months.
Agreement with common review themes - tough but light, clever, professional case design, small enclosure but large enough to get at all the assembly work, well written complete instructions. It is a completely satisfactory solution for taking QRP power to 50w or more. It is worth a lot more to me than the $270 that I paid for it.
I am not a high experience builder; I place this kit at not as difficult and time consuming as the Elecraft KX1 three bands XCVR built about 9 years ago due to so many small parts are already attached to the HR50’s PCB. There was one skill set that I was not prepared for from standpoint of tools and knowhow - that was the #30 Kynar wire. If I had another chance with the correct wire stripper it would have been a snap. Another knowhow problem was how to lightly tin wire leads on transformers. On four of these components by the time I had my lightly tinned wire ready to go into the PCB, I found my prepared wire a little too large for several of the holes. I made a mess in regard to the kynar wire and tinning to point where the amp did could not pass 100% power up test and Jim V WA2EUJ gladly took my effort and made it work with one day turnaround at my cost of only postage- he promises that everyone gets a working amp. I am very happy with my corrected amp- it delivers spec or better power on all bands that I use regularly 40 - 10m and it passed dummy load test for the rest 160- 6n. With ear phones, I don’t pay attention to the quite T/R standard relays (no QSK upgrade) on CW transmit.
I drive it with 2- 3w with an Elecraft KX3 CW output while using a MFJ 941 manual antenna tuner with the PTT connection. This turned out to be breeze to tune the antenna and switch bands (KX3 automatic band switching on HR50 not implemented yet). I rough set the antenna tuning using the KX3 only for a band, tuning the antenna with the 2-3w, then if I need the amp touch up the tune setting with the amps QRO power. I have worked some dx as far as New Zealand from east Tennessee using a simple dipole less than 30' high with this setup.
The HR50 temperature is safe, starting at room temp of about 65F and going to about upper 80s for normal CW QSO back and forth. I have seen as high as 95f on repeated CQ transmissions. This is well below the 140f that JV recommends as safe limit without a cooling fan. I would expect long winded digital mode to require a small fan later.
I am happy with this KX3/HRr50 as my new main station (replacing 10 yr old IC-718). I plan to use the amp on Field day and try it out on a battery. ki4ezc Fred