Dan spots an extremely rare HRO-600 on eBay


SWLing Post contributor, Dan Robinson, writes:

Wow . . . a huge, amazing rarity…this is perhaps the rarest of radios, the HRO-600.

It is almost never seen on the used market and when it is, it is usually in non-operational condition. In its day it was quite advanced, though now, a Tecsun could run rings around it, and it uses NIXIE tubes…good luck obtaining those…anyway for anyone who has never seen one in this condition, and for everybody, here it is…

Click here to view on eBay.

Wow–I thought that receiver might sit on eBay for a while, but it sold for $3,895 US only moments after Dan spotted it.

Assuming this listing will eventually disappear from eBay, I downloaded a few more photos:

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I really enjoy tips like this from Dan.  While rare radios like the HRO 600 are well beyond my budget, it’s so much fun to learn about them. Indeed, I had no idea HRO made a receiver that used Nixie tubes!

What is a Nixie tube you ask? Per Wikipedia:

Nixie2“A Nixie tube, or cold cathode display, is an electronic device for displaying numerals or other information using glow discharge.

The glass tube contains a wire-mesh anode and multiple cathodes, shaped like numerals or other symbols. Applying power to one cathode surrounds it with an orange glow discharge. The tube is filled with a gas at low pressure, usually mostly neon and often a little mercury or argon, in a Penning mixture.

Although it resembles a vacuum tube in appearance, its operation does not depend on thermionic emission of electrons from a heated cathode. It is therefore called a cold-cathode tube (a form of gas-filled tube), or a variant of neon lamp. Such tubes rarely exceed 40 °C (104 °F) even under the most severe of operating conditions in a room at ambient temperature. Vacuum fluorescent displays from the same era use completely different technology—they have a heated cathode together with a control grid and shaped phosphor anodes; Nixies have no heater or control grid, typically a single anode, and shaped bare metal cathodes.”

As Dan states, Nixie tubes can be very difficult to source these days. I’m sure the radio collector that purchased this HRO 600 is well aware.

Update: While I don’t know what Nixie tubes the HRO-600 takes, Leeds Radio, has a substantial collection of Nixie tubes at reasonable prices. Click here to browse through the collection. Leeds, by the way, is a fantastic resource for pretty much any sort of tube/valve you may need. Check out this piece on Leeds Radio from WNYC.

I hope someone uploads a video of the HRO-600 in operation; I’ve never seen one in action.

Dan, thanks again for sharing your eBay finds!

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7 thoughts on “Dan spots an extremely rare HRO-600 on eBay

  1. Moshe Ze'ev Zaharia

    What a radio!
    I wouldn’t mind adding this one to my listening post!
    3895$! WOW!

    Best Regards,

  2. Alan Fahrnee

    And if my eyes don’t deceive me on this small smartphone screen, it sold for $3,895. Wow!

    Interesting post and great catch…

    My best,


    P.S. For that amount I wonder how many times you could buy all in-production Tecsun shortwave radios. 🙂

  3. Michael Black

    The HRO-500 got some coverage in the hobby magazines, it w as on the cover of Popular Electronics in 1964. But it was a solid state receiver when those weren’t yet common, and was maybe the first receiver to use a synthesizer to get signals every 500KHz (for the first conversion). And while it was expensive, it wasn’t super-expensive. I have no idea how many hobbyists, if any, bought one at the time, but every so often in the sixties it would show up in articles about receivers.

    This one, and I think there was also an HRO-600, never got the same attention. All I remember is seeing a photo and a brief blurb, in a quarterly put out by Popular Electronics, which covered the various hobby electronic areas (CB, ham radio, SWLing and scanners). But it was also a sort of product guide, listing available equipment in each field. So it was there, listed with every other SW receiver available, that I learned of this one, in the early seventies.

    The middle section, with the dial and readout, came out, and there were various modules to go in there, for various high level needs.

    And of course, it was an HRO, but without the HRO dial. Even the HRO-500 had the traditional dial (though it didn’t have plug-in coils, and did have accurate frequency readout.


    1. Thomas Post author

      Thanks for the comment, Michael. I had mistakenly labeled this as an HRO-660 instead of an HRO-600. I just updated the post with the correct info, so the 600 you referred to is this model.

      I’m curious how many HRO produced.

      I’ll have to check out the HRO-500. Thanks!

      1. Michael Black

        I was thinking the “hro-660” was an incremental change.

        Somme people have written about finding hro-600s, including having to do repairs. One site is
        where he talks about repairing the synthesizer. He says fewer than 200 were made. Thus perhaps they were made on demand. The receiver was a big step forward at the time, especially for solid state receivers, especially considering the design likely took some years.

        Yes, some of the functionality we now all have in really cheap receivers, but I think it was relatively top end. Lots of crystal filters, it could even receive both sidebands at the same time, though I’m not sure if that was standard or optional. There was some use of ssb where a transmitter would send something on the upper sideband and something else on the lower sideband. The first mixer beats what’s used in most portables now. But without receivers like this to show the path, we might not have all those cheap receivers now.


      2. Jrd

        I own a 600 and thinking of selling. Has not been energized in 40 years. Likely you will see it on the bay as i want it to be seen by many / international. This needs to go to serious collector/ restoration expert. I currently am evaluating logistics etc.
        Ontario Canada


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