Portable Ham Radio Amplifier | DIY599 PA500

Hello Operators

As most of you know, off-grid ham radio is as much about reducing our current consumption, as it is about getting our signals out into the world. In a recent video, I discussed a change in station operating philosophy. I’ve switched over (gone back to) to QRP radios for their lower current consumption, versus their current hungry QRO desktop and mobile counterparts.

00:00 Intro
00:53 PA500 Background & Overview
02:33 New Portable Ham Radio Strategy
04:30 PA500 Detailed feature set
09:12 Field testing
12:09 Q&A
14:32 Final Thoughts

PA500 Home http://diy599.com
Groups.io: https://groups.io/g/diy599
FCC PA500 report: https://fcc.report/FCC-ID/2A2IEPA500

When the decision was made to move over to QRP radios as opposed to more current hungry mobile radios, there was already an understanding that a QRP based station would need to be augmented at times, with an amplifier. There were several amplifiers to choose from. One from Elecraft KXPA100, the Xiegu XPA100, the Hobby PCB Hardrock-50, and an unknown player called DIY599 offering the PA500.

Each of these amplifiers has pros and cons but the only one which had specs purpose built for field communications, was the PA500. The other offerings were designed for desktop use with a QRP radio at home. That’s not what I was looking for! Sometimes I believe the engineers designing these other amplifiers, don’t understand the needs or goals of the field radio operator. Nevertheless, here we are.

Ultimately I settled on the PA500 from DIY599. Here’s some context behind that decision. The Elecraft, Hardrock50 and Xiegu amplifiers are all quite large for field communications. Their size and weight make them perfect for operating a QRP radio at home, but a complete failure when it comes to deployment in the field. Moreover, the current consumption of these amps while idling was unacceptable. For the field radio operator trying to gain an edge without the cost of higher current consumption on receive, the amplifier with the lowest current consumption on RX would be the winner. In part, that’s why the PA500 was chosen.

Version 2.0 of the PA500 consumes about 50ma on receive. That’s an acceptable insertion loss when operating portable with radios like the Lab599 TX-500, Elecraft KXx, Icom IC-705, Xiegu X5105 or Yaesu FT-81x. These rigs all have ridiculously low current consumption, compared to the Yaesu FT-891 or Icom IC-7300 for example. When we are trying to power our Communications gear off grid, we want to measure our current consumption on receive in milliamps not amps.

Latest news

FCC Approval – Update from the Deck.

The FCC compliance measurements are done and we met all the FCC requirements.
Estimated start of delivery to US customers on waitlist will be around end of august.

the following features are already implemented or in progress 

✔ frequency measurement capability – done
✔ power measurement capability – done
✔ no amplification between 26-28MHz – done
✔ automatic band-filter selection based on measured frequency – done
✔ overdrive shutdown – done
— digital temperature reading of the system, with automatic high temperature shutdown option – in progress (SW will implement soon)


More Info

The best place for up-to-date information about the PA500 amplifier is there groups.io page: https://groups.io/g/diy599 here you can get all of your questions answered, and get the latest up-to-date and accurate information about PA500 amplifier.

Julian oh8stn
YouTube: http://www.youtube.com/c/oh8stn
TipJar: https://paypal.me/oh8stn/1usd

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    • I’ll contact him to see if I can get one here. I’ll definitely share it after that.
      Julian oh8stn

  1. I’ve seen this amplifier in several places, and each time it is presented as if this device can actually be purchased. But the DIY599 site doesn’t have a single hint of pricing, a shop link, a reference to distributors or resellers, etc. You say delivery may occur in August, and here we are in September, and still no hints where this vaporware can be purchased. You mention a waiting list, but where does one get on the waiting list?

    • Some of you people are amazing 😂
      I guess the Icom ic-705 was also vaporware, or the tx500 also vaporware or the ft-818 before it was released, that was vaporware too right?
      FCC approval happened in August. As it said in the video, they’re working on a North American distributor. If you’re in Europe, contact Oliver in the diy599 groups.io group as instructed in the video. Links in the video description.
      If this is really so urgent for you, why don’t you just buy in elecraft amplifier!?

  2. Julian, where can I buy a PA 500. I can’t seem to find where to purchase on group.io or lab599.

    Please advise.


    • Just ask this question on the diy599 groups.io page. If you’re in North America, you’re just adding your call sign to the waitlist. When North American distribution is sorted, you’ll get a notification.

  3. Julian, thank you for your articles, really enjoyable and informative. Could you give me an idea of the output power for the PA500 running at 12 volts? I realize it will change with drive levels. Does the amp need 16 volts to put out full power?

    • Hi Terry. Did you see the new article I just put up? It goes through the Thrive level versus output power at certain voltage.

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