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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
M0JMO Rating: 2014-01-04
A 5 Star Kit! Time Owned: 0 to 3 months.
I've blogged about the build of my Hardrock-50 at so I'll try not to repeat myself too much here.

Cost approximately £250 GBP after shipping and import duty to England. Shipping was fast and included tracking.

The instructions for this kit are fantastic; really detailed and thorough. The kit went together without too much drama. I bust the drill bit on the second to last hole... Luckily all the holes for the transistors had been drilled! The Teflon wire is slippery to work with.

50w on all bands from 80m to 10m... Not tried 160. 6m gives about 30w, but I have a problem with the input SWR (4.6:1), so I must have messed up somewhere.

Apart from that, it works exactly as described. The case is rugged and looks good. A really professional product!

Jim replies to queries via email quickly and politely; seems he really cares about customer service!!

Next stop is to update the firmware again and mod the rear board so I can auto band switch with my KX3 :)

Definitely 5-Stars!


N5LDX Rating: 2013-12-31
Great QRP station addition. Time Owned: 0 to 3 months.
Kit shows quality design and was very easy to follow the step-by-step assembly instructions.
I had a 20/17 meter low output problem due to two wrong SMT capacitors types and low output on 6 meter due to one extra turn (6 instead of required 5) on the 6 meter output filter torod.
Jim Veatch, WA2EUJ, the designer of the amplifier suggested I let him look at the issues and fix the problems. He turned the amplifier around in a day after receiving it and it now puts out 50 watts on 160 through 6 meters with 2.5 watts drive. Great product support from Jim!
The amplifier is just what makes my FT817ND perform when needed during difficult band conditions. I operate the entire portable setup with an endfed antenna with a 9:1 balum, and a small MFJ switching power supply for the FT817ND and Hardrock-50 amplifier.
This will be my QRP protable setup for those remote operation conditions while traveling. The extra power makes this setup work for good and reliable contacts when away from the home station.
KB2NGK Rating: 2013-11-26
Works Great - Good Project Time Owned: 0 to 3 months.
I bought this amp as a compromise, not wanting to spend three times as much for the KXPA100 which was yet to be released, especially considering I will seldom need or use an amp. The kit was complete and pretty straight forward. A pleasure to build.

After building, I had low output on a few bands so I contacted Jim Veatch - designer of this amp. He sent me a couple replacement caps, but after replacing them it appeared that the 5V regulator failed. Could have been my fault but not sure. I sent the amp to Jim who repaired it free of charge. You can't ask for better customer service.

This amp does what its supposed to. 50Watts out with minimal drive on all but 6M - 35Watts on 6M.

Overall - Very pleased.
KJ6PTX Rating: 2013-11-10
Great project and amp Time Owned: 0 to 3 months.
A very enjoyable project. The Hardrock-50 provides enough of a challenge that you feel like you’ve accomplished something without being so complex or time consuming that completion is really in doubt. Especially with the great support and encouragement that Jim Veatch, Curtis from HobbyPCB, and the various forums provide. It’s a good, hands-on way to get more familiar with amp components and design as well as some construction and soldering skills. The excellent online instruction manual is easy to follow, thorough, clear and well illustrated.

The amp itself fills a useful niche: 50 watts, under 3 lbs. and less than $300. It adds that extra oomph, when desired, to a QRP rig. The firmware is upgradeable and extra capabilities are evolving in both hardware and software.
VR2XMC Rating: 2013-10-24
Great amplifier and value for money Time Owned: 0 to 3 months.
During field days, power consumption is always of concern. Therefore, I would choose radios with low standby RX current so that I chose Elecraft KX3. However, the output power from a QRP radio is often around 10 watt. Under difficult communication condition, higher power at 25-50 watt is required.

I decided to go for QRP radio + a small linear amplifier covering HF & 6m. This combination in field day (or ARES) will meet my requirements of:
1. low standby RX current;
2. QRO to 25-50 watt if required

Elecraft produced a very nice small linear amplifier KXPA100 with output 100w for KX3. It is also the only linear with built-in ATU in the market.

Regrettably, KXPA100 is beyond my budget. Furthermore, 100w in portable operation will imply quite a demand of power supply.

I eventually go for the kit HardRock 50 (HR50) which covers 6m and well fit my budget. HR50 also gives me the fun of soldering of which the Elecraft KXPA100 is lack.

The soldering and construction work is straight forward with a well written assembly manual. The construction difficulty is less than building my Elecraft K2(s).

At the final stage of construction, I encountered some small problems in the DC bias alignment. An email to Jim WA2EUJ got prompt and detailed reply. The problems were solved after a few email exchanges. The level of service from Jim is as good as the famous Elecraft support services which I often used to. Jim’s advice was concise and right to the point.

The circuit design, which won the ARRL homebrew award, is really good in terms of quality and component cost control. It conservatively uses 4 x RD16HHF1 MOSFET to deliver 50w. RD16HHF1 is readily available in the Chinese component retail market at around US$4 per piece. Therefore, the concern about replacing an expensive RF components in case of builder’s mistakes is not much. Clearly, the circuit design is so well that it is very difficult to cook the RD16HHF1.

All the surface mount components are pre-installed so that only through hole soldering work is required. The wiring work for band pass filters and RF transformers is quite fun to me. This fun is missed in the recent Elecraft kits which only requires the plug-in of PCB (i.e. no soldering work).

The end product HR50 nicely produces 50w for all HF bands with input power less than 5w. It also gives >35w in 6m as per specifications.

Jim has recently rolled out the firmware 1.4E for HR50. I updated the firmware of my HR50 via the USB port in its real panel

I enjoy very much in building (including soldering work) this small linear amplifier which fits my budget very well. I have no business connection with Jim WA2EUJ but am just a happy customer.

AB6WL Rating: 2013-08-25
Great Amplifier for All QRP Rigs Time Owned: 0 to 3 months.
The Hardrock-50 is a great product, and I can only highly recommend it to enthusiastic kitbuilders and QRP/50W QRO operators. It does involve combining your mechanical construction skills with your electronic construction skills, but it is well worth it. Just take your time as you build it, thinking through each step of the process, and if you have any questions along the way, do not hesitate to email Jim, the designer, via the ARRLHBC yahoo group. Either he or Curtis of will send you a quick response. Jim's goal is that every builder end up with an entirely working amp. For example, he promptly sent me some new capacitors when the pre-installed ones happened to have the wrong values. Then, he helped me through some final adjustment problems that I was having, so that now I have a very enjoyable 50W amp with the latest firmware. I use it with five different QRP rigs (with a sixth one and a seventh one soon to be completed as kits). Jim even helped all of us figure out how to obtain a shorter return to receive time, which suits me very well as a strictly CW operator. The bottom line is that the amp is a great design and the support provided by Jim and Curtis is outstanding.
WA5ONL Rating: 2013-01-24
Works fine; a TRUE kit ! Time Owned: 0 to 3 months.
Building this kit was a real adventure! This is NOT your nostalgic Heathkit. You get to wind your own toroids, drill holes, make coax jumpers, etc. I was fortunate to have the help of one of our company machinists in drilling and tapping some of the holes in the chassis/heatsink. This would probably not be a kit that I would recommend to anyone who doesn't have at least a fair knowledge of the things mentioned above, and good soldering skills. I am using the amplifier with the Flex-1500 SDR to get me from 5 watts to 50. This makes a big difference! At present, you have to switch bands on the amp by hand; the designers are working on software to let your rig do this for you. Follow the instructions CAREFULLY and you will be rewarded! Mine worked the first time! There are other amps around, like the Backpacker, for a lot more money. With the experience and test equipment that I have, I decided to have a go at building something myself, and I'm glad I did! Now I have the itch to build something else!
In summary, if you have a QRP rig and want a nice boost in power, and are willing to do some careful assembly, the Hardrock just might be for you too.
N0BS Rating: 2013-01-11
Works great - great value. Time Owned: 0 to 3 months.
The Genesis for the Hardrock-50 was the ARRL Homebrew Challenge II design contest. The winning entry, by Jim Veatch, WA2EUJ, has evolved into the current iteration of the Hardrock 50.
This amplifier covers 160 through 6 meters (not including 60m), and provides a nominal 40w to 50w output (slight variation from band to band, and 30w - 35w on 6m) from a 5w input, making it a very nice accessory for any of the numerous 5w QRP rigs available today. An optional preamp will provide the same output using only 500mw drive, making it the ideal companion for the very popular SoftRock series of transceivers, giving them “big rig” power in a small package.
The kit includes all parts required to construct a fully operational amplifier, including a very heavy duty extruded aluminum enclosure and heat sink. Also provided are extremely attractive front and back panels with all holes pre-punched and labeled, resulting in a piece of gear with a very professional appearance when completed. The front panel sports a lighted display that provides band information, power output and SWR bar graphs, and digital readouts. The amp is powered by a user provided external 13.8 vdc supply, connected via back panel mounted Anderson Power Pole connectors.
The heavy duty printed circuit boards are of very high quality, with all surface mounted devices pre-installed. Only through hole parts are mounted by the builder, and components seem to be of very good quality.
In my opinion, I would recommend that the builder have some prior kit building experience, but anyone with good soldering skills, a few hand tools, and the ability to read and follow instructions carefully, should be able to successfully build this kit. The instructions are clearly written and easy to follow. A number of toroids must be wound, as well as several transformers, and very detailed instructions for properly making these components are provided – nothing to fear.
Note that the final mechanical assembly may be the most challenging aspect of this kit for some builders. The heat sink is not pre-drilled or tapped for mounting the main circuit board, and the 4 MOSFETS also require individual mounting holes to be drilled and tapped. Self tapping screws are provided, but relying on them to properly tap the hole without breaking off in the hole is at best, optimistic, and at worst, a messy problem. A “factory drilled and tapped” heat sink option would be the single greatest improvement that could be made to this kit.
Initial check out and set up is very straightforward, requiring only a decent quality digital multimeter, a few test leads, and small screwdriver to adjust the bias pots.
The Hardrock-50 provides keying via either rf sensing (COR) or via an input signal from your transceiver (PTT). T-R switching is accomplished via a relay, which is quite quiet, even on cw, and works very smoothly. Jim is working on a QSK option for those operators who prefer higher speed T-R switching for cw. A standby mode is also switch selectable, so you can quickly and easily switch between your QRP power level and 50w.
Overall operation is simple, and the amplifier works very smoothly with a variety of radios. Various functions of the amplifier, as well as the display, are controlled in firmware, so additional future options and updates are planned, such as auto band switching with radios like the KX3. Firmware updates can be loaded from your PC to the Hardrock-50 via a built in USB port.
On the air reports are excellent, and running 50w is only 3db (or a half S unit) down from a 100w rig, so this amp gives your QRP rig all the extra power you need for most situations. If you need more, the 50w output is enough to drive most larger amplifiers quite well.
I have been extremely pleased with this amp and would highly recommend it to anyone that wants to be able to give their QRP rig some extra output. For $259 and a few hours work, I consider it to be a very good value.
There is a support forum on the HobbyPCB web site for the Hardrock-50, and Jim Veatch is unsurpassed in the level of support and service that he provides for his designs.
The Hardrock-50 is currently undergoing FCC certification.
I have no affiliation or business relationship – simply a happy user.
K4RYR Rating: 2012-12-13
Great Amplifer for QRP Rigs Time Owned: 0 to 3 months.
Purchased this amplifier and assembled it in about 10 hrs. Take your time and follow instructions and it works great when you first turn it on. Coupled with a Flex 1500 it turned it into a good reliable HF radio for all the hf bands. You don't have to be an experienced kit builder to assemble this kit or need any special test equipment to set it up. A good buy for the $$ with excellent factory support if you need it!