It's a plate choke; the shunt caps are on one end; it's not an output network.
73
Rob
K5UJ
On Tue, Jan 22, 2013 at 4:35 PM, Tom Thompson <tlthompson@qwest.net> wrote:
> 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@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/
>>>
>>> _______________________________________________
>>> Amps mailing list
>>> Amps@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/amps
>>
>> _______________________________________________
>> Amps mailing list
>> Amps@contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>>
>
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|