QRP power amp help

Discussion in 'QRP Corner' started by N9APE, Jul 21, 2019.

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  1. N9APE

    N9APE Ham Member QRZ Page

    I have a mcHF SDR transceiver that works beautifully. I also bought a MiNiPA HF Power Amplifier to use when I want to go to 100w power, but I am unable to find any documentation on the amp and the Chinese manufacturer shows nothing (including the amp). Wonder if anyone knows where I might find documentation for the amp or, in lieu of that, a small amplifier (with documentation) that might be used with the QRP rig.
    Any help or suggestions would be greatly appreciated.

    73 de N9APE, Dovid
  2. KG7WGX

    KG7WGX XML Subscriber QRZ Page

    The Hardrock 50 (kit) is a small amplifier with excellent documentation.


    I believe the mcHF has an accessory jack which can be used to key an external amp, but if you don't want to do that, the Hardrock 50 will work in carrier-detect mode.

    From the Hardrock 50 manual, it looks like it would not support auto-band select with the mcHF, so you would have to select the band on the amp manually.

    There is a diode QSK option and an antenna tuner option, too.

    (I almost bought one of these to use with a KX3, but the tight integration of Elecraft's KXPA100 won out and I bought that instead. Rice and beans for a few months to pay for it... ;))
    KU4X and KU3X like this.
  3. N9APE

    N9APE Ham Member QRZ Page

    I've heard this is a good amp, but it is not what I'm looking for. It only goes to 50 watts and I'm looking for something that will give me 100 watts output, like the MiNiPA. One ham, in another forum, says he has the documentation I need for the MiNiPA. I'll see if he comes through. Otherwise, I'll keep searching on QRZ.
  4. KU3X

    KU3X Ham Member QRZ Page

    Get the Elecraft KPA100. Great amp and it does 100 watts.

    Be very careful of what Chinese or Ebay junk you look at. Remember, first of all it has to have band pass filters for each band. Next you have to make sure it meets FCC specs for harmonic suppression. Just because it's not made in the USA does not mean you are allowed to put junk on the air.
    You are responsible for making sure you station puts out a clean signal.

    The Xiegu XPA125B may fit your bill. But make sure it is the "B" version. The non "B" version does not meet FCC specs.

    You get what you pay for.

    50 watts out is only 3db down from 100 watts. So if your 100 watt signal is S9 to another station, your 50 signal will now be S8-1/2. You are only down
    1/2 of an S unit. Big Deal !

    Don't sell the Hardrock 50 short. It really is a great little amp.

    Barry, KU3X
    KU4X likes this.
  5. K8TDN

    K8TDN Ham Member QRZ Page

    Thanks Barry for the input. I think that is what I am going to buy
  6. KG7WGX

    KG7WGX XML Subscriber QRZ Page

    Just some notes about the KXPA100 vs the Hardrock 50, other than the 100 watts vs 50 watts difference -

    My understanding is that the KXPA100 requires a PA Key input from the transceiver where the Hardrock 50 can run in carrier-detect mode. For some QRP rigs, it can be a problem to devise a PA Key signal. You may have to wire a manual T/R switch to enable the amp.

    On the other hand, the KXPA100 can do automatic band select based on the drive frequency, where the Hardrock 50 cannot. If you don't have a transceiver which supports Hardrock 50 auto band select, you have to do this manually.

    Elecraft made some effort to make the KXPA100 sort of a "generic" QRP amp, but it really shines when used with a KX3.

    (Of course, my bias may be showing... ;) )
    KU3X likes this.
  7. N9APE

    N9APE Ham Member QRZ Page

    Thanks to all. I'll have to give it some more thought. I was able, several month ago, to download a manual for the mcHF rig, so I'll browse through it and see which of the 2 options listed here would serve me best. To have knowledgeable hams such as yourselves helping resolve problems or point in directions where help is available is really appreciated.

    73 de N9APE, Dovid
  8. W1AJO

    W1AJO Ham Member QRZ Page

    Good advice here. I bought the Tokyo Hi-Power HL-50B 50watt amp BEFORE I bought my FT-817ND way back in 2004. It is rock solid. Since THP folded they are very hard to find. If you do come accros one, buy it!! KU3X is right, 50 watts vs 100 watts is a non-issue. My FT-840 is 100 watts but not much different than my FT-817 with the THP amp. Good QRP amp hunting!
    KU3X likes this.
  9. KW6LA

    KW6LA Ham Member QRZ Page

    Last edited: Aug 14, 2019
  10. AE5X

    AE5X Ham Member QRZ Page

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