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Old SBE Console II 23 channel, freq. expansion

Discussion in 'General CB Services Discussion' started by Titan7, Aug 27, 2018.

  1. Titan7

    Titan7 New Member

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    Hello, first post, I have 2 mint SBE radios I picked up about 10 years ago, both work fine. Was wondering if there is a way to get channels 24-40 or at least 35-40? I had this same radio as a teenager and it had a button on the rear that allowed more channels and had the clairifier opened. I can’t seem to find any techs that can do this work so perhaps this is just not possible anymore. Thanks


     
    Shadetree Mechanic likes this.

  2. nomadradio

    nomadradio Analog Retentive

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    This radio has one set of 6 crystals from 11.7 to 11.95 MHz. Each one is selected for four channels in a row. Removing one of them, and replacing it with a different crystal will change the four channels that one covered.

    Only.

    To simply pluck out one and get channels 36,37, 38 and 40, you need a crystal for 12.1 MHz to take the place of the one you removed.

    Just one detail. It has to be the right 12.1 MHz crystal. Not an easy find, most likely. Crystals are not all created equal. The marked frequency will only be right if that crystal is calibrated for the oscillator circuit you use.

    The reason it skips channel 39 is that the skipped "RC" channels are built into the other crystals. To get channel 39 you would need to put a switch on the 7.4825 crystal and add a 7.4925 crystal on the other side of that switch. This would provide a "plus ten" kHz switch that only works on channels 3,7,11,15, and 19.

    40 years ago when it was still kinda new, there were vendors who stocked those crystals, along with wacky setups to swap all six main crystals at once, giving the radio 23 new channels.

    The simpler solution is to hook an external VFO in place of one of those six 11 MHz crystals. Takes a VFO (slider) that puts out 11.7 MHz on channel 1.

    No easy ways to do this.

    73
     
    Dmans and Shadetree Mechanic like this.
  3. Titan7

    Titan7 New Member

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    Thanks, so I would have a better chance winning powerball than finding the correct crystal or VFO. Bummer, I guess I am 40+ years late to this party.

    Any suggestions on where to attempt to look would be appreciated.

    Thx
     
  4. TM86

    TM86 I fix what the snake breaks

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    Just a stray thought, could you use a DDS unit to supply the VFO signal?
     
  5. nomadradio

    nomadradio Analog Retentive

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    The Siltronix 80 and 90 VFOs were built in multiple versions, to suit different ranges of crystal frequency. The single suffix digit after the model number tells you which one it is. It will generally be stamped in black ink on the rear panel.

    The one that matches this radio best is the "1" version.

    Then again, finding a 40 year old VFO that doesn't have problems with drift or nervous twitch probably means finding one that has been restored.

    Maybe not so much restored, as 40-year maintenance.

    Then again, a unit that has been in a climate-controlled closet its whole life might work okay.

    For a while.

    Old stuff brings old problems. All of them can be remedied, but not for cheap.

    73
     
  6. nomadradio

    nomadradio Analog Retentive

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    Whups, cross posted.

    Yeah, this should be a job for a DDS I would think.

    Need to take a few weeks off and write the firmware to make it do this trick. It really should have LEDs for the display. All the off-the-shelf Fleabay boards to do this use LCDs. None of my customers like LCDs.

    They like LEDs.

    Won't be this week.

    73
     
  7. OldTech03

    OldTech03 Well-Known Member

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    You can mod most of those siltronix models they are essentially nothing but hartley osc. I think it's been a while since I installed one but I probably sold and or installed 1500 of those in the heydays and modified many simply by changing cap values. besides they probably need new caps anyway.
     
  8. Titan7

    Titan7 New Member

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    Well, thanks for the help, I will keep my eye out for the VFO 90-1.

    I guess the crystal swap will be impossible. Also, I can’t do this work, never worked on radios, also major issues finding shops that will work on the old radios. If this is going to be a waste of effort exercise for I will give up. I thought I could just get one these mint SBEs up and running on the upper Channels.
     
  9. nomadradio

    nomadradio Analog Retentive

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    At a minimum, we replace all electrolytic caps and swap a 78L08 3-terminal regulator for the original zener diode and resistor. Found that this helps a lot with stability.

    Never mind the maximum.

    [​IMG]

    73
     
    #9 nomadradio, Aug 28, 2018
    Last edited: Aug 28, 2018
    Shadetree Mechanic likes this.
  10. Titan7

    Titan7 New Member

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    I assume you are a radio tech? If so do you take mail in work as there is nobody in So.Cal who does this kind of work.
     
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  11. nomadradio

    nomadradio Analog Retentive

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    Nope, no mail-in work.

    No room for it. And if the place begins to empty out, I'll have to reconsider.

    73
     
  12. Titan7

    Titan7 New Member

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    Thx

    Well if anybody has recs for a tech please let me know otherwise I think it may be garage sale time or Craig’s List free ad, lol.
     
  13. nomadradio

    nomadradio Analog Retentive

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    Like finding a 1975 car under a tarp in a barn with 5000 original miles.

    It's not just the miles, it's the years, too.

    73
     
  14. Titan7

    Titan7 New Member

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    Okay found the 12.100 MHz crystals from Ken’s electronics, he had the one that will work with the SBE. Assume this is a simple act of pulling the 11.700mhz crystal which controls Ch.1-4 and replacing it with the 12.100mhz crystal?

    I took a look at my radios, appears I have the early version and later version. So, what’s the trick to getting that plastic cover off? It does not appear to move, I would hate to cut it open if there is a trick to doing this.

    Here are a couple photos. Note two different radios, one has two white wire really tight to the plastic cover.

    [​IMG]

    [​IMG]

    [​IMG]




    Thx
     
    #14 Titan7, Aug 28, 2018
    Last edited: Aug 29, 2018
    Shadetree Mechanic likes this.
  15. Radio Face

    Radio Face Active Member

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    Did you ever make any headway on this radio? Update?
     

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