PeKo Radio

    If you are the owner of a vintage piece of mobile radio equipment, chances are your equipment is equipped with a plug-in
    radio vibrator.  Such a mechanical vibrator allows for low-voltage DC coming from a vehicle battery to be converted to HT
    voltages as needed for tube radio equipment.
    Radio vibrators were used from the early 1930s up to about 1965. After that, DC to DC converters for mobile tube
    equipment were designed using the newly available semiconductors, first by using early germanium power transistors,
    later also silicon power transistors were used.
    This was done up to the 1980. After that, mobile radio equipment did not use tubes anymore which also eliminated the
    need for DC to DC converters.

    Examples of equipment in which radio vibrators were used:

    Consumer equipment:
    Car radios (6V or 12V)
    CB radios (6V or 12V)
    Early ham radios (6V or 12V)
    Some portable tube radios (mostly 2V)
    Vintage farm radios (48V)
    Specialty equipment like vintage camera flash, metal detectors and portable test equipment

    Commercial equipment:
  • Mobile radio telephones (6V, 12V or 24V)
  • Mobile public address amplifiers (6V, 12V or 24V)

    Military radio equipment:
  • HF transceivers  (6V, 12V or 24V)
  • VHF/UHF transceivers (6V, 12V or 24V)
  • Mobile & portable receivers (2V, 6V, 12V, 24V)
RVB-2 and Radio Vibrators
    As an owner of one or more examples of the above vintage equipment, chances are you have seen the equipment’s
    radio vibrator fail. These failure modes can have multiple causes.
    Mostly radio vibrators fail due to the vibrator contacts becoming dirty, corroded or burned-out. Less likely failure modes
    are mechanical failures (broken reed spring) and/or drive coil failures.

    One way to fix the contact failures is to open up the vibrator case after which the contacts can be cleaned using fine
    abrasive paper. (Mostly this case consists of an aluminum can crimped onto the bottom insulator holding the terminal
    Cleaning the vibrator contacts is only possible as long as the contacts have not worn away from excessive sparking; if the
    latter is the problem your vibrator is beyond fixing.  
    As you might have noticed after doing this, the contact cleaning job is never a lasting fix. The vibrator very soon will fail
    The reason is that most vibrators were filled with an inert gas by the manufacturer. After opening the case, the contacts
    will be exposed to oxygen from the air causing them to fail again very soon after contact cleaning. Another problem is that
    after sanding, the gap between the contacts becomes larger, resulting in a smaller duty cycle for the generated wave
    form as well as an increase in contact bounce (the latter causing additional sparking)
    So you will likely end up cleaning the contacts again soon, shortly after your first contact cleaning job. Buffing the
    contacts again using sandpaper can only be done so many times; the contacts will eventually have worn away too much,
    preventing proper operation.
    Many NOS (New Old Stock) vibrators can still be found offered for sale by surplus dealers.
    Maybe you have bought one of these, only to find out that such a NOS vibrator actually does not work!
    As it turns out, almost any vibrator will suffer corroded contacts over time, even when actually never having seen usage.
    As mentioned earlier, vibrators were not produced any more after 1965 which means that anything you find on the market
    today (either used or NOS) is over 50 years old.

    We have found that the cause of such failures involving NOS vibrators lies in the rubber seal that the vibrator has at its
    base, as well as the foamy rubber that is used to suspend the vibrating mechanics inside the cylindrical case.
    This rubber material has gassed out over the years releasing sulfur. This in its turn will corrode the silver vibrator
    contacts over time. (Keep in mind that the original designers had NEVER envisioned their radio vibrators to last for more
    than 50 years – they clearly did not have collectors of vintage equipment in mind when they designed their product!)
    As a result of all this, functioning radio vibrators are a dying-out breed; even the NOS ones that have been stocked in
    warehouses for all those years will most likely not work anymore.
    So of all the components in your vintage equipment, the radio vibrator is by far the weakest link. Radio tubes can still be
    found in abundance; capacitors can have their innards replaced with modern types to maintain their vintage looks. But
    the radio vibrators, that is an entirely different story.

    This is bad news of course. You own a nice piece of vintage equipment, maybe perfectly restored, but without means to
    keep it running anymore! What is a vintage radio aficionado to do to keep his or her vintage tube equipment running?
    The answer: Our PeKo RVB-2 solid-state radio vibrator board. This board was specially designed by us to replace a wide
    variety of radio vibrators, WITHOUT the need of any modifications to your vintage equipment. The RVB-2 solid-state
    vibrator board is designed to be a direct drop-in replacement to many different mechanical vibrators.

    This was accomplished by designing the RVB-2 solid-state vibrator such that it can replace a wide range of mechanical
    vibrators types, as well as allowing for a large operating voltage range (standard 5-30V with low voltage versions
    available for 2V to 6V and high voltage versions for 24 to 60V DC). It uses modern high-voltage, high-speed MOSFETs
    having a very low ON resistance, and as such it requires NO heat sink. Also, the board is small enough to fit in any
    existing vibrator can, even the narrow European types (Philips brand).
    Last but not least, the RVB-2 board emulates the exact same wave form as the mechanical vibrator; both in terms of duty-
    cycle (Off time during crossover) as well as operating frequency (115Hz and 100Hz are selectable).
    PeKo can do speciaized versions for different operating frequencies and/or duty cycle requirements, as all these
    parameters are programmable under firmware. Just let us know your requirements when ordering the RVB-2.
    The RVB-2 is the next generation model of our successful RVB-1 product.
    The nextgen RVB-2 comes as a family of products to serve your particular application to any need you might have.
    These RVB-2 models offer a number of additional features over our earlier RVB-1 model:

  • A 2 volt solid-state vibrator version is now available for equipment operating on a single 2 volt lead-acid battery
    (examples: BC-728 world-war II portable receiver; General Electric model 250 portable broadcast radio). The 2V model
    can be supplied for both positive ground as well as negative ground.
  • RVB-2 versions are now available for radio equipment using positive ground in addition to the versions for negative
  • An RVB-2 version is now available for 48V farm radios.
  • All RVB-2 versions are now reverse-polarity robust. If you make a reverse-polarity mistake on your vintage radio
    equipment, no harm will be done to the solid-state vibrator, so there is no need to add a crowbar protection diode
  • The RVB-2 board is slightly smaller (shorter) than the earlier RVB-1 model, to assure it will fit in any vintage vibrator
    housing (including the 2V vintage equipment).
  • The RVB-2 has an improved edge connector allowing you to plug it into a standard 6-pin connector in case you would
    like to connector-mount the RVB-2 instead of soldering (We can supply this 6-pin connector as an option).
  • The RVB-2 has a 0.5 second delay before it turns on. This is done to lower the load on your input power supply, to limit
    the inrush current caused by the tube filaments (which is high at initial turn-on). The half second delay from the RVB-2
    prevents a double-whammy on the input current.

    Of course, all the original RVB-1 features are still present in the nextgen RVB-2:

  • Standard model handles everything from 6V to 30V equipment, but can now also be supplied for positive ground radios.
  • Microprocessor controlled waveform shaping to emulate the exact same waveform as what the mechanical vibrator had.
  • Different frequencies can be supplied (microprocessor programmable). Standard supplied frequencies are 100Hz and
    115 Hz (jumper settable by user), custom frequencies can be supplied; anything between 50 Hz and 400 Hz according to
    your specification.
  • The RVB-2 has the same microprocessor-controlled AC detection function as the RVB-1.  This feature protects the RVB-2
    (and the equipment) for certain radio equipment where AC operation is possible while the vibrator is still in its socket
    connected to the transformer. As an example, Gonset equipment is notorious for this particular topology. The RVB-2 will
    detect the presence of external AC and will not turn on under these conditions, to not interfere with the AC function and
    to protect itself.
  • The RVB-2 can be supplied with an optional enable input. This feature is intended for certain vintage equipment where
    the vibrator is used to turn on the high voltage. In that particular vintage equipment, this was done by means of a series
    vibrator in which the vibrator coil is powered with an external switch signal. When replacing the mechanical vibrator with
    an RVB-2 in equipment like this, the on/off signal can be connected to the RVB-2’s enable input, which will make the RVB-
    2 act as the high-voltage on-off switch, just like the original vibrator did.
  • The RVB-2 is using the same high-quality FR-4 boards as the RVB-1.