It allows a lower tank Q so there is less retuning needed and the L takes
care of the higher harmonic content. Ameritron has been doing that since
their beginning.
Carl
KM1H
----- Original Message -----
From: "Vic K2VCO" <vic@rakefet.com>
To: <amps@contesting.com>
Sent: Wednesday, January 26, 2011 10:06 AM
Subject: Re: [Amps] Pi/L in Ameriton amps?
> It's common to use a pi-L only on the lower bands and a simple pi on the
> higher ones. This
> may be in order to use a smaller-sized output capacitor. Or perhaps
> additional harmonic
> suppression is necessary on the lower bands to meet FCC (etc.)
> regulations.
>
> On 1/26/2011 4:35 AM, Ulf (SM0NOR) wrote:
>> Yes, you are right.... I was confused because I thought it said "pi-l"
>> in the specs
>> sheet. But it doesn't.
>>
>> Still my question applies to the bigger amplifiers. For example the
>> specifications of
>> AL-1500 says "pi-l" but if you check the schematics, the third coil,
>> after C2, called
>> L4 is only tapped once!
>>
>>
>> 73's
>>
>> Ulf (SM0NOR) ulf@sm0nor.com
>>
>>
>>
>> On 26 jan 2011, at 13.16, Dave M wrote:
>>
>>>
>>> I hate the layout of the supplied schematic , but it is a standard Pi
>>> network not PiL
>>> the second coil is strictly for the higher freqs
>>>
>>>
>>> ......................................................................................................
>>>
>>>
>>>
> 73 VE3DV , Dave
>>>
>>>
>>>
>>>
>>>
>>>> From: ulf@sm0nor.com Date: Wed, 26 Jan 2011 13:04:07 +0100 To:
>>>> amps@contesting.com
>>>> Subject: [Amps] Pi/L in Ameriton amps?
>>>>
>>>> I'm helping a friend of mine who bought a damaged 811H. Transformer and
>>>> tubes where
>>>> gone. New transformer is on the way from Ameritron and tubes we found
>>>> locally. I
>>>> think we will have it up and running on no time! Now my question: is it
>>>> a pi/l tank
>>>> in this amp? The manual says so but the second coil has only two
>>>> tappings. Does it
>>>> mean that the high bands goes through the same inductance and the low
>>>> bands go
>>>> through the whole coil? What does it do for the intermediate
>>>> resistance? I noticed
>>>> all Ameritron amps are the same.
>
>
> --
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco/
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