Old kit radio... Graymark 502 B Two Band Receiver

Discussion in 'General Technical Questions and Answers' started by KB1ZEC, Oct 2, 2017.

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  1. KB1ZEC

    KB1ZEC Ham Member QRZ Page

    My mother found an old kit radio in her mothers house when cleaning it out after she passed a number of years ago. She gave it to me and I finally opened the shoe box that its stored in (not the original box it came in). I believe it's complete with the parts, but hasn't been assembled at all. I have no idea how rare this is or even what it might be worth, but I don't want to take the chance of trying to assemble it as my "first" project with a soldering iron ever... Has anyone ever seen one of these or know anything about it? I've posted pics of the parts and the begining of the assembly manual (it looks like it was a teaching product at one point). I'll post more if someone wants to see more of the manual.

    Attached Files:

  2. KJ6ZOL

    KJ6ZOL Ham Member QRZ Page

    Looking closer at the introduction page of the manual, there is a date of 1964 in the bottom footer. From what I can discern of the schematic, it looks like a 5 tube, possibly a AA5 version, radio that has been slightly modified to receive some SW freqs in addition to AM BCB. Most likely SW rx capability is the several SW bands in the 10 Mhz area, such as the old 41m band, the 31m band, and a couple others above 10 Mhz. That range was popular to stick on many radios, especially cheap transistor portables, in the early 60s, mainly as an ad gimmick. I think Graymark made educational kits for high school and junior college electronics instruction in the 60s and 70s, a time when electronics was seen as vital to "beating the commies" and electronics classes were commonplace. The funny thing is, in China it's still common to teach kids basic electronics, the kits they use can be bought off ebay for a few bucks. The Chinese eat our lunch in technology now. I just wish Americans cared.
  3. W6ELH

    W6ELH Ham Member QRZ Page

    Well, you have more restraint than I could muster - I'd already have the soldering iron heating up!

    Really though, what do you have to lose in taking a stab at putting it together? If you choose to do so, don't install that "can" capacitor, nor those paper caps that I see. They're pretty likely to be dried out and non functional. Replacements are cheap and easy to get.

    If it's your first project, here's a suggestion. Google "Mr. Carlson's Lab Echophone." That's a nice tutorial on putting a 1940s receiver back into operating condition, and can tell you a great deal about paper and old electrolytic capacitors as well as about "hot chassis" transformerless sets.

    I hope you take on the project and enjoy yourself! Cheers... Jim W6ELH
    WA9UAA and W7UUU like this.
  4. W7UUU

    W7UUU Super Moderator Lifetime Member 133 Administrator Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    Seems the glory days of unbuilt kits has waned a lot on eBay. It might get $100 but who knows? Maybe much less. Was a time it'd get a LOT. But as John Lee Hooker aptly said, "Then days done packed and gone"

    I agree with post #3 - just build it!

    N7ANN likes this.
  5. KB1ZEC

    KB1ZEC Ham Member QRZ Page

    I wasn't asking from the stand point of seeing what I could get for it, I just didn't know how rare it was... I'll have to do some more research on it and thanks for the advice on the caps... They say you can't teach an old dog new tricks, so I guess I'm going to start looking at assembling a radio at 49!
  6. KS4W

    KS4W Ham Member QRZ Page

    OH MY GOSH!!!

    When I was in high school electronics class in 1973 everyone built that exact kit as a project. It was the first time I ever heard a ham radio transmission. All American Five death trap! Thank goodness for a few 75 M hams running AM or I might never have gotten a license.

    I remember having to drill the speaker holes on the front panel on the drill press in the corner of the shop.

    Thanks for the great jog of the memory!
  7. KJ6ZOL

    KJ6ZOL Ham Member QRZ Page

    Here's an idea: instead of using the OEM parts, get near-exact replacements from Mouser and Ebay, wind the coils yourself, and make yourself a semi-original version. :D:D I've been trying to get my hands on a copy of the manual for a Heathkit GR-21 which was a FM-only tube kit so I can do exactly this. And if you want to snail-mail me a photocopy of that manual, my email address on my QRZ page is good. :p:)
  8. KB1ZEC

    KB1ZEC Ham Member QRZ Page

    Well, there is a compelte parts list (attached image) and the schematic with complete instructions, maybe I'll start cobbling together the MODERN parts to assemble it... I can always keep the original as an example and not touch it... It shouldn't be too hard to replicate the base/face out of other materials and build the radio that way... I might have a challange finding the tubes though, we'll see... Heck, I like a challange, maybe that's why I went into IT as a career! :)

    Attached Files:

  9. K8JD

    K8JD Ham Member QRZ Page

    Short Wave AM Listening
    The short wave broadcast bands used to be packed with interesting programming from around the world, but the last decade has been run down by the easy access to the internet by most of the world. Today all that is left to hear on Short Wave are several evangelical preachers and a very few general interest programs from a few countries. If you know or are learning Spanish, French or Arabic there are a lot of programs in those languages still being broadcast.
    This is what you can easily hear if you build that kit and try it out.
    Last edited: Oct 2, 2017
  10. K8JD

    K8JD Ham Member QRZ Page

    About the only parts to replace, if you build the kit, would be the electrolytic capacitors, they dry out and fail after long un-use in storage.
    The remaining parts should be good as new.

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