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Author Topic: Have you tried either HFProjects or HardRock amps  (Read 2674 times)
K7NHB
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Posts: 226




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« on: May 22, 2014, 01:08:15 PM »

I'm posting here because I'm guessing mostly QRP'ers would be interested in the 35W HFProjects amp or 50W Hardrock amp.
Please share your use experience and if you considered both, what specification helped the decision. I believe the Hardrock is 50W and covers 6M.
HF Projects is 35W and only goes up to 10M. I don't know about the weight but physical size is about the same.
There have been questions about low pass filtering in the Hardrock; the HFProjects version does it with a manual switch.

What things should I consider to help me decide? In either case, I'll have the unit built for me. At 67, my eyes, skill, and workspace are all a bit lacking.

73,
Paul K7NHB
PS: I apologize if mentioning 50W in the QRP forum is Heresy.
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KB1GMX
Member

Posts: 745




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« Reply #1 on: May 22, 2014, 06:40:48 PM »

I've build the core of the HFpacker, namely the Wa2eby/k5oor amp for base use (120V to 28V supply)
Mine was built using a board from FarCircuits that conforms the the published article and uses a
second board with switch for the required low pass filter.

Mine is over 5 years old and still solid, I see about 40W on 40 and 20, and it tapers to 35W on 10M.
I run it at less than max output, which for those bands were more like 57W on 40 and 20 and 44 on 10.
Certainly enough power to make a good account for itself.  I run all modes with it.

The Hardrock is fundamentally the same thing using RF rated devices and has a few nice features.

I think both are similar enough in performance for the basic amp that the features added like metering
or band selection are likely where any real difference is. HAving built more than a few amps including
some higher power solid state VHF amps there is no small amount of personal preference rather than
true technical performance difference.  In the end they either can hear you better or you need way more
power.


Allison

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K7NHB
Member

Posts: 226




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« Reply #2 on: June 01, 2014, 09:20:27 AM »

424 views and only 1 reply - perhaps there is a more appropriate forum?
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KF4CQR
Member

Posts: 28




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« Reply #3 on: June 01, 2014, 10:25:45 AM »

424 views and only 1 reply - perhaps there is a more appropriate forum?

Perhaps in the Amplifier section?  It is QRO to you. 
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G4AON
Member

Posts: 525




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« Reply #4 on: June 02, 2014, 01:27:36 AM »

I built the HF Projects LPF100 low pass filter (which is used in their amp), to include in my home brew TX. I was struggling to source silver mica caps, otherwise I would have scratch built one.

There are a couple of shortfalls with the LPF100, firstly the performance is lacking on a couple of bands, on 160m the 2nd harmonic attenuation is marginal as is the 2nd harmonic on 5MHz. Maybe I am being a bit fussy...

The PCB has some very narrow tracks, if you need to remove a component there is a high likelihood of damaging the board.

Finally, the coil winding is ambiguous. Wound as per the instructions the results were poor. I measured the passband on my spectrum analyser and ended up rewinding a couple of coils. Hence the reference to delicate tracks in the last paragraph.

I am not a novice builder, or solderer, having built many projects over the years and worked to component level servicing for 20 years in the mobile radio industry. But I'd opt for scratch building if you can source the parts.

73 Dave
http://www.astromag.co.uk/g4aon_tx/
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