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Zenith C730 Tube-Type AM/FM radio

Organist1982 found this radio for me near a dumpster. I replaced all capacitors, added a new silicon diode, fuse, and power cord.

Duration : 0:5:38


[youtube tqVLYY1HpRQ]

This entry was posted on Sunday, May 16th, 2010 at 5:35 am and is filed under radios fm. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

25 Responses to “Zenith C730 Tube-Type AM/FM radio”

  1. Great job. I just …
    Great job. I just got my Zenith 7C05 working last night. The only cap I plan on replacing is the dual power supply filter cap. My cabinet is in poor shape and I’m missing the inner-left knob, so I have to change FM-AM with long-nose pliers for now. Going to do away with the interlock, one pin is dangling anyway.
    The diode you put in is a Silicon, the one you took out is a Selenium. Did you measure plate voltages before & after the diode swap? Do you have a knob and/or schematic?

  2. coolbluelights on May 16th, 2010 at 5:35 am

    Thanks very much :) …
    Thanks very much :) I’m getting a 50s Zenith tabletop radio soon, I can’t wait to dig in and get it working again :D

  3. Another nice find! …
    Another nice find! Zenith radio rules!!

  4. I certainly can …
    I certainly can make a video on identifying it…
    The square metal type of rectifiers are actually selenium and they tend to go bad too (and I replace these with silicon plus a surge resistor). These were mostly used in the late 40’s through the late 50’s and very early 60’s. by the mid 60’s or so they were using silicon diodes as original equipment in most cases but these old silicon diodes tend to go bad too.

  5. coolbluelights on May 16th, 2010 at 5:35 am

    Ok, thanks :) have …
    Ok, thanks :) have you done a video on how to identify it? I think they’re some sort of square gray thing… I’m used to working on much older radios, never really worked on anything newer than 1945

  6. Yes I always …
    Yes I always replace them. I use a 1N4007 diode (1000 volt rated), they are real inexpensive.
    The old diodes seem to be more prone to shorting out.

  7. coolbluelights on May 16th, 2010 at 5:35 am

    do the silicon …
    do the silicon diodes always have to be replaced? are they prone to going bad?

  8. dfpolitowski2 on May 16th, 2010 at 5:35 am

    I also received two …
    I also received two of these units at around the same time you received yours in 1982. I had received two one with a convects cabinet the other like yours. They played real nice especially FM.

  9. HobieTyourtube on May 16th, 2010 at 5:35 am

    500 stations—— …
    500 stations——But none to listen to?
    Great old time technology!-But-nothing has changed?
    I know I am a cynic!!–BUT?
    Steve.

  10. i have a grundig fm …
    i have a grundig fm and bc radio model 98u do you no whats it is worth

  11. crusher19860138 on May 16th, 2010 at 5:35 am

    What is the AM …
    What is the AM coverage like,as i only heard the FM.

  12. do you know where i …
    do you know where i can get a good legible schematic? I want to replace the signal caps with some decent ones. also, do you know how to use the stereo output feature on the back?

  13. This is the Zenith …
    This is the Zenith radio I mentioned in another post that I have awaiting restoration with a wonky volume/tone control. I also was disappointed this radio didn’t have a dial lamp, I was thinking about putting a bit of electroluminescent tubing across the top of the dial.

  14. All Electronics has …
    All Electronics has 2 20 ohm thermistors for $1.
    So it won’t be too painful when they go up in maximum smoke. I’ll order some next month and let you know….73 Jo

  15. It probably …
    It probably wouldn’t hurt…I know that some tube type TV’s with series filaments did use a thermistor to reduce the surge currentat turn-on. Not sure what value would be best on a radio though.

  16. What do you think …
    What do you think of adding a MOV on the AC input on these old radios? Also perhaps a thermo-resistor in the filament series?

  17. Very nice. Sounds …
    Very nice. Sounds great (love tube audio) and looks great.

    Nice mod with the neon lamp!

  18. coondogtheman1234 on May 16th, 2010 at 5:35 am

    lol its ok i got a …
    lol its ok i got a little gangsta in me so i like this kind of music, does this radio have an aux input on it or no. i like that “right here right now” song the one that plays before the juvenile song

  19. I was reminded of …
    I was reminded of you when I found all that rap and hip hop music on this radio…no I guess I don’t know too much about it lol!

  20. coondogtheman1234 on May 16th, 2010 at 5:35 am

    lol retrochad 2:59 …
    lol retrochad 2:59 you prob dont listen to this kind of music, hip hop that song there was by juvenile and the song is back that thang up i listen to this music but i like other kinds too

  21. coondogtheman1234 on May 16th, 2010 at 5:35 am

    CassetteMaster …
    CassetteMaster these are my favorite kind of tube radios the ones that have tubes in them and AM and FM radio like speedy’s tube table radio from 1962 the one he got while he was in canada he had on here, tube sound on modern AM and FM broadcasts.

  22. CassetteMaster on May 16th, 2010 at 5:35 am

    Neat radio! Neat …
    Neat radio! Neat how you put on that neon light. Electrostatic tweeter? Cool! Vintage stereos and stuff like that are soo much coooler that today’s stuff!!

  23. CassetteMaster on May 16th, 2010 at 5:35 am

    Too bad I have no …
    Too bad I have no room in the house for big consoles! I see them lots of times and they sound FANTASTIC!

  24. Hammondlover2 on May 16th, 2010 at 5:35 am

    That’s nice! I have …
    That’s nice! I have the C725 which is similar, only it’s in a avocado green plastic cabinet.

  25. mylesgifford123 on May 16th, 2010 at 5:35 am

    nice i found mine …
    nice i found mine in the trash

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