Bert thanks so very much for the information on the use of the chokes.
Charles
On Sat, Aug 16, 2014 at 11:55 AM, Bert Hickman <bert@xxxxxxxxxxxxxxxxxxxxx>
wrote:
> Hi Charles,
>
> You have a high-power DC resonant charging reactor (or choke) most likely
> from a fairly large stationary or marine radar system. Bendix was a major
> manufacturer of radar equipment during, and after, the 2nd World War.
> Resonant charging reactors are part of a "line-type modulators". The
> charging reactor efficiently (re)charges the pulse forming network (PFN - a
> combination of inductors and capacitors that was designed to mimic a
> charged length of HV transmission line). The charged PFN is discharged into
> the primary of a step-down pulse transformer, using a spark gap or
> thyratron switch.
>
> The PFN and pulse transformer create a relatively square-shaped high-power
> pulse, typically several microseconds in duration, that powers an RF power
> oscillator tube (a magnetron or klystron). The power oscillator generates
> an approximately square-envelope pulse of microwave energy that is piped
> and transmitted through a highly-directional antenna to echo-locate distant
> objects.
>
> For more information, Google "Pulse Forming Network" or "Line Type
> Modulator". The high-current rating of your reactor would allow it to be
> used with a relatively large storage capacitor in a DC coil. The choke can
> handle a 0.1 uF tank capacitor, allowing you to handle ~25 kW of power at
> maximum break rate of about 480 PPS. Very nice find!
>
> Radar charging chokes appear to be relatively rare at Ham Fests or
> Teslathons. Over the last 25 years, I've only seen one. They tend to be
> real boat anchors - heavy, oil-filled metal-cased, with large asymmetrical
> insulators (a smaller Vdc input insulator and a larger 2X Vdc output
> insulator). For example, here is the one I have:
>
> http://www.capturedlightning.com/photos/Electrical/
> Inductors/Charging/IMG_2513.JPG
> http://www.capturedlightning.com/photos/Electrical/
> Inductors/Charging/IMG_2518.JPG
>
> The above oil-filled charging reactor is rated at 67.2H, 122 mA, 15 kV in,
> 30 kV out, at 192 Hz (or a maximum of 384 PPS). It weighs about 75 pounds.
> It was designed to be used with a PFN having a total line-ground
> capacitance of ~0.01 uF at 15 kV, delivering a bang size of about 4.5
> joules. Unfortunately, the maximum power (at maximum PPS) for a DC TC using
> this reactor would only be about 1700 watts.
>
> Hope this helped and best wishes,
>
> Bert
>
> charles rakes wrote:
>
>> I'm using a Bendix choke on my dc Tesla coil, that has the following
>> ratings, 4.8H, 5 ohms, 2 amps dc and a 17KV working voltage rating with
>> a
>> max of 35Kv . I'm guessing its weight at near 100 lbs or more. I've had
>> the choke for over 20 years and was wondering if anyone might know what
>> it's original use might have been? Are there anymore out there? tnx,
>> Charles
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>>
>>
>>
>
> --
> Bert Hickman
> Stoneridge Engineering
> http://www.capturedlightning.com
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