Royal 51 and Royal 810

These powerful horizontal transistors were Zenith’s first small AM/FM transistor radios. Heavy and solid, they performed much like the 500H. As far as I can tell, these radios are the same and I don’t know why Zenith produced them under two different models? e r

18 thoughts on “Royal 51 and Royal 810”

  1. Hi Gary, I’m enjoying your site very much. Excellent pics and information!
    I have a model 51 and I agree it’s a wonderful radio. It performs like a champ and feels very solid! I found mine in a junk shop for $20…..junk shop?! It sure didn’t belong there as it’s far from junk in my books.

  2. Hi, Gary:

    Your site is fantastic!
    Do these sets share the same oval speaker that the Royal 400 and 500H have and do you know what the speaker output is?

  3. I have a model 810, works fine except you can’t control the volumn without the radio cutting out. Impossible to control the volumn. Is this something that you can repair.
    Thank you

    1. Hi Gary, this is a common problem that is caused either by a lack of use, or other times it can just be worn out from years of use. Try squirting some WD-40 underneath the volume knob and working it back-and-forth to see if that cleans up or improves the problem. If it is worn out that’s nothing I can help you with because parts are not available. Let me know what happens. Gary

    1. Hi Tom, yes, the 810 and twin 51 both have a tendency to develop spots along the volume path where it will lose contact and cut out. This can be caused by minor corrosion building up while in storage, but it can also happen from years of use and general wearing out. The radio will still work, but it just becomes somewhat “touchy” to get the volume where you want it. Hope this helps and thanks for looking. Gary

  4. Gary
    My father bought a model 51 when he was in Vietnam in 67-68. Could it be they just sold the model 51 overseas only? I know nothing about radios. This is just a thought. My dad just gave me the radio yesterday. Something is wrong with it and I would like to get it fixed for him but don’t know who or where to go. Any ideas? I live in the metro Detroit area.
    Thank you for any help.

    1. Hi Rob, I have had many a discussion with other radio collectors about the 51/810 models. No one seems to know for sure why Zenith did that, but as production shifted from the USA to Asia (Japan, Hong Kong, and TWawan), Zenith went from 3 digit Royal numbers to 2 digit numbers. But I believe both the 810 and 51 were produced in Chicago so who knows for sure. I would look at your radio for you if you wanted to pay for shipping both ways. Gary

      1. Gary
        Yes I would like you to look at the radio. Please send me a email with your information on where to ship it to.
        Thank you

  5. Gary,
    Great site, very easy to navigate! I came across a Zenith 810, but it is lacking a power cord. I know it should be a 6 volt, but is that AC or DC, and are there any other things I should be aware of regarding new adaptors for old electronics?
    Thank You,

    1. Hi Chris, glad you like my site. I am a big fan of the Royal 810 (and it’s twin the Royal 51). The power adaptor would be 6 volts DC. You can buy universal adaptors which have several plug sizes and voltage settings. However, with modern AA alkaline batteries, you can easily get over a year of high use out of one set of 4 AA’s so why spend the $10.00 + for an adaptor? Enjoy your nice radio. Gary

  6. The zenith royal 810 and royal 51 are much the same but do have some different capacitor values and the 51 uses a 12 ohm speaker.

    1. Also an ac to dc adapter rated at 6v 2500ma would be the equivalent of four 1.5aa batteries in series. The royal 51 uses sams photofact TSM-84 and the royal 810 uses sams TSM-72. A 2.5mm mono jack would need to be connected to the power adapter.

      1. Wonder what the reason was for the changes. Does this give one an advantage over the other or does it make a difference in the performance? Which one is more desirable then? Thanks again, Gary

  7. Hi Gary,
    I have a Royal 51, and when I was a kid, I got in the back with a screwdriver and turned all those slotted adjust-
    ments! Now years later, using the radio alot and it does not receive many stations. How to adjust the radio?

    1. Hi Jim, many have tried, and many have failed. You need to obtain the alignment procedure from a Zenith service manual and have lots of patience. Good luck.

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