[Amps] 500 uh plate choke

[Tom Thompson]

Rob,
The network is called a PI network because the shunt capacitors and 
series inductor resemble the Greek letter PI.
Tom   W0IVJ

On 1/21/2013 5:46 AM, Rob Atkinson wrote:
> That's a pi wound choke (I'd like to know why it is called that).  I
> usually see them in older ham AM rigs where the B+ is 1.5 KV or less
> and the Ip is no more than a few hundred ma.
>
> I am not saying it won't work in a modern RF power amp but all of the
> ones on the market today seem to use some sort of solenoidal wound
> choke.  Maybe that design is no longer manufactured in quantity?   I
> think they can't handle much more than 200 or 300 ma.
>
> I'd count the number of pi sections and look for a similar one at
> hamfests.  If you want something like 800 ma Ip and 3 KV Ep you are
> probably going to have to go with a solenoidal choke but I think you
> can achieve 500 uH with one.  Actually that RFC-4L choke is lower than
> I'd expect.  Most pi wound chokes I've seen are up over 1 mH, maybe
> even 2 1/2 mH.
>
> Rob
> K5UJ
>
> On Sat, Jan 19, 2013 at 1:44 PM, Vic, K2VCO<k2vco.vic at gmail.com>  wrote:
>> This site
>>
>> http://www.granta.g4axx.com/Linear_design_notes.php3
>>
>> mentions a 500 uh plate choke specified as RF Parts no. RFC-4L. They tested
>> it and report that it has no series resonances between 1 and 100 mHz! RF
>> parts doesn't list this choke anymore. I would like to obtain such a choke
>> -- does anyone know if it is manufactured and if so who sells it?
>>
>> Yes, it sounds too good to be true, but the site is very authoritative. They
>> mounted the choke in a box and used a vna to check it.
>>
>> --
>> Vic, K2VCO
>> Fresno CA
>> http://www.qsl.net/k2vco/
>>
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