Manager - NA4M
Manager Notes

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

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

eMail Subscription

Registered users are allowed to subscribe to specific review topics and receive eMail notifications when new reviews are posted.
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
More Info:
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
AD5HD Rating: 2015-07-04
Worth every cent Time Owned: more than 12 months.
Easy to build, very easy to adjust. Works very well. Upped the bias to 500mA per FT to get the two-tone waveform to look perfect. Swapped out internal power cable for a 10ga version using 45A Anderson contacts and put a lytic across the Fastons on the board. Drop is about 80mV on xmit. Great on-air reports both by itself and as an exciter for an AL80B. Power and SWR display is pretty accurate compared against an LDG AT1000ProII external meter. Voltage display however reads about 400mV low for some reason, haven't looked into it. Paired with an Elecraft K2 but it helps to have some attenuation in the transmit path so the K2 can run at higher power for best linearity. Broke out the xmit path with RG316 to SMAs on the rear panel and put a 5W 7dB fixed attenuator in line with a 2W 0-10dB variable attenuator to make it easier to run the K2 at about 4-6W while being able to control AL80B output power with the variable attenuator without changing the tune and load settings.

Earlier 5-star review posted by AD5HD on 2013-12-23

Easy to build although it helps if you have a small drill press to keep the mounting holes square to the surface. If I had to do it again I'd get a set of wire drills and hand taps to avoid using the thread cutting screws. They worked, mostly, but they don't lend themselves to repeated disassembly. Ended up drilling and tapping the panel screw channels for 8-32 and used regular panhead machine screws to mount the board and FETs after tapping them with the included screws. All this is really trivial though and doesn't keep the amplifier from being particularly difficult to assemble but if this is your first attempt at kit building it might be something of a challenge mechanically.

Electrically it's a great little design that does what's claimed if you do your part. Winding the inductors carefully and tight to the toroids makes a difference as does getting the output transformer properly tinned and heavily soldered to the RF board to handle the RF current. Winding the binocular cores correctly and getting the output transformer wires tightly wound could be a challenge without taking some care but the Teflon insulated wire makes it easier than it could otherwise be.

The crossover distortion had me concerned, likely for no real reason, but I adjusted the bias up to 500mA each and it's gone. It wasn't gone at 100mA and the FET datasheet gain is given with a quiescent current of 500mA, so 500mA it was. Some flat topping shows up around 40W output but it's not terrible unless pushed close to or past 50W. And it varies over the bands. Gain is pretty high with this higher bias, 17dB-20dB so I broke out the relay-out to amp-in path with RG316 to the rear panel with SMA bulkhead jacks and added an Aeroflex 5W 7dB fixed attenuator in series with a JFW 2W 0-10dB rotary attenuator from the relay-out jack to the amp-in jack, in that order.

Going band by band and using a 2-tone source (Agilent 33522A) requisite attenuation varied about 2dB as did mic gain to get a chart for maximum non-compressed output for each. Data were very close to that logged by the designer, confirming the build as successful.

To make sure crosstalk and potential oscillation were minimized the SO239 jacks were installed with Amphenol hoods and the phono plugs were replaced with Switchcraft direct-solder RF RCA plugs, again using RG316. A Nichicon low ESR 1000uF/16V 'lytic was added by soldering its leads around the base of each Faston tab on the board. The 14ga power wires were replaced with a Powerex 10ga zipcord and 45A terminals for the Anderson Power Pole shells. Measured voltage on the RF board drops about 80mV on full power transmit.

Highly recommended at this price. Heck, highly recommended at twice the price. And you just can't beat the support.
W6THW Rating: 2015-06-23
Great service Time Owned: 0 to 3 months.
Had a problem with the COR (carrier operated relay)
Jim had me make a test and after the test he told
me to send the Hardrock 50 in. It took too days
for him to receive it. He fixed it that night and
sent it back the next day. Two days later i
received it back. It works great now. Now i would
call that good customer service.

Mike w6thw
W3CE Rating: 2015-04-23
More than impressed. Time Owned: 0 to 3 months.
I've owned a HR50 for several months now. I had been using a Tokyo Hy-Poser HL-45B along with an outboard tuner with my FT-817. I read the reviews in QST and on this site and decided to give it a try.
The big plus was that you could add an internal tuner. One unit would replace the two I owned.
Construction was super easy, and service and support is the best I have run into.
The display is full of information and is far more useful than the HL-45B's string of LEDs.
I put a 4:1 balun on the output and was able to tune my twin lead fed 80M dublet on all HF bands with ease. I highly recommend this to any QRP operator who wants a few extra S units on the other end. I just purchased an Elecraft KX3 and am anxious to hook it up to the amp.
K4DZQ Rating: 2015-04-09
Worth Every Penny Time Owned: 6 to 12 months.
I built this for my KX3. This amp was chosen after I did what I thought was a lot of research on this site as well as others. Built kits when I was younger and this was no harder than they were. Comes presoldered and aligned. Mostly plug and bolt. A minimum amount of bias adjustment needs to be made, but this should not be a problem for any General or higher class ham. The support you can expect is 2nd to none.

As an asset it can't be beat. It also gives you a foot up when calling CQ. I have mine linked to the KX3 to follow band selection. Real handy.
N3JON Rating: 2015-04-01
A great kit and a great amp. Time Owned: 0 to 3 months.
The Hard Rock 50 is a great amp. 50 watts out on 160 to 10 meters and a little less on 6 meters. It has automatic band selection for popular rigs which works great for my FT-817. A very attractive display lets you see the ban, voltage, SWR, temperature and PEP. The output transistors are almost indestructible. The amp is a first class quality piece of equipment.

Building the amp is easy for a mid-level experience kit builder. If you are not already wound toroids can be purchased separately. The documentation is thorough, the best I have ever seen. Support is fast, friendly, and helpful.

I have gotten good reports using it and 50 watts is helpful when QRP does not make it.

W5RHR Rating: 2015-03-16
QUALITY and SERVICE Time Owned: 0 to 3 months.
OK so it isnt quite a Heathkit© style kit,no paper assembly manual, but this is the 21st century, however assembly was alignment was easy.

I had three USER errors, quickly rectified by reading the forum and the schematic, my biggest issue was L5 s leads got crossed when winding, thus no B+ to the finals.

When everything got straightened out it aligned right away.50 watts out from the FT817.

I had one other niggle,the autoband switching did not work, and I posted to the forum about it. Within a 1/2 hour, Jim responds with a mod to the circuit board, while he was on vacation!!!

I cannot stress how GREAT the company is and the quality of the kit si 1 number one.

My kit somehow got lost in the mail, and Curtis was helpful all the way contacting the post office to get it going again to my house.
W1IZZ Rating: 2015-02-08
Great amp and fun to build Time Owned: 0 to 3 months.
The instructions were very clear, the kit was nicely labeled and complete, and was great fun to build. The support from Jim was awesome. He patiently answered my questions. A couple of the SMT capacitors pre-loaded on the amp board were out of spec and caused an issue. Jim fixed the amp board the same day it was received, fully tested it, and shipped it back.

I also built the antenna tuner option, which works really well and is very easy to build. If you like to build stuff, this is a great kit.
WD8JWJ Rating: 2015-01-15
Great Little Amp Time Owned: 0 to 3 months.
I love to build things and this was right up my alley. The Hardrock50 is a great little amp. I opted for the ATU and glad I did. The two work flawlessly. Mine is hooked up to my KX3 and band changes are piece of cake. Change the KX3 and the amp changes right along with it. It has a nice display giving you swr, watts out, and bar graph of how your driving the amp, plus much more.
The build instructions are easy to follow and makes for an easy build. Hats off to Jim Veatch, WA2EUJ, for a well designed and thought out Amplifier and ATU kit.
73, bill, WD8JWJ
G3VNH Rating: 2014-12-19
Addition of internal ATU Time Owned: 0 to 3 months.
I endorse all previous comments on the Hardrock 50 amplifier. I have a Revision F amplifier (s/n 12**) and have now added the Hardrock 50 internal ATU.
I modified the original board for full output on 60m. This requires changing 3 SMD capacitors on the board and adding two further SMD capacitors. This mod was easily accomplished and now gives 50 W output on 60m.
The amplifier is wired to my KX3 and automatically band changes. The amp is used standalone on the LF bands and is used as a driver for my SPE 1K-FA linear to give 400 W output (the UK legal limit) on 20m and above. The entire system is run using Win4KSuite software by VA2FSQ along with the integration of DXLab. A really great operating system.

Peter G3VNH
KD0MOA Rating: 2014-12-13
Fun unit to build. Time Owned: 0 to 3 months.

It has been a long time since I build a kit, it was fun and easy to follow instructions. It is a very good unit and the ATU is almost as good as the Elecraft KX3 ATU. The set up is very easy.