External add-on PA for HF, suggestions wanted.

I’m considering getting an external HF PA for some SOTA expeditions. Something driven by 5W-10W or so ( so compatible with either my KX2 or IC-705 ) to boost the power to 30W-50W.

Apart from the MX P50 power amp and the Micro PA-50+ (which needs a few mods to bring its performance up to acceptable) are there any other such ready built amps on sale new? I know there is the Hardrock 50 but it’s not listed as available yet.

There are second hand items like the Tokyo Hy-power 50W unit. ( I had one and sold it, damn!) Anything else?

I have a Yaesu FL-110 which is a 100W amp when driven by 10W. But it’s thirsty and weighs over 2.5kg and seems to be made from used battleship armour plate. I don’t want to use up over 10% of my luggage allowance before I consider how to get enough batteries to power it on the plane!

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If you can get the latest version of the Micro PA-50+ most of the inital issues are gone.

I have just added a TRRS (4-pin 3,5mm plug) cable to trigger a MX P50 from the KX2 which worked fine as far as I can tell. I would still consider that as the goto regarding size/weight/features.

Other options I can think of Xiegu XPA125B but that is even heavier with 3.85 kg but is driven with 5W

The Neptune / 60dbn amp is from Ukraine as far as I can tell and looks interesting. But no experience

But let’s see if someone has other ideas


What were the issues with the Micro-PA 50+?

There is thread here in the reflector discussing the issue including improvement solutions:

But as far as I know new hardware / software version have this issue fixed.


I’ve always fancied one of these

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If the problems have been fixed the Micro PA50+ is on offer here:
New micro pa50+ (pa50 plus) 50w 3.5mhz-28.5mhz 1.3inch oled screen intelligent shortwave hf power amplifier swr meter lpf filter Sale - Banggood.com

73 Ed.

Thanks Ed, but I have a MX-P50 that is working fine :slight_smile:

Sorry - the reply was for Andy, Joe.
73 Ed.

Thanks Ed, I knew you’d know somewhere with a good price.

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The question is whether the problems have been fixed or not in this latest version.

There is also the RM Italy HLA 150… which is quite good if you don’t want to produce more than 100 watts with it.

But it also weighs just under 2 kg and is quite expensive.

73 Armin


And also this one:
JUMA PA-100D HF Linear Amplifier 100W | roWaves

100W and fairly lightweigth but not a bargain with 2.997,00 RON ( ~ 599,69 Euro )

@Ed: Here a comparison video in German: https://www.youtube.com/watch?v=CTYhsBc98qA

73 Joe

Adding to the list - there’s this one:

At the cheaper end of the scale - it says it is 3-30MHz - worrying is that it is sold as a CB amplifier though.
I wouldn’t believe those output power claims either and the input current is somewhat worrying.
73 Ed.

Chances are that there are no LP filters for the lower bands included in the design. That would be my guess…


In German shops the BJ300 is sold for 25 - 30 MHz… i.e. a CB power amplifier.

Like so many, it is of course overstated when it comes to its performance data… and it will work in C mode, which is ok for FM and CW… but not for SSB. In addition, it does not have a low-pass filter in the output.

73 Armin


Hey Andy

That is my power solution… :innocent:


MX - P 50 (with connection cable for KX2 PTT) … with the Eremit batteries approx. 25 - 40 watts

RM KL-203P with low pass filter and PTT control cable for KX2 (15 and 10m) only for CW … with the Eremit batteries approx. 80 watts

2 x Ermit 4Ah with cable for parallel connection

SWR meter

Coax connection cable

1:49 Unun for 80 watts… Endfed 40/20/15/10m

I don’t always take it (everything) with me… it depends on the summit…

73 Armin


Afternoon Andy
I use an MXP, or one of Virgils (K5OOR) HF packer amps.
They appear used occasionally, I use the version that has the removable LPF boards.
Pretty bomb proof and very clean, and with the copper heatsink (later versions) can run digital modes if needed.
There was talk a couple of years ago about a new updated design that covered 160-10m but not sure if it ever went on sale.

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For one minute there Armin I thought you were as crazy as me… then my linears are one for HF and one for 2m. The total load of 3.265kg with batteries is pretty impressive. You must use helium filled batteries. :wink:

Edit: just checked the nearest set up I have which is based on separate enclosures inside my back pack

MX-P50 HF linear in enclosure with PL259 to BNC adaptors 782g
2m Linear in enclosure 556g
PTT cable 40g
1:49 103g
40m EFHW and feeder 253g
2 x 4.2AH LiFePO4 batteries 1052g
DG Auto-ATU in enclosure 828g
Total 3614g

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I’ve got one of Virgil Stamps, K5OOR early HF Packer amps.

Unfortunately he’s had to close down his operation because of health issues (from his posts it sounds like he has dementia).

What there is online is available in the HFProjects group on groups.io

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Apart? What do you mean?
Mine works flawlessly with the IC-705 and modifications for 50 MHz (instead 3.6) are being conducted.